1 files changed, 92 insertions, 0 deletions

diff --git a/tarWrite.c b/tarWrite.c
new file mode 100644
index 000000000..0f9a4a4b1
--- /dev/null
+++ b/tarWrite.c
@@ -0,0 +1,92 @@
+/*
+        Copyright 2013 bigbiff/Dees_Troy TeamWin
+        This file is part of TWRP/TeamWin Recovery Project.
+
+        TWRP is free software: you can redistribute it and/or modify
+        it under the terms of the GNU General Public License as published by
+        the Free Software Foundation, either version 3 of the License, or
+        (at your option) any later version.
+
+        TWRP is distributed in the hope that it will be useful,
+        but WITHOUT ANY WARRANTY; without even the implied warranty of
+        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+        GNU General Public License for more details.
+
+        You should have received a copy of the GNU General Public License
+        along with TWRP.  If not, see <http://www.gnu.org/licenses/>.
+		
+		This is a write buffer for use with libtar. Libtar normally writes
+		512 bytes at a time but this results in poor file performance
+		especially on exFAT fuse file systems. This write buffer fixes that
+		problem.
+*/
+
+#include <fcntl.h>
+#include "libtar/libtar.h"
+#include "common.h"
+
+int flush = 0, eot_count = -1;
+unsigned char *write_buffer;
+unsigned buffer_size = 4096;
+unsigned buffer_loc = 0;
+
+void reinit_libtar_buffer(void) {
+	flush = 0;
+	eot_count = -1;
+	buffer_loc = 0;
+}
+
+void init_libtar_buffer(unsigned new_buff_size) {
+	if (new_buff_size != 0)
+		buffer_size = new_buff_size;
+
+	reinit_libtar_buffer();
+	write_buffer = (unsigned char*) malloc(sizeof(char *) * buffer_size);
+}
+
+void free_libtar_buffer(void) {
+	free(write_buffer);
+}
+
+ssize_t write_libtar_buffer(int fd, const void *buffer, size_t size) {
+	void* ptr;
+
+	if (flush == 0) {
+		ptr = write_buffer + buffer_loc;
+		memcpy(ptr, buffer, size);
+		buffer_loc += size;
+		if (eot_count >= 0 && eot_count < 2)
+			eot_count++;
+			/* At the end of the tar file, libtar will add 2 blank blocks.
+			   Once we have received both EOT blocks, we will immediately
+			   write anything in the buffer to the file.
+			*/
+
+		if (buffer_loc >= buffer_size || eot_count >= 2) {
+			flush = 1;
+		}
+	}
+	if (flush == 1) {
+		flush = 0;
+		if (buffer_loc == 0) {
+			// nothing to write
+			return 0;
+		}
+		if (write(fd, write_buffer, buffer_loc) != buffer_loc) {
+			LOGE("Error writing tar file!\n");
+			buffer_loc = 0;
+			return -1;
+		} else {
+			buffer_loc = 0;
+			return size;
+		}
+	} else {
+		return size;
+	}
+	// Shouldn't ever get here
+	return -1;
+}
+
+void flush_libtar_buffer(int fd) {
+	eot_count = 0;
+}