lix/src/libexpr/primops/context.cc

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#include "primops.hh"
#include "eval-inline.hh"
#include "store-api.hh"
namespace nix {
static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
PathSet context;
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v.mkString(state.coerceToString(pos, *args[0], context));
}
static RegisterPrimOp primop_unsafeDiscardStringContext("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
static void prim_hasContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
PathSet context;
state.forceString(*args[0], context, pos);
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v.mkBool(!context.empty());
}
static RegisterPrimOp primop_hasContext("__hasContext", 1, prim_hasContext);
/* Sometimes we want to pass a derivation path (i.e. pkg.drvPath) to a
builder without causing the derivation to be built (for instance,
in the derivation that builds NARs in nix-push, when doing
source-only deployment). This primop marks the string context so
that builtins.derivation adds the path to drv.inputSrcs rather than
drv.inputDrvs. */
static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
PathSet context;
string s = state.coerceToString(pos, *args[0], context);
PathSet context2;
for (auto & p : context)
context2.insert(p.at(0) == '=' ? string(p, 1) : p);
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v.mkString(s, context2);
}
static RegisterPrimOp primop_unsafeDiscardOutputDependency("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
/* Extract the context of a string as a structured Nix value.
The context is represented as an attribute set whose keys are the
paths in the context set and whose values are attribute sets with
the following keys:
path: True if the relevant path is in the context as a plain store
path (i.e. the kind of context you get when interpolating
a Nix path (e.g. ./.) into a string). False if missing.
allOutputs: True if the relevant path is a derivation and it is
in the context as a drv file with all of its outputs
(i.e. the kind of context you get when referencing
.drvPath of some derivation). False if missing.
outputs: If a non-empty list, the relevant path is a derivation
and the provided outputs are referenced in the context
(i.e. the kind of context you get when referencing
.outPath of some derivation). Empty list if missing.
Note that for a given path any combination of the above attributes
may be present.
*/
static void prim_getContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
struct ContextInfo {
bool path = false;
bool allOutputs = false;
Strings outputs;
};
PathSet context;
state.forceString(*args[0], context, pos);
auto contextInfos = std::map<Path, ContextInfo>();
for (const auto & p : context) {
Path drv;
string output;
const Path * path = &p;
if (p.at(0) == '=') {
drv = string(p, 1);
path = &drv;
} else if (p.at(0) == '!') {
std::pair<string, string> ctx = decodeContext(p);
drv = ctx.first;
output = ctx.second;
path = &drv;
}
auto isPath = drv.empty();
auto isAllOutputs = (!drv.empty()) && output.empty();
auto iter = contextInfos.find(*path);
if (iter == contextInfos.end()) {
contextInfos.emplace(*path, ContextInfo{isPath, isAllOutputs, output.empty() ? Strings{} : Strings{std::move(output)}});
} else {
if (isPath)
iter->second.path = true;
else if (isAllOutputs)
iter->second.allOutputs = true;
else
iter->second.outputs.emplace_back(std::move(output));
}
}
auto attrs = state.buildBindings(contextInfos.size());
auto sPath = state.symbols.create("path");
auto sAllOutputs = state.symbols.create("allOutputs");
for (const auto & info : contextInfos) {
auto infoAttrs = state.buildBindings(3);
if (info.second.path)
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infoAttrs.alloc(sPath).mkBool(true);
if (info.second.allOutputs)
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infoAttrs.alloc(sAllOutputs).mkBool(true);
if (!info.second.outputs.empty()) {
auto & outputsVal = infoAttrs.alloc(state.sOutputs);
state.mkList(outputsVal, info.second.outputs.size());
for (const auto & [i, output] : enumerate(info.second.outputs))
(outputsVal.listElems()[i] = state.allocValue())->mkString(output);
}
attrs.alloc(info.first).mkAttrs(infoAttrs);
}
v.mkAttrs(attrs);
}
static RegisterPrimOp primop_getContext("__getContext", 1, prim_getContext);
/* Append the given context to a given string.
See the commentary above unsafeGetContext for details of the
context representation.
