mirror of
https://github.com/NixOS/nix
synced 2025-06-25 06:31:14 +02:00
979d5a7cae
Since we dropped fs::symlink_exists, we no longer have a need for the fs namespace. Having less abstractions makes it easier to lookup the functions in reference documentations.
95 lines
3.3 KiB
C++
95 lines
3.3 KiB
C++
#include "nix/util/environment-variables.hh"
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#include "nix/util/executable-path.hh"
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#include "nix/util/strings-inline.hh"
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#include "nix/util/util.hh"
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#include "nix/util/file-path-impl.hh"
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namespace nix {
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constexpr static const OsStringView path_var_separator{
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&ExecutablePath::separator,
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1,
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};
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ExecutablePath ExecutablePath::load()
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{
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// "If PATH is unset or is set to null, the path search is
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// implementation-defined."
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// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
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return ExecutablePath::parse(getEnvOs(OS_STR("PATH")).value_or(OS_STR("")));
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}
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ExecutablePath ExecutablePath::parse(const OsString & path)
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{
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auto strings = path.empty() ? (std::list<OsString>{})
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: basicSplitString<std::list<OsString>, OsChar>(path, path_var_separator);
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std::vector<std::filesystem::path> ret;
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ret.reserve(strings.size());
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std::transform(
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std::make_move_iterator(strings.begin()),
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std::make_move_iterator(strings.end()),
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std::back_inserter(ret),
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[](OsString && str) {
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return std::filesystem::path{
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str.empty()
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// "A zero-length prefix is a legacy feature that
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// indicates the current working directory. It
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// appears as two adjacent <colon> characters
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// ("::"), as an initial <colon> preceding the rest
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// of the list, or as a trailing <colon> following
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// the rest of the list."
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// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
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? OS_STR(".")
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: std::move(str),
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};
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});
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return {ret};
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}
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OsString ExecutablePath::render() const
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{
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std::vector<PathViewNG> path2;
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path2.reserve(directories.size());
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for (auto & p : directories)
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path2.push_back(p.native());
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return basicConcatStringsSep(path_var_separator, path2);
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}
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std::optional<std::filesystem::path>
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ExecutablePath::findName(const OsString & exe, std::function<bool(const std::filesystem::path &)> isExecutable) const
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{
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// "If the pathname being sought contains a <slash>, the search
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// through the path prefixes shall not be performed."
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// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
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assert(OsPathTrait<std::filesystem::path::value_type>::rfindPathSep(exe) == exe.npos);
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for (auto & dir : directories) {
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auto candidate = dir / exe;
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if (isExecutable(candidate))
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return candidate.lexically_normal();
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}
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return std::nullopt;
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}
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std::filesystem::path ExecutablePath::findPath(
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const std::filesystem::path & exe, std::function<bool(const std::filesystem::path &)> isExecutable) const
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{
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// "If the pathname being sought contains a <slash>, the search
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// through the path prefixes shall not be performed."
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// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
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if (exe.filename() == exe) {
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auto resOpt = findName(exe, isExecutable);
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if (resOpt)
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return *resOpt;
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else
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throw ExecutableLookupError("Could not find executable '%s'", exe.string());
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} else {
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return exe;
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}
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}
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} // namespace nix
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