core: New function gpgrt_add_post_log_func.

* src/gpg-error.h.in (gpgrt_add_post_log_func): New.
* src/gpg-error.vers: Add new function
* src/gpg-error.def.in: Ditto.
* src/visibility.c (gpgrt_add_post_log_func): New.
* src/logging.c (struct post_log_func_item_s): New.
(post_log_func_list): New.
(_gpgrt_add_post_log_func): new.
(run_post_log_funcs): New.
(_gpgrt_logv_internal): Call for fatal and bug log levels.
--

This is required in case an application or library needs to do do some
quick cleanups after a log_fatal.

8 files changed, 88 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index d532c6d..a41520a 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,11 @@ Noteworthy changes in version 1.49 (unreleased) [C35/A35/R_]
 -----------------------------------------------
 
 
+ * Interface changes relative to the 1.48 release:
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ gpgrt_add_post_log_func        NEW.
+
+
  Release-info: https://dev.gnupg.org/T7012
 
 
diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index 3bd18f7..eab681d 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -247,6 +247,6 @@ EXPORTS
 ;; gpgrt_close_all_fds          @188
 
  gpgrt_wipememory             @189
-
+ gpgrt_add_post_log_func      @190
 
 ;; end of file with public symbols for Windows.
diff --git a/src/gpg-error.h.in b/src/gpg-error.h.in
index fcf4eb6..d00bf1b 100644
--- a/src/gpg-error.h.in
+++ b/src/gpg-error.h.in
@@ -995,11 +995,12 @@ enum gpgrt_log_levels
   };
 
 
-/* The next 4 functions are not thread-safe - call them early.  */
+/* The next 5 functions are not thread-safe - call them early.  */
 void gpgrt_log_set_sink (const char *name, gpgrt_stream_t stream, int fd);
 void gpgrt_log_set_socket_dir_cb (const char *(*fnc)(void));
 void gpgrt_log_set_pid_suffix_cb (int (*cb)(unsigned long *r_value));
 void gpgrt_log_set_prefix (const char *text, unsigned int flags);
+void gpgrt_add_post_log_func (void (*f)(int));
 
 int  gpgrt_get_errorcount (int clear);
 void gpgrt_inc_errorcount (void);
diff --git a/src/gpg-error.vers b/src/gpg-error.vers
index 78a0ae8..b095edf 100644
--- a/src/gpg-error.vers
+++ b/src/gpg-error.vers
@@ -211,6 +211,8 @@ GPG_ERROR_1.0 {
 
     gpgrt_wipememory;
 
+    gpgrt_add_post_log_func;
+
   local:
     *;
 };
diff --git a/src/gpgrt-int.h b/src/gpgrt-int.h
index 4ed64be..adddb26 100644
--- a/src/gpgrt-int.h
+++ b/src/gpgrt-int.h
@@ -537,6 +537,7 @@ void _gpgrt_log_set_sink (const char *name, estream_t stream, int fd);
 void _gpgrt_log_set_socket_dir_cb (const char *(*fnc)(void));
 void _gpgrt_log_set_pid_suffix_cb (int (*cb)(unsigned long *r_value));
 void _gpgrt_log_set_prefix (const char *text, unsigned int flags);
+void _gpgrt_add_post_log_func (void (*f)(int));
 const char *_gpgrt_log_get_prefix (unsigned int *flags);
 int  _gpgrt_log_test_fd (int fd);
 int  _gpgrt_log_get_fd (void);
diff --git a/src/logging.c b/src/logging.c
index 4dc0eba..4f52d80 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -101,6 +101,18 @@ static int force_prefixes;
 static int missing_lf;
 static int errorcount;
 
+/* The list of registered functions to be called after logging.  */
+struct post_log_func_item_s;
+typedef struct post_log_func_item_s *post_log_func_item_t;
+struct post_log_func_item_s
+{
+  post_log_func_item_t next;
+  void (*func) (int);
+};
+static post_log_func_item_t post_log_func_list;
+
+
+
 
