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osdep: make readv_writev() work with partial read/write

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With a pipe or other reasons, read/write may return less than the
requested bytes. This happens with the test-io-channel-command test on
Windows. glib spawn code uses a binary pipe of 4096 bytes, and the first
read returns that much (although more are requested), for some unclear
reason...

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20221006113657.2656108-2-marcandre.lureau@redhat.com>
This commit is contained in:
Marc-André Lureau 2022-10-06 15:36:52 +04:00
parent 4db99c9d9c
commit c1f7980913
1 changed files with 8 additions and 3 deletions
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11
util/osdep.c
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@ -538,18 +538,22 @@ int socket_init(void)
#ifndef CONFIG_IOVEC #ifndef CONFIG_IOVEC
/* helper function for iov_send_recv() */
static ssize_t static ssize_t
readv_writev(int fd, const struct iovec *iov, int iov_cnt, bool do_write) readv_writev(int fd, const struct iovec *iov, int iov_cnt, bool do_write)
{ {
unsigned i = 0; unsigned i = 0;
ssize_t ret = 0; ssize_t ret = 0;
ssize_t off = 0;
while (i < iov_cnt) { while (i < iov_cnt) {
ssize_t r = do_write ssize_t r = do_write
? write(fd, iov[i].iov_base, iov[i].iov_len) ? write(fd, iov[i].iov_base + off, iov[i].iov_len - off)
: read(fd, iov[i].iov_base, iov[i].iov_len); : read(fd, iov[i].iov_base + off, iov[i].iov_len - off);
if (r > 0) { if (r > 0) {
ret += r; ret += r;
off += r;
if (off < iov[i].iov_len) {
continue;
}
} else if (!r) { } else if (!r) {
break; break;
} else if (errno == EINTR) { } else if (errno == EINTR) {
@ -562,6 +566,7 @@ readv_writev(int fd, const struct iovec *iov, int iov_cnt, bool do_write)
} }
break; break;
} }
off = 0;
i++; i++;
} }
return ret; return ret;