nix-super/src/libutil/filesystem.cc
Théophane Hufschmitt 6f89fb6008 rename: Fallback to a copy if the filesystems mismatch
In `nix::rename`, if the call to `rename` fails with `EXDEV` (failure
because the source and the destination are in a different filesystems)
switch to copying and removing the source.

To avoid having to re-implement the copy manually, I switched the
function to use the c++17 `filesystem` library (which has a `copy`
function that should do what we want).

Fix #6262
2022-08-03 10:27:25 +02:00

60 lines
1.5 KiB
C++

#include <sys/time.h>
#include <filesystem>
#include "util.hh"
#include "types.hh"
namespace fs = std::filesystem;
namespace nix {
void createSymlink(const Path & target, const Path & link,
std::optional<time_t> mtime)
{
if (symlink(target.c_str(), link.c_str()))
throw SysError("creating symlink from '%1%' to '%2%'", link, target);
if (mtime) {
struct timeval times[2];
times[0].tv_sec = *mtime;
times[0].tv_usec = 0;
times[1].tv_sec = *mtime;
times[1].tv_usec = 0;
if (lutimes(link.c_str(), times))
throw SysError("setting time of symlink '%s'", link);
}
}
void replaceSymlink(const Path & target, const Path & link,
std::optional<time_t> mtime)
{
for (unsigned int n = 0; true; n++) {
Path tmp = canonPath(fmt("%s/.%d_%s", dirOf(link), n, baseNameOf(link)));
try {
createSymlink(target, tmp, mtime);
} catch (SysError & e) {
if (e.errNo == EEXIST) continue;
throw;
}
moveFile(tmp, link);
break;
}
}
void moveFile(const Path & oldName, const Path & newName)
{
auto oldPath = fs::path(oldName);
auto newPath = fs::path(newName);
try {
fs::rename(oldPath, newPath);
} catch (fs::filesystem_error & e) {
if (e.code().value() == EXDEV) {
fs::copy(oldName, newName, fs::copy_options::copy_symlinks);
fs::remove_all(oldName);
}
}
}
}