mirror of
git://sourceware.org/git/lvm2.git
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124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
#include <errno.h>
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#include <stdio.h>
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#include <malloc.h>
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#include <string.h>
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#include <unistd.h>
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#include <assert.h>
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#include "daemon-shared.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 read_buffer(int fd, char **buffer) {
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int bytes = 0;
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int buffersize = 32;
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char *new;
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char *end;
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*buffer = malloc(buffersize + 1);
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while (1) {
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int result = read(fd, (*buffer) + bytes, buffersize - bytes);
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if (result > 0)
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bytes += result;
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if (result == 0)
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goto fail; /* we should never encounter EOF here */
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if (result < 0 && errno != EAGAIN && errno != EWOULDBLOCK)
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goto fail;
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if ((!strncmp((*buffer) + bytes - 4, "\n##\n", 4))) {
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*(*buffer + bytes - 4) = 0;
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break; /* success, we have the full message now */
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}
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if (bytes == buffersize) {
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buffersize += 1024;
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if (!(new = realloc(*buffer, buffersize + 1)))
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goto fail;
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*buffer = new;
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}
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/* TODO call select here if we encountered EAGAIN/EWOULDBLOCK */
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}
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return 1;
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fail:
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free(*buffer);
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*buffer = NULL;
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return 0;
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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 to avoid useless spinning
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*/
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int write_buffer(int fd, const char *buffer, int length) {
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int done = 0;
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int written = 0;
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write:
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while (1) {
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int result = write(fd, buffer + written, length - written);
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if (result > 0)
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written += result;
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if (result < 0 && errno != EWOULDBLOCK && errno != EAGAIN)
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return 0; /* too bad */
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if (written == length) {
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if (done)
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return 1;
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else
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break; /* done */
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}
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}
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const char *terminate = "\n##\n";
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buffer = terminate;
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length = 4;
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written = 0;
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done = 1;
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goto write;
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}
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char *format_buffer(const char *what, const char *id, va_list ap)
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{
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char *buffer, *old;
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char *next;
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int keylen;
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dm_asprintf(&buffer, "%s = \"%s\"\n", what, id);
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if (!buffer) goto fail;
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while ((next = va_arg(ap, char *))) {
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old = buffer;
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assert(strchr(next, '='));
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keylen = strchr(next, '=') - next;
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if (strstr(next, "%d")) {
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int value = va_arg(ap, int);
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dm_asprintf(&buffer, "%s%.*s= %d\n", buffer, keylen, next, value);
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dm_free(old);
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} else if (strstr(next, "%s")) {
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char *value = va_arg(ap, char *);
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dm_asprintf(&buffer, "%s%.*s= \"%s\"\n", buffer, keylen, next, value);
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dm_free(old);
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} else if (strstr(next, "%b")) {
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char *block = va_arg(ap, char *);
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if (!block)
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continue;
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dm_asprintf(&buffer, "%s%.*s%s", buffer, keylen, next, block);
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dm_free(old);
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} else {
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dm_asprintf(&buffer, "%s%s", buffer, next);
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dm_free(old);
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}
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if (!buffer) goto fail;
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}
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return buffer;
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fail:
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dm_free(buffer);
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return NULL;
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}
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