stats: Avoid double-frees on a failed mapping

Added debugging statements and ensure, following calls to g_free, that
the statistics file name field is set to NULL to ensure that a failed
file mapping and a subsequent call to stats_free doesn't fault when
trying to double-free it.

diff --git a/src/stats.c b/src/stats.c
index 679a372..30c0169 100644 (file)
--- a/src/stats.c
+++ b/src/stats.c
@@ -214,6 +214,9 @@ static void stats_free(gpointer user_data)
 {
        struct stats_file *file = user_data;
 
+       if (file == NULL)
+               return;
+
        msync(file->addr, file->len, MS_SYNC);
 
        munmap(file->addr, file->len);
@@ -232,8 +235,7 @@ static void stats_free(gpointer user_data)
                file->name = NULL;
        }
 
-       if (file != NULL)
-               g_free(file);
+       g_free(file);
 }
 
 static void update_first(struct stats_file *file)
@@ -275,6 +277,9 @@ static int stats_file_remap(struct stats_file *file, size_t size)
        void *addr;
        int err;
 
+       DBG("file %p size %u addr %p len %u", file, size, file->addr,
+               file->len);
+
        page_size = sysconf(_SC_PAGESIZE);
        new_size = (size + page_size - 1) & ~(page_size - 1);
 
@@ -315,6 +320,8 @@ static int stats_file_remap(struct stats_file *file, size_t size)
 static int stats_open(struct stats_file *file,
                        const char *name)
 {
+       DBG("file %p name %s", file, name);
+
        file->name = g_strdup(name);
 
        file->fd = TFR(open(file->name, O_RDWR | O_CREAT, 0644));
@@ -322,6 +329,7 @@ static int stats_open(struct stats_file *file,
                connman_error("open error %s for %s",
                                strerror(errno), file->name);
                g_free(file->name);
+               file->name = NULL;
                return -errno;
        }
 
@@ -337,6 +345,7 @@ static int stats_open_temp(struct stats_file *file)
                connman_error("create tempory file error %s for %s",
                                strerror(errno), file->name);
                g_free(file->name);
+               file->name = NULL;
                return -errno;
        }
 
@@ -350,6 +359,8 @@ static int stats_file_setup(struct stats_file *file)
        size_t size = 0;
        int err;
 
+       DBG("file %p fd %d name %s", file, file->fd, file->name);
+
        err = fstat(file->fd, &st);
        if (err < 0) {
                connman_error("fstat error %s for %s\n",
@@ -357,6 +368,7 @@ static int stats_file_setup(struct stats_file *file)
 
                TFR(close(file->fd));
                g_free(file->name);
+               file->name = NULL;
 
                return -errno;
        }
@@ -371,6 +383,7 @@ static int stats_file_setup(struct stats_file *file)
        if (err < 0) {
                TFR(close(file->fd));
                g_free(file->name);
+               file->name = NULL;
 
                return err;
        }
@@ -586,6 +599,7 @@ static void stats_file_cleanup(struct stats_file *file)
 {
        file->fd = -1;
        g_free(file->name);
+       file->name = NULL;
 }
 
 static int stats_file_close_swap(struct stats_file *history_file,