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Import C bindings from NixOS/nix#8699

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Co-authored-by: Yorick van Pelt <yorick@yorickvanpelt.nl>
Co-authored-by: José Luis Lafuente <jose.lafuente@tweag.io>
Change-Id: I48aa262d880aa75aa5b230553f663c35c283d5f6
This commit is contained in:
puck 2024-03-17 16:29:09 +00:00
parent de17a2f0fa
commit e425a1d18d
19 changed files with 2679 additions and 0 deletions
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31
src/libexpr/c/meson.build Normal file
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pkg = import('pkgconfig')
libexprc_sources = files(
'nix_api_expr.cc',
'nix_api_external.cc',
'nix_api_value.cc',
)
all_sources += {
'libexprc': libexprc_sources
}
libexprc = library(
'nix-expr-c',
libexprc_sources,
dependencies : [
liblixutil,
liblixstore,
liblixexpr,
liblixutilc,
liblixstorec,
boehm,
],
)
pkg.generate(libexprc, requires: [ 'nix-store-c' ])
liblixexprc = declare_dependency(
include_directories : include_directories('.'),
link_with : libexprc,
)

178
src/libexpr/c/nix_api_expr.cc Normal file
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#include <cstring>
#include <iostream>
#include <stdexcept>
#include <string>
#include "config.hh"
#include "eval.hh"
#include "globals.hh"
#include "util.hh"
#include "nix_api_expr.h"
#include "nix_api_expr_internal.h"
#include "nix_api_store.h"
#include "nix_api_store_internal.h"
#include "nix_api_util.h"
#include "nix_api_util_internal.h"
#ifdef HAVE_BOEHMGC
#include <mutex>
#define GC_INCLUDE_NEW 1
#include "gc_cpp.h"
#endif
nix_err nix_libexpr_init(nix_c_context * context)
{
if (context)
context->last_err_code = NIX_OK;
{
auto ret = nix_libutil_init(context);
if (ret != NIX_OK)
return ret;
}
{
auto ret = nix_libstore_init(context);
if (ret != NIX_OK)
return ret;
}
try {
nix::initGC();
}
NIXC_CATCH_ERRS
}
nix_err nix_expr_eval_from_string(
nix_c_context * context, EvalState * state, const char * expr, const char * path, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::Expr * parsedExpr = state->state.parseExprFromString(expr, state->state.rootPath(nix::CanonPath(path)));
state->state.eval(parsedExpr, *(nix::Value *) value);
state->state.forceValue(*(nix::Value *) value, nix::noPos);
}
NIXC_CATCH_ERRS
}
nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, Value * arg, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
state->state.callFunction(*(nix::Value *) fn, *(nix::Value *) arg, *(nix::Value *) value, nix::noPos);
state->state.forceValue(*(nix::Value *) value, nix::noPos);
}
NIXC_CATCH_ERRS
}
nix_err nix_value_force(nix_c_context * context, EvalState * state, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
state->state.forceValue(*(nix::Value *) value, nix::noPos);
}
NIXC_CATCH_ERRS
}
nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
state->state.forceValueDeep(*(nix::Value *) value);
}
NIXC_CATCH_ERRS
}
EvalState * nix_state_create(nix_c_context * context, const char ** searchPath_c, Store * store)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::Strings searchPath;
if (searchPath_c != nullptr)
for (size_t i = 0; searchPath_c[i] != nullptr; i++)
searchPath.push_back(searchPath_c[i]);
return new EvalState{nix::EvalState(nix::SearchPath::parse(searchPath), store->ptr)};
}
NIXC_CATCH_ERRS_NULL
}
void nix_state_free(EvalState * state)
{
delete state;
}
#ifdef HAVE_BOEHMGC
std::unordered_map<
const void *,
unsigned int,
std::hash<const void *>,
std::equal_to<const void *>,
traceable_allocator<std::pair<const void * const, unsigned int>>>
nix_refcounts;
std::mutex nix_refcount_lock;
nix_err nix_gc_incref(nix_c_context * context, const void * p)
{
if (context)
context->last_err_code = NIX_OK;
try {
std::scoped_lock lock(nix_refcount_lock);
auto f = nix_refcounts.find(p);
if (f != nix_refcounts.end()) {
f->second++;
} else {
nix_refcounts[p] = 1;
}
}
NIXC_CATCH_ERRS
}
nix_err nix_gc_decref(nix_c_context * context, const void * p)
{
if (context)
context->last_err_code = NIX_OK;
try {
std::scoped_lock lock(nix_refcount_lock);
auto f = nix_refcounts.find(p);
if (f != nix_refcounts.end()) {
if (--f->second == 0)
nix_refcounts.erase(f);
} else
throw std::runtime_error("nix_gc_decref: object was not referenced");
}
NIXC_CATCH_ERRS
}
void nix_gc_now()
{
GC_gcollect();
}
#else
void nix_gc_incref(nix_c_context * context, const void *)
{
if (context)
context->last_err_code = NIX_OK;
return NIX_OK;
}
void nix_gc_decref(nix_c_context * context, const void *)
{
if (context)
context->last_err_code = NIX_OK;
return NIX_OK;
}
void nix_gc_now() {}
#endif
void nix_gc_register_finalizer(void * obj, void * cd, void (*finalizer)(void * obj, void * cd))
{
#ifdef HAVE_BOEHMGC
GC_REGISTER_FINALIZER(obj, finalizer, cd, 0, 0);
#endif
}

