Add special case for when the agi cannot be executed, to comply with the documentation that

we return failure in that case.
(closes issue #12462)
 Reported by: fmueller
 Patches: 
       20080416__bug12462.diff.txt uploaded by Corydon76 (license 14)
 Tested by: fmueller


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@114195 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_agi.c

@@ -346,6 +346,8 @@ static enum agi_result launch_script(char *script, char *argv[], int *fds, int *
 		execv(script, argv);
 		/* Can't use ast_log since FD's are closed */
 		fprintf(stdout, "verbose \"Failed to execute '%s': %s\" 2\n", script, strerror(errno));
+		/* Special case to set status of AGI to failure */
+		fprintf(stdout, "failure\n");
 		fflush(stdout);
 		_exit(1);
 	}
@@ -1904,6 +1906,12 @@ static enum agi_result run_agi(struct ast_channel *chan, char *request, AGI *agi
 				break;
 			}
 
+			/* Special case for inability to execute child process */
+			if (*buf && strncasecmp(buf, "failure", 7) == 0) {
+				returnstatus = AGI_RESULT_FAILURE;
+				break;
+			}
+
 			/* get rid of trailing newline, if any */
 			if (*buf && buf[strlen(buf) - 1] == '\n')
 				buf[strlen(buf) - 1] = 0;
@@ -2047,6 +2055,7 @@ static int agi_exec_full(struct ast_channel *chan, void *data, int enhanced, int
 		}
 	}
 #endif
+	ast_replace_sigchld();
 	res = launch_script(argv[0], argv, fds, enhanced ? &efd : NULL, &pid);
 	if (res == AGI_RESULT_SUCCESS || res == AGI_RESULT_SUCCESS_FAST) {
 		int status = 0;
@@ -2062,8 +2071,8 @@ static int agi_exec_full(struct ast_channel *chan, void *data, int enhanced, int
 			close(fds[1]);
 		if (efd > -1)
 			close(efd);
-		ast_unreplace_sigchld();
 	}
+	ast_unreplace_sigchld();
 	ast_module_user_remove(u);
 
 	switch (res) {