Merge pull request #1986 from libgit2/rb/error-handling-cleanups

Clean up some error handling and change callback error behavior

1 files changed, 47 insertions, 14 deletions

diff --git a/src/common.h b/src/common.h
index a1888785e..e315b5979 100644
--- a/src/common.h
+++ b/src/common.h
@@ -62,7 +62,7 @@
  * Check a return value and propogate result if non-zero.
  */
 #define GITERR_CHECK_ERROR(code) \
-	do { int _err = (code); if (_err < 0) return _err; } while (0)
+	do { int _err = (code); if (_err) return _err; } while (0)
 
 /**
  * Set the error message for this thread, formatting as needed.
@@ -76,28 +76,61 @@ void giterr_set(int error_class, const char *string, ...);
 int giterr_set_regex(const regex_t *regex, int error_code);
 
 /**
- * Gets the system error code for this thread.
+ * Set error message for user callback if needed.
+ *
+ * If the error code in non-zero and no error message is set, this
+ * sets a generic error message.
+ *
+ * @return This always returns the `error_code` parameter.
  */
-GIT_INLINE(int) giterr_system_last(void)
+GIT_INLINE(int) giterr_set_after_callback_function(
+	int error_code, const char *action)
 {
+	if (error_code) {
+		const git_error *e = giterr_last();
+		if (!e || !e->message)
+			giterr_set(e ? e->klass : GITERR_CALLBACK,
+				"%s callback returned %d", action, error_code);
+	}
+	return error_code;
+}
+
 #ifdef GIT_WIN32
-	return GetLastError();
+#define giterr_set_after_callback(code) \
+	giterr_set_after_callback_function((code), __FUNCTION__)
 #else
-	return errno;
+#define giterr_set_after_callback(code) \
+	giterr_set_after_callback_function((code), __func__)
 #endif
-}
+
+/**
+ * Gets the system error code for this thread.
+ */
+int giterr_system_last(void);
 
 /**
  * Sets the system error code for this thread.
  */
-GIT_INLINE(void) giterr_system_set(int code)
-{
-#ifdef GIT_WIN32
-	SetLastError(code);
-#else
-	errno = code;
-#endif
-}
+void giterr_system_set(int code);
+
+/**
+ * Structure to preserve libgit2 error state
+ */
+typedef struct {
+	int       error_code;
+	git_error error_msg;
+} git_error_state;
+
+/**
+ * Capture current error state to restore later, returning error code.
+ * If `error_code` is zero, this does nothing and returns zero.
+ */
+int giterr_capture(git_error_state *state, int error_code);
+
+/**
+ * Restore error state to a previous value, returning saved error code.
+ */
+int giterr_restore(git_error_state *state);
 
 /**
  * Check a versioned structure for validity