Introduce ast_careful_fwrite() and use in AMI to prevent partial writes.
This patch introduces a function to do careful writes on a file stream which will handle timeouts and partial writes. It is currently used in AMI to address the issue that has been reported. However, there are probably a few other places where this could be used. (closes issue #13546) Reported by: srt Tested by: russell http://reviewboard.digium.com/r/104/ git-svn-id: http://svn.digium.com/svn/asterisk/trunk@166282 f38db490-d61c-443f-a65b-d21fe96a405b
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@ -326,6 +326,25 @@ int ast_wait_for_input(int fd, int ms);
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*/
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int ast_carefulwrite(int fd, char *s, int len, int timeoutms);
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/*!
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* \brief Write data to a file stream with a timeout
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*
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* \param f the file stream to write to
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* \param fd the file description to poll on to know when the file stream can
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* be written to without blocking.
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* \param s the buffer to write from
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* \param len the number of bytes to write
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* \param timeoutms The maximum amount of time to block in this function trying
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* to write, specified in milliseconds.
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*
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* \note This function assumes that the associated file stream has been set up
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* as non-blocking.
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*
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* \retval 0 success
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* \retval -1 error
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*/
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int ast_careful_fwrite(FILE *f, int fd, const char *s, size_t len, int timeoutms);
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/*
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* Thread management support (should be moved to lock.h or a different header)
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*/
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@ -899,30 +899,7 @@ struct ast_variable *astman_get_variables(const struct message *m)
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*/
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static int send_string(struct mansession *s, char *string)
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{
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int len = strlen(string); /* residual length */
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char *src = string;
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struct timeval start = ast_tvnow();
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int n = 0;
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for (;;) {
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int elapsed;
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struct pollfd fd;
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n = fwrite(src, 1, len, s->f); /* try to write the string, non blocking */
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if (n == len /* ok */ || n < 0 /* error */)
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break;
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len -= n; /* skip already written data */
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src += n;
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fd.fd = s->fd;
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fd.events = POLLOUT;
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n = -1; /* error marker */
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elapsed = ast_tvdiff_ms(ast_tvnow(), start);
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if (elapsed > s->writetimeout)
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break;
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if (poll(&fd, 1, s->writetimeout - elapsed) < 1)
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break;
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}
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fflush(s->f);
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return n < 0 ? -1 : 0;
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return ast_careful_fwrite(s->f, s->fd, string, strlen(string), s->writetimeout);
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}
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/*!
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114
main/utils.c
114
main/utils.c
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@ -1057,6 +1057,38 @@ int ast_wait_for_input(int fd, int ms)
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return poll(pfd, 1, ms);
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}
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static int ast_wait_for_output(int fd, int timeoutms)
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{
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struct pollfd pfd = {
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.fd = fd,
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.events = POLLOUT,
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};
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int res;
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/* poll() until the fd is writable without blocking */
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while ((res = poll(&pfd, 1, timeoutms)) <= 0) {
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if (res == 0) {
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/* timed out. */
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ast_log(LOG_NOTICE, "Timed out trying to write\n");
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return -1;
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} else if (res == -1) {
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/* poll() returned an error, check to see if it was fatal */
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if (errno == EINTR || errno == EAGAIN) {
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/* This was an acceptable error, go back into poll() */
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continue;
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}
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/* Fatal error, bail. */
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ast_log(LOG_ERROR, "poll returned error: %s\n", strerror(errno));
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return -1;
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}
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}
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return 0;
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}
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/*!
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* Try to write string, but wait no more than ms milliseconds before timing out.
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*
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@ -1077,30 +1109,8 @@ int ast_carefulwrite(int fd, char *s, int len, int timeoutms)
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int res = 0;
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while (len) {
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struct pollfd pfd = {
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.fd = fd,
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.events = POLLOUT,
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};
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/* poll() until the fd is writable without blocking */
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while ((res = poll(&pfd, 1, timeoutms)) <= 0) {
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if (res == 0) {
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/* timed out. */
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ast_log(LOG_NOTICE, "Timed out trying to write\n");
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return -1;
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} else if (res == -1) {
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/* poll() returned an error, check to see if it was fatal */
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if (errno == EINTR || errno == EAGAIN) {
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/* This was an acceptable error, go back into poll() */
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continue;
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}
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/* Fatal error, bail. */
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ast_log(LOG_ERROR, "poll returned error: %s\n", strerror(errno));
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return -1;
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}
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if (ast_wait_for_output(fd, timeoutms)) {
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return -1;
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}
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res = write(fd, s, len);
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@ -1125,6 +1135,62 @@ int ast_carefulwrite(int fd, char *s, int len, int timeoutms)
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return res;
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}
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int ast_careful_fwrite(FILE *f, int fd, const char *src, size_t len, int timeoutms)
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{
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struct timeval start = ast_tvnow();
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int n = 0;
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while (len) {
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int elapsed;
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if (ast_wait_for_output(fd, timeoutms)) {
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/* poll returned a fatal error, so bail out immediately. */
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return -1;
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}
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/* Clear any errors from a previous write */
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clearerr(f);
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n = fwrite(src, 1, len, f);
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if (ferror(f) && errno != EINTR && errno != EAGAIN) {
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/* fatal error from fwrite() */
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if (!feof(f)) {
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/* Don't spam the logs if it was just that the connection is closed. */
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ast_log(LOG_ERROR, "fwrite() returned error: %s\n", strerror(errno));
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}
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n = -1;
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break;
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}
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/* Update for data already written to the socket */
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len -= n;
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src += n;
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elapsed = ast_tvdiff_ms(ast_tvnow(), start);
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if (elapsed > timeoutms) {
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/* We've taken too long to write
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* This is only an error condition if we haven't finished writing. */
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n = len ? -1 : 0;
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break;
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}
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}
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while (fflush(f)) {
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if (errno == EAGAIN || errno == EINTR) {
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continue;
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}
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if (!feof(f)) {
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/* Don't spam the logs if it was just that the connection is closed. */
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ast_log(LOG_ERROR, "fflush() returned error: %s\n", strerror(errno));
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}
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n = -1;
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break;
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}
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return n < 0 ? -1 : 0;
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}
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char *ast_strip_quoted(char *s, const char *beg_quotes, const char *end_quotes)
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{
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char *e;
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