Improve queryprogram behaviour when not running as root.

[exim.git] / src / src / child.c

diff --git a/src/src/child.c b/src/src/child.c
index cf426e465001b75b803978b3d19c165fb35938a0..4a1a89887ee029a409014c2d304a73a74dba9a49 100644 (file)
--- a/src/src/child.c
+++ b/src/src/child.c
@@ -1,10 +1,10 @@
-/* $Cambridge: exim/src/src/child.c,v 1.2 2004/10/15 13:21:21 ph10 Exp $ */
+/* $Cambridge: exim/src/src/child.c,v 1.8 2006/02/07 14:05:17 ph10 Exp $ */
 
 /*************************************************
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2004 */
+/* Copyright (c) University of Cambridge 1995 - 2006 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 
@@ -32,13 +32,13 @@ static void
 force_fd(int oldfd, int newfd)
 {
 if (oldfd == newfd) return;
-close(newfd);
-dup2(oldfd, newfd);
-close(oldfd);
+(void)close(newfd);
+(void)dup2(oldfd, newfd);
+(void)close(oldfd);
 }
 
 
-
+#ifndef STAND_ALONE
 /*************************************************
 *   Build argv list and optionally re-exec Exim  *
 *************************************************/
@@ -201,7 +201,7 @@ Exim. Failure is signalled with EX_EXECFAILED, but this shouldn't occur! */
 if (pid == 0)
   {
   force_fd(pfd[pipe_read], 0);
-  close(pfd[pipe_write]);
+  (void)close(pfd[pipe_write]);
   if (debug_fd > 0) force_fd(debug_fd, 2);
   if (bounce_sender_authentication != NULL)
     child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 8,
@@ -217,7 +217,7 @@ if (pid == 0)
 pipe. */
 
 save_errno = errno;
-close(pfd[pipe_read]);
+(void)close(pfd[pipe_read]);
 
 /* Fork succeeded */
 
@@ -229,11 +229,11 @@ if (pid > 0)
 
 /* Fork failed */
 
-close(pfd[pipe_write]);
+(void)close(pfd[pipe_write]);
 errno = save_errno;
 return (pid_t)(-1);
 }
-
+#endif
 
 
 
@@ -263,7 +263,7 @@ Arguments:
                 process is placed
   wd          if not NULL, a path to be handed to chdir() in the new process
   make_leader if TRUE, make the new process a process group leader
-  
+
 Returns:      the pid of the created process or -1 if anything has gone wrong
 */
 
@@ -280,8 +280,8 @@ pid_t pid;
 if (pipe(inpfd) != 0) return (pid_t)(-1);
 if (pipe(outpfd) != 0)
   {
-  close(inpfd[pipe_read]);
-  close(inpfd[pipe_write]);
+  (void)close(inpfd[pipe_read]);
+  (void)close(inpfd[pipe_write]);
   return (pid_t)(-1);
   }
 
@@ -292,34 +292,57 @@ otherwise. Save the old state for resetting on the wait. */
 oldsignal = signal(SIGCHLD, SIG_DFL);
 pid = fork();
 
-/* The child process becomes a process group leader if requested, and then
-organizes the pipes. Any unexpected failure is signalled with EX_EXECFAILED;
-these are all "should never occur" failures, except perhaps for exec failing
-because the command doesn't exist. */
+/* Handle the child process. First, set the required environment. We must do
+this before messing with the pipes, in order to be able to write debugging
+output when things go wrong. */
 
 if (pid == 0)
   {
-  if (make_leader && setpgid(0,0) < 0) goto CHILD_FAILED;
+  signal(SIGUSR1, SIG_IGN);
 
-  close(inpfd[pipe_write]);
-  force_fd(inpfd[pipe_read], 0);
+  if (newgid != NULL && setgid(*newgid) < 0)
+    {
+    DEBUG(D_any) debug_printf("failed to set gid=%ld in subprocess: %s\n",
+      (long int)(*newgid), strerror(errno));
+    goto CHILD_FAILED;
+    }
 
-  close(outpfd[pipe_read]);
-  force_fd(outpfd[pipe_write], 1);
+  if (newuid != NULL && setuid(*newuid) < 0)
+    {
+    DEBUG(D_any) debug_printf("failed to set uid=%ld in subprocess: %s\n",
+      (long int)(*newuid), strerror(errno));
+    goto CHILD_FAILED;
+    }
 
-  close(2);
-  dup2(1, 2);
+  (void)umask(newumask);
 
-  /* Set the required environment. */
+  if (wd != NULL && Uchdir(wd) < 0)
+    {
+    DEBUG(D_any) debug_printf("failed to chdir to %s: %s\n", wd,
+      strerror(errno));
+    goto CHILD_FAILED;
+    }
 
-  signal(SIGUSR1, SIG_IGN);
-  if (newgid != NULL && setgid(*newgid) < 0) goto CHILD_FAILED;
-  if (newuid != NULL && setuid(*newuid) < 0) goto CHILD_FAILED;
-  (void)umask(newumask);
+  /* Becomes a process group leader if requested, and then organize the pipes.
+  Any unexpected failure is signalled with EX_EXECFAILED; these are all "should
+  never occur" failures, except for exec failing because the command doesn't
+  exist. */
+
+  if (make_leader && setpgid(0,0) < 0)
+    {
+    DEBUG(D_any) debug_printf("failed to set group leader in subprocess: %s\n",
+      strerror(errno));
+    goto CHILD_FAILED;
+    }
 
-  /* Set the working directory if required */
+  (void)close(inpfd[pipe_write]);
+  force_fd(inpfd[pipe_read], 0);
+
+  (void)close(outpfd[pipe_read]);
+  force_fd(outpfd[pipe_write], 1);
 
-  if (wd != NULL && Uchdir(wd) < 0) goto CHILD_FAILED;
+  (void)close(2);
+  (void)dup2(1, 2);
 
   /* Now do the exec */
 
@@ -328,7 +351,7 @@ if (pid == 0)
 
   /* Failed to execv. Signal this failure using EX_EXECFAILED. We are
   losing the actual errno we got back, because there is no way to return
-  this. */
+  this information. */
 
   CHILD_FAILED:
   _exit(EX_EXECFAILED);      /* Note: must be _exit(), NOT exit() */
@@ -338,8 +361,8 @@ if (pid == 0)
 stdin pipe, and the writing end of the stdout pipe. */
 
 save_errno = errno;
-close(inpfd[pipe_read]);
-close(outpfd[pipe_write]);
+(void)close(inpfd[pipe_read]);
+(void)close(outpfd[pipe_write]);
 
 /* Fork succeeded; return the input/output pipes and the pid */
 
@@ -352,8 +375,8 @@ if (pid > 0)
 
 /* Fork failed; reset fork errno before returning */
 
-close(inpfd[pipe_write]);
-close(outpfd[pipe_read]);
+(void)close(inpfd[pipe_write]);
+(void)close(outpfd[pipe_read]);
 errno = save_errno;
 return (pid_t)(-1);
 }