Add a data reader based sqfs_istream_t implementation

To the sqfs_data_reader_t is added, an sqfs_istream_t implementation
that internally reads through the data reader. The uses of the
data_reader_dump function are removed and the function is subsequently
removed from libcommon.

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

3 files changed, 198 insertions, 68 deletions

diff --git a/lib/common/Makemodule.am b/lib/common/Makemodule.am
index 61d87d4..e0cc551 100644
--- a/lib/common/Makemodule.am
+++ b/lib/common/Makemodule.am
@@ -1,7 +1,7 @@
 libcommon_a_SOURCES = include/common.h include/simple_writer.h \
 	include/compress_cli.h \
 	lib/common/src/hardlink.c lib/common/src/print_version.c \
-	lib/common/src/data_reader_dump.c lib/common/src/compress.c \
+	lib/common/src/compress.c \
 	lib/common/src/comp_opt.c lib/common/src/data_writer.c \
 	lib/common/src/parse_size.c lib/common/src/print_size.c \
 	lib/common/src/writer/init.c lib/common/src/writer/cleanup.c \
diff --git a/lib/common/src/data_reader_dump.c b/lib/common/src/data_reader_dump.c
deleted file mode 100644
index 920b2bd..0000000
--- a/lib/common/src/data_reader_dump.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * data_reader_dump.c
- *
- * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
- */
-#include "common.h"
-
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-#include <errno.h>
-
-int sqfs_data_reader_dump(const char *name, sqfs_data_reader_t *data,
-			  const sqfs_inode_generic_t *inode,
-			  sqfs_ostream_t *fp, size_t block_size)
-{
-	size_t i, diff, chunk_size;
-	sqfs_u64 filesz;
-	sqfs_u8 *chunk;
-	int err;
-
-	sqfs_inode_get_file_size(inode, &filesz);
-
-	for (i = 0; i < sqfs_inode_get_file_block_count(inode); ++i) {
-		diff = (filesz < block_size) ? filesz : block_size;
-
-		if (SQFS_IS_SPARSE_BLOCK(inode->extra[i])) {
-			err = fp->append(fp, NULL, diff);
-		} else {
-			err = sqfs_data_reader_get_block(data, inode, i,
-							 &chunk_size, &chunk);
-			if (err) {
-				sqfs_perror(name, "reading data block", err);
-				return -1;
-			}
-
-			err = fp->append(fp, chunk, chunk_size);
-			free(chunk);
-		}
-
-		if (err)
-			goto fail_io;
-
-		filesz -= diff;
-	}
-
-	if (filesz > 0) {
-		err = sqfs_data_reader_get_fragment(data, inode,
-						    &chunk_size, &chunk);
-		if (err) {
-			sqfs_perror(name, "reading fragment block", err);
-			return -1;
-		}
-
-		err = fp->append(fp, chunk, chunk_size);
-		free(chunk);
-
-		if (err)
-			goto fail_io;
-	}
-
-	return 0;
-fail_io:
-	sqfs_perror(fp->get_filename(fp), "writing data block", err);
-	return -1;
-}
diff --git a/lib/sqfs/src/data_reader.c b/lib/sqfs/src/data_reader.c
index 3f0cd74..e87259f 100644
--- a/lib/sqfs/src/data_reader.c
+++ b/lib/sqfs/src/data_reader.c
@@ -372,3 +372,200 @@ sqfs_s32 sqfs_data_reader_read(sqfs_data_reader_t *data,
 
