Read in blocks rather than one char at a time, greatly improves speed

1 files changed, 23 insertions, 4 deletions

diff --git a/archival/libunarchive/seek_by_char.c b/archival/libunarchive/seek_by_char.c
index f33935cb5..77da4ef2e 100644
--- a/archival/libunarchive/seek_by_char.c
+++ b/archival/libunarchive/seek_by_char.c
@@ -14,12 +14,31 @@
  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
+#include <stdlib.h>
+
 #include "unarchive.h"
+#include "busybox.h"
 
-extern void seek_by_char(const archive_handle_t *archive_handle, const unsigned int amount)
+/*	If we are reading through a pipe(), or from stdin then we cant lseek,
+ *  we must read and discard the data to skip over it.
+ *
+ *  TODO: rename to seek_by_read
+ */
+extern void seek_by_char(const archive_handle_t *archive_handle, const unsigned int jump_size)
 {
-	unsigned int i;
-	for (i = 0; i < amount; i++) {
-		archive_xread_char(archive_handle);
+	unsigned int remaining = jump_size;
+	unsigned int read_amount;
+	RESERVE_CONFIG_BUFFER(buf, BUFSIZ);
+
+	while (remaining > 0) {
+		if (remaining > BUFSIZ) {
+			read_amount = BUFSIZ;
+		} else {
+			read_amount = remaining;
+		}
+		read_amount = archive_xread(archive_handle, buf, read_amount);
+		remaining -= read_amount;
 	}
+
+	RELEASE_CONFIG_BUFFER(buf);
 }