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-rw-r--r--tar/skip.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/tar/skip.c b/tar/skip.c
new file mode 100644
index 0000000..69208b2
--- /dev/null
+++ b/tar/skip.c
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "util.h"
+#include "tar.h"
+
+#include <stdio.h>
+
+static int skip_bytes(int fd, uint64_t size)
+{
+ unsigned char buffer[1024];
+ ssize_t ret;
+ size_t diff;
+
+ while (size != 0) {
+ diff = sizeof(buffer);
+ if (diff > size)
+ diff = size;
+
+ ret = read_retry(fd, buffer, diff);
+
+ if (ret < 0) {
+ perror("reading tar record data");
+ return -1;
+ }
+
+ if ((size_t)ret < diff) {
+ fputs("unexpected end of file\n", stderr);
+ return -1;
+ }
+
+ size -= diff;
+ }
+
+ return 0;
+}
+
+int skip_padding(int fd, uint64_t size)
+{
+ size_t tail = size % 512;
+
+ return tail ? skip_bytes(fd, 512 - tail) : 0;
+}
+
+int skip_entry(int fd, uint64_t size)
+{
+ size_t tail = size % 512;
+
+ return skip_bytes(fd, tail ? (size + 512 - tail) : size);
+}