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Merge branch 'upstream-KWSys' into update-kwsys

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# By KWSys Upstream
* upstream-KWSys:
  KWSys 2025-01-16 (843e99e2)
This commit is contained in:
Brad King
2025-01-16 11:52:07 -05:00
parent 1d5c1b0023 5224aabf05
commit 889ebedf81
1 changed files with 36 additions and 13 deletions
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49
Source/kwsys/SystemTools.cxx
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@@ -2445,16 +2445,25 @@ SystemTools::CopyStatus SystemTools::CopyFileContentBlockwise(
}
/**
* Clone the source file to the destination file
* Attempt to copy source file to the destination file using
* operating system mechanisms.
*
* If available, the Linux FICLONE ioctl is used to create a check
* copy-on-write clone of the source file.
* If available, copy-on-write/clone will be used.
* On Linux, the FICLONE ioctl is used to create a clone of the source file.
* On macOS, the copyfile() call is used to make a clone of the file, and
* it will fall back to a regular copy if that's not possible.
*
* The method returns false for the following cases:
* - The code has not been compiled on Linux or the ioctl was unknown
* - The source and destination is on different file systems
* - The underlying filesystem does not support file cloning
* - An unspecified error occurred
* This function will follow symlinks (ie copy the file being
* pointed-to, not the symlink itself), and the resultant
* file will be owned by the uid of this process. It will overwrite
* an existing destination file.
*
* Examples of why this method may fail -
* - We're running on an OS for which this method is not implemented.
* - The underlying OS won't do a copy for us, and -
* - The source and destination are on different file systems
* thus a clone is not possible.
* - The underlying filesystem does not support file cloning.
*/
SystemTools::CopyStatus SystemTools::CloneFileContent(
std::string const& source, std::string const& destination)
@@ -2493,12 +2502,26 @@ SystemTools::CopyStatus SystemTools::CloneFileContent(
// NOTE: we cannot use `clonefile` as the {a,c,m}time for the file needs to
// be updated by `copy_file_if_different` and `copy_file`.
// These flags are meant to be COPYFILE_METADATA | COPYFILE_CLONE, but CLONE
// forces COPYFILE_NOFOLLOW_SRC and that violates the invariant that this
// should result in a file.
//
// COPYFILE_CLONE forces COPYFILE_NOFOLLOW_SRC and that violates the
// invariant that this should result in a file. We used to manually specify
// COPYFILE_EXCL | COPYFILE_STAT | COPYFILE_XATTR | COPYFILE_DATA here, but
// what the copyfile() manpage does not tell you is that COPYFILE_DATA
// appears to disable cloning all together. Instead, explicitly reject
// copying symlinks here.
//
// COPYFILE_CLONE implies a few flags, including COPYFILE_EXCL.
// We add COPYFILE_UNLINK to be consistent with the Linux implementation
// above, as well as CopyFileContentBlockwise(). This will remove the
// destination file before cloning, allowing this call to complete
// if the destination file already exists.
//
if (SystemTools::FileIsSymlink(source)) {
return CopyStatus{ Status::POSIX(ENOSYS), CopyStatus::NoPath };
}
if (copyfile(source.c_str(), destination.c_str(), nullptr,
COPYFILE_METADATA | COPYFILE_EXCL | COPYFILE_STAT |
COPYFILE_XATTR | COPYFILE_DATA) < 0) {
COPYFILE_METADATA | COPYFILE_CLONE | COPYFILE_UNLINK) < 0) {
return CopyStatus{ Status::POSIX_errno(), CopyStatus::NoPath };
}
# if KWSYS_CXX_HAS_UTIMENSAT