+ return i;
+}
+
+void
+close_all_files()
+{
+
+ while (fp_head)
+ if (fp_head->pipe)
+ (void) Pclose(fp_head->fp);
+ else
+ (void) Fclose(fp_head->fp);
+}
+
+void
+register_file(fp, pipe, pid)
+ FILE *fp;
+ int pipe, pid;
+{
+ struct fp *fpp;
+
+ if ((fpp = (struct fp *) malloc(sizeof *fpp)) == NULL)
+ panic("Out of memory");
+ fpp->fp = fp;
+ fpp->pipe = pipe;
+ fpp->pid = pid;
+ fpp->link = fp_head;
+ fp_head = fpp;
+}
+
+void
+unregister_file(fp)
+ FILE *fp;
+{
+ struct fp **pp, *p;
+
+ for (pp = &fp_head; p = *pp; pp = &p->link)
+ if (p->fp == fp) {
+ *pp = p->link;
+ free((char *) p);
+ return;
+ }
+ panic("Invalid file pointer");
+}
+
+file_pid(fp)
+ FILE *fp;
+{
+ struct fp *p;
+
+ for (p = fp_head; p; p = p->link)
+ if (p->fp == fp)
+ return (p->pid);
+ panic("Invalid file pointer");
+ /*NOTREACHED*/
+}
+
+/*
+ * Run a command without a shell, with optional arguments and splicing
+ * of stdin and stdout. The command name can be a sequence of words.
+ * Signals must be handled by the caller.
+ * "Mask" contains the signals to ignore in the new process.
+ * SIGINT is enabled unless it's in the mask.
+ */
+/*VARARGS4*/
+int
+run_command(cmd, mask, infd, outfd, a0, a1, a2)
+ char *cmd;
+ int mask, infd, outfd;
+ char *a0, *a1, *a2;
+{
+ int pid;
+
+ if ((pid = start_command(cmd, mask, infd, outfd, a0, a1, a2)) < 0)
+ return -1;
+ return wait_command(pid);
+}
+
+/*VARARGS4*/
+int
+start_command(cmd, mask, infd, outfd, a0, a1, a2)
+ char *cmd;
+ int mask, infd, outfd;
+ char *a0, *a1, *a2;
+{
+ int pid;
+
+ if ((pid = vfork()) < 0) {
+ perror("fork");
+ return -1;
+ }
+ if (pid == 0) {
+ char *argv[100];
+ int i = getrawlist(cmd, argv, sizeof argv / sizeof *argv);
+
+ if ((argv[i++] = a0) != NOSTR &&
+ (argv[i++] = a1) != NOSTR &&
+ (argv[i++] = a2) != NOSTR)
+ argv[i] = NOSTR;
+ prepare_child(mask, infd, outfd);
+ execvp(argv[0], argv);
+ perror(argv[0]);
+ _exit(1);
+ }
+ return pid;
+}
+
+void
+prepare_child(mask, infd, outfd)
+ int mask, infd, outfd;
+{
+ int i;
+
+ /*
+ * All file descriptors other than 0, 1, and 2 are supposed to be
+ * close-on-exec.
+ */
+ if (infd >= 0)
+ dup2(infd, 0);
+ if (outfd >= 0)
+ dup2(outfd, 1);
+ for (i = 1; i <= NSIG; i++)
+ if (mask & sigmask(i))
+ (void) signal(i, SIG_IGN);
+ if ((mask & sigmask(SIGINT)) == 0)
+ (void) signal(SIGINT, SIG_DFL);
+ (void) sigsetmask(0);
+}
+
+int
+wait_command(pid)
+ int pid;
+{
+
+ if (wait_child(pid) < 0) {
+ printf("Fatal error in process.\n");
+ return -1;
+ }
+ return 0;
+}
+
+static struct child *
+findchild(pid)
+ int pid;
+{
+ register struct child **cpp;
+
+ for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
+ cpp = &(*cpp)->link)
+ ;
+ if (*cpp == NULL) {
+ *cpp = (struct child *) malloc(sizeof (struct child));
+ (*cpp)->pid = pid;
+ (*cpp)->done = (*cpp)->free = 0;
+ (*cpp)->link = NULL;
+ }
+ return *cpp;
+}
+
+static void
+delchild(cp)
+ register struct child *cp;
+{
+ register struct child **cpp;
+
+ for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
+ ;
+ *cpp = cp->link;
+ free((char *) cp);
+}
+
+void
+sigchild(signo)
+ int signo;
+{
+ int pid;
+ union wait status;
+ register struct child *cp;
+
+ while ((pid =
+ wait3((int *)&status, WNOHANG, (struct rusage *)0)) > 0) {
+ cp = findchild(pid);
+ if (cp->free)
+ delchild(cp);
+ else {
+ cp->done = 1;
+ cp->status = status;
+ }
+ }
+}
+
+union wait wait_status;
+
+/*
+ * Wait for a specific child to die.
+ */
+int
+wait_child(pid)
+ int pid;
+{
+ int mask = sigblock(sigmask(SIGCHLD));
+ register struct child *cp = findchild(pid);
+
+ while (!cp->done)
+ sigpause(mask);
+ wait_status = cp->status;
+ delchild(cp);
+ sigsetmask(mask);
+ return wait_status.w_status ? -1 : 0;
+}
+
+/*
+ * Mark a child as don't care.
+ */
+void
+free_child(pid)
+ int pid;
+{
+ int mask = sigblock(sigmask(SIGCHLD));
+ register struct child *cp = findchild(pid);
+
+ if (cp->done)
+ delchild(cp);
+ else
+ cp->free = 1;
+ sigsetmask(mask);