+
+
+/*
+ * Filter the body of a message through a specified format program
+ */
+
+void
+filterbody (struct mcomp *c1, char *buf, int bufsz, int state, FILE *fp)
+{
+ struct mcomp holder;
+ char name[NAMESZ];
+ int fdinput[2], fdoutput[2], waitstat;
+ ssize_t cc;
+ pid_t writerpid, filterpid;
+
+ /*
+ * Create pipes so we can communicate with our filter process.
+ */
+
+ if (pipe(fdinput) < 0) {
+ adios(NULL, "Unable to create input pipe");
+ }
+
+ if (pipe(fdoutput) < 0) {
+ adios(NULL, "Unable to create output pipe");
+ }
+
+ /*
+ * Here's what we're doing to do.
+ *
+ * - Fork ourselves and start writing data to the write side of the
+ * input pipe (fdinput[1]).
+ *
+ * - Fork and exec our filter program. We set the standard input of
+ * our filter program to be the read side of our input pipe (fdinput[0]).
+ * Standard output is set to the write side of our output pipe
+ * (fdoutput[1]).
+ *
+ * - We read from the read side of the output pipe (fdoutput[0]).
+ *
+ * We're forking because that's the simplest way to prevent any deadlocks.
+ * (without doing something like switching to non-blocking I/O and using
+ * select or poll, and I'm not interested in doing that).
+ */
+
+ switch (writerpid = fork()) {
+ case 0:
+ /*
+ * Our child process - just write to the filter input (fdinput[1]).
+ * Close all other descriptors that we don't need.
+ */
+
+ close(fdinput[0]);
+ close(fdoutput[0]);
+ close(fdoutput[1]);
+
+ /*
+ * Call m_getfld() until we're no longer in the BODY state
+ */
+
+ while (state == BODY) {
+ write(fdinput[1], buf, strlen(buf));
+ state = m_getfld(state, name, buf, bufsz, fp);
+ }
+
+ /*
+ * We should be done; time to exit.
+ */
+
+ close(fdinput[1]);
+ exit(0);
+ break;
+ case -1:
+ adios(NULL, "Unable to fork for filter writer process");
+ break;
+ }
+
+ /*
+ * Fork and exec() our filter program, after redirecting standard in
+ * and standard out appropriately.
+ */
+
+ switch (filterpid = fork()) {
+ case 0:
+ if (dup2(fdinput[0], STDIN_FILENO) < 0) {
+ adios("formatproc", "Unable to dup2() standard input");
+ }
+ if (dup2(fdoutput[1], STDOUT_FILENO) < 0) {
+ adios("formatproc", "Unable to dup2() standard output");
+ }
+
+ /*
+ * Close everything (especially the old input and output
+ * descriptors, since they've been dup'd to stdin and stdout),
+ * and exec the formatproc.
+ */
+
+ close(fdinput[0]);
+ close(fdinput[1]);
+ close(fdoutput[0]);
+ close(fdoutput[1]);
+
+ execlp(formatproc, formatproc, (char *) NULL);
+
+ adios(formatproc, "Unable to execute filter");
+
+ break;
+
+ case -1:
+ adios(NULL, "Unable to fork format program");
+ }
+
+ /*
+ * Close everything except our reader (fdoutput[0]);
+ */
+
+ close(fdinput[0]);
+ close(fdinput[1]);
+ close(fdoutput[1]);
+
+ /*
+ * As we read in this data, send it to putcomp
+ */
+
+ holder.c_text = buf;
+
+ while ((cc = read(fdoutput[0], buf, bufsz - 1)) > 0) {
+ buf[cc] = '\0';
+ putcomp(c1, &holder, BODYCOMP);
+ }
+
+ if (cc < 0) {
+ adios(NULL, "reading from formatproc");
+ }
+
+ /*
+ * See if we got any errors along the way. I'm a little leery of calling
+ * waitpid() without WNOHANG, but it seems to be the most correct solution.
+ */
+
+ if (waitpid(filterpid, &waitstat, 0) < 0) {
+ if (errno != ECHILD) {
+ adios("filterproc", "Unable to determine status");
+ }
+ } else {
+ if (! (WIFEXITED(waitstat) && WEXITSTATUS(waitstat) == 0)) {
+ pidstatus(waitstat, stderr, "filterproc");
+ }
+ }
+
+ if (waitpid(writerpid, &waitstat, 0) < 0) {
+ if (errno != ECHILD) {
+ adios("writer process", "Unable to determine status");
+ done(1);
+ }
+ } else {
+ if (! (WIFEXITED(waitstat) && WEXITSTATUS(waitstat) == 0)) {
+ pidstatus(waitstat, stderr, "writer process");
+ done(1);
+ }
+ }
+
+ close(fdoutput[0]);
+}