[PATCH 3/4] Xorg.wrap: Clarify error messages

[Guillem Jover]

Not printing the program name produces very confusing messages that
might be difficult to attribute while trying to diagnose problems,
let's be explicit about who we are.

Also add a missing "/" between SUID_WRAPPER_DIR and "Xorg.bin".

Signed-off-by: Guillem Jover <guillem at hadrons.org>
---
 hw/xfree86/xorg-wrapper.c | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/hw/xfree86/xorg-wrapper.c b/hw/xfree86/xorg-wrapper.c
index 80889e8..12ea2c3 100644
--- a/hw/xfree86/xorg-wrapper.c
+++ b/hw/xfree86/xorg-wrapper.c
@@ -25,6 +25,7 @@
 
 #include "dix-config.h"
 
+#include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <stdint.h>
@@ -40,6 +41,8 @@
 
 #define CONFIG_FILE SYSCONFDIR "/X11/Xwrapper.config"
 
+static const char *progname;
+
 enum { ROOT_ONLY, CONSOLE_ONLY, ANYBODY };
 
 /* KISS non locale / LANG parsing isspace version */
@@ -88,18 +91,21 @@ static void parse_config(int *allowed, int *needs_root_rights)
         /* Split in a key + value pair */
         equals = strchr(stripped, '=');
         if (!equals) {
-            fprintf(stderr, "Syntax error at %s line %d\n", CONFIG_FILE, line);
+            fprintf(stderr, "%s: Syntax error at %s line %d\n", progname,
+                CONFIG_FILE, line);
             exit(1);
         }
         *equals = 0;
         key   = strip(stripped);   /* To remove trailing whitespace from key */
         value = strip(equals + 1); /* To remove leading whitespace from val */
         if (!key[0]) {
-            fprintf(stderr, "Missing key at %s line %d\n", CONFIG_FILE, line);
+            fprintf(stderr, "%s: Missing key at %s line %d\n", progname,
+                CONFIG_FILE, line);
             exit(1);
         }
         if (!value[0]) {
-            fprintf(stderr, "Missing value at %s line %d\n", CONFIG_FILE, line);
+            fprintf(stderr, "%s: Missing value at %s line %d\n", progname,
+                CONFIG_FILE, line);
             exit(1);
         }
 
@@ -113,8 +119,8 @@ static void parse_config(int *allowed, int *needs_root_rights)
                 *allowed = ANYBODY;
             else {
                 fprintf(stderr,
-                    "Invalid value '%s' for 'allowed_users' at %s line %d\n",
-                    value, CONFIG_FILE, line);
+                    "%s: Invalid value '%s' for 'allowed_users' at %s line %d\n",
+                    progname, value, CONFIG_FILE, line);
                 exit(1);
             }
         }
@@ -127,8 +133,8 @@ static void parse_config(int *allowed, int *needs_root_rights)
                 *needs_root_rights = -1;
             else {
                 fprintf(stderr,
-                    "Invalid value '%s' for 'needs_root_rights' at %s line %d\n",
-                    value, CONFIG_FILE, line);
+                    "%s: Invalid value '%s' for 'needs_root_rights' at %s line %d\n",
+                    progname, value, CONFIG_FILE, line);
                 exit(1);
             }
         }
@@ -136,8 +142,8 @@ static void parse_config(int *allowed, int *needs_root_rights)
             /* Backward compatibility with older Debian Xwrapper, ignore */
         }
         else {
-            fprintf(stderr, "Invalid key '%s' at %s line %d\n", key,
-                    CONFIG_FILE, line);
+            fprintf(stderr, "%s: Invalid key '%s' at %s line %d\n", key,
+                progname, CONFIG_FILE, line);
             exit(1);
         }
     }
@@ -155,6 +161,8 @@ int main(int argc, char *argv[])
     int allowed = CONSOLE_ONLY;
     int needs_root_rights = -1;
 
+    progname = argv[0];
+
     parse_config(&allowed, &needs_root_rights);
 
     /* For non root users check if they are allowed to run the X server */
@@ -207,11 +215,13 @@ int main(int argc, char *argv[])
         uid_t realuid = getuid();
 
         if (setresgid(-1, realgid, realgid) != 0) {
-            perror("Could not drop setgid privileges");
+            fprintf(stderr, "%s: Could not drop setgid privileges: %s\n",
+                progname, strerror(errno));
             exit(1);
         }
         if (setresuid(-1, realuid, realuid) != 0) {
-            perror("Could not drop setuid privileges");
+            fprintf(stderr, "%s: Could not drop setuid privileges: %s\n",
+                progname, strerror(errno));
             exit(1);
         }
     }
@@ -220,12 +230,14 @@ int main(int argc, char *argv[])
 
     /* Check if the server is executable by our real uid */
     if (access(buf, X_OK) != 0) {
-        perror("Missing execute permissions for " SUID_WRAPPER_DIR "Xorg.bin");
+        fprintf(stderr, "%s: Missing execute permissions for %s/Xorg.bin: %s\n",
+            progname, SUID_WRAPPER_DIR, strerror(errno));
         exit(1);
     }
 
     argv[0] = buf;
     (void) execv(argv[0], argv);
-    perror("Failed to execute " SUID_WRAPPER_DIR "/Xorg.bin");
+    fprintf(stderr, "%s: Failed to execute %s/Xorg.bin: %s\n",
+        progname, SUID_WRAPPER_DIR, strerror(errno));
     exit(1);
 }
-- 
1.9.1.662.g3e70902