hush: report [v]fork failures

hush: more correct handling of piping
config: add CONFIG_NOMMU

1 files changed, 30 insertions, 32 deletions

diff --git a/shell/hush.c b/shell/hush.c
index b08fe10b6..9dc85d0ba 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1777,8 +1777,8 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
 static int run_pipe_real(struct pipe *pi)
 {
         int i;
-        int nextin, nextout;
-        int pipefds[2];                         /* pipefds[0] is for reading */
+        int nextin;
+        int pipefds[2];         /* pipefds[0] is for reading */
         struct child_prog *child;
         const struct built_in_command *x;
         char *p;
@@ -1789,7 +1789,6 @@ static int run_pipe_real(struct pipe *pi)
 
         debug_printf_exec("run_pipe_real start: single_fg=%d\n", single_fg);
 
-        nextin = 0;
 #if ENABLE_HUSH_JOB
         pi->pgrp = -1;
 #endif
@@ -1874,13 +1873,14 @@ static int run_pipe_real(struct pipe *pi)
 #endif
         }
 
-        /* Going to fork a child per each pipe member */
-        pi->running_progs = 0;
-
         /* Disable job control signals for shell (parent) and
          * for initial child code after fork */
         set_jobctrl_sighandler(SIG_IGN);
 
+        /* Going to fork a child per each pipe member */
+        pi->running_progs = 0;
+        nextin = 0;
+
         for (i = 0; i < pi->num_progs; i++) {
                 child = &(pi->progs[i]);
                 if (child->argv)
@@ -1889,24 +1889,20 @@ static int run_pipe_real(struct pipe *pi)
                         debug_printf_exec(": pipe member with no argv\n");
 
                 /* pipes are inserted between pairs of commands */
-                if ((i + 1) < pi->num_progs) {
-                        pipe(pipefds);
-                        nextout = pipefds[1];
-                } else {
-                        nextout = 1;
-                        pipefds[0] = -1;
-                }
+                pipefds[0] = 0;
+                pipefds[1] = 1;
+                if ((i + 1) < pi->num_progs)
+                        xpipe(pipefds);
 
-                /* XXX test for failed fork()? */
 #if BB_MMU
                 child->pid = fork();
 #else
                 child->pid = vfork();
 #endif
                 if (!child->pid) { /* child */
+#if ENABLE_HUSH_JOB
                         /* Every child adds itself to new process group
                          * with pgid == pid of first child in pipe */
-#if ENABLE_HUSH_JOB
                         if (run_list_level == 1 && interactive_fd) {
                                 /* Don't do pgrp restore anymore on fatal signals */
                                 set_fatal_sighandler(SIG_DFL);
@@ -1919,12 +1915,10 @@ static int run_pipe_real(struct pipe *pi)
                                 }
                         }
 #endif
-                        /* in non-interactive case fatal sigs are already SIG_DFL */
                         xmove_fd(nextin, 0);
-                        xmove_fd(nextout, 1);
-                        if (pipefds[0] != -1) {
-                                close(pipefds[0]);  /* opposite end of our output pipe */
-                        }
+                        xmove_fd(pipefds[1], 1); /* write end */
+                        if (pipefds[0] > 1)
+                                close(pipefds[0]); /* read end */
                         /* Like bash, explicit redirects override pipes,
                          * and the pipe fd is available for dup'ing. */
                         setup_redirects(child, NULL);
@@ -1933,25 +1927,29 @@ static int run_pipe_real(struct pipe *pi)
                         set_jobctrl_sighandler(SIG_DFL);
                         set_misc_sighandler(SIG_DFL);
                         signal(SIGCHLD, SIG_DFL);
-                        pseudo_exec(child);
+                        pseudo_exec(child); /* does not return */
                 }
 
-                pi->running_progs++;
-
+                if (child->pid < 0) { /* [v]fork failed */
+                        /* Clearly indicate, was it fork or vfork */
+                        bb_perror_msg(BB_MMU ? "cannot fork" : "cannot vfork");
+                } else {
+                        pi->running_progs++;
 #if ENABLE_HUSH_JOB
-                /* Second and next children need to know pid of first one */
-                if (pi->pgrp < 0)
-                        pi->pgrp = child->pid;
+                        /* Second and next children need to know pid of first one */
+                        if (pi->pgrp < 0)
+                                pi->pgrp = child->pid;
 #endif
-                if (nextin != 0)
-                        close(nextin);
-                if (nextout != 1)
-                        close(nextout);
+                }
 
-                /* If there isn't another process, nextin is garbage
-                   but it doesn't matter */
+                if (i)
+                        close(nextin);
+                if ((i + 1) < pi->num_progs)
+                        close(pipefds[1]); /* write end */
+                /* Pass read (output) pipe end to next iteration */
                 nextin = pipefds[0];
         }
+
         debug_printf_exec("run_pipe_real return -1\n");
         return -1;
 }