Add super block and padding functions

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 126 insertions, 0 deletions

diff --git a/mkfs/super.c b/mkfs/super.c
new file mode 100644
index 0000000..b3755d1
--- /dev/null
+++ b/mkfs/super.c
@@ -0,0 +1,126 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "mksquashfs.h"
+#include "util.h"
+
+#include <endian.h>
+
+int sqfs_super_init(sqfs_super_t *s, const options_t *opt)
+{
+	unsigned int i;
+
+	if (opt->blksz & (opt->blksz - 1)) {
+		fputs("Block size must be a power of 2!\n", stderr);
+		return -1;
+	}
+
+	if (opt->blksz < 8192 || opt->blksz >= (1 << 24)) {
+		fputs("Block size must be between 8k and 1M\n", stderr);
+		return -1;
+	}
+
+	memset(s, 0, sizeof(*s));
+	s->magic = SQFS_MAGIC;
+	s->modification_time = opt->def_mtime;
+	s->block_size = opt->blksz;
+	s->compression_id = opt->compressor;
+	s->flags = SQFS_FLAG_NO_FRAGMENTS | SQFS_FLAG_NO_XATTRS;
+	s->version_major = SQFS_VERSION_MAJOR;
+	s->version_minor = SQFS_VERSION_MINOR;
+	s->bytes_used = sizeof(*s);
+	s->id_table_start = 0xFFFFFFFFFFFFFFFFUL;
+	s->xattr_id_table_start = 0xFFFFFFFFFFFFFFFFUL;
+	s->inode_table_start = 0xFFFFFFFFFFFFFFFFUL;
+	s->directory_table_start = 0xFFFFFFFFFFFFFFFFUL;
+	s->fragment_table_start = 0xFFFFFFFFFFFFFFFFUL;
+	s->export_table_start = 0xFFFFFFFFFFFFFFFFUL;
+
+	for (i = opt->blksz; i != 0x01; i >>= 1)
+		s->block_log += 1;
+
+	return 0;
+}
+
+int sqfs_padd_file(sqfs_super_t *s, const options_t *opt, int outfd)
+{
+	size_t padd_sz = s->bytes_used % opt->devblksz;
+	uint8_t *buffer;
+	ssize_t ret;
+
+	if (padd_sz == 0)
+		return 0;
+
+	padd_sz = opt->devblksz - padd_sz;
+
+	buffer = calloc(1, padd_sz);
+	if (buffer == NULL) {
+		perror("padding output file to block size");
+		return -1;
+	}
+
+	ret = write_retry(outfd, buffer, padd_sz);
+
+	if (ret < 0) {
+		perror("Error padding squashfs image to page size");
+		free(buffer);
+		return -1;
+	}
+
+	if ((size_t)ret < padd_sz) {
+		fputs("Truncated write trying to padd squashfs image\n",
+		      stderr);
+		return -1;
+	}
+
+	free(buffer);
+	return 0;
+}
+
+int sqfs_super_write(const sqfs_super_t *super, int outfd)
+{
+	sqfs_super_t copy;
+	ssize_t ret;
+
+	copy.magic = htole32(super->magic);
+	copy.inode_count = htole32(super->inode_count);
+	copy.modification_time = htole32(super->modification_time);
+	copy.block_size = htole32(super->block_size);
+	copy.fragment_entry_count = htole32(super->fragment_entry_count);
+	copy.compression_id = htole16(super->compression_id);
+	copy.block_log = htole16(super->block_log);
+	copy.flags = htole16(super->flags);
+	copy.id_count = htole16(super->id_count);
+	copy.version_major = htole16(super->version_major);
+	copy.version_minor = htole16(super->version_minor);
+	copy.root_inode_ref = htole64(super->root_inode_ref);
+	copy.bytes_used = htole64(super->bytes_used);
+	copy.id_table_start = htole64(super->id_table_start);
+	copy.xattr_id_table_start = htole64(super->xattr_id_table_start);
+	copy.inode_table_start = htole64(super->inode_table_start);
+	copy.directory_table_start = htole64(super->directory_table_start);
+	copy.fragment_table_start = htole64(super->fragment_table_start);
+	copy.export_table_start = htole64(super->export_table_start);
+
+	if (lseek(outfd, 0, SEEK_SET) == (off_t)-1)
+		goto fail_seek;
+
+	ret = write_retry(outfd, &copy, sizeof(copy));
+
+	if (ret < 0) {
+		perror("squashfs writing super block");
+		return -1;
+	}
+
+	if ((size_t)ret < sizeof(copy)) {
+		fputs("squashfs writing super block: truncated write\n",
+		      stderr);
+		return -1;
+	}
+
+	if (lseek(outfd, 0, SEEK_END) == (off_t)-1)
+		goto fail_seek;
+
+	return 0;
+fail_seek:
+	perror("squashfs writing super block: seek on output file");
+	return -1;
+}