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Don't use mmap() for non-regular files, since st_size is only meaningful

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for regular files.  This fixes recent breakage of cp'ing from /dev/zero.
/dev/zero doesn't support mmap(), but the device driver mmap routines are
not called for mapping 0 bytes, so the error was not detected.  mmap()
can't even be used for cp'ing special files that support mmap(), since
there is general way to determine the file size.
This commit is contained in:
Bruce Evans 1998-11-18 11:47:45 +00:00
parent 4f699173cb
commit 40fc4ee2de
1 changed files with 2 additions and 2 deletions
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4
bin/cp/utils.c
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@ -36,7 +36,7 @@
static char sccsid[] = "@(#)utils.c 8.3 (Berkeley) 4/1/94";
#endif
static const char rcsid[] =
"$Id: utils.c,v 1.19 1998/06/09 03:38:26 imp Exp $";
"$Id: utils.c,v 1.20 1998/06/10 06:29:23 peter Exp $";
#endif /* not lint */
#include <sys/param.h>
@ -124,7 +124,7 @@ copy_file(entp, dne)
* wins some CPU back.
*/
#ifdef VM_AND_BUFFER_CACHE_SYNCHRONIZED
if (fs->st_size <= 8 * 1048576) {
if (S_ISREG(fs->st_mode) && fs->st_size <= 8 * 1048576) {
if ((p = mmap(NULL, (size_t)fs->st_size, PROT_READ,
MAP_SHARED, from_fd, (off_t)0)) == MAP_FAILED) {
warn("%s", entp->fts_path);