https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=288985
Bug ID: 288985
Summary: [regression 14.2] copy_file_range fails to update
inoffp and outoffp
Product: Base System
Version: 14.3-RELEASE
Hardware: Any
OS: Any
Status: New
Severity: Affects Only Me
Priority: ---
Component: kern
Assignee: [email protected]
Reporter: [email protected]
Ref: https://bugreports.qt.io/browse/QTBUG-138570
Testcase:
#include <sys/types.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char **argv)
{
if (argc < 2) {
puts("usage: copyfilerangetest src dst");
return 0;
}
int src = open(argv[1], O_RDONLY);
int dst = open(argv[2], O_WRONLY | O_CREAT, 0777);
off_t srcoffset = 0;
off_t dstoffset = 0;
ssize_t copied;
do {
copied = copy_file_range(src, &srcoffset, dst, &dstoffset, SSIZE_MAX,
0);
} while (copied < 0);
printf("copied %zd bytes (srcoffset now %ld dstoffset now %ld)\n",
copied, srcoffset, dstoffset);
}
Execute:
echo hello > foo
./a.out foo bar
If you run this on 14.2, it will say "copied 6 bytes (srcoffset now 6 dstoffset
now 6)". If you run this on 14.3, it will say "srcoffset now 0 dstoffset now
0".
This broke the Qt implementation which relied on a similar loop to the above to
copy a full file, if interruptions might happen:
do {
copied = ::copy_file_range(srcfd, &srcoffset, dstfd, &dstoffset,
SSIZE_MAX, 0);
} while (copied > 0 || (copied < 0 && errno == EINTR));
Because srcoffset = 0 on return, we ended up copying the same bytes over and
over again.
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