fix: Fix potential error scenarios

Configuring the build with CFLAGS="-O2 -g -fanalyzer", we ran into some
build errors, which we address in this commit.

First off, GCC identified a false positive file descriptor leak in
x52d_client.c, this instance is suppressed to avoid breaking the build.

There was a bug in x52d_clock.c, where if the original timezone could
not have a copy due to malloc failure, it would fail when resetting the
TZ environment. This is fixed by ensuring the copy is valid.

Finally, there was a potential NULL pointer dereference if the pinelog
module messes up the log levels, and the lmap_get_string method ends up
returning a NULL which was passed to the DATA macro. This is fixed by
checking for NULL and handling it in case of failure.

daemon/x52d_client.c

@@ -27,6 +27,11 @@ bool x52d_client_register(int client_fd[X52D_MAX_CLIENTS], int sock_fd)
     int fd;
     int i;
 
+    #if defined(__GNUC__) && !defined(__clang__)
+        #pragma GCC diagnostic push
+        #pragma GCC diagnostic ignored "-Wanalyzer-fd-leak"
+    #endif
+
     fd = accept(sock_fd, NULL, NULL);
     if (fd < 0) {
         PINELOG_ERROR(_("Error accepting client connection on socket fd %d: %s"),
@@ -40,6 +45,11 @@ bool x52d_client_register(int client_fd[X52D_MAX_CLIENTS], int sock_fd)
         goto error;
     }
 
+    #if defined(__GNUC__) && !defined(__clang__)
+        #pragma GCC diagnostic pop
+    #endif
+
+
     for (i = 0; i < X52D_MAX_CLIENTS; i++) {
         if (client_fd[i] == INVALID_CLIENT) {
             PINELOG_TRACE("Accepted client %d on socket %d, slot %d", fd, sock_fd, i);

daemon/x52d_clock.c

@@ -97,8 +97,11 @@ cleanup:
     if (orig_tz == NULL) {
         unsetenv("TZ");
     } else {
-        setenv("TZ", orig_tz_copy, true);
-        free(orig_tz_copy);
+        // If the copy is NULL, then we didn't change TZ, so don't bother
+        if (orig_tz_copy != NULL) {
+            setenv("TZ", orig_tz_copy, true);
+            free(orig_tz_copy);
+        }
     }
 
     if (new_tz != NULL) {

daemon/x52d_command.c

@@ -239,6 +239,19 @@ static const char *lmap_get_string(const struct level_map *map, int level)
     return NULL;
 }
 
+#define DATA_LMAP(map, level, resp) do {\
+    int input_level_ ## __LINE__ = level; \
+    const char *lmap_level_ ## __LINE__ = lmap_get_string(map, input_level_ ## __LINE__); \
+    char lmap_unknown_level ## __LINE__[32] = {0}; \
+    if (lmap_level_ ## __LINE__ == NULL) { \
+        snprintf(lmap_unknown_level ## __LINE__, sizeof(lmap_unknown_level ## __LINE__), \
+                 "unknown (%d)", input_level_ ## __LINE__); \
+        lmap_level_ ## __LINE__ = lmap_unknown_level ## __LINE__; \
+    } \
+    DATA(resp, lmap_level_ ## __LINE__); \
+} while(0)
+
+
 static int array_find_index(const char **array, int nmemb, const char *string)
 {
     int i;
@@ -287,14 +300,13 @@ static void cmd_logging(char *buffer, int *buflen, int argc, char **argv)
     // logging show [module]
     MATCH(1, "show") {
         if (argc == 2) {
-            // Show default logging level
-            DATA("global", lmap_get_string(loglevels, pinelog_get_level()));
+            DATA_LMAP(loglevels, pinelog_get_level(), "global");
         } else if (argc == 3) {
             int module = array_find_index(modules, X52D_MOD_MAX, argv[2]);
             if (module == X52D_MOD_MAX) {
                 ERR_fmt("Invalid module '%s'", argv[2]);
             } else {
-                DATA(argv[2], lmap_get_string(loglevels, pinelog_get_module_level(module)));
+                DATA_LMAP(loglevels, pinelog_get_module_level(module), argv[2]);
             }
         } else {
             ERR_fmt("Unexpected arguments for 'logging show' command; got %d, expected 2 or 3", argc);