ChangeLog, Makefile.in, e2image.h, ext2_err.et.in, ext2fs.h, imager.c:

  imager.c (ext2fs_image_{inode,super,bitmap}_{read,write}, ext2_fs.h,
  	Makefile.in: New file that has routines that save ext2fs metadata to a
  	file.
  ext2_err.et.in (EXT2_ET_MAGIC_E2IMAGE): New error code assigned.
  e2image.h: New file which defines the file format for the ext2 image
  	file.  (Saved copy of ext2 metadata to a file as a saving throw
  	against worst-case damage.)
ChangeLog, Makefile.in, e2image.c:
  e2image.c, Makefile.in: New program which saves ext2 metadata to a
  	file for people who need a last-ditch saving throw.

1 files changed, 386 insertions, 0 deletions

diff --git a/lib/ext2fs/imager.c b/lib/ext2fs/imager.c
new file mode 100644
index 00000000..79b88ee6
--- /dev/null
+++ b/lib/ext2fs/imager.c
@@ -0,0 +1,386 @@
+/*
+ * image.c --- writes out the critical parts of the filesystem as a
+ * 	flat file.
+ *
+ * Copyright (C) 2000 Theodore Ts'o.
+ *
+ * Note: this uses the POSIX IO interfaces, unlike most of the other
+ * functions in this library.  So sue me.  
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#include <stdio.h>
+#include <string.h>
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#if HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <fcntl.h>
+#include <time.h>
+#if HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#if HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#if EXT2_FLAT_INCLUDES
+#include "ext2_fs.h"
+#else
+#include <linux/ext2_fs.h>
+#endif
+
+#include "ext2fs.h"
+
+/*
+ * This function returns 1 if the specified block is all zeros
+ */
+static int check_zero_block(char *buf, int blocksize)
+{
+	char	*cp = buf;
+	int	left = blocksize;
+
+	while (left > 0) {
+		if (*cp++)
+			return 0;
+		left--;
+	}
+	return 1;
+}
+
+/*
+ * Write the inode table out as a single block.
+ */
+#define BUF_BLOCKS	32
+
+errcode_t ext2fs_image_inode_write(ext2_filsys fs, int fd, int flags)
+{
+	unsigned int	group, left, c, d;
+	char		*buf, *cp;
+	blk_t		blk;
+	ssize_t		actual;
+	errcode_t	retval;
+
+	buf = malloc(fs->blocksize * BUF_BLOCKS);
+	if (!buf)
+		return ENOMEM;
+	
+	for (group = 0; group < fs->group_desc_count; group++) {
+		blk = fs->group_desc[(unsigned)group].bg_inode_table;
+		if (!blk)
+			return EXT2_ET_MISSING_INODE_TABLE;
+		left = fs->inode_blocks_per_group;
+		while (left) {
+			c = BUF_BLOCKS;
+			if (c > left)
+				c = left;
+			retval = io_channel_read_blk(fs->io, blk, c, buf);
+			if (retval)
+				goto errout;
+			cp = buf;
+			while (c) {
+				if (!(flags & IMAGER_FLAG_SPARSEWRITE)) {
+					d = c;
+					goto skip_sparse;
+				}
+				/* Skip zero blocks */
+				if (check_zero_block(cp, fs->blocksize)) {
+					c--;
+					blk++;
+					left--;
+					cp += fs->blocksize;
+					lseek(fd, fs->blocksize, SEEK_CUR);
+					continue;
+				}
+				/* Find non-zero blocks */
+				for (d=1; d < c; d++) {
+					if (check_zero_block(cp + d*fs->blocksize, fs->blocksize))
+						break;
+				}
+			skip_sparse:
+				actual = write(fd, cp, fs->blocksize * d);
+				if (actual == -1) {
+					errno = retval;
+					goto errout;
+				}
+				if (actual != fs->blocksize * d) {
+					retval = EXT2_ET_SHORT_WRITE;
+					goto errout;
+				}
+				blk += d;
+				left -= d;
+				cp += fs->blocksize * d;
+				c -= d;
+			}
+		}
+	}
+	retval = 0;
+
+errout:
+	free(buf);
+	return retval;
+}
+
+/*
+ * Read in the inode table and stuff it into place
+ */
+errcode_t ext2fs_image_inode_read(ext2_filsys fs, int fd, int flags)
+{
+	unsigned int	group, i, c, left;
+	char		*buf;
+	blk_t		blk;
+	ssize_t		actual;
+	errcode_t	retval;
+
+	buf = malloc(fs->blocksize * BUF_BLOCKS);
+	if (!buf)
+		return ENOMEM;
+	
+	for (group = 0; group < fs->group_desc_count; group++) {
+		blk = fs->group_desc[(unsigned)group].bg_inode_table;
+		if (!blk)
+			return EXT2_ET_MISSING_INODE_TABLE;
+		left = fs->inode_blocks_per_group;
+		while (left) {
+			c = BUF_BLOCKS;
+			if (c > left)
+				c = left;
+			actual = read(fd, buf, fs->blocksize * c);
+			if (actual == -1) {
+				errno = retval;
+				goto errout;
+			}
+			if (actual != fs->blocksize * c) {
+				retval = EXT2_ET_SHORT_READ;
+				goto errout;
+			}
+			retval = io_channel_write_blk(fs->io, blk, c, buf);
+			if (retval)
