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cp: fall back to read/write if copy_file_range fails

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Even though copy_file_range has a file-system agnostic version, it still
fails on devfs (perhaps because the file descriptor is non-seekable?) In
that case, fallback to old-fashioned read/write. Fixes
"cp /dev/null /tmp/null"

PR:		249248
Reported by:	Michael Butler
Reviewed by:	mjg
MFC-With:	365549
Differential Revision:	https://reviews.freebsd.org/D26395
This commit is contained in:
Alan Somers 2020-09-11 20:49:36 +00:00
parent d8dc46f6e9
commit 1ea95ba231
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=365643
1 changed files with 35 additions and 4 deletions
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39
bin/cp/utils.c
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@ -74,6 +74,26 @@ __FBSDID("$FreeBSD$");
*/
#define BUFSIZE_SMALL (MAXPHYS)
static int
copy_fallback(int from_fd, int to_fd, char *buf, size_t bufsize)
{
int rcount;
ssize_t wresid, wcount = 0;
char *bufp;
rcount = read(from_fd, buf, bufsize);
if (rcount <= 0)
return (rcount);
for (bufp = buf, wresid = rcount; ; bufp += wcount, wresid -= wcount) {
wcount = write(to_fd, bufp, wresid);
if (wcount <= 0)
break;
if (wcount >= (ssize_t)wresid)
break;
}
return (wcount < 0 ? wcount : rcount);
}
int
copy_file(const FTSENT *entp, int dne)
{
@ -88,6 +108,7 @@ copy_file(const FTSENT *entp, int dne)
#ifdef VM_AND_BUFFER_CACHE_SYNCHRONIZED
char *p;
#endif
int use_copy_file_range = 1;
from_fd = to_fd = -1;
if (!lflag && !sflag &&
@ -212,9 +233,19 @@ copy_file(const FTSENT *entp, int dne)
err(1, "Not enough memory");
}
wtotal = 0;
while ((rcount = copy_file_range(from_fd, NULL,
to_fd, NULL, bufsize, 0)) > 0)
{
do {
if (use_copy_file_range) {
rcount = copy_file_range(from_fd, NULL,
to_fd, NULL, bufsize, 0);
if (rcount < 0 && errno == EINVAL) {
/* Prob a non-seekable FD */
use_copy_file_range = 0;
}
}
if (!use_copy_file_range) {
rcount = copy_fallback(from_fd, to_fd,
buf, bufsize);
}
wtotal += rcount;
if (info) {
info = 0;
@ -223,7 +254,7 @@ copy_file(const FTSENT *entp, int dne)
entp->fts_path, to.p_path,
cp_pct(wtotal, fs->st_size));
}
}
} while (rcount > 0);
if (rcount < 0) {
warn("%s", entp->fts_path);
rval = 1;