 	return total;
 }
+
+/*****************************************************************************/
+
+typedef struct {
+	sqfs_istream_t base;
+
+	sqfs_data_reader_t *rd;
+	const char *filename;
+	const sqfs_u32 *blocks;
+
+	sqfs_u8 *buffer;
+	size_t buf_used;
+	size_t buf_off;
+
+	sqfs_u64 filesz;
+	sqfs_u64 disk_offset;
+
+	sqfs_u32 frag_idx;
+	sqfs_u32 frag_off;
+
+	sqfs_u32 blk_idx;
+	sqfs_u32 blk_count;
+
+	sqfs_u32 inodata[];
+} data_reader_istream_t;
+
+static int dr_stream_get_buffered_data(sqfs_istream_t *base,
+				       const sqfs_u8 **out,
+				       size_t *size, size_t want)
+{
+	data_reader_istream_t *stream = (data_reader_istream_t *)base;
+	sqfs_data_reader_t *rd = stream->rd;
+	int ret;
+	(void)want;
+
+	if (stream->buf_off < stream->buf_used) {
+		*out = stream->buffer + stream->buf_off;
+		*size = stream->buf_used - stream->buf_off;
+		return 0;
+	}
+
+	if (stream->filesz == 0) {
+		ret = 1;
+		goto fail;
+	}
+
+	stream->buf_off = 0;
+	stream->buf_used = rd->block_size;
+	if (stream->filesz < (sqfs_u64)stream->buf_used)
+		stream->buf_used = stream->filesz;
+
+	if (stream->blk_idx < stream->blk_count) {
+		sqfs_u32 blkword = stream->blocks[stream->blk_idx++];
+		sqfs_u32 disksz = SQFS_ON_DISK_BLOCK_SIZE(blkword);
+
+		if (disksz == 0) {
+			memset(stream->buffer, 0, stream->buf_used);
+		} else if (SQFS_IS_BLOCK_COMPRESSED(blkword)) {
+			ret = rd->file->read_at(rd->file, stream->disk_offset,
+						rd->scratch, disksz);
+			if (ret)
+				goto fail;
+
+			ret = rd->cmp->do_block(rd->cmp, rd->scratch, disksz,
+						stream->buffer,
+						stream->buf_used);
+			if (ret <= 0) {
+				ret = ret < 0 ? ret : SQFS_ERROR_OVERFLOW;
+				goto fail;
+			}
+
+			if ((size_t)ret < stream->buf_used) {
+				memset(stream->buffer + ret, 0,
+				       stream->buf_used - ret);
+			}
+		} else {
+			ret = rd->file->read_at(rd->file, stream->disk_offset,
+						stream->buffer, disksz);
+			if (ret)
+				goto fail;
+			if (disksz < stream->buf_used) {
+				memset(stream->buffer + disksz, 0,
+				       stream->buf_used - disksz);
+			}
+		}
+
+		stream->disk_offset += disksz;
+	} else {
+		ret = precache_fragment_block(rd, stream->frag_idx);
+		if (ret)
+			return ret;
+
+		if (rd->frag_blk_size < stream->frag_off ||
+		    (rd->frag_blk_size - stream->frag_off) < stream->buf_used) {
+			ret = SQFS_ERROR_CORRUPTED;
+			goto fail;
+		}
+
+		memcpy(stream->buffer, rd->frag_block + stream->frag_off,
+		       stream->buf_used);
+	}
+
+	stream->filesz -= stream->buf_used;
+	*out = stream->buffer;
+	*size = stream->buf_used;
+	return 0;
+fail:
+	free(stream->buffer);
+	stream->buffer = NULL;
+	stream->buf_used = 0;
+	stream->buf_off = 0;
+	stream->filesz = 0;
+	*out = NULL;
+	*size = 0;
+	return ret;
+}
+
+static void dr_stream_advance_buffer(sqfs_istream_t *base, size_t count)
+{
+	data_reader_istream_t *stream = (data_reader_istream_t *)base;
+	size_t diff = stream->buf_used - stream->buf_off;
+
+	stream->buf_off += (diff < count ? diff : count);
+}
+
+static const char *dr_stream_get_filename(sqfs_istream_t *base)
+{
+	return ((data_reader_istream_t *)base)->filename;
+}
+
+static void dr_stream_destroy(sqfs_object_t *obj)
+{
+	data_reader_istream_t *stream = (data_reader_istream_t *)obj;
+
+	sqfs_drop(stream->rd);
+	free(stream->buffer);
+	free(stream);
+}
+
+int sqfs_data_reader_create_stream(sqfs_data_reader_t *data,
+				   const sqfs_inode_generic_t *inode,
+				   const char *filename, sqfs_istream_t **out)
+{
+	data_reader_istream_t *stream;
+	size_t ino_sz, namelen, sz;
+	sqfs_u64 filesz;
+	char *nameptr;
+	int ret;
+
+	*out = NULL;
+
+	ret = sqfs_inode_get_file_size(inode, &filesz);
+	if (ret != 0)
+		return ret;
+
+	ino_sz = inode->payload_bytes_used;
+	namelen = strlen(filename) + 1;
+
+	if (SZ_ADD_OV(ino_sz, namelen, &sz))
+		return SQFS_ERROR_ALLOC;
+	if (SZ_ADD_OV(sz, sizeof(*stream), &sz))
+		return SQFS_ERROR_ALLOC;
+
+	stream = calloc(1, sz);
+	if (stream == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	stream->buffer = malloc(data->block_size);
+	if (stream->buffer == NULL) {
+		free(stream);
+		return SQFS_ERROR_ALLOC;
+	}
+
+	sqfs_object_init(stream, dr_stream_destroy, NULL);
+
+	memcpy(stream->inodata, inode->extra, ino_sz);
+	stream->blocks = stream->inodata;
+	stream->blk_count = ino_sz / sizeof(stream->blocks[0]);
+	stream->filesz = filesz;
+
+	nameptr = (char *)stream->inodata + ino_sz;
+	memcpy(nameptr, filename, namelen);
+	stream->filename = nameptr;
+
+	sqfs_inode_get_file_block_start(inode, &stream->disk_offset);
+	sqfs_inode_get_frag_location(inode, &stream->frag_idx,
+				     &stream->frag_off);
+	stream->rd = sqfs_grab(data);
+
+	((sqfs_istream_t *)stream)->advance_buffer = dr_stream_advance_buffer;
+	((sqfs_istream_t *)stream)->get_filename = dr_stream_get_filename;
+	((sqfs_istream_t *)stream)->get_buffered_data =
+		dr_stream_get_buffered_data;
+
+	*out = (sqfs_istream_t *)stream;
+	return 0;
+}