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authorDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-06-19 15:04:17 +0200
committerDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-06-19 15:18:01 +0200
commit2f172ede7115d0a2730a3b689131042ba559e272 (patch)
tree4b25a22ac49eefd2eb7a5df557a2b716b90e6076 /lib/tar/skip.c
parent0135734e41046c051a018d6c5d97e1b6ea7638b5 (diff)
Split generic tar code off to static library
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Diffstat (limited to 'lib/tar/skip.c')
-rw-r--r--lib/tar/skip.c48
1 files changed, 48 insertions, 0 deletions
diff --git a/lib/tar/skip.c b/lib/tar/skip.c
new file mode 100644
index 0000000..69208b2
--- /dev/null
+++ b/lib/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);
+}