Fixed wrong pid bug

The issue was that the thread ID wasn't factored in. A presumption was,
that FUSE already returned the PID, not TID. The issue was fixed by
implementing a function that translates the TID to PID.

src/perm_permissions_table.c

@@ -272,7 +272,7 @@ access_t check_perm_access(const char *filename, struct process_info pi) {
     }
     current_pi.name = NULL;
     while (current_pi.name == NULL) {
-      current_pi.PID = get_parent_pid(current_pi.PID);
+      current_pi.PID = get_main_thread_pid(get_parent_pid(current_pi.PID));
       if (current_pi.PID != 0) {
         current_pi.name = get_process_name_by_pid(current_pi.PID);
       } else {

src/proc_operations.c

@@ -7,9 +7,49 @@
 */
 
 #include "proc_operations.h"
+#include <linux/limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 
+/**
+ * @brief Returns the PID of the main thread (i.e., the process ID) of the
+ * process that the given thread ID (tid) belongs to.
+ *
+ * @param tid The thread ID (TID) of any thread in the process.
+ * @return pid_t The process ID (main thread's PID), or -1 on error.
+ */
+pid_t get_main_thread_pid(pid_t tid) {
+  // Validate input
+  if (tid <= 0) {
+    // errno = EINVAL;
+    return 0;
+  }
+
+  char path[PATH_MAX];
+  snprintf(path, sizeof(path), "/proc/%d/status", tid);
+
+  FILE *fp = fopen(path, "r");
+  if (!fp) {
+    return 0; // Could not open the file
+  }
+
+  pid_t tgid = 0;
+  char line[256];
+
+  while (fgets(line, sizeof(line), fp)) {
+    if (sscanf(line, "Tgid: %d", &tgid) == 1) {
+      break;
+    }
+  }
+
+  fclose(fp);
+  if (tgid != tid) {
+    fprintf(stderr, "The tid and and pid wasn't equal. tid:%d, pid:%d.\n", tid,
+            tgid);
+  }
+  return tgid;
+}
+
 char *get_process_name_by_pid(const int pid) {
   char path[1024];
   sprintf(path, "/proc/%d/exe", pid);

src/proc_operations.h

@@ -22,4 +22,13 @@ char *get_process_name_by_pid(const int pid);
  */
 pid_t get_parent_pid(pid_t pid);
 
+/**
+ * @brief Returns the PID of the main thread (i.e., the process ID) of the
+ * process that the given thread ID (tid) belongs to.
+ *
+ * @param tid The thread ID (TID) of any thread in the process.
+ * @return pid_t The process ID (main thread's PID), or -1 on error.
+ */
+pid_t get_main_thread_pid(pid_t tid);
+
 #endif // !PROC_OPERATIONS

src/process_info.h

@@ -10,7 +10,11 @@
 #define PROCESS_INFO_H
 
 #include "proc_operations.h"
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
 #include <sys/types.h>
+#include <unistd.h>
 struct process_info {
   pid_t PID;
   char *name;
@@ -18,7 +22,7 @@ struct process_info {
 
 static inline struct process_info get_process_info(pid_t pid) {
   struct process_info pi;
-  pi.PID = pid;
+  pi.PID = get_main_thread_pid(pid);
   pi.name = get_process_name_by_pid(pi.PID);
   if (pi.name == NULL) {
     pi.PID = 0;

src/temp_permissions_table.c

@@ -237,7 +237,7 @@ access_t check_temp_access(const char *filename, struct process_info pi) {
     if (access != NDEF) {
       return access;
     }
-    current_pid = get_parent_pid(current_pid);
+    current_pid = get_main_thread_pid(get_parent_pid(current_pid));
   }
 
   return NDEF;