Source: kfreebsd-9
Severity: important
Tags: upstream
When a write() cannot transfer as many bytes as requested (because of a file
limit), it fails instead of transferring as many bytes as there is room to
write.
This is a violation of the POSIX standard:
http://pubs.opengroup.org/onlinepubs/007904975/functions/write.html
fsize-lim.c (attached) illustrates the problem. With a freebsd kernel, the
output is:
failed when adding 27 bytes after 59994 bytes (error: File too large)
The expected output (like with a linux kernel) should be:
added 6 bytes instead of 27 bytes after 59994 bytes
failed when adding 27 bytes after 60000 bytes (error: File too large)
-- System Information:
Debian Release: wheezy/sid
APT prefers testing
APT policy: (500, 'testing')
Architecture: kfreebsd-amd64 (x86_64)
Kernel: kFreeBSD 9.0-1-amd64
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/dash
#include <unistd.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#define TARGETSIZE 80000
#define LIMSIZE 60000
#define PATTSIZE 27
int main(void)
{
struct rlimit lim;
int fd;
ssize_t retc;
size_t count = 0;
const char pattern[PATTSIZE] = "Hello world!";
signal(SIGXFSZ, SIG_IGN);
lim.rlim_cur = LIMSIZE;
setrlimit(RLIMIT_FSIZE, &lim);
fd = open("result.txt", O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
while (count < TARGETSIZE) {
retc = write(fd, pattern, PATTSIZE);
if (retc < PATTSIZE && retc > 0)
fprintf(stderr,
"added %zi bytes instead of %u bytes after %zu bytes\n",
retc, PATTSIZE, count);
else if (retc < 0) {
fprintf(stderr,
"failed when adding %u bytes after %zu bytes (error: %s)\n",
PATTSIZE, count, strerror(errno));
break;
}
count += retc;
}
close(fd);
return 0;
}
