Commit 9b21d9f9 authored by Paul Eggert's avatar Paul Eggert
Browse files

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.
parent 0fca290d
...@@ -1638,6 +1638,7 @@ fi ...@@ -1638,6 +1638,7 @@ fi
dnl checks for header files dnl checks for header files
AC_CHECK_HEADERS_ONCE( AC_CHECK_HEADERS_ONCE(
linux/fs.h
malloc.h malloc.h
sys/systeminfo.h sys/systeminfo.h
sys/sysinfo.h sys/sysinfo.h
......
...@@ -52,6 +52,11 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */ ...@@ -52,6 +52,11 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include "region-cache.h" #include "region-cache.h"
#include "frame.h" #include "frame.h"
#ifdef HAVE_LINUX_FS_H
# include <sys/ioctl.h>
# include <linux/fs.h>
#endif
#ifdef WINDOWSNT #ifdef WINDOWSNT
#define NOMINMAX 1 #define NOMINMAX 1
#include <windows.h> #include <windows.h>
...@@ -1829,6 +1834,16 @@ barf_or_query_if_file_exists (Lisp_Object absname, bool known_to_exist, ...@@ -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, DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 6,
"fCopy file: \nGCopy %s to file: \np\nP", "fCopy file: \nGCopy %s to file: \np\nP",
doc: /* Copy FILE to NEWNAME. Both args must be strings. doc: /* Copy FILE to NEWNAME. Both args must be strings.
...@@ -1975,7 +1990,7 @@ permissions. */) ...@@ -1975,7 +1990,7 @@ permissions. */)
record_unwind_protect_int (close_file_unwind, ofd); record_unwind_protect_int (close_file_unwind, ofd);
off_t oldsize = 0, newsize = 0; off_t oldsize = 0, newsize;
if (already_exists) if (already_exists)
{ {
...@@ -1991,17 +2006,19 @@ permissions. */) ...@@ -1991,17 +2006,19 @@ permissions. */)
immediate_quit = 1; immediate_quit = 1;
QUIT; QUIT;
while (true)
if (clone_file (ofd, ifd))
newsize = st.st_size;
else
{ {
char buf[MAX_ALLOCA]; char buf[MAX_ALLOCA];
ptrdiff_t n = emacs_read (ifd, buf, sizeof buf); ptrdiff_t n;
if (n < 0) for (newsize = 0; 0 < (n = emacs_read (ifd, buf, sizeof buf));
report_file_error ("Read error", file); newsize += n)
if (n == 0)
break;
if (emacs_write_sig (ofd, buf, n) != n) if (emacs_write_sig (ofd, buf, n) != n)
report_file_error ("Write error", newname); report_file_error ("Write error", newname);
newsize += n; if (n < 0)
report_file_error ("Read error", file);
} }
/* Truncate any existing output file after writing the data. This /* Truncate any existing output file after writing the data. This
......
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