Replace direct file I/O with abstraction layer

This should make it easier to use libsquashfs with custom setups that
embedd a squashfs image inside something else. Also, it should make
it easier to port to non unix-like platforms.

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

7 files changed, 47 insertions, 55 deletions

diff --git a/lib/sqfshelper/data_reader.c b/lib/sqfshelper/data_reader.c
index fc92e28..d1a9cce 100644
--- a/lib/sqfshelper/data_reader.c
+++ b/lib/sqfshelper/data_reader.c
@@ -25,7 +25,7 @@ struct data_reader_t {
 
 	sqfs_compressor_t *cmp;
 	size_t block_size;
-	int sqfsfd;
+	sqfs_file_t *file;
 
 	void *block;
 	void *scratch;
@@ -44,8 +44,10 @@ static ssize_t read_block(data_reader_t *data, off_t offset, uint32_t size,
 	if (size > data->block_size)
 		goto fail_bs;
 
-	if (read_data_at("reading block", offset, data->sqfsfd, ptr, size))
+	if (data->file->read_at(data->file, offset, ptr, size)) {
+		fputs("error reading data block from input file\n", stderr);
 		return -1;
+	}
 
 	if (compressed) {
 		ret = data->cmp->do_block(data->cmp, data->scratch, size,
@@ -104,7 +106,7 @@ static int precache_fragment_block(data_reader_t *data, size_t idx)
 	return 0;
 }
 
-data_reader_t *data_reader_create(int fd, sqfs_super_t *super,
+data_reader_t *data_reader_create(sqfs_file_t *file, sqfs_super_t *super,
 				  sqfs_compressor_t *cmp)
 {
 	data_reader_t *data = alloc_flex(sizeof(*data), super->block_size, 3);
@@ -123,7 +125,7 @@ data_reader_t *data_reader_create(int fd, sqfs_super_t *super,
 	data->scratch = (char *)data->block + super->block_size;
 	data->frag_block = (char *)data->scratch + super->block_size;
 	data->current_block = -1;
-	data->sqfsfd = fd;
+	data->file = file;
 	data->block_size = super->block_size;
 	data->cmp = cmp;
 
@@ -144,7 +146,7 @@ data_reader_t *data_reader_create(int fd, sqfs_super_t *super,
 		return NULL;
 	}
 
-	ret = sqfs_read_table(fd, cmp, size, super->fragment_table_start,
+	ret = sqfs_read_table(file, cmp, size, super->fragment_table_start,
 			      super->directory_table_start,
 			      super->fragment_table_start, &raw_frag);
 
diff --git a/lib/sqfshelper/data_writer.c b/lib/sqfshelper/data_writer.c
index 62e3e2a..b94bdb6 100644
--- a/lib/sqfshelper/data_writer.c
+++ b/lib/sqfshelper/data_writer.c
@@ -32,7 +32,7 @@ struct data_writer_t {
 	sqfs_compressor_t *cmp;
 	file_info_t *list;
 	sqfs_super_t *super;
-	int outfd;
+	sqfs_file_t *file;
 };
 
 enum {
@@ -45,32 +45,19 @@ enum {
 static int save_position(data_writer_t *data)
 {
 	data->bytes_written = data->super->bytes_used;
-	data->start = lseek(data->outfd, 0, SEEK_CUR);
-
-	if (data->start == (off_t)-1) {
-		perror("querying current position on squashfs image");
-		return -1;
-	}
-
+	data->start = data->file->get_size(data->file);
 	return 0;
 }
 
 static int restore_position(data_writer_t *data)
 {
-	if (lseek(data->outfd, data->start, SEEK_SET) == (off_t)-1)
-		goto fail_seek;
-
-	if (ftruncate(data->outfd, data->start))
-		goto fail_truncate;
+	if (data->file->truncate(data->file, data->start)) {
+		perror("truncating squashfs image after file deduplication");
+		return -1;
+	}
 
 	data->super->bytes_used = data->bytes_written;
 	return 0;
-fail_seek:
-	perror("seeking on squashfs image after file deduplication");
-	return -1;
-fail_truncate:
-	perror("truncating squashfs image after file deduplication");
-	return -1;
 }
 
 static int allign_file(data_writer_t *data)
@@ -80,7 +67,7 @@ static int allign_file(data_writer_t *data)
 	if (diff == 0)
 		return 0;
 
