Add function to read generic inode from meta data reader

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

2 files changed, 317 insertions, 1 deletions

diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index 08b53e1..b521a7e 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -13,7 +13,7 @@ libsquashfs_a_SOURCES += lib/sqfs/id_table.c include/id_table.h
 libsquashfs_a_SOURCES += lib/sqfs/table.c include/table.h
 libsquashfs_a_SOURCES += lib/sqfs/read_super.c lib/sqfs/meta_reader.c
 libsquashfs_a_SOURCES += include/meta_reader.h lib/sqfs/id_table_write.c
-libsquashfs_a_SOURCES += lib/sqfs/id_table_read.c
+libsquashfs_a_SOURCES += lib/sqfs/id_table_read.c lib/sqfs/read_inode.c
 
 libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_retry.c
 libutil_a_SOURCES += lib/util/read_retry.c include/util.h
diff --git a/lib/sqfs/read_inode.c b/lib/sqfs/read_inode.c
new file mode 100644
index 0000000..71b3a54
--- /dev/null
+++ b/lib/sqfs/read_inode.c
@@ -0,0 +1,316 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "meta_reader.h"
+
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define SWAB16(x) x = le16toh(x)
+#define SWAB32(x) x = le32toh(x)
+#define SWAB64(x) x = le64toh(x)
+
+static int check_mode(sqfs_inode_t *inode)
+{
+	switch (inode->mode & S_IFMT) {
+	case S_IFSOCK:
+		if (inode->type != SQFS_INODE_SOCKET &&
+		    inode->type != SQFS_INODE_EXT_SOCKET) {
+			goto fail_mismatch;
+		}
+		break;
+	case S_IFLNK:
+		if (inode->type != SQFS_INODE_SLINK &&
+		    inode->type != SQFS_INODE_EXT_SLINK) {
+			goto fail_mismatch;
+		}
+		break;
+	case S_IFREG:
+		if (inode->type != SQFS_INODE_FILE &&
+		    inode->type != SQFS_INODE_EXT_FILE) {
+			goto fail_mismatch;
+		}
+		break;
+	case S_IFBLK:
+		if (inode->type != SQFS_INODE_BDEV &&
+		    inode->type != SQFS_INODE_EXT_BDEV) {
+			goto fail_mismatch;
+		}
+		break;
+	case S_IFDIR:
+		if (inode->type != SQFS_INODE_DIR &&
+		    inode->type != SQFS_INODE_EXT_DIR) {
+			goto fail_mismatch;
+		}
+		break;
+	case S_IFCHR:
+		if (inode->type != SQFS_INODE_CDEV &&
+		    inode->type != SQFS_INODE_EXT_CDEV) {
+			goto fail_mismatch;
+		}
+		break;
+	case S_IFIFO:
+		if (inode->type != SQFS_INODE_FIFO &&
+		    inode->type != SQFS_INODE_EXT_FIFO) {
+			goto fail_mismatch;
+		}
+		break;
+	default:
+		fputs("Found inode with unknown file mode\n", stderr);
+		return -1;
+	}
+
+	return 0;
+fail_mismatch:
+	fputs("Found inode where type does not match mode\n", stderr);
+	return -1;
+}
+
+static sqfs_inode_generic_t *read_inode_file(meta_reader_t *ir,
+					     sqfs_inode_t *base,
+					     size_t block_size)
+{
+	sqfs_inode_generic_t *out;
+	sqfs_inode_file_t file;
+	size_t i, count;
+
+	if (meta_reader_read(ir, &file, sizeof(file)))
+		return NULL;
+
+	SWAB32(file.blocks_start);
+	SWAB32(file.fragment_index);
+	SWAB32(file.fragment_offset);
+	SWAB32(file.file_size);
+
+	count = file.file_size / block_size;
+
+	out = calloc(1, sizeof(*out) + count * sizeof(uint32_t));
+	if (out == NULL) {
+		perror("reading extended file inode");
+		return NULL;
+	}
+
+	out->base = *base;
+	out->data.file = file;
+	out->block_sizes = (uint32_t *)out->extra;
+
+	if (meta_reader_read(ir, out->block_sizes, count * sizeof(uint32_t))) {
+		free(out);
+		return NULL;
+	}
+
+	for (i = 0; i < count; ++i)
+		SWAB32(out->block_sizes[i]);
+
+	return out;
+}
+
+static sqfs_inode_generic_t *read_inode_file_ext(meta_reader_t *ir,
+						 sqfs_inode_t *base,
+						 size_t block_size)
+{
+	sqfs_inode_file_ext_t file;
+	sqfs_inode_generic_t *out;
+	size_t i, count;
+
+	if (meta_reader_read(ir, &file, sizeof(file)))
+		return NULL;
+
+	SWAB64(file.blocks_start);
+	SWAB64(file.file_size);
+	SWAB64(file.sparse);
+	SWAB32(file.nlink);
+	SWAB32(file.fragment_idx);
+	SWAB32(file.fragment_offset);
+	SWAB32(file.xattr_idx);
+
+	count = file.file_size / block_size;
+
+	out = calloc(1, sizeof(*out) + count * sizeof(uint32_t));
+	if (out == NULL) {
+		perror("reading extended file inode");
+		return NULL;
+	}
+
+	out->base = *base;
+	out->data.file_ext = file;
+	out->block_sizes = (uint32_t *)out->extra;
+
+	if (meta_reader_read(ir, out->block_sizes, count * sizeof(uint32_t))) {