213
src/libexpr/c/nix_api_expr.h Normal file
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#ifndef NIX_API_EXPR_H
#define NIX_API_EXPR_H
/** @defgroup libexpr libexpr
* @brief Bindings to the Nix language evaluator
*
* Example (without error handling):
* @code{.c}
* int main() {
* nix_libexpr_init(NULL);
*
* Store* store = nix_store_open(NULL, "dummy", NULL);
* EvalState* state = nix_state_create(NULL, NULL, store); // empty nix path
* Value *value = nix_alloc_value(NULL, state);
*
* nix_expr_eval_from_string(NULL, state, "builtins.nixVersion", ".", value);
* nix_value_force(NULL, state, value);
* printf("nix version: %s\n", nix_get_string(NULL, value));
*
* nix_gc_decref(NULL, value);
* nix_state_free(state);
* nix_store_free(store);
* return 0;
* }
* @endcode
* @{
*/
/** @file
* @brief Main entry for the libexpr C bindings
*/
#include "nix_api_store.h"
#include "nix_api_util.h"
#ifdef __cplusplus
extern "C" {
#endif
// cffi start
// Type definitions
/**
* @brief Represents a state of the Nix language evaluator.
*
* Multiple states can be created for multi-threaded
* operation.
* @struct EvalState
* @see nix_state_create
*/
typedef struct EvalState EvalState; // nix::EvalState
/**
* @brief Represents a value in the Nix language.
*
* Owned by the garbage collector.
* @struct Value
* @see value_manip
*/
typedef void Value; // nix::Value
// Function prototypes
/**
* @brief Initialize the Nix language evaluator.
*
* This function must be called at least once,
* at some point before constructing a EvalState for the first time.
* This function can be called multiple times, and is idempotent.
*
* @param[out] context Optional, stores error information
* @return NIX_OK if the initialization was successful, an error code otherwise.
*/
nix_err nix_libexpr_init(nix_c_context * context);
/**
* @brief Parses and evaluates a Nix expression from a string.
*
* @param[out] context Optional, stores error information
* @param[in] state The state of the evaluation.
* @param[in] expr The Nix expression to parse.
* @param[in] path The file path to associate with the expression.
* This is required for expressions that contain relative paths (such as `./.`) that are resolved relative to the given
* directory.
* @param[out] value The result of the evaluation. You must allocate this
* yourself.
* @return NIX_OK if the evaluation was successful, an error code otherwise.
*/
nix_err nix_expr_eval_from_string(
nix_c_context * context, EvalState * state, const char * expr, const char * path, Value * value);
/**
* @brief Calls a Nix function with an argument.
*
* @param[out] context Optional, stores error information
* @param[in] state The state of the evaluation.
* @param[in] fn The Nix function to call.
* @param[in] arg The argument to pass to the function.
* @param[out] value The result of the function call.
* @return NIX_OK if the function call was successful, an error code otherwise.
*/
nix_err nix_value_call(nix_c_context * context, EvalState * state, Value * fn, Value * arg, Value * value);
/**
* @brief Forces the evaluation of a Nix value.
*
* The Nix interpreter is lazy, and not-yet-evaluated Values can be
* of type NIX_TYPE_THUNK instead of their actual value.
*
* This function converts these Values into their final type.
*
* @note You don't need this function for basic API usage, since all functions
* that return a value call it for you. The only place you will see a
* NIX_TYPE_THUNK is in the arguments that are passed to a PrimOp function
* you supplied to nix_alloc_primop.
*
* @param[out] context Optional, stores error information
* @param[in] state The state of the evaluation.
* @param[in,out] value The Nix value to force.
* @post value is not of type NIX_TYPE_THUNK
* @return NIX_OK if the force operation was successful, an error code
* otherwise.
*/
nix_err nix_value_force(nix_c_context * context, EvalState * state, Value * value);
/**
* @brief Forces the deep evaluation of a Nix value.
*
* Recursively calls nix_value_force
*
* @see nix_value_force
* @warning Calling this function on a recursive data structure will cause a
* stack overflow.
* @param[out] context Optional, stores error information
* @param[in] state The state of the evaluation.
* @param[in,out] value The Nix value to force.
* @return NIX_OK if the deep force operation was successful, an error code
* otherwise.
*/
nix_err nix_value_force_deep(nix_c_context * context, EvalState * state, Value * value);
/**
* @brief Create a new Nix language evaluator state.
*
* @param[out] context Optional, stores error information
* @param[in] searchPath Array of strings corresponding to entries in NIX_PATH.
* @param[in] store The Nix store to use.
* @return A new Nix state or NULL on failure.
*/
EvalState * nix_state_create(nix_c_context * context, const char ** searchPath, Store * store);
/**
* @brief Frees a Nix state.
*
* Does not fail.
*
* @param[in] state The state to free.
*/
void nix_state_free(EvalState * state);
/** @addtogroup GC
* @brief Reference counting and garbage collector operations
*
* The Nix language evaluator uses a garbage collector. To ease C interop, we implement
* a reference counting scheme, where objects will be deallocated
* when there are no references from the Nix side, and the reference count kept
* by the C API reaches `0`.
*
* Functions returning a garbage-collected object will automatically increase
* the refcount for you. You should make sure to call `nix_gc_decref` when
* you're done with a value returned by the evaluator.
* @{
*/
/**
* @brief Increment the garbage collector reference counter for the given object.
*
* The Nix language evaluator C API keeps track of alive objects by reference counting.
* When you're done with a refcounted pointer, call nix_gc_decref().
*
* @param[out] context Optional, stores error information
* @param[in] object The object to keep alive
*/
nix_err nix_gc_incref(nix_c_context * context, const void * object);
/**
* @brief Decrement the garbage collector reference counter for the given object
*
* @param[out] context Optional, stores error information
* @param[in] object The object to stop referencing
*/
nix_err nix_gc_decref(nix_c_context * context, const void * object);
/**
* @brief Trigger the garbage collector manually
*
* You should not need to do this, but it can be useful for debugging.
*/
void nix_gc_now();
/**
* @brief Register a callback that gets called when the object is garbage
* collected.
* @note Objects can only have a single finalizer. This function overwrites existing values
* silently.
* @param[in] obj the object to watch
* @param[in] cd the data to pass to the finalizer
* @param[in] finalizer the callback function, called with obj and cd
*/
void nix_gc_register_finalizer(void * obj, void * cd, void (*finalizer)(void * obj, void * cd));
/** @} */
// cffi end
#ifdef __cplusplus
}
#endif
/** @} */
#endif // NIX_API_EXPR_H

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src/libexpr/c/nix_api_expr_internal.h Normal file
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#ifndef NIX_API_EXPR_INTERNAL_H
#define NIX_API_EXPR_INTERNAL_H
#include "eval.hh"
#include "attr-set.hh"
#include "nix_api_value.h"
class CListBuilder
{
private:
std::vector<nix::Value *> values;
public:
CListBuilder(size_t capacity)
{
values.reserve(capacity);
}
void push_back(nix::Value * value)
{
values.push_back(value);
}
Value * finish(nix::EvalState * state, nix::Value * list)
{
state->mkList(*list, values.size());
for (size_t n = 0; n < list->listSize(); ++n) {
list->listElems()[n] = values[n];
}
return list;
}
};
struct EvalState
{
nix::EvalState state;
};
struct BindingsBuilder
{
nix::BindingsBuilder builder;
};
struct ListBuilder
{
CListBuilder builder;
};
struct nix_string_return
{
std::string str;
};
struct nix_printer
{
std::ostream & s;
};
struct nix_string_context
{
nix::NixStringContext & ctx;
};
#endif // NIX_API_EXPR_INTERNAL_H

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#include "attr-set.hh"
#include "config.hh"
#include "eval.hh"
#include "gc/gc.h"
#include "globals.hh"
#include "value.hh"
#include "nix_api_expr.h"
#include "nix_api_expr_internal.h"
#include "nix_api_external.h"
#include "nix_api_util.h"
#include "nix_api_util_internal.h"
#include "nix_api_value.h"
#include "value/context.hh"
#include <nlohmann/json.hpp>
#ifdef HAVE_BOEHMGC
#define GC_INCLUDE_NEW 1
#include "gc_cpp.h"
#endif
void nix_set_string_return(nix_string_return * str, const char * c)
{
str->str = c;
}
nix_err nix_external_print(nix_c_context * context, nix_printer * printer, const char * c)
{
if (context)
context->last_err_code = NIX_OK;
try {
printer->s << c;
}
NIXC_CATCH_ERRS
}
nix_err nix_external_add_string_context(nix_c_context * context, nix_string_context * ctx, const char * c)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto r = nix::NixStringContextElem::parse(c);
ctx->ctx.insert(r);
}
NIXC_CATCH_ERRS
}
class NixCExternalValue : public nix::ExternalValueBase
{
NixCExternalValueDesc & desc;
void * v;
public:
NixCExternalValue(NixCExternalValueDesc & desc, void * v)
: desc(desc)
, v(v){};
void * get_ptr()
{
return v;
}
/**
* Print out the value
*/
virtual std::ostream & print(std::ostream & str) const override
{
nix_printer p{str};
desc.print(v, &p);
return str;
}
/**
* Return a simple string describing the type
*/
virtual std::string showType() const override
{
nix_string_return res;
desc.showType(v, &res);
return std::move(res.str);
}
/**
* Return a string to be used in builtins.typeOf
*/
virtual std::string typeOf() const override
{
nix_string_return res;
desc.typeOf(v, &res);
return std::move(res.str);
}
/**
* Coerce the value to a string.
*/
virtual std::string coerceToString(
nix::EvalState & state,
const nix::PosIdx & pos,
nix::NixStringContext & context,
bool copyMore,
bool copyToStore) const override
{
if (!desc.coerceToString) {
return nix::ExternalValueBase::coerceToString(state, pos, context, copyMore, copyToStore);
}
nix_string_context ctx{context};
nix_string_return res{""};
// todo: pos, errors
desc.coerceToString(v, &ctx, copyMore, copyToStore, &res);
if (res.str.empty()) {
return nix::ExternalValueBase::coerceToString(state, pos, context, copyMore, copyToStore);
}
return std::move(res.str);
}
/**
* Compare to another value of the same type.
*/
virtual bool operator==(const ExternalValueBase & b) const override
{
if (!desc.equal) {
return false;
}
auto r = dynamic_cast<const NixCExternalValue *>(&b);
if (!r)
return false;
return desc.equal(v, r->v);
}
/**
* Print the value as JSON.
*/
virtual nlohmann::json printValueAsJSON(
nix::EvalState & state, bool strict, nix::NixStringContext & context, bool copyToStore = true) const override
{
if (!desc.printValueAsJSON) {
return nix::ExternalValueBase::printValueAsJSON(state, strict, context, copyToStore);
}
nix_string_context ctx{context};
nix_string_return res{""};
desc.printValueAsJSON(v, (EvalState *) &state, strict, &ctx, copyToStore, &res);
if (res.str.empty()) {
return nix::ExternalValueBase::printValueAsJSON(state, strict, context, copyToStore);
}
return nlohmann::json::parse(res.str);
}
/**
* Print the value as XML.
*/
virtual void printValueAsXML(
nix::EvalState & state,
bool strict,
bool location,
nix::XMLWriter & doc,
nix::NixStringContext & context,
nix::PathSet & drvsSeen,
const nix::PosIdx pos) const override
{
if (!desc.printValueAsXML) {
return nix::ExternalValueBase::printValueAsXML(state, strict, location, doc, context, drvsSeen, pos);
}
nix_string_context ctx{context};
desc.printValueAsXML(
v, (EvalState *) &state, strict, location, &doc, &ctx, &drvsSeen,
*reinterpret_cast<const uint32_t *>(&pos));
}
virtual ~NixCExternalValue() override{};
};
ExternalValue * nix_create_external_value(nix_c_context * context, NixCExternalValueDesc * desc, void * v)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto ret = new
#ifdef HAVE_BOEHMGC
(GC)
#endif
NixCExternalValue(*desc, v);
nix_gc_incref(nullptr, ret);
return (ExternalValue *) ret;
}
NIXC_CATCH_ERRS_NULL
}
void * nix_get_external_value_content(nix_c_context * context, ExternalValue * b)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto r = dynamic_cast<NixCExternalValue *>((nix::ExternalValueBase *) b);
if (r)
return r->get_ptr();
return nullptr;
}
NIXC_CATCH_ERRS_NULL
}

