4 files changed, 42 insertions, 12 deletions

diff --git a/src/filebuf.c b/src/filebuf.c
index acfdcd141..86a643d38 100644
--- a/src/filebuf.c
+++ b/src/filebuf.c
@@ -360,29 +360,48 @@ int git_filebuf_reserve(git_filebuf *file, void **buffer, size_t len)
 int git_filebuf_printf(git_filebuf *file, const char *format, ...)
 {
 	va_list arglist;
-	size_t space_left = file->buf_size - file->buf_pos;
+	size_t space_left;
 	int len, error;
+	char *tmp_buffer;
 
-	va_start(arglist, format);
-	len = vsnprintf((char *)file->buffer + file->buf_pos, space_left, format, arglist);
-	va_end(arglist);
+	space_left = file->buf_size - file->buf_pos;
+
+	do {
+		va_start(arglist, format);
+		len = p_vsnprintf((char *)file->buffer + file->buf_pos, space_left, format, arglist);
+		va_end(arglist);
+
+		if (len < 0)
+			return git__throw(GIT_EOSERR, "Failed to format string");
+
+		if ((size_t)len <= space_left) {
+			file->buf_pos += len;
+			return GIT_SUCCESS;
+		}
 
-	if (len < 0 || (size_t)len >= space_left) {
 		if ((error = flush_buffer(file)) < GIT_SUCCESS)
 			return git__rethrow(error, "Failed to output to buffer");
 
 		space_left = file->buf_size - file->buf_pos;
 
-		va_start(arglist, format);
-		len = vsnprintf((char *)file->buffer + file->buf_pos, space_left, format, arglist);
-		va_end(arglist);
+	} while ((size_t)len <= space_left);
 
-		if (len < 0 || (size_t)len > file->buf_size)
-			return GIT_ENOMEM;
+	tmp_buffer = git__malloc(len + 1);
+	if (!tmp_buffer)
+		return GIT_ENOMEM;
+
+	va_start(arglist, format);
+	len = p_vsnprintf(tmp_buffer, len + 1, format, arglist);
+	va_end(arglist);
+
+	if (len < 0) {
+		free(tmp_buffer);
+		return git__throw(GIT_EOSERR, "Failed to format string");
 	}
 
-	file->buf_pos += len;
-	return GIT_SUCCESS;
+	error = git_filebuf_write(file, tmp_buffer, len);
+	free(tmp_buffer);
 
+	return error;
 }
 
diff --git a/src/unix/posix.h b/src/unix/posix.h
index d52aa095c..16daf15bd 100644
--- a/src/unix/posix.h
+++ b/src/unix/posix.h
@@ -12,5 +12,6 @@
 #define p_fsync(fd) fsync(fd)
 #define p_realpath(p, po) realpath(p, po)
 #define p_fnmatch(p, s, f) fnmatch(p, s, f)
+#define p_vsnprintf(b, c, f, a) vsnprintf(b, c, f, a)
 
 #endif
diff --git a/src/win32/posix.c b/src/win32/posix.c
index dfa4e1a2c..c4d9eb387 100644
--- a/src/win32/posix.c
+++ b/src/win32/posix.c
@@ -209,3 +209,12 @@ char *p_realpath(const char *orig_path, char *buffer)
 	return buffer;
 }
 
+int p_vsnprintf(char *buffer, size_t count, const char *format, va_list argptr)
+{
+#ifdef _MSV_VER
+	int len = _vsnprintf(buffer, count, format, argptr);
+	return (len < 0) ? _vscprintf(format, argptr) : len;
+#else /* MinGW */
+	return vsnprintf(buffer, count, format, argptr);
+#endif
+}
diff --git a/src/win32/posix.h b/src/win32/posix.h
index 503c5d874..efac68e74 100644
--- a/src/win32/posix.h
+++ b/src/win32/posix.h
@@ -23,5 +23,6 @@ extern int p_lstat(const char *file_name, struct stat *buf);
 extern int p_readlink(const char *link, char *target, size_t target_len);
 extern int p_hide_directory__w32(const char *path);
 extern char *p_realpath(const char *orig_path, char *buffer);
+extern int p_vsnprintf(char *buffer, size_t count, const char *format, va_list argptr);
 
 #endif