 /* An object to convey data to the fmt_string_filter.  */
 struct fmt_string_filter_s
@@ -655,6 +667,59 @@ _gpgrt_log_get_stream (void)
 }
 
 
+/* Add a function F to the list of functions called after a log_fatal
+ * or log_bug right before terminating the process.  If a function
+ * with that address has already been registered, it is not added a
+ * second time.  */
+void
+_gpgrt_add_post_log_func (void (*f)(int))
+{
+  post_log_func_item_t item;
+
+  for (item = post_log_func_list; item; item = item->next)
+    if (item->func == f)
+      return; /* Function has already been registered.  */
+
+  /* We use a standard malloc here.  */
+  item = malloc (sizeof *item);
+  if (item)
+    {
+      item->func = f;
+      item->next = post_log_func_list;
+      post_log_func_list = item;
+    }
+  else
+    _gpgrt_log_fatal ("out of core in gpgrt_add_post_log_func\n");
+}
+
+
+/* Run the post log function handlers.  These are only called for
+ * fatal and bug errors and should be aware that the process will
+ * terminate.  */
+static void
+run_post_log_funcs (int level)
+{
+  static int running;  /* Just to avoid recursive calls.  */
+  post_log_func_item_t next;
+  void (*f)(int);
+
+  if (running)
+    return;
+  running = 1;
+
+  while (post_log_func_list)
+    {
+      next = post_log_func_list->next;
+      f = post_log_func_list->func;
+      post_log_func_list->func = NULL;
+      post_log_func_list = next;
+      if (f)
+        f (level);
+    }
+}
+
+
+
 /* A filter used with the fprintf_sf function to sanitize the args for
  * "%s" format specifiers.  */
 static char *
@@ -983,6 +1048,7 @@ _gpgrt_logv_internal (int level, int ignore_arg_ptr, const char *extrastring,
     {
       if (missing_lf)
         _gpgrt_putc_unlocked ('\n', logstream);
+      run_post_log_funcs (level);
       _gpgrt_funlockfile (logstream);
       exit (2);
     }
@@ -990,6 +1056,7 @@ _gpgrt_logv_internal (int level, int ignore_arg_ptr, const char *extrastring,
     {
       if (missing_lf)
         _gpgrt_putc_unlocked ('\n', logstream );
+      run_post_log_funcs (level);
       _gpgrt_funlockfile (logstream);
       /* Using backtrace requires a configure test and to pass
        * -rdynamic to gcc.  Thus we do not enable it now.  */
diff --git a/src/visibility.c b/src/visibility.c
index 5ecef45..8c00168 100644
--- a/src/visibility.c
+++ b/src/visibility.c
@@ -961,6 +961,14 @@ gpgrt_log_get_stream (void)
   return _gpgrt_log_get_stream ();
 }
 
+
+void
+gpgrt_add_post_log_func (void (*f)(int))
+{
+  _gpgrt_add_post_log_func (f);
+}
+
+
 void
 gpgrt_log (int level, const char *fmt, ...)
 {
diff --git a/src/visibility.h b/src/visibility.h
index 75aec0d..8f3bd8c 100644
--- a/src/visibility.h
+++ b/src/visibility.h
@@ -184,6 +184,7 @@ MARK_VISIBLE (gpgrt_log_get_prefix)
 MARK_VISIBLE (gpgrt_log_test_fd)
 MARK_VISIBLE (gpgrt_log_get_fd)
 MARK_VISIBLE (gpgrt_log_get_stream)
+MARK_VISIBLE (gpgrt_add_post_log_func)
 MARK_VISIBLE (gpgrt_log)
 MARK_VISIBLE (gpgrt_logv)
 MARK_VISIBLE (gpgrt_logv_prefix)
@@ -375,6 +376,7 @@ MARK_VISIBLE (gpgrt_absfnameconcat)
 #define gpgrt_log_test_fd           _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_log_get_fd            _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_log_get_stream        _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_add_post_log_func     _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_log                   _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_logv                  _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_logv_prefix           _gpgrt_USE_UNDERSCORED_FUNCTION