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#ifndef NIX_API_EXTERNAL_H
#define NIX_API_EXTERNAL_H
/** @ingroup libexpr
* @addtogroup Externals
* @brief Deal with external values
* @{
*/
/** @file
* @brief libexpr C bindings dealing with external values
*/
#include "nix_api_expr.h"
#include "nix_api_util.h"
#include "nix_api_value.h"
#include "stdbool.h"
#include "stddef.h"
#include "stdint.h"
#ifdef __cplusplus
extern "C" {
#endif
// cffi start
/**
* @brief Represents a string owned by the Nix language evaluator.
* @see nix_set_owned_string
*/
typedef struct nix_string_return nix_string_return;
/**
* @brief Wraps a stream that can output multiple string pieces.
*/
typedef struct nix_printer nix_printer;
/**
* @brief A list of string context items
*/
typedef struct nix_string_context nix_string_context;
/**
* @brief Sets the contents of a nix_string_return
*
* Copies the passed string.
* @param[out] str the nix_string_return to write to
* @param[in] c The string to copy
*/
void nix_set_string_return(nix_string_return * str, const char * c);
/**
* Print to the nix_printer
*
* @param[out] context Optional, stores error information
* @param printer The nix_printer to print to
* @param[in] str The string to print
* @returns NIX_OK if everything worked
*/
nix_err nix_external_print(nix_c_context * context, nix_printer * printer, const char * str);
/**
* Add string context to the nix_string_context object
* @param[out] context Optional, stores error information
* @param[out] string_context The nix_string_context to add to
* @param[in] c The context string to add
* @returns NIX_OK if everything worked
*/
nix_err nix_external_add_string_context(nix_c_context * context, nix_string_context * string_context, const char * c);
/**
* @brief Definition for a class of external values
*
* Create and implement one of these, then pass it to nix_create_external_value
* Make sure to keep it alive while the external value lives.
*
* Optional functions can be set to NULL
*
* @see nix_create_external_value
*/
typedef struct NixCExternalValueDesc
{
/**
* @brief Called when printing the external value
*
* @param[in] self the void* passed to nix_create_external_value
* @param[out] printer The printer to print to, pass to nix_external_print
*/
void (*print)(void * self, nix_printer * printer);
/**
* @brief Called on :t
* @param[in] self the void* passed to nix_create_external_value
* @param[out] res the return value
*/
void (*showType)(void * self, nix_string_return * res);
/**
* @brief Called on `builtins.typeOf`
* @param self the void* passed to nix_create_external_value
* @param[out] res the return value
*/
void (*typeOf)(void * self, nix_string_return * res);
/**
* @brief Called on "${str}" and builtins.toString.
*
* The latter with coerceMore=true
* Optional, the default is to throw an error.
* @param[in] self the void* passed to nix_create_external_value
* @param[out] c writable string context for the resulting string
* @param[in] coerceMore boolean, try to coerce to strings in more cases
* instead of throwing an error
* @param[in] copyToStore boolean, whether to copy referenced paths to store
* or keep them as-is
* @param[out] res the return value. Not touching this, or setting it to the
* empty string, will make the conversion throw an error.
*/
void (*coerceToString)(
void * self, nix_string_context * c, int coerceMore, int copyToStore, nix_string_return * res);
/**
* @brief Try to compare two external values
*
* Optional, the default is always false.
* If the other object was not a Nix C external value, this comparison will
* also return false
* @param[in] self the void* passed to nix_create_external_value
* @param[in] other the void* passed to the other object's
* nix_create_external_value
* @returns true if the objects are deemed to be equal
*/
int (*equal)(void * self, void * other);
/**
* @brief Convert the external value to json
*
* Optional, the default is to throw an error
* @param[in] self the void* passed to nix_create_external_value
* @param[in] state The evaluator state
* @param[in] strict boolean Whether to force the value before printing
* @param[out] c writable string context for the resulting string
* @param[in] copyToStore whether to copy referenced paths to store or keep
* them as-is
* @param[out] res the return value. Gets parsed as JSON. Not touching this,
* or setting it to the empty string, will make the conversion throw an error.
*/
void (*printValueAsJSON)(
void * self, EvalState *, bool strict, nix_string_context * c, bool copyToStore, nix_string_return * res);
/**
* @brief Convert the external value to XML
*
* Optional, the default is to throw an error
* @todo The mechanisms for this call are incomplete. There are no C
* bindings to work with XML, pathsets and positions.
* @param[in] self the void* passed to nix_create_external_value
* @param[in] state The evaluator state
* @param[in] strict boolean Whether to force the value before printing
* @param[in] location boolean Whether to include position information in the
* xml
* @param[out] doc XML document to output to
* @param[out] c writable string context for the resulting string
* @param[in,out] drvsSeen a path set to avoid duplicating derivations
* @param[in] pos The position of the call.
*/
void (*printValueAsXML)(
void * self,
EvalState *,
int strict,
int location,
void * doc,
nix_string_context * c,
void * drvsSeen,
int pos);
} NixCExternalValueDesc;
/**
* @brief Create an external value, that can be given to nix_init_external
*
* Owned by the GC. Use nix_gc_decref when you're done with the pointer.
*
* @param[out] context Optional, stores error information
* @param[in] desc a NixCExternalValueDesc, you should keep this alive as long
* as the ExternalValue lives
* @param[in] v the value to store
* @returns external value, owned by the garbage collector
* @see nix_init_external
*/
ExternalValue * nix_create_external_value(nix_c_context * context, NixCExternalValueDesc * desc, void * v);
/**
* @brief Extract the pointer from a nix c external value.
* @param[out] context Optional, stores error information
* @param[in] b The external value
* @returns The pointer, or null if the external value was not from nix c.
* @see nix_get_external
*/
void * nix_get_external_value_content(nix_c_context * context, ExternalValue * b);
// cffi end
#ifdef __cplusplus
}
#endif
/** @} */
#endif // NIX_API_EXTERNAL_H

