[tracker-miners/wip/carlosg/tracker-process-readlink] tracker: Double check readlink result to find out process names

[Carlos Garnacho <carlosg src gnome org>]

commit 83000f1183d52877f47fc894d0478088596b0d3e
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Aug 25 17:24:46 2020 +0200

    tracker: Double check readlink result to find out process names
    
    Handle errors, ensure the string is \0 terminated, and ensure to trim
    the " (deleted)" suffix that links get when you replace the executable
    (eg. us developers doing ninja install again).

 src/tracker/tracker-process.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)
---
diff --git a/src/tracker/tracker-process.c b/src/tracker/tracker-process.c
index 9827320f9..7f3d4d0eb 100644
--- a/src/tracker/tracker-process.c
+++ b/src/tracker/tracker-process.c
@@ -69,9 +69,21 @@ static gchar *
 find_command (pid_t pid)
 {
        gchar *proc_path, path[PATH_MAX];
+       ssize_t len;
 
        proc_path = g_strdup_printf ("/proc/%d/exe", pid);
-       readlink (proc_path, path, PATH_MAX);
+       len = readlink (proc_path, path, PATH_MAX);
+
+       if (len < 0)
+               return NULL;
+
+       path[len] = '\0';
+
+       /* Trim the " (deleted)" suffix, if the miner happened to be reinstalled */
+       if (g_str_has_suffix (path, " (deleted)")) {
+               len -= strlen (" (deleted)");
+               path[len] = '\0';
+       }
 
        return g_path_get_basename (path);
 }
@@ -121,18 +133,25 @@ tracker_process_find_all (void)
        pid_t miner_fs, miner_rss;
        GSList *processes = NULL;
        TrackerProcessData *data;
+       gchar *command;
 
        connection = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, NULL);
        miner_fs = get_pid_for_service (connection, "org.freedesktop.Tracker3.Miner.Files");
        if (miner_fs > 0) {
-               data = process_data_new (find_command (miner_fs), miner_fs);
-               processes = g_slist_prepend (processes, data);
+               command = find_command (miner_fs);
+               if (command) {
+                       data = process_data_new (command, miner_fs);
+                       processes = g_slist_prepend (processes, data);
+               }
        }
 
        miner_rss = get_pid_for_service (connection, "org.freedesktop.Tracker3.Miner.RSS");
        if (miner_rss > 0) {
-               data = process_data_new (find_command (miner_rss), miner_rss);
-               processes = g_slist_prepend (processes, data);
+               command = find_command (miner_rss);
+               if (command) {
+                       data = process_data_new (command, miner_rss);
+                       processes = g_slist_prepend (processes, data);
+               }
        }
 
        g_object_unref (connection);