mirror of
git://sourceware.org/git/lvm2.git
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84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
/*
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* Copyright (C) 2011-2013 Red Hat, Inc.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v.2.1.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include "daemon-io.h"
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#include "libdevmapper.h"
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/*
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* Read a single message from a (socket) filedescriptor. Messages are delimited
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* by blank lines. This call will block until all of a message is received. The
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* memory will be allocated from heap. Upon error, all memory is freed and the
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* buffer pointer is set to NULL.
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*
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* See also write_buffer about blocking (read_buffer has identical behaviour).
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*/
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int buffer_read(int fd, struct buffer *buffer) {
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int result;
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if (!buffer_realloc(buffer, 32)) /* ensure we have some space */
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return 0;
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while (1) {
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result = read(fd, buffer->mem + buffer->used, buffer->allocated - buffer->used);
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if (result > 0) {
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buffer->used += result;
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if (!strncmp((buffer->mem) + buffer->used - 4, "\n##\n", 4)) {
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buffer->used -= 4;
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buffer->mem[buffer->used] = 0;
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break; /* success, we have the full message now */
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}
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if ((buffer->allocated - buffer->used < 32) &&
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!buffer_realloc(buffer, 1024))
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return 0;
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} else if (result == 0) {
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errno = ECONNRESET;
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return 0; /* we should never encounter EOF here */
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} else if (result < 0 && errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR)
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return 0;
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/* TODO call select here if we encountered EAGAIN/EWOULDBLOCK/EINTR */
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}
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return 1;
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}
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/*
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* Write a buffer to a filedescriptor. Keep trying. Blocks (even on
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* SOCK_NONBLOCK) until all of the write went through.
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*
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* TODO use select on EWOULDBLOCK/EAGAIN/EINTR to avoid useless spinning
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*/
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int buffer_write(int fd, const struct buffer *buffer) {
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static const struct buffer _terminate = { .mem = (char *) "\n##\n", .used = 4 };
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const struct buffer *use;
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int done, written, result;
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for (done = 0; done < 2; ++done) {
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use = (done == 0) ? buffer : &_terminate;
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for (written = 0; written < use->used;) {
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result = write(fd, use->mem + written, use->used - written);
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if (result > 0)
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written += result;
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else if (result < 0 && errno != EWOULDBLOCK && errno != EAGAIN && errno != EINTR)
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return 0; /* too bad */
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}
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}
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return 1;
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}
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