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-rw-r--r--lib/sqfs/meta_writer.c93
1 files changed, 93 insertions, 0 deletions
diff --git a/lib/sqfs/meta_writer.c b/lib/sqfs/meta_writer.c
new file mode 100644
index 0000000..95092d5
--- /dev/null
+++ b/lib/sqfs/meta_writer.c
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "meta_writer.h"
+#include "squashfs.h"
+#include "util.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+
+meta_writer_t *meta_writer_create(int fd, compressor_t *cmp)
+{
+ meta_writer_t *m = calloc(1, sizeof(*m));
+
+ if (m == NULL) {
+ perror("creating meta data writer");
+ return NULL;
+ }
+
+ m->cmp = cmp;
+ m->outfd = fd;
+ return m;
+}
+
+void meta_writer_destroy(meta_writer_t *m)
+{
+ free(m);
+}
+
+int meta_writer_flush(meta_writer_t *m)
+{
+ ssize_t ret, count;
+
+ if (m->offset == 0)
+ return 0;
+
+ ret = m->cmp->do_block(m->cmp, m->data + 2, m->offset);
+ if (ret < 0)
+ return -1;
+
+ if (ret > 0) {
+ ((uint16_t *)m->data)[0] = htole16(ret);
+ count = ret + 2;
+ } else {
+ ((uint16_t *)m->data)[0] = htole16(m->offset | 0x8000);
+ count = m->offset + 2;
+ }
+
+ ret = write_retry(m->outfd, m->data, count);
+
+ if (ret < 0) {
+ perror("writing meta data");
+ return -1;
+ }
+
+ if (ret < count) {
+ fputs("meta data written to file was truncated\n", stderr);
+ return -1;
+ }
+
+ memset(m->data, 0, sizeof(m->data));
+ m->offset = 0;
+ m->block_offset += count;
+ return 0;
+}
+
+int meta_writer_append(meta_writer_t *m, const void *data, size_t size)
+{
+ size_t diff;
+
+ while (size != 0) {
+ diff = sizeof(m->data) - 2 - m->offset;
+
+ if (diff == 0) {
+ if (meta_writer_flush(m))
+ return -1;
+ diff = sizeof(m->data) - 2;
+ }
+
+ if (diff > size)
+ diff = size;
+
+ memcpy(m->data + 2 + m->offset, data, diff);
+ m->offset += diff;
+ size -= diff;
+ data = (const char *)data + diff;
+ }
+
+ if (m->offset == (sizeof(m->data) - 2))
+ return meta_writer_flush(m);
+
+ return 0;
+}