+		free(out);
+		return NULL;
+	}
+
+	for (i = 0; i < count; ++i)
+		SWAB32(out->block_sizes[i]);
+
+	return out;
+}
+
+static sqfs_inode_generic_t *read_inode_slink(meta_reader_t *ir,
+					      sqfs_inode_t *base)
+{
+	sqfs_inode_generic_t *out;
+	sqfs_inode_slink_t slink;
+
+	if (meta_reader_read(ir, &slink, sizeof(slink)))
+		return NULL;
+
+	SWAB32(slink.nlink);
+	SWAB32(slink.target_size);
+
+	out = calloc(1, sizeof(*out) + slink.target_size + 1);
+	if (out == NULL) {
+		perror("reading symlink inode");
+		return NULL;
+	}
+
+	out->slink_target = (char *)out->extra;
+	out->base = *base;
+	out->data.slink = slink;
+
+	if (meta_reader_read(ir, out->slink_target, slink.target_size)) {
+		free(out);
+		return NULL;
+	}
+
+	return out;
+}
+
+static sqfs_inode_generic_t *read_inode_slink_ext(meta_reader_t *ir,
+						  sqfs_inode_t *base)
+{
+	sqfs_inode_generic_t *out = read_inode_slink(ir, base);
+	uint32_t xattr;
+
+	if (out != NULL) {
+		if (meta_reader_read(ir, &xattr, sizeof(xattr))) {
+			free(out);
+			return NULL;
+		}
+
+		out->data.slink_ext.xattr_idx = le32toh(xattr);
+	}
+	return 0;
+}
+
+sqfs_inode_generic_t *meta_reader_read_inode(meta_reader_t *ir,
+					     sqfs_super_t *super,
+					     uint64_t block_start,
+					     size_t offset)
+{
+	sqfs_inode_generic_t *out;
+	sqfs_inode_t inode;
+
+	/* read base inode */
+	block_start += super->inode_table_start;
+
+	if (meta_reader_seek(ir, block_start, offset))
+		return NULL;
+
+	if (meta_reader_read(ir, &inode, sizeof(inode)))
+		return NULL;
+
+	SWAB16(inode.type);
+	SWAB16(inode.mode);
+	SWAB16(inode.uid_idx);
+	SWAB16(inode.gid_idx);
+	SWAB32(inode.mod_time);
+	SWAB32(inode.inode_number);
+
+	if (check_mode(&inode))
+		return NULL;
+
+	/* inode types where the size is variable */
+	switch (inode.type) {
+	case SQFS_INODE_FILE:
+		return read_inode_file(ir, &inode, super->block_size);
+	case SQFS_INODE_SLINK:
+		return read_inode_slink(ir, &inode);
+	case SQFS_INODE_EXT_FILE:
+		return read_inode_file_ext(ir, &inode, super->block_size);
+	case SQFS_INODE_EXT_SLINK:
+		return read_inode_slink_ext(ir, &inode);
+	default:
+		break;
+	}
+
+	/* everything else */
+	out = calloc(1, sizeof(*out));
+	if (out == NULL) {
+		perror("reading symlink inode");
+		return NULL;
+	}
+
+	out->base = inode;
+
+	switch (inode.type) {
+	case SQFS_INODE_DIR:
+		if (meta_reader_read(ir, &out->data.dir,
+				     sizeof(out->data.dir))) {
+			goto fail_free;
+		}
+		SWAB32(out->data.dir.start_block);
+		SWAB32(out->data.dir.nlink);
+		SWAB16(out->data.dir.size);
+		SWAB16(out->data.dir.offset);
+		SWAB32(out->data.dir.parent_inode);
+		break;
+	case SQFS_INODE_BDEV:
+	case SQFS_INODE_CDEV:
+		if (meta_reader_read(ir, &out->data.dev,
+				     sizeof(out->data.dev))) {
+			goto fail_free;
+		}
+		SWAB32(out->data.dev.nlink);
+		SWAB32(out->data.dev.devno);
+		break;
+	case SQFS_INODE_FIFO:
+	case SQFS_INODE_SOCKET:
+		if (meta_reader_read(ir, &out->data.ipc,
+				     sizeof(out->data.ipc))) {
+			goto fail_free;
+		}
+		SWAB32(out->data.ipc.nlink);
+		break;
+	case SQFS_INODE_EXT_DIR:
+		if (meta_reader_read(ir, &out->data.dir_ext,
+				     sizeof(out->data.dir_ext))) {
+			goto fail_free;
+		}
+		SWAB32(out->data.dir_ext.nlink);
+		SWAB32(out->data.dir_ext.size);
+		SWAB32(out->data.dir_ext.start_block);
+		SWAB32(out->data.dir_ext.parent_inode);
+		SWAB16(out->data.dir_ext.inodex_count);
+		SWAB16(out->data.dir_ext.offset);
+		SWAB32(out->data.dir_ext.xattr_idx);
+		break;
+	case SQFS_INODE_EXT_BDEV:
+	case SQFS_INODE_EXT_CDEV:
+		if (meta_reader_read(ir, &out->data.dev_ext,
+				     sizeof(out->data.dev_ext))) {
+			goto fail_free;
+		}
+		SWAB32(out->data.dev_ext.nlink);
+		SWAB32(out->data.dev_ext.devno);
+		SWAB32(out->data.dev_ext.xattr_idx);
+		break;
+	case SQFS_INODE_EXT_FIFO:
+	case SQFS_INODE_EXT_SOCKET:
+		if (meta_reader_read(ir, &out->data.ipc_ext,
+				     sizeof(out->data.ipc_ext))) {
+			goto fail_free;
+		}
+		SWAB32(out->data.ipc_ext.nlink);
+		SWAB32(out->data.ipc_ext.xattr_idx);
+		break;
+	default:
+		fputs("Unknown inode type found\n", stderr);
+		goto fail_free;
+	}
+
+	return out;
+fail_free:
+	free(out);
+	return NULL;
+}