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/*
* Copyright (C) 2011-2013 Red Hat, Inc.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#define _REENTRANT
#include "tool.h"
#include "daemon-io.h"
#include <errno.h>
/*
* Read a single message from a (socket) filedescriptor. Messages are delimited
* by blank lines. This call will block until all of a message is received. The
* memory will be allocated from heap. Upon error, all memory is freed and the
* buffer pointer is set to NULL.
*
* See also write_buffer about blocking (read_buffer has identical behaviour).
*/
int buffer_read(int fd, struct buffer *buffer) {
int result;
if (!buffer_realloc(buffer, 32)) /* ensure we have some space */
return 0;
while (1) {
result = read(fd, buffer->mem + buffer->used, buffer->allocated - buffer->used);
if (result > 0) {
buffer->used += result;
if (buffer->used >= 4 && !strncmp((buffer->mem) + buffer->used - 4, "\n##\n", 4)) {
buffer->used -= 4;
buffer->mem[buffer->used] = 0;
break; /* success, we have the full message now */
}
if ((buffer->allocated - buffer->used < 32) &&
!buffer_realloc(buffer, 1024))
return 0;
} else if (result == 0) {
errno = ECONNRESET;
return 0; /* we should never encounter EOF here */
} else if (result < 0 && ( errno == EAGAIN || errno == EWOULDBLOCK ||
errno == EINTR || errno == EIO)) {
fd_set in;
FD_ZERO(&in);
FD_SET(fd, &in);
/* ignore the result, this is just a glorified sleep */
select(FD_SETSIZE, &in, NULL, NULL, NULL);
} else if (result < 0)
return 0;
}
return 1;
}
/*
* Write a buffer to a filedescriptor. Keep trying. Blocks (even on
* SOCK_NONBLOCK) until all of the write went through.
*/
int buffer_write(int fd, const struct buffer *buffer) {
static const struct buffer _terminate = { .mem = (char *) "\n##\n", .used = 4 };
const struct buffer *use;
int done, written, result;
for (done = 0; done < 2; ++done) {
use = (done == 0) ? buffer : &_terminate;
for (written = 0; written < use->used;) {
result = write(fd, use->mem + written, use->used - written);
if (result > 0)
written += result;
else if (result < 0 && ( errno == EAGAIN || errno == EWOULDBLOCK ||
errno == EINTR || errno == EIO)) {
fd_set out;
FD_ZERO(&out);
FD_SET(fd, &out);
/* ignore the result, this is just a glorified sleep */
select(FD_SETSIZE, NULL, &out, NULL, NULL);
} else if (result < 0)
return 0; /* too bad */
}
}
return 1;
}
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