*/
static void prim_appendContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
PathSet context;
auto orig = state.forceString(*args[0], context, pos);
state.forceAttrs(*args[1], pos);
auto sPath = state.symbols.create("path");
auto sAllOutputs = state.symbols.create("allOutputs");
for (auto & i : *args[1]->attrs) {
if (!state.store->isStorePath(i.name))
throw EvalError({
Improve error formatting Changes: * The divider lines are gone. These were in practice a bit confusing, in particular with --show-trace or --keep-going, since then there were multiple lines, suggesting a start/end which wasn't the case. * Instead, multi-line error messages are now indented to align with the prefix (e.g. "error: "). * The 'description' field is gone since we weren't really using it. * 'hint' is renamed to 'msg' since it really wasn't a hint. * The error is now printed *before* the location info. * The 'name' field is no longer printed since most of the time it wasn't very useful since it was just the name of the exception (like EvalError). Ideally in the future this would be a unique, easily googleable error ID (like rustc). * "trace:" is now just "…". This assumes error contexts start with something like "while doing X". Example before: error: --- AssertionError ---------------------------------------------------------------------------------------- nix at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix 6| 7| x = assert false; 1; | ^ 8| assertion 'false' failed ----------------------------------------------------- show-trace ----------------------------------------------------- trace: while evaluating the attribute 'x' of the derivation 'hello-2.10' at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix 191| // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) { 192| name = "${attrs.pname}-${attrs.version}"; | ^ 193| } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) { Example after: error: assertion 'false' failed at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix 6| 7| x = assert false; 1; | ^ 8| … while evaluating the attribute 'x' of the derivation 'hello-2.10' at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix 191| // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) { 192| name = "${attrs.pname}-${attrs.version}"; | ^ 193| } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {
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.msg = hintfmt("Context key '%s' is not a store path", i.name),
.errPos = *i.pos
});
if (!settings.readOnlyMode)
state.store->ensurePath(state.store->parseStorePath(i.name));
state.forceAttrs(*i.value, *i.pos);
auto iter = i.value->attrs->find(sPath);
if (iter != i.value->attrs->end()) {
if (state.forceBool(*iter->value, *iter->pos))
context.insert(i.name);
}
iter = i.value->attrs->find(sAllOutputs);
if (iter != i.value->attrs->end()) {
if (state.forceBool(*iter->value, *iter->pos)) {
if (!isDerivation(i.name)) {
throw EvalError({
Improve error formatting Changes: * The divider lines are gone. These were in practice a bit confusing, in particular with --show-trace or --keep-going, since then there were multiple lines, suggesting a start/end which wasn't the case. * Instead, multi-line error messages are now indented to align with the prefix (e.g. "error: "). * The 'description' field is gone since we weren't really using it. * 'hint' is renamed to 'msg' since it really wasn't a hint. * The error is now printed *before* the location info. * The 'name' field is no longer printed since most of the time it wasn't very useful since it was just the name of the exception (like EvalError). Ideally in the future this would be a unique, easily googleable error ID (like rustc). * "trace:" is now just "…". This assumes error contexts start with something like "while doing X". Example before: error: --- AssertionError ---------------------------------------------------------------------------------------- nix at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix 6| 7| x = assert false; 1; | ^ 8| assertion 'false' failed ----------------------------------------------------- show-trace ----------------------------------------------------- trace: while evaluating the attribute 'x' of the derivation 'hello-2.10' at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix 191| // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) { 192| name = "${attrs.pname}-${attrs.version}"; | ^ 193| } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) { Example after: error: assertion 'false' failed at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix 6| 7| x = assert false; 1; | ^ 8| … while evaluating the attribute 'x' of the derivation 'hello-2.10' at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix 191| // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) { 192| name = "${attrs.pname}-${attrs.version}"; | ^ 193| } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {
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.msg = hintfmt("Tried to add all-outputs context of %s, which is not a derivation, to a string", i.name),
.errPos = *i.pos
});
}
context.insert("=" + string(i.name));
}
}
iter = i.value->attrs->find(state.sOutputs);
if (iter != i.value->attrs->end()) {
state.forceList(*iter->value, *iter->pos);
if (iter->value->listSize() && !isDerivation(i.name)) {
throw EvalError({
Improve error formatting Changes: * The divider lines are gone. These were in practice a bit confusing, in particular with --show-trace or --keep-going, since then there were multiple lines, suggesting a start/end which wasn't the case. * Instead, multi-line error messages are now indented to align with the prefix (e.g. "error: "). * The 'description' field is gone since we weren't really using it. * 'hint' is renamed to 'msg' since it really wasn't a hint. * The error is now printed *before* the location info. * The 'name' field is no longer printed since most of the time it wasn't very useful since it was just the name of the exception (like EvalError). Ideally in the future this would be a unique, easily googleable error ID (like rustc). * "trace:" is now just "…". This assumes error contexts start with something like "while doing X". Example before: error: --- AssertionError ---------------------------------------------------------------------------------------- nix at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix 6| 7| x = assert false; 1; | ^ 8| assertion 'false' failed ----------------------------------------------------- show-trace ----------------------------------------------------- trace: while evaluating the attribute 'x' of the derivation 'hello-2.10' at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix 191| // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) { 192| name = "${attrs.pname}-${attrs.version}"; | ^ 193| } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) { Example after: error: assertion 'false' failed at: (7:7) in file: /home/eelco/Dev/nixpkgs/pkgs/applications/misc/hello/default.nix 6| 7| x = assert false; 1; | ^ 8| … while evaluating the attribute 'x' of the derivation 'hello-2.10' at: (192:11) in file: /home/eelco/Dev/nixpkgs/pkgs/stdenv/generic/make-derivation.nix 191| // (lib.optionalAttrs (!(attrs ? name) && attrs ? pname && attrs ? version)) { 192| name = "${attrs.pname}-${attrs.version}"; | ^ 193| } // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix && (attrs ? name || (attrs ? pname && attrs ? version)))) {
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.msg = hintfmt("Tried to add derivation output context of %s, which is not a derivation, to a string", i.name),
.errPos = *i.pos
});
}
for (auto elem : iter->value->listItems()) {
auto name = state.forceStringNoCtx(*elem, *iter->pos);
context.insert("!" + name + "!" + string(i.name));
}
}
}
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v.mkString(orig, context);
}
static RegisterPrimOp primop_appendContext("__appendContext", 2, prim_appendContext);
}