On modern file-systems (BTRFS, ZFS) it is possible to copy a file using
copy-on-write method. For large files it has the advantage of being
much faster and saving disk space (since identical extents are not
duplicated). This feature is stable and for example coreutils' `cp'
does use it automatically (see --reflink).
This commit adds support for this feature into our copy-file procedure.
Same as `cp', it defaults to 'auto, meaning the copy-on-write is
attempted, and in case of failure the regular copy is performed.
No tests are provided, because the behavior depends on the system,
underlying file-system and its configuration. That makes it challenging
to write a test for it. Manual testing was performed instead:
$ btrfs filesystem du /tmp/cow*
Total Exclusive Set shared Filename
36.00KiB 36.00KiB 0.00B /tmp/cow
$ cat cow-test.scm
(copy-file "/tmp/cow" "/tmp/cow-unspecified")
(copy-file "/tmp/cow" "/tmp/cow-always" #:copy-on-write 'always)
(copy-file "/tmp/cow" "/tmp/cow-auto" #:copy-on-write 'auto)
(copy-file "/tmp/cow" "/tmp/cow-never" #:copy-on-write 'never)
(copy-file "/tmp/cow" "/dev/shm/cow-unspecified")
(copy-file "/tmp/cow" "/dev/shm/cow-auto" #:copy-on-write 'auto)
(copy-file "/tmp/cow" "/dev/shm/cow-never" #:copy-on-write 'never)
$ ./meta/guile -s cow-test.scm
$ btrfs filesystem du /tmp/cow*
Total Exclusive Set shared Filename
36.00KiB 0.00B 36.00KiB /tmp/cow
36.00KiB 0.00B 36.00KiB /tmp/cow-always
36.00KiB 0.00B 36.00KiB /tmp/cow-auto
36.00KiB 36.00KiB 0.00B /tmp/cow-never
36.00KiB 0.00B 36.00KiB /tmp/cow-unspecified
$ sha1sum /tmp/cow* /dev/shm/cow*
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /tmp/cow
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /tmp/cow-always
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /tmp/cow-auto
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /tmp/cow-never
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /tmp/cow-unspecified
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /dev/shm/cow-auto
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /dev/shm/cow-never
4c665f87b5dc2e7d26279c4b48968d085e1ace32 /dev/shm/cow-unspecified
This commit also adds to new failure modes for (copy-file).
Failure to copy-on-write when 'always was passed in:
scheme@(guile-user)> (copy-file "/tmp/cow" "/dev/shm/cow" #:copy-on-write 'always)
ice-9/boot-9.scm:1676:22: In procedure raise-exception:
In procedure copy-file: copy-on-write failed: Invalid cross-device link
Passing in invalid value for the #:copy-on-write keyword argument:
scheme@(guile-user)> (copy-file "/tmp/cow" "/dev/shm/cow" #:copy-on-write 'nevr)
ice-9/boot-9.scm:1676:22: In procedure raise-exception:
In procedure copy-file: invalid value for #:copy-on-write: nevr
* NEWS: Add note for copy-file supporting copy-on-write.
* configure.ac: Check for linux/fs.h.
* doc/ref/posix.texi (File System)[copy-file]: Document the new
signature.
* libguile/filesys.c (clone_file): New function cloning a file using
FICLONE, if supported.
(k_copy_on_write): New keyword.
(sym_always, sym_auto, sym_never): New symbols.
(scm_copy_file2): Renamed from scm_copy_file. New #:copy-on-write
keyword argument. Attempt copy-on-write copy by default.
(scm_copy_file): Call scm_copy_file2.
* libguile/filesys.h: Add scm_copy_file2 as SCM_INTERNAL.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac: Detect if ‘openat’ is defined.
* libguile/filesys.c
(flags_to_mode): Extract from ...
(scm_mode): ... here.
(scm_open_fdes_at, scm_openat): Define the Scheme bindings.
* libguile/filesys.h (scm_open_fdes_at, scm_openat): Make them part
of the API.
* doc/ref/posix.texi (File System): Document them.
* test-suite/tests/filesys.test ("openat"): Test ‘openat’.
* libguile/syscalls.h (openat_or_openat64): Decide between ‘openat’
and ‘openat64’.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac: Detect if ‘fstatat’ is defined.
* libguile/filesys.c (scm_statat): Define a Scheme binding to ‘fstatat’.
* libguile/filesys.h (scm_statat): Make it part of the C API.
* doc/ref/posix.texi (File System): Document it.
* libguile/syscalls.h (fstatat_or_fstatat64): Choose between ‘fstatat’
and ‘fstatat64’.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac: Detect whether ‘fchownat’ is available.
* libguile/filesys.c (scm_chownat): Define a Scheme binding to
‘fchownat’ when available.
* libguile/filesys.h (scm_chownat): Make it part of the API.
* doc/ref/posix.texi (File System): Document it.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
‘unlinkat’ is used for both unlinking regular files
and removing empty directories.
* configure.ac: Detect if ‘unlinkat’ exists.
* doc/ref/posix.texi (File System): Document why there is no
‘rmdirat’ procedure, and document the ‘delete-file-at’ procedure.
* libguile/filesys.c
(scm_rmdir): Adjust the docstring here as well.
