implement thread enumeration

include/process.h

@@ -38,9 +38,12 @@ int process_parse_status(pid_t pid, process_status_t* status);
 // deallocate list with free later
 int processes_by_name(const char* name, process_status_t** list, size_t* count);
 
-// will determine parent process amongst children and set parent pointer to element in list
+// determine parent process amongst children and set parent pointer to element in list
 // process list must consist of parent and children processes,
 // obtained from processes_by_name call. of course parent pointer shouldn't be NULL
 int determine_parent_process(process_status_t* list, size_t count, process_status_t** parent);
 
+// get all process threads. for list and count same rules applies as for processes_by_name
+int process_get_threads(pid_t pid, process_status_t** list, size_t* count);
+
 #endif

src/main.c

@@ -23,17 +23,34 @@ int main(int argc, char** argv)
     process_status_t* list = NULL;
     size_t count = 0;
 
+    // find process
     processes_by_name("dummy_target", &list, &count);
+    // get real parent
     process_status_t* parent;
     if (determine_parent_process(list, count, &parent))
     {
-        fputs("unable to determine parent process. exiting", stderr);
+        fputs("unable to determine parent process. exiting\n", stderr);
         free(list);
         return 1;
     }
 
     print_process(parent);
 
+    // get threads
+    process_status_t* threads = NULL;
+    size_t thread_count = 0;
+    if (process_get_threads(parent->pid, &threads, &thread_count))
+    {
+        fputs("failed to obtain process threads\n", stderr);
         free(list);
+        return 1;
+    }
+
+    puts("Threads:");
+    for (size_t i = 0; i < thread_count; i++)
+        print_process(&threads[i]);
+    
+    free(list);
+    free(threads);
     return 0;
 }

src/process.c

@@ -137,3 +137,53 @@ int determine_parent_process(process_status_t* list, size_t count, process_statu
 
     return 1;
 }
+
+int process_get_threads(pid_t pid, process_status_t** list, size_t* count)
+{
+    char taskPath[256] = {0};
+    snprintf(taskPath, sizeof(taskPath), "/proc/%d/task", pid);
+
+    DIR* taskDir = opendir(taskPath);
+    if (!taskDir) return 1;
+
+    struct dirent* entry;
+    while ((entry = readdir(taskDir)))
+    {
+        if (entry->d_type != DT_DIR) continue;
+        if (!is_numeric(entry->d_name)) continue;
+
+        pid_t pid = strtod(entry->d_name, NULL);
+        process_status_t status = {};
+        if (process_parse_status(pid, &status))
+        {
+            // if we can't some threads, we should fail completely
+            // failure is better than incomplete info
+            TRACE("failed to parse %d task status\n", pid);
+            closedir(taskDir);
+            return 1;
+        }
+
+        // add thread to list
+        process_status_t* _list = *list;
+        size_t _count = *count;
+
+        if (_count) _list = (process_status_t*)realloc(_list, ++_count * sizeof(process_status_t));
+        else _list = (process_status_t*)malloc(++_count * sizeof(process_status_t));
+
+        if (!_list)
+        {
+            TRACE("out of memory for process status!\n");
+            closedir(taskDir);
+            return 1;
+        }
+
+        // copy thread to list
+        memcpy(&_list[_count - 1], &status, sizeof(process_status_t));
+
+        *list = _list;
+        *count = _count;
+    }
+
+    closedir(taskDir);
+    return 0;
+}