Resolve paths with readlink and realpath for path comparison

1 files changed, 17 insertions, 9 deletions

diff --git a/main.c b/main.c
index e59691f..ba046f5 100644
--- a/main.c
+++ b/main.c
@@ -9,15 +9,14 @@
 #include <sys/sendfile.h>
 #include <sys/capability.h>
 
-static int get_self_filepath(char *buffer) {
-    char self_path[PATH_MAX];
-
-    ssize_t bytes_written = readlink("/proc/self/exe", self_path, sizeof(self_path) - 1);
+static int readlink_realpath(const char *filepath, char *buffer) {
+    char symlinked_path[PATH_MAX];
+    ssize_t bytes_written = readlink(filepath, symlinked_path, sizeof(symlinked_path) - 1);
     if(bytes_written == -1)
         return 0;
 
-    self_path[bytes_written] = '\0';
-    if(!realpath(self_path, buffer))
+    symlinked_path[bytes_written] = '\0';
+    if(!realpath(symlinked_path, buffer))
         return 0;
 
     return 1;
@@ -120,7 +119,7 @@ int main(int argc, char **argv) {
     const char *user_homepath = argv[3];
 
     char self_path[PATH_MAX];
-    if(!get_self_filepath(self_path))
+    if(!readlink_realpath("/proc/self/exe", self_path))
         return 1;
 
     char kms_server_proxy_local_filepath[PATH_MAX];
@@ -130,8 +129,17 @@ int main(int argc, char **argv) {
         const char *args[] = { gsr_kms_server_filepath, initial_socket_path, card_path, NULL };
         return execv(args[0], (char *const*)args);
     } else if(file_has_sys_admin_capability(kms_server_proxy_local_filepath)) {
-        if(strcmp(self_path, kms_server_proxy_local_filepath) != 0) {
-            const char *args[] = { kms_server_proxy_local_filepath, initial_socket_path, card_path, user_homepath, NULL };
+        /* Need to resolve kms_server_proxy_local_filepath because /home can be a symlink to another location */
+        char kms_server_proxy_local_filepath_full[PATH_MAX];
+        if(!readlink_realpath(kms_server_proxy_local_filepath, kms_server_proxy_local_filepath_full))
+            return 1;
+
+        /*
+            Run cached ~/.local/share/gpu-screen-recorder/kms-server-proxy which has sys admin capability.
+            The one in flatpak location gets capabilities overwritten on flatpak update.
+        */
+        if(strcmp(self_path, kms_server_proxy_local_filepath_full) != 0) {
+            const char *args[] = { kms_server_proxy_local_filepath_full, initial_socket_path, card_path, user_homepath, NULL };
             return execv(args[0], (char *const*)args);
         }