-	if (padd_file(data->outfd, data->super->bytes_used, data->devblksz))
+	if (padd_sqfs(data->file, data->super->bytes_used, data->devblksz))
 		return -1;
 
 	data->super->bytes_used += data->devblksz - diff;
@@ -122,8 +109,10 @@ static int block_callback(void *user, sqfs_block_t *blk)
 			fi->blocks[blk->index].size = htole32(out);
 		}
 
-		if (write_data("writing data block", data->outfd,
-			       blk->data, blk->size)) {
+		offset = data->file->get_size(data->file);
+
+		if (data->file->write_at(data->file, offset,
+					 blk->data, blk->size)) {
 			return -1;
 		}
 
@@ -489,7 +478,7 @@ int write_data_from_fd_condensed(data_writer_t *data, file_info_t *fi,
 }
 
 data_writer_t *data_writer_create(sqfs_super_t *super, sqfs_compressor_t *cmp,
-				  int outfd, size_t devblksize,
+				  sqfs_file_t *file, size_t devblksize,
 				  unsigned int num_jobs)
 {
 	data_writer_t *data = calloc(1, sizeof(*data));
@@ -504,7 +493,7 @@ data_writer_t *data_writer_create(sqfs_super_t *super, sqfs_compressor_t *cmp,
 						 block_callback);
 	data->cmp = cmp;
 	data->super = super;
-	data->outfd = outfd;
+	data->file = file;
 	data->devblksz = devblksize;
 	return data;
 }
@@ -529,7 +518,7 @@ int data_writer_write_fragment_table(data_writer_t *data)
 	}
 
 	size = sizeof(data->fragments[0]) * data->num_fragments;
-	ret = sqfs_write_table(data->outfd, data->super, data->cmp,
+	ret = sqfs_write_table(data->file, data->super, data->cmp,
 			       data->fragments, size, &start);
 	if (ret)
 		return -1;
diff --git a/lib/sqfshelper/deserialize_fstree.c b/lib/sqfshelper/deserialize_fstree.c
index 1953f9b..37861e6 100644
--- a/lib/sqfshelper/deserialize_fstree.c
+++ b/lib/sqfshelper/deserialize_fstree.c
@@ -203,7 +203,7 @@ static int fill_dir(sqfs_meta_reader_t *ir, sqfs_meta_reader_t *dr,
 }
 
 int deserialize_fstree(fstree_t *out, sqfs_super_t *super,
-		       sqfs_compressor_t *cmp, int fd, int flags)
+		       sqfs_compressor_t *cmp, sqfs_file_t *file, int flags)
 {
 	uint64_t block_start, limit;
 	sqfs_meta_reader_t *ir, *dr;
@@ -213,7 +213,7 @@ int deserialize_fstree(fstree_t *out, sqfs_super_t *super,
 	int status = -1;
 	size_t offset;
 
-	ir = sqfs_meta_reader_create(fd, cmp, super->inode_table_start,
+	ir = sqfs_meta_reader_create(file, cmp, super->inode_table_start,
 				     super->directory_table_start);
 	if (ir == NULL)
 		return -1;
@@ -224,7 +224,7 @@ int deserialize_fstree(fstree_t *out, sqfs_super_t *super,
 	if (super->fragment_table_start < limit)
 		limit = super->fragment_table_start;
 
-	dr = sqfs_meta_reader_create(fd, cmp, super->directory_table_start,
+	dr = sqfs_meta_reader_create(file, cmp, super->directory_table_start,
 				     limit);
 	if (dr == NULL)
 		goto out_ir;
@@ -233,10 +233,10 @@ int deserialize_fstree(fstree_t *out, sqfs_super_t *super,
 	if (idtbl == NULL)
 		goto out_dr;
 
