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nix/src/libutil/executable-path.cc
John Ericson a97a08411c More support for std::filepath in libnixutil
We're not replacing `Path` in exposed definitions in many cases, but
just adding alternatives. This will allow us to "top down" change `Path`
to `std::fileysystem::path`, and then we can remove the `Path`-using
utilities which will become unused.

Also add some test files which we forgot to include in the libutil unit
tests `meson.build`.

Co-Authored-By: siddhantCodes <siddhantk232@gmail.com>
2024-08-26 17:23:56 -04:00

97 lines
3.2 KiB
C++

#include "environment-variables.hh"
#include "executable-path.hh"
#include "strings-inline.hh"
#include "util.hh"
#include "file-path-impl.hh"
namespace nix {
namespace fs {
using namespace std::filesystem;
}
constexpr static const OsStringView path_var_separator{
&ExecutablePath::separator,
1,
};
ExecutablePath ExecutablePath::load()
{
// "If PATH is unset or is set to null, the path search is
// implementation-defined."
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
return ExecutablePath::parse(getEnvOs(OS_STR("PATH")).value_or(OS_STR("")));
}
ExecutablePath ExecutablePath::parse(const OsString & path)
{
auto strings = path.empty() ? (std::list<OsString>{})
: basicSplitString<std::list<OsString>, OsChar>(path, path_var_separator);
std::vector<fs::path> ret;
ret.reserve(strings.size());
std::transform(
std::make_move_iterator(strings.begin()),
std::make_move_iterator(strings.end()),
std::back_inserter(ret),
[](auto && str) {
return fs::path{
str.empty()
// "A zero-length prefix is a legacy feature that
// indicates the current working directory. It
// appears as two adjacent <colon> characters
// ("::"), as an initial <colon> preceding the rest
// of the list, or as a trailing <colon> following
// the rest of the list."
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
? OS_STR(".")
: std::move(str),
};
});
return {ret};
}
OsString ExecutablePath::render() const
{
std::vector<PathViewNG> path2;
for (auto & p : directories)
path2.push_back(p.native());
return basicConcatStringsSep(path_var_separator, path2);
}
std::optional<fs::path>
ExecutablePath::findName(const OsString & exe, std::function<bool(const fs::path &)> isExecutable) const
{
// "If the pathname being sought contains a <slash>, the search
// through the path prefixes shall not be performed."
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
assert(OsPathTrait<fs::path::value_type>::rfindPathSep(exe) == exe.npos);
for (auto & dir : directories) {
auto candidate = dir / exe;
if (isExecutable(candidate))
return std::filesystem::canonical(candidate);
}
return std::nullopt;
}
fs::path ExecutablePath::findPath(const fs::path & exe, std::function<bool(const fs::path &)> isExecutable) const
{
// "If the pathname being sought contains a <slash>, the search
// through the path prefixes shall not be performed."
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03
if (exe.filename() == exe) {
auto resOpt = findName(exe, isExecutable);
if (resOpt)
return *resOpt;
else
throw ExecutableLookupError("Could not find executable '%s'", exe.string());
} else {
return exe;
}
}
} // namespace nix