* NEWS, src/su.c: When su receives a signal, wait for the child to

terminate (after sending a SIGTERM), and kill it only if it did
	not terminate by itself. No delay will be enforced if the child
	cooperates. See http://bugs.gentoo.org/282094
	* NEWS, man/su.1.xml: Document su's exit values.

ChangeLog

@@ -1,3 +1,11 @@
+2009-09-08  Nicolas François  <nicolas.francois@centraliens.net>
+
+	* NEWS, src/su.c: When su receives a signal, wait for the child to
+	terminate (after sending a SIGTERM), and kill it only if it did
+	not terminate by itself. No delay will be enforced if the child
+	cooperates. See http://bugs.gentoo.org/282094
+	* NEWS, man/su.1.xml: Document su's exit values.
+
 2009-09-08  Nicolas François  <nicolas.francois@centraliens.net>
 
 	* src/useradd.c: The default value for the CREATE_MAIL_SPOOL

NEWS

@@ -6,6 +6,12 @@ shadow-4.1.4.2 -> shadow-4.1.4.3						UNRELEASED
   * report usage error to stderr, but report usage help to stdout (and return
     zero) when explicitly requested (e.g. with --help).
 
+- su
+  * Document the su exit values.
+  * When su receives a signal, wait for the child to terminate (after
+    sending a SIGTERM), and kill it only if it did not terminate by itself.
+    No delay will be enforced if the child cooperates.
+
 shadow-4.1.4.1 -> shadow-4.1.4.2						2009-07-24
 
 - general

man/su.1.xml

@@ -358,6 +358,53 @@
     </variablelist>
   </refsect1>
 
+  <refsect1 id='exit_values'>
+    <title>EXIT VALUES</title>
+    <para>
+      On success, <command>su</command> returns the exit value of the
+      command it executed.
+    </para>
+    <para>
+      If this command was terminated by a signal, <command>su</command>
+      returns the number of this signal plus 128.
+    </para>
+    <para>
+      If su has to kill the command (because it was asked to terminate,
+      and the command did not terminate in time), <command>su</command>
+      returns 255.
+    </para>
+    <para>
+      Some exit values from <command>su</command> are independent from the
+      executed command:
+      <variablelist>
+	<varlistentry>
+	  <term><replaceable>0</replaceable></term>
+	  <listitem>
+	    <para>success (<option>--help</option> only)</para>
+	  </listitem>
+	</varlistentry>
+	<varlistentry>
+	  <term><replaceable>1</replaceable></term>
+	  <listitem>
+	    <para>System or authentication failure</para>
+	  </listitem>
+	</varlistentry>
+	<varlistentry>
+	  <term><replaceable>126</replaceable></term>
+	  <listitem>
+	    <para>The requested command was not found</para>
+	  </listitem>
+	</varlistentry>
+	<varlistentry>
+	  <term><replaceable>127</replaceable></term>
+	  <listitem>
+	    <para>The requested command could not be executed</para>
+	  </listitem>
+	</varlistentry>
+      </variablelist>
+    </para>
+  </refsect1>
+
   <refsect1 id='see_also'>
     <title>SEE ALSO</title>
     <para><citerefentry>

src/su.c

@@ -78,6 +78,8 @@
  * Global variables
  */
 char *Prog;
+/* PID of the child, in case it needs to be killed */
+static pid_t pid_child = 0;
 
 /* not needed by sulog.c anymore */
 static char name[BUFSIZ];
@@ -103,11 +105,16 @@ extern size_t newenvc;
 
 /* local function prototypes */
 
+static void execve_shell (const char *shellstr,
+                          char *args[],
+                          char *const envp[]);
+static RETSIGTYPE kill_child (int s);
 #ifndef USE_PAM
-
 static RETSIGTYPE die (int);
 static int iswheel (const char *);
+#endif				/* !USE_PAM */
 
+#ifndef USE_PAM
 /*
  * die - set or reset termio modes.
  *
@@ -126,7 +133,7 @@ static RETSIGTYPE die (int killed)
 
 	if (killed) {
 		closelog ();
-		exit (killed);
+		exit (128+killed);
 	}
 }
 
@@ -143,6 +150,18 @@ static int iswheel (const char *username)
 }
 #endif				/* !USE_PAM */
 
+static RETSIGTYPE kill_child (int unused(s))
+{
+	if (0 != pid_child) {
+		(void) kill (pid_child, SIGKILL);
+		(void) fputs (_(" ...killed.\n"), stderr);
+	} else {
+		(void) fputs (_(" ...waiting for child to terminate.\n"),
+		              stderr);
+	}
+	exit (255);
+}
+
 /* borrowed from GNU sh-utils' "su.c" */
 static bool restricted_shell (const char *shellstr)
 {
@@ -252,6 +271,7 @@ static void run_shell (const char *shellstr, char *args[], bool doshell,
 		exit (1);
 	}
 	/* parent only */
+	pid_child = child;
 	sigfillset (&ourset);
 	if (sigprocmask (SIG_BLOCK, &ourset, NULL) != 0) {
 		(void) fprintf (stderr, "%s: signal malfunction\n", Prog);
@@ -293,7 +313,9 @@ static void run_shell (const char *shellstr, char *args[], bool doshell,
 	}
 
 	if (caught) {
-		fprintf (stderr, "\nSession terminated, killing shell...");
+		(void) fputs ("\n", stderr);
+		(void) fputs (_("Session terminated, terminating shell..."),
+		              stderr);
 		kill (child, SIGTERM);
 	}
 
@@ -309,10 +331,11 @@ static void run_shell (const char *shellstr, char *args[], bool doshell,
 	ret = pam_end (pamh, PAM_SUCCESS);
 
 	if (caught) {
-		sleep (2);
+		(void) signal (SIGALRM, kill_child);
-		kill (child, SIGKILL);
+		(void) alarm (2);
-		fprintf (stderr, " ...killed.\n");
+
-		exit (-1);
+		(void) wait (&status);
+		(void) fputs (_(" ...terminated.\n"), stderr);
 	}
 
 	exit ((0 != WIFEXITED (status)) ? WEXITSTATUS (status)