Get netdata execution path early to avoid user permission issues (#9339)

* Get netdata execution path early to avoid user permission issues

daemon/daemon.c

@@ -5,6 +5,27 @@
 
 char pidfile[FILENAME_MAX + 1] = "";
 char claimingdirectory[FILENAME_MAX + 1];
+char exepath[FILENAME_MAX + 1];
+
+void get_netdata_execution_path(void)
+{
+    int ret;
+    size_t exepath_size = 0;
+    struct passwd *passwd = NULL;
+    char *user = NULL;
+
+    passwd = getpwuid(getuid());
+    user = (passwd && passwd->pw_name) ? passwd->pw_name : "";
+
+    exepath_size = sizeof(exepath) - 1;
+    ret = uv_exepath(exepath, &exepath_size);
+    if (0 != ret) {
+        error("uv_exepath(\"%s\", %u) (user: %s) failed (%s).", exepath, (unsigned)exepath_size, user,
+              uv_strerror(ret));
+        fatal("Cannot start netdata without getting execution path.");
+    }
+    exepath[exepath_size] = '\0';
+}
 
 static void chown_open_file(int fd, uid_t uid, gid_t gid) {
     if(fd == -1) return;

daemon/daemon.h

@@ -10,7 +10,9 @@ extern int become_daemon(int dont_fork, const char *user);
 extern void netdata_cleanup_and_exit(int i);
 extern void send_statistics(const char *action, const char *action_result, const char *action_data);
 
-extern char pidfile[];
+extern void get_netdata_execution_path(void);
 
+extern char pidfile[];
+extern char exepath[];
 
 #endif /* NETDATA_DAEMON_H */

daemon/main.c

@@ -1272,6 +1272,9 @@ int main(int argc, char **argv) {
         // files using relative filenames
         if(chdir(netdata_configured_user_config_dir) == -1)
             fatal("Cannot cd to '%s'", netdata_configured_user_config_dir);
+
+        // Get execution path before switching user to avoid permission issues
+        get_netdata_execution_path();
     }
 
     {

spawn/spawn.c

@@ -190,8 +190,6 @@ struct spawn_cmd_info *spawn_get_unprocessed_cmd(void)
 int create_spawn_server(uv_loop_t *loop, uv_pipe_t *spawn_channel, uv_process_t *process)
 {
     uv_process_options_t options = {0};
-    size_t exepath_size;
-    char exepath[FILENAME_MAX];
     char *args[3];
     int ret;
 #define SPAWN_SERVER_DESCRIPTORS (3)
@@ -202,15 +200,6 @@ int create_spawn_server(uv_loop_t *loop, uv_pipe_t *spawn_channel, uv_process_t
     passwd = getpwuid(getuid());
     user = (passwd && passwd->pw_name) ? passwd->pw_name : "";
 
-    exepath_size = sizeof(exepath);
-    ret = uv_exepath(exepath, &exepath_size);
-    if (0 != ret) {
-        error("uv_exepath(\"%s\", %u) (user: %s) failed (%s).", exepath, (unsigned)exepath_size, user,
-              uv_strerror(ret));
-        fatal("Cannot start netdata without the spawn server.");
-    }
-
-    exepath[exepath_size] = '\0';
     args[0] = exepath;
     args[1] = SPAWN_SERVER_COMMAND_LINE_ARGUMENT;
     args[2] = NULL;
@@ -231,8 +220,7 @@ int create_spawn_server(uv_loop_t *loop, uv_pipe_t *spawn_channel, uv_process_t
 
     ret = uv_spawn(loop, process, &options); /* execute the netdata binary again as the netdata user */
     if (0 != ret) {
-        error("uv_spawn (process: \"%s\", %u) (user: %s) failed (%s).", exepath, (unsigned)exepath_size, user,
+        error("uv_spawn (process: \"%s\") (user: %s) failed (%s).", exepath, user, uv_strerror(ret));
-              uv_strerror(ret));
         fatal("Cannot start netdata without the spawn server.");
     }