Utilities: Implement ArmedScopeGuard in userdel to unlink temp files

Userland/Utilities/userdel.cpp

@@ -5,6 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ScopeGuard.h>
 #include <AK/String.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ArgsParser.h>
@@ -60,6 +61,17 @@ int main(int argc, char** argv)
     char temp_passwd[] = "/etc/passwd.XXXXXX";
     char temp_shadow[] = "/etc/shadow.XXXXXX";
 
+    auto unlink_temp_files = [&] {
+        if (unlink(temp_passwd) < 0)
+            perror("unlink");
+        if (unlink(temp_shadow) < 0)
+            perror("unlink");
+    };
+
+    ArmedScopeGuard unlink_temp_files_guard = [&] {
+        unlink_temp_files();
+    };
+
     auto temp_passwd_fd = mkstemp(temp_passwd);
     if (temp_passwd_fd == -1) {
         perror("failed to create temporary passwd file");
@@ -75,34 +87,24 @@ int main(int argc, char** argv)
     FILE* temp_passwd_file = fdopen(temp_passwd_fd, "w");
     if (!temp_passwd_file) {
         perror("fdopen");
-        if (unlink(temp_passwd) < 0) {
-            perror("unlink");
-        }
-
         return 1;
     }
 
     FILE* temp_shadow_file = fdopen(temp_shadow_fd, "w");
     if (!temp_shadow_file) {
         perror("fdopen");
-        if (unlink(temp_shadow) < 0) {
-            perror("unlink");
-        }
-
         return 1;
     }
 
     bool user_exists = false;
     String home_directory;
 
-    int rc = 0;
     setpwent();
     for (auto* pw = getpwent(); pw; pw = getpwent()) {
         if (strcmp(pw->pw_name, username)) {
             if (putpwent(pw, temp_passwd_file) != 0) {
                 perror("failed to put an entry in the temporary passwd file");
-                rc = 1;
-                break;
+                return 1;
             }
         } else {
             user_exists = true;
@@ -117,8 +119,7 @@ int main(int argc, char** argv)
         if (strcmp(spwd->sp_namp, username)) {
             if (putspent(spwd, temp_shadow_file) != 0) {
                 perror("failed to put an entry in the temporary shadow file");
-                rc = 1;
-                break;
+                return 1;
             }
         }
     }
@@ -126,52 +127,40 @@ int main(int argc, char** argv)
 
     if (fclose(temp_passwd_file)) {
         perror("fclose");
-        if (!rc)
-            rc = 1;
+        return 1;
     }
 
     if (fclose(temp_shadow_file)) {
         perror("fclose");
-        if (!rc)
-            rc = 1;
+        return 1;
     }
 
-    if (rc == 0 && !user_exists) {
+    if (!user_exists) {
         warnln("specified user doesn't exist");
-        rc = 6;
+        return 1;
     }
 
-    if (rc == 0 && chmod(temp_passwd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) {
+    if (chmod(temp_passwd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) {
         perror("chmod");
-        rc = 1;
+        return 1;
     }
 
-    if (rc == 0 && chmod(temp_shadow, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) {
+    if (chmod(temp_shadow, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) {
         perror("chmod");
-        rc = 1;
+        return 1;
     }
 
-    if (rc == 0 && rename(temp_passwd, "/etc/passwd") < 0) {
+    if (rename(temp_passwd, "/etc/passwd") < 0) {
         perror("failed to rename the temporary passwd file");
-        rc = 1;
+        return 1;
     }
 
-    if (rc == 0 && rename(temp_shadow, "/etc/shadow") < 0) {
+    if (rename(temp_shadow, "/etc/shadow") < 0) {
         perror("failed to rename the temporary shadow file");
-        rc = 1;
+        return 1;
     }
 
-    if (rc) {
-        if (unlink(temp_passwd) < 0) {
-            perror("unlink");
-        }
-
-        if (unlink(temp_shadow) < 0) {
-            perror("unlink");
-        }
-
-        return rc;
-    }
+    unlink_temp_files_guard.disarm();
 
     if (remove_home) {
         if (access(home_directory.characters(), F_OK) == -1)