diff options
Diffstat (limited to 'libdaemon/client/daemon-io.c')
-rw-r--r-- | libdaemon/client/daemon-io.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/libdaemon/client/daemon-io.c b/libdaemon/client/daemon-io.c new file mode 100644 index 000000000..4af9343f8 --- /dev/null +++ b/libdaemon/client/daemon-io.c @@ -0,0 +1,99 @@ +/* + * Copyright (C) 2011-2012 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 + */ + +#include <errno.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> + +#include "daemon-io.h" +#include "dm-logging.h" +#include "libdevmapper.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 read_buffer(int fd, char **buffer) { + int bytes = 0; + int buffersize = 32; + char *new; + *buffer = dm_malloc(buffersize + 1); + + while (1) { + int result = read(fd, (*buffer) + bytes, buffersize - bytes); + if (result > 0) { + bytes += result; + if (!strncmp((*buffer) + bytes - 4, "\n##\n", 4)) { + *(*buffer + bytes - 4) = 0; + break; /* success, we have the full message now */ + } + if (bytes == buffersize) { + buffersize += 1024; + if (!(new = realloc(*buffer, buffersize + 1))) + goto fail; + *buffer = new; + } + continue; + } + if (result == 0) { + errno = ECONNRESET; + goto fail; /* we should never encounter EOF here */ + } + if (result < 0 && errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR) + goto fail; + /* TODO call select here if we encountered EAGAIN/EWOULDBLOCK/EINTR */ + } + return 1; +fail: + dm_free(*buffer); + *buffer = NULL; + return 0; +} + +/* + * Write a buffer to a filedescriptor. Keep trying. Blocks (even on + * SOCK_NONBLOCK) until all of the write went through. + * + * TODO use select on EWOULDBLOCK/EAGAIN/EINTR to avoid useless spinning + */ +int write_buffer(int fd, const char *buffer, int length) { + static const char terminate[] = "\n##\n"; + int done = 0; + int written = 0; +write: + while (1) { + int result = write(fd, buffer + written, length - written); + if (result > 0) + written += result; + if (result < 0 && errno != EWOULDBLOCK && errno != EAGAIN && errno != EINTR) + return 0; /* too bad */ + if (written == length) { + if (done) + return 1; + else + break; /* done */ + } + } + + buffer = terminate; + length = 4; + written = 0; + done = 1; + goto write; +} |