diff options
| author | Paul Eggert <eggert@cs.ucla.edu> | 2016-09-10 12:51:27 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2016-09-10 19:14:44 -0700 |
| commit | 9b21d9f9110445846dce25c3505c4ee04572fade (patch) | |
| tree | e133e7d94a10ae19a7f8a4d44974a99151b0ca20 /src | |
| parent | 0fca290ddff9eabcd2e866b1361cd5b5ba868281 (diff) | |
copy-file now uses GNU/Linux file cloning
From a suggestion by Kieran Colford (see Bug#23904).
* configure.ac: Check for linux/fs.h.
* src/fileio.c [HAVE_LINUX_FS_H]: Include sys/ioctl.h and linux/fs.h.
(clone_file): New function.
(Fcopy_file): Use it.
Diffstat (limited to 'src')
| -rw-r--r-- | src/fileio.c | 33 |
1 files changed, 25 insertions, 8 deletions
diff --git a/src/fileio.c b/src/fileio.c index bf6bf622ab..b4316b3da9 100644 --- a/src/fileio.c +++ b/src/fileio.c @@ -52,6 +52,11 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ #include "region-cache.h" #include "frame.h" +#ifdef HAVE_LINUX_FS_H +# include <sys/ioctl.h> +# include <linux/fs.h> +#endif + #ifdef WINDOWSNT #define NOMINMAX 1 #include <windows.h> @@ -1829,6 +1834,16 @@ barf_or_query_if_file_exists (Lisp_Object absname, bool known_to_exist, } } +/* Copy data to DEST from SOURCE if possible. Return true if OK. */ +static bool +clone_file (int dest, int source) +{ +#ifdef FICLONE + return ioctl (dest, FICLONE, source) == 0; +#endif + return false; +} + DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 6, "fCopy file: \nGCopy %s to file: \np\nP", doc: /* Copy FILE to NEWNAME. Both args must be strings. @@ -1975,7 +1990,7 @@ permissions. */) record_unwind_protect_int (close_file_unwind, ofd); - off_t oldsize = 0, newsize = 0; + off_t oldsize = 0, newsize; if (already_exists) { @@ -1991,17 +2006,19 @@ permissions. */) immediate_quit = 1; QUIT; - while (true) + + if (clone_file (ofd, ifd)) + newsize = st.st_size; + else { char buf[MAX_ALLOCA]; - ptrdiff_t n = emacs_read (ifd, buf, sizeof buf); + ptrdiff_t n; + for (newsize = 0; 0 < (n = emacs_read (ifd, buf, sizeof buf)); + newsize += n) + if (emacs_write_sig (ofd, buf, n) != n) + report_file_error ("Write error", newname); if (n < 0) report_file_error ("Read error", file); - if (n == 0) - break; - if (emacs_write_sig (ofd, buf, n) != n) - report_file_error ("Write error", newname); - newsize += n; } /* Truncate any existing output file after writing the data. This |