521
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@ -0,0 +1,521 @@
#include "attr-set.hh"
#include "config.hh"
#include "eval.hh"
#include "gc/gc.h"
#include "globals.hh"
#include "primops.hh"
#include "value.hh"
#include "nix_api_expr.h"
#include "nix_api_expr_internal.h"
#include "nix_api_util.h"
#include "nix_api_util_internal.h"
#include "nix_api_value.h"
#ifdef HAVE_BOEHMGC
#define GC_INCLUDE_NEW 1
#include "gc_cpp.h"
#endif
// Helper function to throw an exception if value is null
static const nix::Value & check_value_not_null(const Value * value)
{
if (!value) {
throw std::runtime_error("Value is null");
}
return *((const nix::Value *) value);
}
static nix::Value & check_value_not_null(Value * value)
{
if (!value) {
throw std::runtime_error("Value is null");
}
return *((nix::Value *) value);
}
/**
* Helper function to convert calls from nix into C API.
*
* Deals with errors and converts arguments from C++ into C types.
*/
static void nix_c_primop_wrapper(
PrimOpFun f, void * userdata, nix::EvalState & state, const nix::PosIdx pos, nix::Value ** args, nix::Value & v)
{
nix_c_context ctx;
f(userdata, &ctx, (EvalState *) &state, (Value **) args, (Value *) &v);
/* TODO: In the future, this should throw different errors depending on the error code */
if (ctx.last_err_code != NIX_OK)
state.error<nix::EvalError>("Error from builtin function: %s", *ctx.last_err).atPos(pos).debugThrow();
}
PrimOp * nix_alloc_primop(
nix_c_context * context,
PrimOpFun fun,
int arity,
const char * name,
const char ** args,
const char * doc,
void * user_data)
{
if (context)
context->last_err_code = NIX_OK;
try {
using namespace std::placeholders;
auto p = new
#ifdef HAVE_BOEHMGC
(GC)
#endif
nix::PrimOp{
.name = name,
.args = {},
.arity = (size_t) arity,
.doc = doc,
.fun = std::bind(nix_c_primop_wrapper, fun, user_data, _1, _2, _3, _4)};
if (args)
for (size_t i = 0; args[i]; i++)
p->args.emplace_back(*args);
nix_gc_incref(nullptr, p);
return (PrimOp *) p;
}
NIXC_CATCH_ERRS_NULL
}
nix_err nix_register_primop(nix_c_context * context, PrimOp * primOp)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::RegisterPrimOp r(std::move(*((nix::PrimOp *) primOp)));
}
NIXC_CATCH_ERRS
}
Value * nix_alloc_value(nix_c_context * context, EvalState * state)
{
if (context)
context->last_err_code = NIX_OK;
try {
Value * res = state->state.allocValue();
nix_gc_incref(nullptr, res);
return res;
}
NIXC_CATCH_ERRS_NULL
}
ValueType nix_get_type(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
using namespace nix;
switch (v.type()) {
case nThunk:
return NIX_TYPE_THUNK;
case nInt:
return NIX_TYPE_INT;
case nFloat:
return NIX_TYPE_FLOAT;
case nBool:
return NIX_TYPE_BOOL;
case nString:
return NIX_TYPE_STRING;
case nPath:
return NIX_TYPE_PATH;
case nNull:
return NIX_TYPE_NULL;
case nAttrs:
return NIX_TYPE_ATTRS;
case nList:
return NIX_TYPE_LIST;
case nFunction:
return NIX_TYPE_FUNCTION;
case nExternal:
return NIX_TYPE_EXTERNAL;
}
return NIX_TYPE_NULL;
}
NIXC_CATCH_ERRS_RES(NIX_TYPE_NULL);
}
const char * nix_get_typename(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
auto s = nix::showType(v);
return strdup(s.c_str());
}
NIXC_CATCH_ERRS_NULL
}
bool nix_get_bool(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nBool);
return v.boolean;
}
NIXC_CATCH_ERRS_RES(false);
}
const char * nix_get_string(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nString);
return v.string.s;
}
NIXC_CATCH_ERRS_NULL
}
const char * nix_get_path_string(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nPath);
return v._path;
}
NIXC_CATCH_ERRS_NULL
}
unsigned int nix_get_list_size(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nList);
return v.listSize();
}
NIXC_CATCH_ERRS_RES(0);
}
unsigned int nix_get_attrs_size(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nAttrs);
return v.attrs->size();
}
NIXC_CATCH_ERRS_RES(0);
}
double nix_get_float(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nFloat);
return v.fpoint;
}
NIXC_CATCH_ERRS_RES(NAN);
}
int64_t nix_get_int(nix_c_context * context, const Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nInt);
return v.integer;
}
NIXC_CATCH_ERRS_RES(0);
}
ExternalValue * nix_get_external(nix_c_context * context, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nExternal);
return (ExternalValue *) v.external;
}
NIXC_CATCH_ERRS_NULL;
}
Value * nix_get_list_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int ix)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nList);
auto * p = v.listElems()[ix];
nix_gc_incref(nullptr, p);
state->state.forceValue(*p, nix::noPos);
return (Value *) p;
}
NIXC_CATCH_ERRS_NULL
}
Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nAttrs);
nix::Symbol s = state->state.symbols.create(name);
auto attr = v.attrs->get(s);
if (attr) {
nix_gc_incref(nullptr, attr->value);
state->state.forceValue(*attr->value, nix::noPos);
return attr->value;
}
nix_set_err_msg(context, NIX_ERR_KEY, "missing attribute");
return nullptr;
}
NIXC_CATCH_ERRS_NULL
}
bool nix_has_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
assert(v.type() == nix::nAttrs);
nix::Symbol s = state->state.symbols.create(name);
auto attr = v.attrs->get(s);
if (attr)
return true;
return false;
}
NIXC_CATCH_ERRS_RES(false);
}
Value *
nix_get_attr_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i, const char ** name)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
const nix::Attr & a = (*v.attrs)[i];
*name = ((const std::string &) (state->state.symbols[a.name])).c_str();
nix_gc_incref(nullptr, a.value);
state->state.forceValue(*a.value, nix::noPos);
return a.value;
}
NIXC_CATCH_ERRS_NULL
}
const char * nix_get_attr_name_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
const nix::Attr & a = (*v.attrs)[i];
return ((const std::string &) (state->state.symbols[a.name])).c_str();
}
NIXC_CATCH_ERRS_NULL
}
nix_err nix_init_bool(nix_c_context * context, Value * value, bool b)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkBool(b);
}
NIXC_CATCH_ERRS
}
// todo string context
nix_err nix_init_string(nix_c_context * context, Value * value, const char * str)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkString(std::string_view(str));
}
NIXC_CATCH_ERRS
}
nix_err nix_init_path_string(nix_c_context * context, EvalState * s, Value * value, const char * str)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkPath(s->state.rootPath(nix::CanonPath(str)));
}
NIXC_CATCH_ERRS
}
nix_err nix_init_float(nix_c_context * context, Value * value, double d)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkFloat(d);
}
NIXC_CATCH_ERRS
}
nix_err nix_init_int(nix_c_context * context, Value * value, int64_t i)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkInt(i);
}
NIXC_CATCH_ERRS
}
nix_err nix_init_null(nix_c_context * context, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkNull();
}
NIXC_CATCH_ERRS
}
nix_err nix_init_external(nix_c_context * context, Value * value, ExternalValue * val)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
auto r = (nix::ExternalValueBase *) val;
v.mkExternal(r);
}
NIXC_CATCH_ERRS
}
ListBuilder * nix_make_list_builder(nix_c_context * context, EvalState * state, size_t capacity)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto builder = CListBuilder(capacity);
return new
#if HAVE_BOEHMGC
(NoGC)
#endif
ListBuilder{std::move(builder)};
}
NIXC_CATCH_ERRS_NULL
}
nix_err nix_list_builder_insert(nix_c_context * context, ListBuilder * list_builder, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
list_builder->builder.push_back((nix::Value *) value);
}
NIXC_CATCH_ERRS
}
void nix_list_builder_free(ListBuilder * bb)
{
#if HAVE_BOEHMGC
GC_FREE(bb);
#else
delete bb;
#endif
}
nix_err nix_make_list(nix_c_context * context, EvalState * s, ListBuilder * list_builder, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
list_builder->builder.finish(&(s->state), &v);
}
NIXC_CATCH_ERRS
}
nix_err nix_init_primop(nix_c_context * context, Value * value, PrimOp * p)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkPrimOp((nix::PrimOp *) p);
}
NIXC_CATCH_ERRS
}
nix_err nix_copy_value(nix_c_context * context, Value * value, Value * source)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
auto & s = check_value_not_null(source);
v = s;
}
NIXC_CATCH_ERRS
}
nix_err nix_make_attrs(nix_c_context * context, Value * value, BindingsBuilder * b)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
v.mkAttrs(b->builder);
}
NIXC_CATCH_ERRS
}
BindingsBuilder * nix_make_bindings_builder(nix_c_context * context, EvalState * state, size_t capacity)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto bb = state->state.buildBindings(capacity);
return new
#if HAVE_BOEHMGC
(NoGC)
#endif
BindingsBuilder{std::move(bb)};
}
NIXC_CATCH_ERRS_NULL
}
nix_err nix_bindings_builder_insert(nix_c_context * context, BindingsBuilder * bb, const char * name, Value * value)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto & v = check_value_not_null(value);
nix::Symbol s = bb->builder.state.symbols.create(name);
bb->builder.insert(s, &v);
}
NIXC_CATCH_ERRS
}
void nix_bindings_builder_free(BindingsBuilder * bb)
{
#if HAVE_BOEHMGC
GC_FREE((nix::BindingsBuilder *) bb);
#else
delete (nix::BindingsBuilder *) bb;
#endif
}