-	if (sqfs_id_table_read(idtbl, fd, super, cmp))
+	if (sqfs_id_table_read(idtbl, file, super, cmp))
 		goto out_id;
 
-	xr = sqfs_xattr_reader_create(fd, super, cmp);
+	xr = sqfs_xattr_reader_create(file, super, cmp);
 	if (xr == NULL)
 		goto out_id;
 
diff --git a/lib/sqfshelper/serialize_fstree.c b/lib/sqfshelper/serialize_fstree.c
index dfadedd..ea3d479 100644
--- a/lib/sqfshelper/serialize_fstree.c
+++ b/lib/sqfshelper/serialize_fstree.c
@@ -41,7 +41,7 @@ static int write_dir_entries(sqfs_dir_writer_t *dirw, tree_node_t *node)
 	return 0;
 }
 
-int sqfs_serialize_fstree(int outfd, sqfs_super_t *super, fstree_t *fs,
+int sqfs_serialize_fstree(sqfs_file_t *file, sqfs_super_t *super, fstree_t *fs,
 			  sqfs_compressor_t *cmp, sqfs_id_table_t *idtbl)
 {
 	sqfs_inode_generic_t *inode;
@@ -52,11 +52,11 @@ int sqfs_serialize_fstree(int outfd, sqfs_super_t *super, fstree_t *fs,
 	int ret = -1;
 	size_t i;
 
-	im = sqfs_meta_writer_create(outfd, cmp, false);
+	im = sqfs_meta_writer_create(file, cmp, false);
 	if (im == NULL)
 		return -1;
 
-	dm = sqfs_meta_writer_create(outfd, cmp, true);
+	dm = sqfs_meta_writer_create(file, cmp, true);
 	if (dm == NULL)
 		goto out_im;
 
diff --git a/lib/sqfshelper/sqfs_reader.c b/lib/sqfshelper/sqfs_reader.c
index 598b3c4..e9c9c33 100644
--- a/lib/sqfshelper/sqfs_reader.c
+++ b/lib/sqfshelper/sqfs_reader.c
@@ -18,13 +18,11 @@ int sqfs_reader_open(sqfs_reader_t *rd, const char *filename, int rdtree_flags)
 
 	memset(rd, 0, sizeof(*rd));
 
-	rd->sqfsfd = open(filename, O_RDONLY);
-	if (rd->sqfsfd < 0) {
-		perror(filename);
+	rd->file = sqfs_open_file(filename, SQFS_FILE_OPEN_READ_ONLY);
+	if (rd->file == NULL)
 		return -1;
-	}
 
-	if (sqfs_super_read(&rd->super, rd->sqfsfd))
+	if (sqfs_super_read(&rd->super, rd->file))
 		goto fail_fd;
 
 	if (!sqfs_compressor_exists(rd->super.compression_id)) {
@@ -41,21 +39,21 @@ int sqfs_reader_open(sqfs_reader_t *rd, const char *filename, int rdtree_flags)
 		goto fail_fd;
 
 	if (rd->super.flags & SQFS_FLAG_COMPRESSOR_OPTIONS) {
-		if (rd->cmp->read_options(rd->cmp, rd->sqfsfd))
+		if (rd->cmp->read_options(rd->cmp, rd->file))
 			goto fail_cmp;
 	}
 
 	if (rd->super.flags & SQFS_FLAG_NO_XATTRS)
 		rdtree_flags &= ~RDTREE_READ_XATTR;
 
-	if (deserialize_fstree(&rd->fs, &rd->super, rd->cmp, rd->sqfsfd,
+	if (deserialize_fstree(&rd->fs, &rd->super, rd->cmp, rd->file,
 			       rdtree_flags)) {
 		goto fail_cmp;
 	}
 
 	fstree_gen_file_list(&rd->fs);
 
