errors: move system error message getter to util

Provide the system error message functionality (strerror or the string
handling for GetLastError on Windows) into a utility class.

3 files changed, 35 insertions, 21 deletions

diff --git a/src/buffer.c b/src/buffer.c
index ce97ccffa..e50b40977 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1080,3 +1080,33 @@ int git_buf_getenv(git_buf *out, const char *name)
 	return git_buf_puts(out, val);
 }
 #endif /* GIT_WIN32 */
+
+int git_buf_system_errmsg(git_buf *out)
+{
+#ifdef GIT_WIN32
+	if (GetLastError() != 0) {
+		char *msg = git_win32_get_error_message(GetLastError());
+
+		if (msg == NULL) {
+			out->ptr = git_buf__oom;
+			return -1;
+		}
+
+		git_buf_puts(out, msg);
+		git__free(msg);
+
+		SetLastError(0);
+		return 0;
+	}
+#endif
+
+	if (errno) {
+		git_buf_puts(out, strerror(errno));
+
+		errno = 0;
+		return 0;
+	}
+
+	git_buf_puts(out, "no error");
+	return 0;
+}
diff --git a/src/buffer.h b/src/buffer.h
index e2023cc59..c845c7de5 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -229,6 +229,9 @@ int git_buf_decode_percent(git_buf *buf, const char *str, size_t len);
 /* Place the value of the given environment variable into the buffer */
 int git_buf_getenv(git_buf *buf, const char *name);
 
+/* Place the value of the current system error message into the buffer */
+int git_buf_system_errmsg(git_buf *buf);
+
 /*
  * Insert, remove or replace a portion of the buffer.
  *
diff --git a/src/errors.c b/src/errors.c
index b34aa3abb..dfb5e3c4f 100644
--- a/src/errors.c
+++ b/src/errors.c
@@ -60,10 +60,6 @@ void git_error_set(int error_class, const char *fmt, ...)
 
 void git_error_vset(int error_class, const char *fmt, va_list ap)
 {
-#ifdef GIT_WIN32
-	DWORD win32_error_code = (error_class == GIT_ERROR_OS) ? GetLastError() : 0;
-#endif
-	int error_code = (error_class == GIT_ERROR_OS) ? errno : 0;
 	git_buf *buf = &GIT_GLOBAL->error_buf;
 
 	git_buf_clear(buf);
@@ -73,23 +69,8 @@ void git_error_vset(int error_class, const char *fmt, va_list ap)
 			git_buf_PUTS(buf, ": ");
 	}
 
-	if (error_class == GIT_ERROR_OS) {
-#ifdef GIT_WIN32
-		char * win32_error = git_win32_get_error_message(win32_error_code);
-		if (win32_error) {
-			git_buf_puts(buf, win32_error);
-			git__free(win32_error);
-
-			SetLastError(0);
-		}
-		else
-#endif
-		if (error_code)
-			git_buf_puts(buf, strerror(error_code));
-
-		if (error_code)
-			errno = 0;
-	}
+	if (error_class == GIT_ERROR_OS)
+		git_buf_system_errmsg(buf);
 
 	if (!git_buf_oom(buf))
 		set_error_from_buffer(error_class);