Date: Wed, 7 Jul 2010 10:24:41 -0700 From: "Ming Fu" <Ming.Fu@watchguard.com> To: <freebsd-net@freebsd.org> Subject: kern/123095 kern/131602 sendfile Message-ID: <7C3D15DD6E8F464998CA1470D8A322F302BB9F72@ES02CO.wgti.net>
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Hi,
I was trying to use sendfile and hit with problem very similar to the
123095 and 131602.=20
It seems that when the file is large enough (in megs), the file can be
corrupted even if it is open read-only and exist on disk as read-only
file, though the filesystem is mounted read-write.
I have a small program to reliably reproduce the problem.
---------- corrupt.c -----------------
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <strings.h>
#include <stdio.h>
#include <err.h>
main () {
int s, f;
struct sockaddr_in addr;
int flags;
char str[32]=3D"\r\n800\r\n";
char *p =3D str;
struct stat sb;
int n;
fd_set wset;
int64_t size;
off_t sbytes;
off_t sent =3D 0;
int chunk;
s =3D socket(AF_INET, SOCK_STREAM, 0);
bzero(&addr, sizeof(addr));
addr.sin_family =3D AF_INET;
addr.sin_port =3D htons(7000);
addr.sin_addr.s_addr =3D inet_addr("10.1.19.16");
n =3D connect(s, (struct sockaddr *)&addr, sizeof (addr));
if (n < 0)
warn ("fail to connect");
flags =3D fcntl(s, F_GETFL);
flags |=3D O_NONBLOCK;
fcntl(s, F_SETFL);
f =3D open("large", O_RDONLY);
if (f<0)
warn("fail to open file");
n =3D fstat(f, &sb);
if (n<0)
warn("fstat failed");
size =3D sb.st_size;
chunk =3D 0;
while (size > 0) {
FD_ZERO(&wset);
FD_SET(s, &wset);
n =3D select(f+1, NULL, &wset, NULL, NULL);
if (n < 0)
continue;
if (chunk > 0) {
sbytes =3D 0;
n =3D sendfile(f, s, sent, chunk, NULL, &sbytes,
0);
if (n < 0)
continue;
chunk -=3D sbytes;
size -=3D sbytes;
sent +=3D sbytes;
continue;
}
if (size > 2048)
chunk =3D 2048;
else
chunk =3D size;
n =3D sprintf(str, "\r\n%x\r\n", 2048);
p =3D str;
write(s, p, n);
}
}
------------- end ---------------------------------------------
Run nc to receive the sendfile
$ nc -l 7000
Copy a large from for sendfile to send
$ cp /usr/lib/libc_pic.a large
$ md5 large
MD5 (large) =3D 252def82f9d75df11df7123e9fd376f6
$ cc -o co corrupt.c
$./co
$ md5 large=20
MD5 (large) =3D 81ee84e55f4611434459f637c83b892e
I run this on 8.0-RELEASE. The same happens on 7.2 and 6.3. The disk are
SATA ide. I run all these command under unprivileged user account. I
also run the same program on several different hardware, the result is
the same. Although the corrupted file is not the same. The corruption
looks random to me.
I know a bit of the network side of FreeBSD kernel code, but the I have
no idea how the filesystem side work. I can dig a bit further if someone
give me a hint as where to look.
Best Regards,
Ming
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