(scm_delete_file_at): Define a Scheme binding to ‘unlinkat’.
* libguile/filesys.h (scm_delete_file_at): Make ‘scm_delete_file_at’
part of the C API.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac: Detect existence of fchmodat.
* libguile/filesys.c (scm_chmodat): New procedure.
* libguile/filesys.h (scm_chmodat): Make it part of the API.
* test-suite/tests/filesys.test ("chmodat"): Test it.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac: Detect if ‘renameat’ is defined.
* libguile/filesys.c (scm_renameat): Define a Scheme binding
to the ‘renameat’ system call.
* doc/ref/posix.texi (File System): Document it.
* libguile/filesys.h (scm_renameat): Make it part of the C API.
* test-suite/tests/filesys.test ("rename-file-at"): New tests.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac: Detect whether ‘symlinkat’ exists.
* libguile/filesys.c (scm_symlinkat): Define a Scheme binding
when it exists.
* libguile/filesys.h: Make the binding part of the public C API.
* doc/ref/posix.texi (File System): Document the binding.
* test-suite/tests/filesys.test ("symlinkat"): Test it.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
* configure.ac (AC_CHECK_FUNCS): add mkdtemp! test
* doc/ref/posix.texi: document mkdtemp!
* libguile/filesys.c (scm_mkdtemp_x): new function
* libguile/filesys.h: new declaration for scm_mkdtemp_x
* test-suite/tests/filesys.test: add tests for mkdtemp!
Adapted from a patch by Rob Browning.
The underlying function was moved to filesys.c in
073167ef7b but the declaration didn't follow
* libguile/filesys.h: add declaration for scm_mkstemp
* libguile/posix.h: remove declaration for scm_mkstemp
As the FSF advises, 'There is no legal significance to using the
three-character sequence “(C)”, but it does no harm.' It does take up
space though! For that reason, we remove it here from our C files.
* configure.ac: Check for <sys/sendfile.h> and `sendfile'.
* libguile/filesys.c (scm_sendfile): New function.
* libguile/filesys.h (scm_sendfile): New declaration.
* test-suite/tests/filesys.test ("sendfile"): New test prefix.
* doc/ref/posix.texi (File System): Document `sendfile'.
* libguile/filesys.h:
* libguile/filesys.c (scm_i_relativize_path): New function, moved here
from fports.c. Internal for now; we can make it external though if
people like its interface.
* libguile/fports.c (fport_canonicalize_filename): Move all of the
tricky bits to filesys.c. Also fixes a bug in which a delimiter wasn't
stripped.
* libguile/filesys.h:
* libguile/filesys.c (scm_canonicalize_path): New function,
canonicalize-path.
* module/system/base/compile.scm (compiled-file-name): Canonicalize the
filename so that compiling e.g. ../foo.scm doesn't compile to
~/.guile-ccache/1.9/../foo.scm.
* libguile/filesys.h:
* libguile/filesys.c (scm_stat): Add optional arg, exception-on-error,
which if #f (not the default) will just return #f instead of raising an
exception if the stat fails.
* ports.c (scm_port_for_each): new proc. implements port-for-each,
which applies a procedure to each port in the port table.
ports.h: declare scm_port_for_each.
* ioext.c (scm_dup2): new proc. implements "dup2" which is a simple
wrapper for the dup2 system call (unlike dup->fdes or
primitive-move->fdes).
* ioext.h: declare scm_dup2.
* filesys.c (scm_close_fdes): new proc. implements "close-fdes"
which is a simple wrapper for close system call (unlike scm_close).
* filesys.h: declare for scm_close_fdes.
name for a Scheme object (now a void*), and SCM as 32 bit word for
storing tags and immediates (now a long int). Introduced
SCM_ASWORD and SCM_ASSCM for conversion. Fixed various dubious
code in the process: arbiter.c (use macros), unif.c (scm_array_p),
added append docs from R4RS.
* strings.c: Docstring typo fix, + eliminate unneeded IMP tests.
Thanks Dirk Hermann!
* chars.h: Provide SCM_CHARP, SCM_CHAR, SCM_MAKE_CHAR and
deprecate SCM_ICHRP, SCM_ICHR, SCM_MAKICHR. Thanks Dirk Hermann!
* *.h, *.c: Use SCM_CHARP, SCM_CHAR, SCM_MAKE_CHAR throughout.
Drop use of SCM_P for function prototypes... assume an ANSI C
compiler. Thanks Dirk Hermann!
"directory" to "directory stream". A predicate named "directory?"
would be confusing.
* filesys.c (scm_directory_stream_p): Renamed from scm_directory_p.
At the Scheme level, "directory?" -> "directory-stream?".
(scm_dir_print): Use the phrase "directory stream" in printed form.
* filesys.h (scm_directory_stream_p): Prototype renamed
accordingly.
* filesys.c (scm_directory_p): new procedure "directory?" Returns
a boolean indicating whether its argument is a directory
port as returned by opendir (thanks to Dirk Herrmann for the
suggestion.)
* gdbint.c (gdb_print, gdb_read): call scm_truncate_file.
* ports.c (scm_truncate_file): renamed from scm_ftruncate.
allow the 1st argument to be a fdes or filename as well as a
port (as in the filesys.c version).
* filesys.c (scm_truncate_file): removed.
