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Fix exception handling around realisePath()

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This no longer worked correctly because 'path' is uninitialised when
an exception occurs, leading to errors like

       … while importing ''

       at /nix/store/rrzz5b1pshvzh1437ac9nkl06br81lkv-source/flake.nix:352:13:

So move the adding of the error context into realisePath().
This commit is contained in:
Eelco Dolstra 2022-01-21 13:51:05 +01:00
parent e85cf34ea3
commit 128098040b
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GPG key ID: 8170B4726D7198DE
1 changed files with 33 additions and 82 deletions
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101
src/libexpr/primops.cc
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@ -102,10 +102,19 @@ static Path realisePath(EvalState & state, const Pos & pos, Value & v, const Rea
{
PathSet context;
Path path = flags.requireAbsolutePath
auto path = [&]()
{
try {
return flags.requireAbsolutePath
? state.coerceToPath(pos, v, context)
: state.coerceToString(pos, v, context, false, false);
} catch (Error & e) {
e.addTrace(pos, "while realising the context of a path");
throw;
}
}();
try {
StringMap rewrites = state.realiseContext(context);
auto realPath = state.toRealPath(rewriteStrings(path, rewrites), context);
@ -113,6 +122,10 @@ static Path realisePath(EvalState & state, const Pos & pos, Value & v, const Rea
return flags.checkForPureEval
? state.checkSourcePath(realPath)
: realPath;
} catch (Error & e) {
e.addTrace(pos, "while realising the context of path '%s'", path);
throw;
}
}
/* Add and attribute to the given attribute map from the output name to
@ -150,18 +163,7 @@ static void mkOutputString(
argument. */
static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vScope, Value & v)
{
Path path;
try {
path = realisePath(state, pos, vPath);
} catch (InvalidPathError & e) {
throw EvalError({
.msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
.errPos = pos
});
} catch (Error & e) {
e.addTrace(pos, "while importing '%s'", path);
throw;
}
auto path = realisePath(state, pos, vPath);
// FIXME
auto isValidDerivationInStore = [&]() -> std::optional<StorePath> {
@ -314,18 +316,7 @@ extern "C" typedef void (*ValueInitializer)(EvalState & state, Value & v);
/* Load a ValueInitializer from a DSO and return whatever it initializes */
void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
Path path;
try {
path = realisePath(state, pos, *args[0]);
} catch (InvalidPathError & e) {
throw EvalError({
.msg = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
.errPos = pos
});
} catch (Error & e) {
e.addTrace(pos, "while importing '%s'", path);
throw;
}
auto path = realisePath(state, pos, *args[0]);
string sym = state.forceStringNoCtx(*args[1], pos);
@ -1379,22 +1370,12 @@ static RegisterPrimOp primop_storePath({
static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
Path path;
try {
// We don’t check the path right now, because we don’t want to throw if
// the path isn’t allowed, but just return false
// (and we can’t just catch the exception here because we still want to
// throw if something in the evaluation of `*args[0]` tries to access an
// unauthorized path)
path = realisePath(state, pos, *args[0], { .checkForPureEval = false });
} catch (InvalidPathError & e) {
throw EvalError({
.msg = hintfmt(
"cannot check the existence of '%1%', since path '%2%' is not valid",
path, e.path),
.errPos = pos
});
}
/* We don’t check the path right now, because we don’t want to
throw if the path isn’t allowed, but just return false (and we
can’t just catch the exception here because we still want to
throw if something in the evaluation of `*args[0]` tries to
access an unauthorized path). */
auto path = realisePath(state, pos, *args[0], { .checkForPureEval = false });
try {
v.mkBool(pathExists(state.checkSourcePath(path)));
@ -1460,15 +1441,7 @@ static RegisterPrimOp primop_dirOf({
/* Return the contents of a file as a string. */
static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
Path path;
try {
path = realisePath(state, pos, *args[0]);
} catch (InvalidPathError & e) {
throw EvalError({
.msg = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
.errPos = pos
});
}
auto path = realisePath(state, pos, *args[0]);
string s = readFile(path);
if (s.find((char) 0) != string::npos)
throw Error("the contents of the file '%1%' cannot be represented as a Nix string", path);
@ -1512,16 +1485,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
pos
);
Path path;
try {
path = realisePath(state, pos, *i->value, { .requireAbsolutePath = false });
} catch (InvalidPathError & e) {
throw EvalError({
.msg = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
.errPos = pos
});
}
auto path = realisePath(state, pos, *i->value, { .requireAbsolutePath = false });
searchPath.emplace_back(prefix, path);
}
@ -1548,12 +1512,7 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
.errPos = pos
});
Path path;
try {
path = realisePath(state, pos, *args[1]);
} catch (InvalidPathError & e) {
throw EvalError("cannot read '%s' since path '%s' is not valid, at %s", path, e.path, pos);
}
auto path = realisePath(state, pos, *args[1]);
v.mkString(hashFile(*ht, path).to_string(Base16, false));
}
@ -1572,15 +1531,7 @@ static RegisterPrimOp primop_hashFile({
/* Read a directory (without . or ..) */
static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
Path path;
try {
path = realisePath(state, pos, *args[0]);
} catch (InvalidPathError & e) {
throw EvalError({
.msg = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
.errPos = pos
});
}
auto path = realisePath(state, pos, *args[0]);
DirEntries entries = readDirectory(path);