Use C++ scoping for handling buffer deletion

davidedmundson · davidedmundson · commit 047ef56e5cfa · 2019-02-07T14:45:42.000Z
diff --git a/src/helper/UserSession.cpp b/src/helper/UserSession.cpp
@@ -135,21 +135,19 @@ namespace SDDM {
         long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
         if (bufsize == -1)
             bufsize = 16384;
-        char *buffer = (char *)malloc(bufsize);
-        if (buffer == NULL)
+        QScopedPointer<char, QScopedPointerPodDeleter> buffer(static_cast<char*>(malloc(bufsize)));
+        if (buffer.isNull())
             exit(Auth::HELPER_OTHER_ERROR);
-        int err = getpwnam_r(username.constData(), &pw, buffer, bufsize, &rpw);
+        int err = getpwnam_r(username.constData(), &pw, buffer.data(), bufsize, &rpw);
         if (rpw == NULL) {
             if (err == 0)
                 qCritical() << "getpwnam_r(" << username << ") username not found!";
             else
                 qCritical() << "getpwnam_r(" << username << ") failed with error: " << strerror(err);
-            free(buffer);
             exit(Auth::HELPER_OTHER_ERROR);
         }
         if (setgid(pw.pw_gid) != 0) {
             qCritical() << "setgid(" << pw.pw_gid << ") failed for user: " << username;
-            free(buffer);
             exit(Auth::HELPER_OTHER_ERROR);
         }
 
@@ -181,7 +179,6 @@ namespace SDDM {
                                               &n_user_groups)) == -1 ) {
                 qCritical() << "getgrouplist(" << username << ", " << pw.pw_gid
                             << ") failed";
-                free(buffer);
                 exit(Auth::HELPER_OTHER_ERROR);
             }
         }
@@ -198,7 +195,6 @@ namespace SDDM {
             // setgroups(2) handles duplicate groups
             if (setgroups(n_groups, groups) != 0) {
                 qCritical() << "setgroups() failed for user: " << username;
-                free(buffer);
                 exit (Auth::HELPER_OTHER_ERROR);
             }
             delete[] groups;
@@ -210,31 +206,28 @@ namespace SDDM {
 
         if (initgroups(pw.pw_name, pw.pw_gid) != 0) {
             qCritical() << "initgroups(" << pw.pw_name << ", " << pw.pw_gid << ") failed for user: " << username;
-            free(buffer);
             exit(Auth::HELPER_OTHER_ERROR);
         }
 
 #endif /* USE_PAM */
 
         if (setuid(pw.pw_uid) != 0) {
             qCritical() << "setuid(" << pw.pw_uid << ") failed for user: " << username;
-            free(buffer);
             exit(Auth::HELPER_OTHER_ERROR);
         }
         if (chdir(pw.pw_dir) != 0) {
             qCritical() << "chdir(" << pw.pw_dir << ") failed for user: " << username;
             qCritical() << "verify directory exist and has sufficient permissions";
-            free(buffer);
             exit(Auth::HELPER_OTHER_ERROR);
         }
-        free(buffer);
+        const QString homeDir = QString::fromLocal8Bit(pw.pw_dir);
 
         //we cannot use setStandardError file as this code is run in the child process
         //we want to redirect after we setuid so that the log file is owned by the user
 
         // determine stderr log file based on session type
         QString sessionLog = QStringLiteral("%1/%2")
-                .arg(QString::fromLocal8Bit(pw.pw_dir))
+                .arg(homeDir)
                 .arg(sessionType == QLatin1String("x11")
                      ? mainConfig.X11.SessionLogFile.get()
                      : mainConfig.Wayland.SessionLogFile.get());