433
src/libexpr/c/nix_api_value.h Normal file
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#ifndef NIX_API_VALUE_H
#define NIX_API_VALUE_H
/** @addtogroup libexpr
* @{
*/
/** @file
* @brief libexpr C bindings dealing with values
*/
#include "nix_api_util.h"
#include "stdbool.h"
#include "stddef.h"
#include "stdint.h"
#ifdef __cplusplus
extern "C" {
#endif
// cffi start
// Type definitions
typedef enum {
NIX_TYPE_THUNK,
NIX_TYPE_INT,
NIX_TYPE_FLOAT,
NIX_TYPE_BOOL,
NIX_TYPE_STRING,
NIX_TYPE_PATH,
NIX_TYPE_NULL,
NIX_TYPE_ATTRS,
NIX_TYPE_LIST,
NIX_TYPE_FUNCTION,
NIX_TYPE_EXTERNAL
} ValueType;
// forward declarations
typedef void Value;
typedef struct EvalState EvalState;
// type defs
/** @brief Stores an under-construction set of bindings
* @ingroup value_manip
*
* Do not reuse.
* @see nix_make_bindings_builder, nix_bindings_builder_free, nix_make_attrs
* @see nix_bindings_builder_insert
*/
typedef struct BindingsBuilder BindingsBuilder;
/** @brief Stores an under-construction list
* @ingroup value_manip
*
* Do not reuse.
* @see nix_make_list_builder, nix_list_builder_free, nix_make_list
* @see nix_list_builder_insert
*/
typedef struct ListBuilder ListBuilder;
/** @brief PrimOp function
* @ingroup primops
*
* Owned by the GC
* @see nix_alloc_primop, nix_init_primop
*/
typedef struct PrimOp PrimOp;
/** @brief External Value
* @ingroup Externals
*
* Owned by the GC
*/
typedef struct ExternalValue ExternalValue;
/** @defgroup primops
* @brief Create your own primops
* @{
*/
/** @brief Function pointer for primops
* When you want to return an error, call nix_set_err_msg(context, NIX_ERR_UNKNOWN, "your error message here").
*
* @param[in] user_data Arbitrary data that was initially supplied to nix_alloc_primop
* @param[out] context Stores error information.
* @param[in] state Evaluator state
* @param[in] args list of arguments. Note that these can be thunks and should be forced using nix_value_force before
* use.
* @param[out] ret return value
* @see nix_alloc_primop, nix_init_primop
*/
typedef void (*PrimOpFun)(void * user_data, nix_c_context * context, EvalState * state, Value ** args, Value * ret);
/** @brief Allocate a PrimOp
*
* Owned by the garbage collector.
* Use nix_gc_decref() when you're done with the returned PrimOp.
*
* @param[out] context Optional, stores error information
* @param[in] fun callback
* @param[in] arity expected number of function arguments
* @param[in] name function name
* @param[in] args array of argument names, NULL-terminated
* @param[in] doc optional, documentation for this primop
* @param[in] user_data optional, arbitrary data, passed to the callback when it's called
* @return primop, or null in case of errors
* @see nix_init_primop
*/
PrimOp * nix_alloc_primop(
nix_c_context * context,
PrimOpFun fun,
int arity,
const char * name,
const char ** args,
const char * doc,
void * user_data);
/** @brief add a primop to the `builtins` attribute set
*
* Only applies to States created after this call.
*
* Moves your PrimOp content into the global evaluator
* registry, meaning your input PrimOp pointer is no longer usable.
* You are free to remove your references to it,
* after which it will be garbage collected.
*
* @param[out] context Optional, stores error information
* @return primop, or null in case of errors
*
*/
nix_err nix_register_primop(nix_c_context * context, PrimOp * primOp);
/** @} */
// Function prototypes
/** @brief Allocate a Nix value
*
* Owned by the GC. Use nix_gc_decref() when you're done with the pointer
* @param[out] context Optional, stores error information
* @param[in] state nix evaluator state
* @return value, or null in case of errors
*
*/
Value * nix_alloc_value(nix_c_context * context, EvalState * state);
/** @addtogroup value_manip Manipulating values
* @brief Functions to inspect and change Nix language values, represented by Value.
* @{
*/
/** @name Getters
*/
/**@{*/
/** @brief Get value type
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return type of nix value
*/
ValueType nix_get_type(nix_c_context * context, const Value * value);
/** @brief Get type name of value as defined in the evaluator
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return type name, owned string
* @todo way to free the result
*/
const char * nix_get_typename(nix_c_context * context, const Value * value);
/** @brief Get boolean value
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return true or false, error info via context
*/
bool nix_get_bool(nix_c_context * context, const Value * value);
/** @brief Get string
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return string
* @return NULL in case of error.
*/
const char * nix_get_string(nix_c_context * context, const Value * value);
/** @brief Get path as string
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return string
* @return NULL in case of error.
*/
const char * nix_get_path_string(nix_c_context * context, const Value * value);
/** @brief Get the length of a list
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return length of list, error info via context
*/
unsigned int nix_get_list_size(nix_c_context * context, const Value * value);
/** @brief Get the element count of an attrset
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return attrset element count, error info via context
*/
unsigned int nix_get_attrs_size(nix_c_context * context, const Value * value);
/** @brief Get float value in 64 bits
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return float contents, error info via context
*/
double nix_get_float(nix_c_context * context, const Value * value);
/** @brief Get int value
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return int contents, error info via context
*/
int64_t nix_get_int(nix_c_context * context, const Value * value);
/** @brief Get external reference
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @return reference to external, NULL in case of error
*/
ExternalValue * nix_get_external(nix_c_context * context, Value *);
/** @brief Get the ix'th element of a list
*
* Owned by the GC. Use nix_gc_decref when you're done with the pointer
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @param[in] state nix evaluator state
* @param[in] ix list element to get
* @return value, NULL in case of errors
*/
Value * nix_get_list_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int ix);
/** @brief Get an attr by name
*
* Owned by the GC. Use nix_gc_decref when you're done with the pointer
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @param[in] state nix evaluator state
* @param[in] name attribute name
* @return value, NULL in case of errors
*/
Value * nix_get_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name);
/** @brief Check if an attribute name exists on a value
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @param[in] state nix evaluator state
* @param[in] name attribute name
* @return value, error info via context
*/
bool nix_has_attr_byname(nix_c_context * context, const Value * value, EvalState * state, const char * name);
/** @brief Get an attribute by index in the sorted bindings
*
* Also gives you the name.
*
* Owned by the GC. Use nix_gc_decref when you're done with the pointer
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @param[in] state nix evaluator state
* @param[in] i attribute index
* @param[out] name will store a pointer to the attribute name
* @return value, NULL in case of errors
*/
Value *
nix_get_attr_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i, const char ** name);
/** @brief Get an attribute name by index in the sorted bindings
*
* Useful when you want the name but want to avoid evaluation.
*
* Owned by the nix EvalState
* @param[out] context Optional, stores error information
* @param[in] value Nix value to inspect
* @param[in] state nix evaluator state
* @param[in] i attribute index
* @return name, NULL in case of errors
*/
const char * nix_get_attr_name_byidx(nix_c_context * context, const Value * value, EvalState * state, unsigned int i);
/**@}*/
/** @name Initializers
*
* Values are typically "returned" by initializing already allocated memory that serves as the return value.
* For this reason, the construction of values is not tied their allocation.
* Nix is a language with immutable values. Respect this property by only initializing Values once; and only initialize
* Values that are meant to be initialized by you. Failing to adhere to these rules may lead to undefined behavior.
*/
/**@{*/
/** @brief Set boolean value
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] b the boolean value
* @return error code, NIX_OK on success.
*/
nix_err nix_init_bool(nix_c_context * context, Value * value, bool b);
/** @brief Set a string
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] str the string, copied
* @return error code, NIX_OK on success.
*/
nix_err nix_init_string(nix_c_context * context, Value * value, const char * str);
/** @brief Set a path
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] str the path string, copied
* @return error code, NIX_OK on success.
*/
nix_err nix_init_path_string(nix_c_context * context, EvalState * s, Value * value, const char * str);
/** @brief Set a float
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] d the float, 64-bits
* @return error code, NIX_OK on success.
*/
nix_err nix_init_float(nix_c_context * context, Value * value, double d);
/** @brief Set an int
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] i the int
* @return error code, NIX_OK on success.
*/
nix_err nix_init_int(nix_c_context * context, Value * value, int64_t i);
/** @brief Set null
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @return error code, NIX_OK on success.
*/
nix_err nix_init_null(nix_c_context * context, Value * value);
/** @brief Set an external value
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] val the external value to set. Will be GC-referenced by the value.
* @return error code, NIX_OK on success.
*/
nix_err nix_init_external(nix_c_context * context, Value * value, ExternalValue * val);
/** @brief Create a list from a list builder
* @param[out] context Optional, stores error information
* @param[in] list_builder list builder to use. Make sure to unref this afterwards.
* @param[out] value Nix value to modify
* @return error code, NIX_OK on success.
*/
nix_err nix_make_list(nix_c_context * context, EvalState * s, ListBuilder * list_builder, Value * value);
/** @brief Create a list builder
* @param[out] context Optional, stores error information
* @param[in] state nix evaluator state
* @param[in] capacity how many bindings you'll add. Don't exceed.
* @return owned reference to a list builder. Make sure to unref when you're done.
*/
ListBuilder * nix_make_list_builder(nix_c_context * context, EvalState * state, size_t capacity);
/** @brief Insert bindings into a builder
* @param[out] context Optional, stores error information
* @param[in] list_builder ListBuilder to insert into
* @param[in] value value to insert
* @return error code, NIX_OK on success.
*/
nix_err nix_list_builder_insert(nix_c_context * context, ListBuilder * list_builder, Value * value);
/** @brief Free a list builder
*
* Does not fail.
* @param[in] builder the builder to free
*/
void nix_list_builder_free(ListBuilder * builder);
/** @brief Create an attribute set from a bindings builder
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] b bindings builder to use. Make sure to unref this afterwards.
* @return error code, NIX_OK on success.
*/
nix_err nix_make_attrs(nix_c_context * context, Value * value, BindingsBuilder * b);
/** @brief Set primop
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] op primop, will be gc-referenced by the value
* @see nix_alloc_primop
* @return error code, NIX_OK on success.
*/
nix_err nix_init_primop(nix_c_context * context, Value * value, PrimOp * op);
/** @brief Copy from another value
* @param[out] context Optional, stores error information
* @param[out] value Nix value to modify
* @param[in] source value to copy from
* @return error code, NIX_OK on success.
*/
nix_err nix_copy_value(nix_c_context * context, Value * value, Value * source);
/**@}*/
/** @brief Create a bindings builder
* @param[out] context Optional, stores error information
* @param[in] state nix evaluator state
* @param[in] capacity how many bindings you'll add. Don't exceed.
* @return owned reference to a bindings builder. Make sure to unref when you're
done.
*/
BindingsBuilder * nix_make_bindings_builder(nix_c_context * context, EvalState * state, size_t capacity);
/** @brief Insert bindings into a builder
* @param[out] context Optional, stores error information
* @param[in] builder BindingsBuilder to insert into
* @param[in] name attribute name, copied into the symbol store
* @param[in] value value to give the binding
* @return error code, NIX_OK on success.
*/
nix_err
nix_bindings_builder_insert(nix_c_context * context, BindingsBuilder * builder, const char * name, Value * value);
/** @brief Free a bindings builder
*
* Does not fail.
* @param[in] builder the builder to free
*/
void nix_bindings_builder_free(BindingsBuilder * builder);
/**@}*/
// cffi end
#ifdef __cplusplus
}
#endif
/** @} */
#endif // NIX_API_VALUE_H

