On Jan 15 09:12, Brian Inglis via Cygwin wrote: > On 2025-01-14 03:13, Roland Mainz via Cygwin wrote: > > On Tue, Jan 14, 2025 at 7:19 AM Brian Inglis via Cygwin > > <cygwin@cygwin.com> wrote: > > > On 2025-01-13 13:10, Roland Mainz via Cygwin wrote: > > > > I just hit an endless loop with /usr/bin/cp from "coreutils" version > > > > 9.5-1 copying a larger *.pdb file (it seems that only this specific > > > > file is affected...) from Visual Studio 19. > > > > [...] > > I think I found the problem: > > The *.pdb file uses NTFS compression: > > ---- snip ---- > > /bin/winfsinfo filebasicinfo "$(cygpath -w > > $PWD/../build.vc19/x64/Debug/nfs41_driver.pdb)" > > ( > > > > filename='C:\cygwin64\home\roland_mainz\work\msnfs41_uidmapping\ms-nfs41-client-kofemannvacation\build.vc19\x64\Debug\nfs41_driver.pdb' > > CreationTime=133812707624654816 > > LastAccessTime=133813220892976366 > > LastWriteTime=133812707639811081 > > ChangeTime=133812707639811081 > > typeset -a FileAttributes=( > > FILE_ATTRIBUTE_ARCHIVE > > FILE_ATTRIBUTE_COMPRESSED > > ) > > ) > > ---- snip ---- > > > > If I remove the "FILE_ATTRIBUTE_COMPRESSED" flag /bin/cp works without > > problems. > > I think the issues here are: > > 1. Coreutils 9.5-1 /bin/cp erroneously assumes that a file is sparse > > if the number of blocks is smaller than $((filesize / fs_blocksize)) - > > but in this case the file is NOT sparse, just compressed. > > 2. The loop to copy a sparse file is faulty because there are no holes > > in that file. That itself is IMHO already a bad idea to have a > > separate codepath for sparse files, just the normal codepath should > > use SEEK_HOLE and just skip those in the destination > > A possible issue is that Cygwin assumes sparse files on SSD
No, that's not the problem, because SPARSE handling requires that the FILE_ATTRIBUTE_SPARSE_FILE flag of the file is actually set. For instance, see lseek w/ SEEK_DATA/SEEK_HOLE, which handles non-sparse files as documented by the Linux man page https://man7.org/linux/man-pages/man2/lseek.2.html: if (!has_attribute (FILE_ATTRIBUTE_SPARSE_FILE)) { /* Default behaviour if sparse files are not supported: SEEK_DATA: seek to offset SEEK_HOLE: seek to EOF */ fpi.CurrentByteOffset.QuadPart = (whence == SEEK_DATA) ? offset : fsi.EndOfFile.QuadPart; break; } > so we need > fhandler/disk_file:fstat_helper to allow cp to handle compressed files > normally. Say again? What exactly are you expecting from stat()? Fibbing about the number of blocks taken by a FS-compressed file? For the time being, it seems the assumption that #blocks * blocksize < filesize is not really correct. Actually cp(1) should test if lseek(SEEK_HOLE) returns EOF. If so, the file isn't sparse. On Cygwin it could also check with (ioctl (fd, FS_IOC_GETFLAGS, &flags) & FS_SPARSE_FL) != 0 that the file is sparse, but the lseek test is target-independent. On Cygwin and Linux you could also test with (ioctl (fd, FS_IOC_GETFLAGS, &flags) & FS_COMPR_FL) != 0 that the file is compressed, but there's a problem so far. The Linux flag is called FS_COMPR_FL but the Cygwin flag is called FS_COMPRESSED_FL. THis flag is only supported on btrfs and I'm not sure it already existed when I added FS_IOC_GETFLAGS... Anyway, I'll change FS_COMPR_FL to FS_COMPRESSED_FL and make FS_COMPRESSED_FL an alias for backward compat... Corinna -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
