mirror of https://github.com/vitalif/e2fsprogs
ChangeLog, fileio.c:
fileio.c (ext2fs_file_read): Factored out common code and cleaned up function. Fixed a bug where if there was an error reading from the disk, the number of bytes read wasn't reliably set. (Fixes Debian bug #79163) (ext2fs_file_write): Factored out common code and made function more efficient; if writing a full block, don't bother to do a read-modify-write cycle.bitmap-optimize
Theodore Ts'o
parent
bfcd9a116f
commit
0f6794591e
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@ -1,3 +1,13 @@
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2001-05-05 Theodore Tso <tytso@valinux.com>
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* fileio.c (ext2fs_file_read): Factored out common code and
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cleaned up function. Fixed a bug where if there was an
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error reading from the disk, the number of bytes read
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wasn't reliably set. (Fixes Debian bug #79163)
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(ext2fs_file_write): Factored out common code and made
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function more efficient; if writing a full block, don't
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bother to do a read-modify-write cycle.
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2001-05-04 Theodore Tso <tytso@valinux.com>
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* dirblock.c (ext2fs_read_dir_block): Check for an directory
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@ -35,6 +35,8 @@ struct ext2_file {
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char *buf;
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};
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#define BMAP_BUFFER (file->buf + fs->blocksize)
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errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
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int flags, ext2_file_t *ret)
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{
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@ -63,7 +65,7 @@ errcode_t ext2fs_file_open(ext2_filsys fs, ext2_ino_t ino,
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if (retval)
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goto fail;
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retval = ext2fs_get_mem(fs->blocksize * 2, (void **) &file->buf);
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retval = ext2fs_get_mem(fs->blocksize * 3, (void **) &file->buf);
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if (retval)
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goto fail;
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@ -94,8 +96,10 @@ ext2_filsys ext2fs_file_get_fs(ext2_file_t file)
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static errcode_t ext2fs_file_flush(ext2_file_t file)
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{
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errcode_t retval;
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ext2_filsys fs;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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fs = file->fs;
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if (!(file->flags & EXT2_FILE_BUF_VALID) ||
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!(file->flags & EXT2_FILE_BUF_DIRTY))
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@ -106,14 +110,14 @@ static errcode_t ext2fs_file_flush(ext2_file_t file)
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* Allocate it.
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*/
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if (!file->physblock) {
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retval = ext2fs_bmap(file->fs, file->ino, &file->inode,
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file->buf, BMAP_ALLOC,
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retval = ext2fs_bmap(fs, file->ino, &file->inode,
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BMAP_BUFFER, BMAP_ALLOC,
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file->blockno, &file->physblock);
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if (retval)
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return retval;
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}
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retval = io_channel_write_blk(file->fs->io, file->physblock,
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retval = io_channel_write_blk(fs->io, file->physblock,
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1, file->buf);
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if (retval)
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return retval;
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@ -123,6 +127,62 @@ static errcode_t ext2fs_file_flush(ext2_file_t file)
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return retval;
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}
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/*
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* This function synchronizes the file's block buffer and the current
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* file position, possibly invalidating block buffer if necessary
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*/
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static errcode_t sync_buffer_position(ext2_file_t file)
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{
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blk_t b;
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errcode_t retval;
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b = file->pos / file->fs->blocksize;
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if (b != file->blockno) {
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retval = ext2fs_file_flush(file);
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if (retval)
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return retval;
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file->flags &= ~EXT2_FILE_BUF_VALID;
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}
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file->blockno = b;
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return 0;
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}
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/*
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* This function loads the file's block buffer with valid data from
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* the disk as necessary.