2
src/libexpr/meson.build
View file

@ -87,3 +87,5 @@ liblixexpr = declare_dependency(
include_directories : include_directories('.'),
link_with : libexpr,
)
subdir('c')

26
src/libstore/c/meson.build Normal file
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@ -0,0 +1,26 @@
pkg = import('pkgconfig')
libstorec_sources = files(
'nix_api_store.cc',
)
all_sources += {
'libstorec': libstorec_sources,
}
libstorec = library(
'nix-store-c',
libstorec_sources,
dependencies : [
liblixutil, # Internal.
liblixstore, # Internal.
liblixutilc, # Internal.
],
)
pkg.generate(libstorec, requires : [ 'nix-util-c' ])
liblixstorec = declare_dependency(
include_directories : include_directories('.'),
link_with : libstorec,
)

136
src/libstore/c/nix_api_store.cc Normal file
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@ -0,0 +1,136 @@
#include "nix_api_store.h"
#include "nix_api_store_internal.h"
#include "nix_api_util.h"
#include "nix_api_util_internal.h"
#include "path.hh"
#include "store-api.hh"
#include "build-result.hh"
#include "globals.hh"
nix_err nix_libstore_init(nix_c_context * context)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::initLibStore();
}
NIXC_CATCH_ERRS
}
nix_err nix_init_plugins(nix_c_context * context)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::initPlugins();
}
NIXC_CATCH_ERRS
}
Store * nix_store_open(nix_c_context * context, const char * uri, const char *** params)
{
if (context)
context->last_err_code = NIX_OK;
try {
std::string uri_str = uri ? uri : "";
if (uri_str.empty())
return new Store{nix::openStore()};
if (!params)
return new Store{nix::openStore(uri_str)};
nix::Store::Params params_map;
for (size_t i = 0; params[i] != nullptr; i++) {
params_map[params[i][0]] = params[i][1];
}
return new Store{nix::openStore(uri_str, params_map)};
}
NIXC_CATCH_ERRS_NULL
}
void nix_store_free(Store * store)
{
delete store;
}
nix_err nix_store_get_uri(nix_c_context * context, Store * store, char * dest, unsigned int n)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto res = store->ptr->getUri();
return nix_export_std_string(context, res, dest, n);
}
NIXC_CATCH_ERRS
}
nix_err nix_store_get_version(nix_c_context * context, Store * store, char * dest, unsigned int n)
{
if (context)
context->last_err_code = NIX_OK;
try {
auto res = store->ptr->getVersion();
if (!res)
res = "";
return nix_export_std_string(context, *res, dest, n);
}
NIXC_CATCH_ERRS
}
bool nix_store_is_valid_path(nix_c_context * context, Store * store, StorePath * path)
{
if (context)
context->last_err_code = NIX_OK;
try {
return store->ptr->isValidPath(path->path);
}
NIXC_CATCH_ERRS_RES(false);
}
StorePath * nix_store_parse_path(nix_c_context * context, Store * store, const char * path)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::StorePath s = store->ptr->parseStorePath(path);
return new StorePath{std::move(s)};
}
NIXC_CATCH_ERRS_NULL
}
nix_err nix_store_realise(
nix_c_context * context,
Store * store,
StorePath * path,
void * userdata,
void (*callback)(void * userdata, const char *, const char *))
{
if (context)
context->last_err_code = NIX_OK;
try {
const std::vector<nix::DerivedPath> paths{nix::DerivedPath::Built{
.drvPath = nix::makeConstantStorePathRef(path->path), .outputs = nix::OutputsSpec::All{}}};
const auto nixStore = store->ptr;
auto results = nixStore->buildPathsWithResults(paths, nix::bmNormal, nixStore);
if (callback) {
for (const auto & result : results) {
for (const auto & [outputName, realisation] : result.builtOutputs) {
auto op = store->ptr->printStorePath(realisation.outPath);
callback(userdata, outputName.c_str(), op.c_str());
}
}
}
}
NIXC_CATCH_ERRS
}
void nix_store_path_free(StorePath * sp)
{
delete sp;
}

