Die on mksquashfs failure. (#1189)

* Die on mksquashfs failure.

* review

* Use %d to print pid_t

Author: lalten

ci/test-appimagetool.sh

@@ -119,8 +119,6 @@ if [ "$hash1" != "$hash2" ]; then
 fi
 
 log "check --mksquashfs-opt forwarding"
-out=$("$appimagetool" appimagetool.AppDir appimagetool.AppImage --mksquashfs-opt "-misspelt-option" 2>&1)
-echo "${out}" | grep -q "invalid option"
 "$appimagetool" appimagetool.AppDir appimagetool.AppImage.1
 "$appimagetool" appimagetool.AppDir appimagetool.AppImage.2 --mksquashfs-opt "-mem" --mksquashfs-opt "100M"
 "$appimagetool" appimagetool.AppDir appimagetool.AppImage.3 --mksquashfs-opt "-all-time" --mksquashfs-opt "12345"
@@ -135,3 +133,13 @@ if [ "$hash1" == "$hash3" ]; then
     echo "Hashes of regular and mtime-modified AppImages don't differ"
     exit 1
 fi
+
+log "check appimagetool dies when mksquashfs fails"
+set +e # temporarily disable error trapping as next line is supposed to fail
+out=$("$appimagetool" appimagetool.AppDir appimagetool.AppImage --mksquashfs-opt "-misspelt-option" 2>&1)
+rc=$?
+set -e
+test ${rc} == 1
+echo "${out}" | grep -q "invalid option"
+echo "${out}" | grep -qP 'mksquashfs \(pid \d+\) exited with code 1'
+echo "${out}" | grep -q "sfs_mksquashfs error"

src/appimagetool.c

@@ -134,13 +134,26 @@ int sfs_ls(char* image) {
 * execlp(), execvp(), and execvpe() search on the $PATH */
 int sfs_mksquashfs(char *source, char *destination, int offset) {
     pid_t pid = fork();
-    
     if (pid == -1) {
-        // error, failed to fork()
+        perror("sfs_mksquashfs fork() failed");
         return(-1);
-    } else if (pid > 0) {
+    }
+
+    if (pid > 0) {
+        // This is the parent process. Wait for the child to termiante and check its exit status.
         int status;
-        waitpid(pid, &status, 0);
+        if(waitpid(pid, &status, 0) == -1) {
+            perror("sfs_mksquashfs waitpid() failed");
+            return(-1);
+        }
+        
+        int retcode = WEXITSTATUS(status);
+        if (retcode) {
+            fprintf(stderr, "mksquashfs (pid %d) exited with code %d\n", pid, retcode);
+            return(-1);
+        }
+        
+        return 0;
     } else {
         // we are the child
         gchar* offset_string;
@@ -223,11 +236,11 @@ int sfs_mksquashfs(char *source, char *destination, int offset) {
 
 #ifndef AUXILIARY_FILES_DESTINATION
         execvp("mksquashfs", args);
+        perror("execvp(\"mksquashfs\") failed");
 #else
         execvp(pathToMksquashfs, args);
+        fprintf(stderr, "execvp(\"%s\") failed: %s\n", pathToMksquashfs, strerror(errno));
 #endif
-
-        perror("execlp");   // exec*() returns only on error
         return -1; // exec never returns
     }
     return 0;