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*
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* If dontfill is true, then skip initializing the buffer since we're
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* going to be replacing its entire contents anyway. If set, then the
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* function basically only sets file->physblock and EXT2_FILE_BUF_VALID
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*/
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#define DONTFILL 1
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static errcode_t load_buffer(ext2_file_t file, int dontfill)
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{
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ext2_filsys fs = file->fs;
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errcode_t retval;
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if (!(file->flags & EXT2_FILE_BUF_VALID)) {
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retval = ext2fs_bmap(fs, file->ino, &file->inode,
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BMAP_BUFFER, 0, file->blockno,
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&file->physblock);
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if (retval)
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return retval;
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if (!dontfill) {
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if (file->physblock) {
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retval = io_channel_read_blk(fs->io,
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file->physblock,
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1, file->buf);
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if (retval)
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return retval;
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} else
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memset(file->buf, 0, fs->blocksize);
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}
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file->flags |= EXT2_FILE_BUF_VALID;
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}
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return 0;
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}
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errcode_t ext2fs_file_close(ext2_file_t file)
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{
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errcode_t retval;
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@ -143,68 +203,39 @@ errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
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unsigned int wanted, unsigned int *got)
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{
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ext2_filsys fs;
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errcode_t retval;
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blk_t b, pb;
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errcode_t retval = 0;
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unsigned int start, left, c, count = 0;
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char *ptr = (char *) buf;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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fs = file->fs;
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again:
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if (file->pos >= file->inode.i_size)
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goto done;
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while ((file->pos < file->inode.i_size) && (wanted > 0)) {
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retval = sync_buffer_position(file);
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if (retval)
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goto fail;
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retval = load_buffer(file, 0);
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if (retval)
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goto fail;
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b = file->pos / fs->blocksize;
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if (b != file->blockno) {
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retval = ext2fs_file_flush(file);
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if (retval)
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goto fail;
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file->flags &= ~EXT2_FILE_BUF_VALID;
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}
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file->blockno = b;
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if (!(file->flags & EXT2_FILE_BUF_VALID)) {
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retval = ext2fs_bmap(fs, file->ino, &file->inode,
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file->buf, 0, b, &pb);
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if (retval)
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goto fail;
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if (pb) {
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file->physblock = pb;
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retval = io_channel_read_blk(fs->io, pb, 1, file->buf);
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if (retval)
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goto fail;
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} else {
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file->physblock = 0;
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memset(file->buf, 0, fs->blocksize);
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}
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file->flags |= EXT2_FILE_BUF_VALID;
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}
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start = file->pos % fs->blocksize;
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c = fs->blocksize - start;
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if (c > wanted)
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c = wanted;
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left = file->inode.i_size - file->pos ;
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if (c > left)
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c = left;
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start = file->pos % fs->blocksize;
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c = fs->blocksize - start;
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if (c > wanted)
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c = wanted;
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left = file->inode.i_size - file->pos ;
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if (c > left)
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c = left;
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memcpy(ptr, file->buf+start, c);
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file->pos += c;
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ptr += c;
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count += c;
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wanted -= c;
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if (wanted > 0)
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goto again;
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done:
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memcpy(ptr, file->buf+start, c);
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file->pos += c;
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ptr += c;
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count += c;
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wanted -= c;
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}
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fail:
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if (got)
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*got = count;
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return 0;
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fail:
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if (count)
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goto done;
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return retval;
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}
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@ -213,10 +244,11 @@ errcode_t ext2fs_file_write(ext2_file_t file, void *buf,
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unsigned int nbytes, unsigned int *written)
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{
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ext2_filsys fs;
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errcode_t retval;
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blk_t b, pb;
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unsigned int start, c, count = 0;
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blk_t pb;
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errcode_t retval = 0;
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unsigned int start, c, count = 0;
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char *ptr = (char *) buf;
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int dontfill;
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EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
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fs = file->fs;
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@ -224,54 +256,38 @@ errcode_t ext2fs_file_write(ext2_file_t file, void *buf,
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if (!(file->flags & EXT2_FILE_WRITE))
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return EXT2_ET_FILE_RO;
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again:
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b = file->pos / fs->blocksize;
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if (b != file->blockno) {
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retval = ext2fs_file_flush(file);
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while (nbytes > 0) {
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retval = sync_buffer_position(file);
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if (retval)
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goto fail;
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file->flags &= ~EXT2_FILE_BUF_VALID;
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}
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file->blockno = b;
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if (!(file->flags & EXT2_FILE_BUF_VALID)) {
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retval = ext2fs_bmap(fs, file->ino, &file->inode,
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file->buf, BMAP_ALLOC, b, &pb);
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if (retval)
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goto fail;
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file->physblock = pb;
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retval = io_channel_read_blk(fs->io, pb, 1, file->buf);
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start = file->pos % fs->blocksize;
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c = fs->blocksize - start;
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if (c > nbytes)
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c = nbytes;
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/*
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* We only need to do a read-modify-update cycle if
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* we're doing a partial write.
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*/
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retval = load_buffer(file, (c == fs->blocksize));
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if (retval)
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goto fail;
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file->flags |= EXT2_FILE_BUF_VALID;
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file->flags |= EXT2_FILE_BUF_DIRTY;
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memcpy(file->buf+start, ptr, c);
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file->pos += c;
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ptr += c;
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count += c;
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nbytes -= c;
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}
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start = file->pos % fs->blocksize;
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c = fs->blocksize - start;
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if (c > nbytes)
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c = nbytes;
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file->flags |= EXT2_FILE_BUF_DIRTY;
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memcpy(file->buf+start, ptr, c);
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file->pos += c;
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ptr += c;
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count += c;
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nbytes -= c;
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if (nbytes > 0)
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goto again;
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done:
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fail:
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if (written)
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*written = count;
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return 0;
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fail:
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if (count)
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goto done;
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return retval;
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}
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errcode_t ext2fs_file_lseek(ext2_file_t file, ext2_off_t offset,
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int whence, ext2_off_t *ret_pos)
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{
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