146
src/libstore/c/nix_api_store.h Normal file
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@ -0,0 +1,146 @@
#ifndef NIX_API_STORE_H
#define NIX_API_STORE_H
/**
* @defgroup libstore libstore
* @brief C bindings for nix libstore
*
* libstore is used for talking to a Nix store
* @{
*/
/** @file
* @brief Main entry for the libstore C bindings
*/
#include "nix_api_util.h"
#include <stdbool.h>
#ifdef __cplusplus
extern "C" {
#endif
// cffi start
/** @brief Reference to a Nix store */
typedef struct Store Store;
/** @brief Nix store path */
typedef struct StorePath StorePath;
/**
* @brief Initializes the Nix store library
*
* This function should be called before creating a Store
* This function can be called multiple times.
*
* @param[out] context Optional, stores error information
* @return NIX_OK if the initialization was successful, an error code otherwise.
*/
nix_err nix_libstore_init(nix_c_context * context);
/**
* @brief Loads the plugins specified in Nix's plugin-files setting.
*
* Call this once, after calling your desired init functions and setting
* relevant settings.
*
* @param[out] context Optional, stores error information
* @return NIX_OK if the initialization was successful, an error code otherwise.
*/
nix_err nix_init_plugins(nix_c_context * context);
/**
* @brief Open a nix store
* Store instances may share state and resources behind the scenes.
* @param[out] context Optional, stores error information
* @param[in] uri URI of the nix store, copied
* @param[in] params optional, array of key-value pairs, {{"endpoint",
* "https://s3.local"}}
* @return a Store pointer, NULL in case of errors
* @see nix_store_free
*/
Store * nix_store_open(nix_c_context *, const char * uri, const char *** params);
/**
* @brief Deallocate a nix store and free any resources if not also held by other Store instances.
*
* Does not fail.
*
* @param[in] store the store to free
*/
void nix_store_free(Store * store);
/**
* @brief get the URI of a nix store
* @param[out] context Optional, stores error information
* @param[in] store nix store reference
* @param[out] dest The allocated area to write the string to.
* @param[in] n Maximum size of the returned string.
* @return error code, NIX_OK on success.
*/
nix_err nix_store_get_uri(nix_c_context * context, Store * store, char * dest, unsigned int n);
// returns: owned StorePath*
/**
* @brief Parse a Nix store path into a StorePath
*
* @note Don't forget to free this path using nix_store_path_free()!
* @param[out] context Optional, stores error information
* @param[in] store nix store reference
* @param[in] path Path string to parse, copied
* @return owned store path, NULL on error
*/
StorePath * nix_store_parse_path(nix_c_context * context, Store * store, const char * path);
/** @brief Deallocate a StorePath
*
* Does not fail.
* @param[in] p the path to free
*/
void nix_store_path_free(StorePath * p);
/**
* @brief Check if a StorePath is valid (i.e. that corresponding store object and its closure of references exists in
* the store)
* @param[out] context Optional, stores error information
* @param[in] store Nix Store reference
* @param[in] path Path to check
* @return true or false, error info in context
*/
bool nix_store_is_valid_path(nix_c_context * context, Store * store, StorePath * path);
// nix_err nix_store_ensure(Store*, const char*);
// nix_err nix_store_build_paths(Store*);
/**
* @brief Realise a Nix store path
*
* Blocking, calls callback once for each realised output
*
* @param[out] context Optional, stores error information
* @param[in] store Nix Store reference
* @param[in] path Path to build
* @param[in] userdata data to pass to every callback invocation
* @param[in] callback called for every realised output
*/
nix_err nix_store_realise(
nix_c_context * context,
Store * store,
StorePath * path,
void * userdata,
void (*callback)(void * userdata, const char * outname, const char * out));
/**
* @brief get the version of a nix store.
* If the store doesn't have a version (like the dummy store), returns an empty string.
* @param[out] context Optional, stores error information
* @param[in] store nix store reference
* @param[out] dest The allocated area to write the string to.
* @param[in] n Maximum size of the returned string.
* @return error code, NIX_OK on success.
*/
nix_err nix_store_get_version(nix_c_context *, Store * store, char * dest, unsigned int n);
// cffi end
#ifdef __cplusplus
}
#endif
/**
* @}
*/
#endif // NIX_API_STORE_H

15
src/libstore/c/nix_api_store_internal.h Normal file
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@ -0,0 +1,15 @@
#ifndef NIX_API_STORE_INTERNAL_H
#define NIX_API_STORE_INTERNAL_H
#include "store-api.hh"
struct Store
{
nix::ref<nix::Store> ptr;
};
struct StorePath
{
nix::StorePath path;
};
#endif

2
src/libstore/meson.build
View file

@ -120,3 +120,5 @@ liblixstore = declare_dependency(
include_directories : include_directories('.'),
link_with : libstore,
)
subdir('c')

25
src/libutil/c/meson.build Normal file
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@ -0,0 +1,25 @@
pkg = import('pkgconfig')
libutilc_sources = files(
'nix_api_util.cc',
)
all_sources += {
'libutilc': libutilc_sources,
}
libutilc = library(
'nix-util-c',
libutilc_sources,
dependencies : [
liblixutil,
],
implicit_include_directories : true,
)
pkg.generate(libutilc)
liblixutilc = declare_dependency(
include_directories : include_directories('.'),
link_with : libutilc
)

151
src/libutil/c/nix_api_util.cc Normal file
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@ -0,0 +1,151 @@
#include "nix_api_util.h"
#include "config.hh"
#include "error.hh"
#include "nix_api_util_internal.h"
#include "util.hh"
#include <cxxabi.h>
#include <typeinfo>
nix_c_context * nix_c_context_create()
{
return new nix_c_context();
}
void nix_c_context_free(nix_c_context * context)
{
delete context;
}
nix_err nix_context_error(nix_c_context * context)
{
if (context == nullptr) {
throw;
}
try {
throw;
} catch (nix::Error & e) {
/* Storing this exception is annoying, take what we need here */
context->last_err = e.what();
context->info = e.info();
int status;
const char * demangled = abi::__cxa_demangle(typeid(e).name(), 0, 0, &status);
if (demangled) {
context->name = demangled;
// todo: free(demangled);
} else {
context->name = typeid(e).name();
}
context->last_err_code = NIX_ERR_NIX_ERROR;
return context->last_err_code;
} catch (const std::exception & e) {
context->last_err = e.what();
context->last_err_code = NIX_ERR_UNKNOWN;
return context->last_err_code;
}
// unreachable
}
nix_err nix_set_err_msg(nix_c_context * context, nix_err err, const char * msg)
{
if (context == nullptr) {
// todo last_err_code
throw nix::Error("Nix C api error: %s", msg);
}
context->last_err_code = err;
context->last_err = msg;
return err;
}
const char * nix_version_get()
{
return PACKAGE_VERSION;
}
// Implementations
nix_err nix_setting_get(nix_c_context * context, const char * key, char * value, int n)
{
if (context)
context->last_err_code = NIX_OK;
try {
std::map<std::string, nix::AbstractConfig::SettingInfo> settings;
nix::globalConfig.getSettings(settings);
if (settings.contains(key))
return nix_export_std_string(context, settings[key].value, value, n);
else {
return nix_set_err_msg(context, NIX_ERR_KEY, "Setting not found");
}
}
NIXC_CATCH_ERRS
}
nix_err nix_setting_set(nix_c_context * context, const char * key, const char * value)
{
if (context)
context->last_err_code = NIX_OK;
if (nix::globalConfig.set(key, value))
return NIX_OK;
else {
return nix_set_err_msg(context, NIX_ERR_KEY, "Setting not found");
}
}
nix_err nix_libutil_init(nix_c_context * context)
{
if (context)
context->last_err_code = NIX_OK;
try {
nix::initLibUtil();
return NIX_OK;
}
NIXC_CATCH_ERRS
}
const char * nix_err_msg(nix_c_context * context, const nix_c_context * read_context, unsigned int * n)
{
if (context)
context->last_err_code = NIX_OK;
if (read_context->last_err) {
if (n)
*n = read_context->last_err->size();
return read_context->last_err->c_str();
}
nix_set_err_msg(context, NIX_ERR_UNKNOWN, "No error message");
return nullptr;
}
nix_err nix_err_name(nix_c_context * context, const nix_c_context * read_context, char * value, int n)
{
if (context)
context->last_err_code = NIX_OK;
if (read_context->last_err_code != NIX_ERR_NIX_ERROR) {
return nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Last error was not a nix error");
}
return nix_export_std_string(context, read_context->name, value, n);
}
nix_err nix_err_info_msg(nix_c_context * context, const nix_c_context * read_context, char * value, int n)
{
if (context)
context->last_err_code = NIX_OK;
if (read_context->last_err_code != NIX_ERR_NIX_ERROR) {
return nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Last error was not a nix error");
}
return nix_export_std_string(context, read_context->info->msg.str(), value, n);
}
nix_err nix_err_code(const nix_c_context * read_context)
{
return read_context->last_err_code;
}
// internal
nix_err nix_export_std_string(nix_c_context * context, const std::string_view str, char * dest, unsigned int n)
{
size_t i = str.copy(dest, n - 1);
dest[i] = 0;
if (i == n - 1) {
return nix_set_err_msg(context, NIX_ERR_OVERFLOW, "Provided buffer too short");
} else
return NIX_OK;
}