+				goto errout;
+			
+			blk += c;
+			left -= c;
+		}
+	}
+	retval = ext2fs_flush_icache(fs);
+
+errout:
+	free(buf);
+	return retval;
+}
+
+/*
+ * Write out superblock and group descriptors
+ */
+errcode_t ext2fs_image_super_write(ext2_filsys fs, int fd, int flags)
+{
+	unsigned int	i;
+	char		*buf, *cp;
+	blk_t		blk;
+	ssize_t		actual;
+	errcode_t	retval;
+
+	buf = malloc(fs->blocksize);
+	if (!buf)
+		return ENOMEM;
+
+	/*
+	 * Write out the superblock
+	 */
+	memset(buf, 0, fs->blocksize);
+	memcpy(buf, fs->super, SUPERBLOCK_SIZE);
+	actual = write(fd, buf, fs->blocksize);
+	if (actual == -1) {
+		errno = retval;
+		goto errout;
+	}
+	if (actual != fs->blocksize) {
+		retval = EXT2_ET_SHORT_WRITE;
+		goto errout;
+	}
+
+	/*
+	 * Now write out the block group descriptors
+	 */
+	cp = (char *) fs->group_desc;
+	actual = write(fd, cp, fs->blocksize * fs->desc_blocks);
+	if (actual == -1) {
+		errno = retval;
+		goto errout;
+	}
+	if (actual != fs->blocksize * fs->desc_blocks) {
+		retval = EXT2_ET_SHORT_WRITE;
+		goto errout;
+	}
+	
+	retval = 0;
+
+errout:
+	free(buf);
+	return retval;
+}
+
+/*
+ * Read the superblock and group descriptors and overwrite them.
+ */
+errcode_t ext2fs_image_super_read(ext2_filsys fs, int fd, int flags)
+{
+	unsigned int	i;
+	char		*buf, *cp;
+	blk_t		blk;
+	ssize_t		actual, size;
+	errcode_t	retval;
+
+	size = fs->blocksize * (fs->group_desc_count + 1);
+	buf = malloc(size);
+	if (!buf)
+		return ENOMEM;
+
+	/*
+	 * Read it all in.
+	 */
+	actual = read(fd, buf, size);
+	if (actual == -1) {
+		errno = retval;
+		goto errout;
+	}
+	if (actual != size) {
+		retval = EXT2_ET_SHORT_READ;
+		goto errout;
+	}
+
+	/*
+	 * Now copy in the superblock and group descriptors
+	 */
+	memcpy(fs->super, buf, SUPERBLOCK_SIZE);
+
+	memcpy(fs->group_desc, buf + fs->blocksize,
+	       fs->blocksize * fs->group_desc_count);
+
+	retval = 0;
+
+errout:
+	free(buf);
+	return retval;
+}
+
+/*
+ * Write the block/inode bitmaps.
+ */
+errcode_t ext2fs_image_bitmap_write(ext2_filsys fs, int fd, int flags)
+{
+	char		*ptr;
+	int		c, size;
+	char		zero_buf[1024];
+	ssize_t		actual;
+	errcode_t	retval;
+
+	if (flags & IMAGER_FLAG_INODEMAP) {
+		if (!fs->inode_map) {
+			retval = ext2fs_read_inode_bitmap(fs);
+			if (retval)
+				return retval;
+		}
+		ptr = fs->inode_map->bitmap;
+		size = ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
+	} else {
+		if (!fs->block_map) {
+			retval = ext2fs_read_block_bitmap(fs);
+			if (retval)
+				return retval;
+		}
+		ptr = fs->block_map->bitmap;
+		size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
+	}
+
+	actual = write(fd, ptr, size);
+	if (actual == -1) {
+		errno = retval;
+		goto errout;
+	}
+	if (actual != size) {
+		retval = EXT2_ET_SHORT_WRITE;
+		goto errout;
+	}
+	size = size % fs->blocksize;
+	memset(zero_buf, 0, sizeof(zero_buf));
+	if (size) {
+		size = fs->blocksize - size;
+		while (size) {
+			c = size;
+			if (c > sizeof(zero_buf))
+				c = sizeof(zero_buf);
+			actual = write(fd, zero_buf, c);
+			if (actual == -1) {
+				errno = retval;
+				goto errout;
+			}
+			if (actual != c) {
+				retval = EXT2_ET_SHORT_WRITE;
+				goto errout;
+			}
+			size -= c;
+		}
+	}
+	retval = 0;
+errout:
+	return (retval);
+}
+
+
+/*
+ * Read the block/inode bitmaps.
+ */
+errcode_t ext2fs_image_bitmap_read(ext2_filsys fs, int fd, int flags)
+{
+	char		*ptr, *buf = 0;
+	int		c, size;
+	char		zero_buf[1024];
+	ssize_t		actual;
+	errcode_t	retval;
+
+	if (flags & IMAGER_FLAG_INODEMAP) {
+		if (!fs->inode_map) {
+			retval = ext2fs_read_inode_bitmap(fs);
+			if (retval)
+				return retval;
+		}
+		ptr = fs->inode_map->bitmap;
+		size = ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
+	} else {
+		if (!fs->block_map) {
+			retval = ext2fs_read_block_bitmap(fs);
+			if (retval)
+				return retval;
+		}
+		ptr = fs->block_map->bitmap;
+		size = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
+	}
+
+	buf = malloc(size);
+	if (!buf)
+		return ENOMEM;
+
+	actual = read(fd, buf, size);
+	if (actual == -1) {
+		errno = retval;
+		goto errout;
+	}
+	if (actual != size) {
+		retval = EXT2_ET_SHORT_WRITE;
+		goto errout;
+	}
+	memcpy(ptr, buf, size);
+	
+	retval = 0;
+errout:
+	if (buf)
+		free(buf);
+	return (retval);
+}