1 files changed, 43 insertions, 0 deletions

diff --git a/src/firejail/util.c b/src/firejail/util.c
index a9e96266c..9ad937f55 100644
--- a/src/firejail/util.c
+++ b/src/firejail/util.c
@@ -492,3 +492,46 @@ const char *gnu_basename(const char *path)
                 return path;
         return last_slash+1;
 }
+
+uid_t pid_get_uid(pid_t pid) {
+        uid_t rv = 0;
+        
+        // open status file
+        char *file;
+        if (asprintf(&file, "/proc/%u/status", pid) == -1) {
+                perror("asprintf");
+                exit(1);
+        }
+        FILE *fp = fopen(file, "r");
+        if (!fp) {
+                free(file);
+                fprintf(stderr, "Error: cannot open /proc file\n");
+                exit(1);
+        }
+
+        // extract uid
+        static const int PIDS_BUFLEN = 1024;
+        char buf[PIDS_BUFLEN];
+        while (fgets(buf, PIDS_BUFLEN - 1, fp)) {
+                if (strncmp(buf, "Uid:", 4) == 0) {
+                        char *ptr = buf + 5;
+                        while (*ptr != '\0' && (*ptr == ' ' || *ptr == '\t')) {
+                                ptr++;
+                        }
+                        if (*ptr == '\0')
+                                break;
+                                
+                        rv = atoi(ptr);
+                        break; // break regardless!
+                }
+        }
+
+        fclose(fp);
+        free(file);
+        
+        if (rv == 0) {
+                fprintf(stderr, "Error: cannot read /proc file\n");
+                exit(1);
+        }
+        return rv;
+}