290
src/libutil/c/nix_api_util.h Normal file
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@ -0,0 +1,290 @@
#ifndef NIX_API_UTIL_H
#define NIX_API_UTIL_H
/**
* @defgroup libutil libutil
* @brief C bindings for nix libutil
*
* libutil is used for functionality shared between
* different Nix modules.
* @{
*/
/** @file
* @brief Main entry for the libutil C bindings
*
* Also contains error handling utilities
*/
#ifdef __cplusplus
extern "C" {
#endif
// cffi start
/** @defgroup errors Handling errors
* @brief Dealing with errors from the Nix side
*
* To handle errors that can be returned from the Nix API,
* a nix_c_context can be passed to any function that potentially returns an
* error.
*
* Error information will be stored in this context, and can be retrieved
* using nix_err_code and nix_err_msg.
*
* Passing NULL instead will cause the API to throw C++ errors.
*
* Example:
* @code{.c}
* int main() {
* nix_c_context* ctx = nix_c_context_create();
* nix_libutil_init(ctx);
* if (nix_err_code(ctx) != NIX_OK) {
* printf("error: %s\n", nix_err_msg(NULL, ctx, NULL));
* return 1;
* }
* return 0;
* }
* @endcode
* @{
*/
// Error codes
/**
* @brief Type for error codes in the NIX system
*
* This type can have one of several predefined constants:
* - NIX_OK: No error occurred (0)
* - NIX_ERR_UNKNOWN: An unknown error occurred (-1)
* - NIX_ERR_OVERFLOW: An overflow error occurred (-2)
* - NIX_ERR_KEY: A key error occurred (-3)
* - NIX_ERR_NIX_ERROR: A generic Nix error occurred (-4)
*/
typedef int nix_err;
/**
* @brief No error occurred.
*
* This error code is returned when no error has occurred during the function
* execution.
*/
#define NIX_OK 0
/**
* @brief An unknown error occurred.
*
* This error code is returned when an unknown error occurred during the
* function execution.
*/
#define NIX_ERR_UNKNOWN -1
/**
* @brief An overflow error occurred.
*
* This error code is returned when an overflow error occurred during the
* function execution.
*/
#define NIX_ERR_OVERFLOW -2
/**
* @brief A key error occurred.
*
* This error code is returned when a key error occurred during the function
* execution.
*/
#define NIX_ERR_KEY -3
/**
* @brief A generic Nix error occurred.
*
* This error code is returned when a generic Nix error occurred during the
* function execution.
*/
#define NIX_ERR_NIX_ERROR -4
/**
* @brief This object stores error state.
* @struct nix_c_context
*
* Passed as a first parameter to functions that can fail, to store error
* information.
*
* Optional wherever it can be used, passing NULL instead will throw a C++
* exception.
*
* The struct is laid out so that it can also be cast to nix_err* to inspect
* directly:
* @code{.c}
* assert(*(nix_err*)ctx == NIX_OK);
* @endcode
* @note These can be reused between different function calls,
* but make sure not to use them for multiple calls simultaneously (which can
* happen in callbacks).
*/
typedef struct nix_c_context nix_c_context;
// Function prototypes
/**
* @brief Allocate a new nix_c_context.
* @throws std::bad_alloc
* @return allocated nix_c_context, owned by the caller. Free using
* `nix_c_context_free`.
*/
nix_c_context * nix_c_context_create();
/**
* @brief Free a nix_c_context. Does not fail.
* @param[out] context The context to free, mandatory.
*/
void nix_c_context_free(nix_c_context * context);
/**
* @}
*/
/**
* @brief Initializes nix_libutil and its dependencies.
*
* This function can be called multiple times, but should be called at least
* once prior to any other nix function.
*
* @param[out] context Optional, stores error information
* @return NIX_OK if the initialization is successful, or an error code
* otherwise.
*/
nix_err nix_libutil_init(nix_c_context * context);
/** @defgroup settings
* @{
*/
/**
* @brief Retrieves a setting from the nix global configuration.
*
* This function requires nix_libutil_init() to be called at least once prior to
* its use.
*
* @param[out] context optional, Stores error information
* @param[in] key The key of the setting to retrieve.
* @param[out] value A pointer to a buffer where the value of the setting will
* be stored.
* @param[in] n The size of the buffer pointed to by value.
* @return NIX_ERR_KEY if the setting is unknown, NIX_ERR_OVERFLOW if the
* provided buffer is too short, or NIX_OK if the setting was retrieved
* successfully.
*/
nix_err nix_setting_get(nix_c_context * context, const char * key, char * value, int n);
/**
* @brief Sets a setting in the nix global configuration.
*
* Use "extra-<setting name>" to append to the setting's value.
*
* Settings only apply for new State%s. Call nix_plugins_init() when you are
* done with the settings to load any plugins.
*
* @param[out] context optional, Stores error information
* @param[in] key The key of the setting to set.
* @param[in] value The value to set for the setting.
* @return NIX_ERR_KEY if the setting is unknown, or NIX_OK if the setting was
* set successfully.
*/
nix_err nix_setting_set(nix_c_context * context, const char * key, const char * value);
/**
* @}
*/
// todo: nix_plugins_init()
/**
* @brief Retrieves the nix library version.
*
* Does not fail.
* @return A static string representing the version of the nix library.
*/
const char * nix_version_get();
/** @addtogroup errors
* @{
*/
/**
* @brief Retrieves the most recent error message from a context.
*
* @pre This function should only be called after a previous nix function has
* returned an error.
*
* @param[out] context optional, the context to store errors in if this function
* fails
* @param[in] ctx the context to retrieve the error message from
* @param[out] n optional: a pointer to an unsigned int that is set to the
* length of the error.
* @return nullptr if no error message was ever set,
* a borrowed pointer to the error message otherwise.
*/
const char * nix_err_msg(nix_c_context * context, const nix_c_context * ctx, unsigned int * n);
/**
* @brief Retrieves the error message from errorInfo in a context.
*
* Used to inspect nix Error messages.
*
* @pre This function should only be called after a previous nix function has
* returned a NIX_ERR_NIX_ERROR
*
* @param[out] context optional, the context to store errors in if this function
* fails
* @param[in] read_context the context to retrieve the error message from
* @param[out] value The allocated area to write the error string to.
* @param[in] n Maximum size of the returned string.
* @return NIX_OK if there were no errors, an error code otherwise.
*/
nix_err nix_err_info_msg(nix_c_context * context, const nix_c_context * read_context, char * value, int n);
/**
* @brief Retrieves the error name from a context.
*
* Used to inspect nix Error messages.
*
* @pre This function should only be called after a previous nix function has
* returned a NIX_ERR_NIX_ERROR
*
* @param context optional, the context to store errors in if this function
* fails
* @param[in] read_context the context to retrieve the error message from
* @param[out] value The allocated area to write the error string to.
* @param[in] n Maximum size of the returned string.
* @return NIX_OK if there were no errors, an error code otherwise.
*/
nix_err nix_err_name(nix_c_context * context, const nix_c_context * read_context, char * value, int n);
/**
* @brief Retrieves the most recent error code from a nix_c_context
*
* Equivalent to reading the first field of the context.
*
* Does not fail
*
* @param[in] read_context the context to retrieve the error message from
* @return most recent error code stored in the context.
*/
nix_err nix_err_code(const nix_c_context * read_context);
/**
* @brief Set an error message on a nix context.
*
* This should be used when you want to throw an error from a PrimOp callback.
*
* All other use is internal to the API.
*
* @param context context to write the error message to, or NULL
* @param err The error code to set and return
* @param msg The error message to set.
* @returns the error code set
*/
nix_err nix_set_err_msg(nix_c_context * context, nix_err err, const char * msg);
/**
* @}
*/
// cffi end
#ifdef __cplusplus
}
#endif
/** @} */
#endif // NIX_API_UTIL_H

49
src/libutil/c/nix_api_util_internal.h Normal file
View file

@ -0,0 +1,49 @@
#ifndef NIX_API_UTIL_INTERNAL_H
#define NIX_API_UTIL_INTERNAL_H
#include <string>
#include <optional>
#include "error.hh"
#include "nix_api_util.h"
struct nix_c_context
{
nix_err last_err_code = NIX_OK;
std::optional<std::string> last_err = {};
std::optional<nix::ErrorInfo> info = {};
std::string name = "";
};
nix_err nix_context_error(nix_c_context * context);
/**
* Internal use only.
*
* Export a std::string across the C api boundary
* @param context optional, the context to store errors in if this function
* fails
* @param str The string to export
* @param value The allocated area to write the string to.
* @param n Maximum size of the returned string.
* @return NIX_OK if there were no errors, NIX_ERR_OVERFLOW if the string length
* exceeds `n`.
*/
nix_err nix_export_std_string(nix_c_context * context, const std::string_view str, char * dest, unsigned int n);
#define NIXC_CATCH_ERRS \
catch (...) \
{ \
return nix_context_error(context); \
} \
return NIX_OK;
#define NIXC_CATCH_ERRS_RES(def) \
catch (...) \
{ \
nix_context_error(context); \
return def; \
}
#define NIXC_CATCH_ERRS_NULL NIXC_CATCH_ERRS_RES(nullptr)
#endif // NIX_API_UTIL_INTERNAL_H

3
src/libutil/meson.build
View file

@ -54,3 +54,6 @@ liblixutil = declare_dependency(
include_directories : include_directories('.'),
link_with : libutil
)
subdir('c')