-	rd->data = data_reader_create(rd->sqfsfd, &rd->super, rd->cmp);
+	rd->data = data_reader_create(rd->file, &rd->super, rd->cmp);
 	if (rd->data == NULL)
 		goto fail_fs;
 
@@ -65,7 +63,7 @@ fail_fs:
 fail_cmp:
 	rd->cmp->destroy(rd->cmp);
 fail_fd:
-	close(rd->sqfsfd);
+	rd->file->destroy(rd->file);
 	memset(rd, 0, sizeof(*rd));
 	return -1;
 }
@@ -75,6 +73,6 @@ void sqfs_reader_close(sqfs_reader_t *rd)
 	data_reader_destroy(rd->data);
 	fstree_cleanup(&rd->fs);
 	rd->cmp->destroy(rd->cmp);
-	close(rd->sqfsfd);
+	rd->file->destroy(rd->file);
 	memset(rd, 0, sizeof(*rd));
 }
diff --git a/lib/sqfshelper/write_export_table.c b/lib/sqfshelper/write_export_table.c
index b0ad4ce..f4c6658 100644
--- a/lib/sqfshelper/write_export_table.c
+++ b/lib/sqfshelper/write_export_table.c
@@ -12,7 +12,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 
-int write_export_table(int outfd, fstree_t *fs, sqfs_super_t *super,
+int write_export_table(sqfs_file_t *file, fstree_t *fs, sqfs_super_t *super,
 		       sqfs_compressor_t *cmp)
 {
 	uint64_t *table, start;
@@ -38,7 +38,7 @@ int write_export_table(int outfd, fstree_t *fs, sqfs_super_t *super,
 	}
 
 	size = sizeof(uint64_t) * (fs->inode_tbl_size - 1);
-	ret = sqfs_write_table(outfd, super, cmp, table, size, &start);
+	ret = sqfs_write_table(file, super, cmp, table, size, &start);
 
 	super->export_table_start = start;
 	super->flags |= SQFS_FLAG_EXPORTABLE;
diff --git a/lib/sqfshelper/write_xattr.c b/lib/sqfshelper/write_xattr.c
index 6f71eeb..c4fb86e 100644
--- a/lib/sqfshelper/write_xattr.c
+++ b/lib/sqfshelper/write_xattr.c
@@ -167,7 +167,7 @@ static uint64_t *create_ool_locations_table(fstree_t *fs)
 	return table;
 }
 
-int write_xattr(int outfd, fstree_t *fs, sqfs_super_t *super,
+int write_xattr(sqfs_file_t *file, fstree_t *fs, sqfs_super_t *super,
 		sqfs_compressor_t *cmp)
 {
 	uint64_t kv_start, id_start, block, *tbl, *ool_locations;
@@ -185,7 +185,7 @@ int write_xattr(int outfd, fstree_t *fs, sqfs_super_t *super,
 	if (ool_locations == NULL)
 		return -1;
 
-	mw = sqfs_meta_writer_create(outfd, cmp, false);
+	mw = sqfs_meta_writer_create(file, cmp, false);
 	if (mw == NULL)
 		goto fail_ool;
 
@@ -254,11 +254,14 @@ int write_xattr(int outfd, fstree_t *fs, sqfs_super_t *super,
 	idtbl.xattr_ids = htole32(count);
 	idtbl.unused = 0;
 
-	if (write_data("writing xattr ID table", outfd, &idtbl, sizeof(idtbl)))
+	if (file->write_at(file, file->get_size(file), &idtbl, sizeof(idtbl))) {
+		perror("writing xattr ID table");
 		goto fail_tbl;
+	}
 
-	if (write_data("writing xattr ID table",
-		       outfd, tbl, sizeof(tbl[0]) * blocks)) {
+	if (file->write_at(file, file->get_size(file),
+			   tbl, sizeof(tbl[0]) * blocks)) {
+		perror("writing xattr ID table");
 		goto fail_tbl;
 	}