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[Backport 2.33-maintenance] libutil: Gracefully fall back from unsupported O_TMPFILE #14834

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Merged
internal-nix-ci merged 1 commit into from
Dec 18, 2025
Merged

[Backport 2.33-maintenance] libutil: Gracefully fall back from unsupported O_TMPFILE #14834

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22 changes: 16 additions & 6 deletions src/libutil/file-system.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -713,17 +713,27 @@ AutoCloseFD createAnonymousTempFile()
{
AutoCloseFD fd;
#ifdef O_TMPFILE
fd = ::open(defaultTempDir().c_str(), O_TMPFILE | O_CLOEXEC | O_RDWR, S_IWUSR | S_IRUSR);
if (!fd)
throw SysError("creating anonymous temporary file");
#else
static std::atomic_flag tmpfileUnsupported{};
if (!tmpfileUnsupported.test()) /* Try with O_TMPFILE first. */ {
/* Use O_EXCL, because the file is never supposed to be linked into filesystem. */
fd = ::open(defaultTempDir().c_str(), O_TMPFILE | O_CLOEXEC | O_RDWR | O_EXCL, S_IWUSR | S_IRUSR);
if (!fd) {
/* Not supported by the filesystem or the kernel. */
if (errno == EOPNOTSUPP || errno == EISDIR)
tmpfileUnsupported.test_and_set(); /* Set flag and fall through to createTempFile. */
else
throw SysError("creating anonymous temporary file");
} else {
return fd; /* Successfully created. */
}
}
#endif
auto [fd2, path] = createTempFile("nix-anonymous");
if (!fd2)
throw SysError("creating temporary file '%s'", path);
fd = std::move(fd2);
# ifndef _WIN32
#ifndef _WIN32
unlink(requireCString(path)); /* We only care about the file descriptor. */
# endif
#endif
return fd;
}
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