From: Simon Glass <simon.glass@canonical.com> Add ext4l_read() function to read file contents. The function resolves the path to an inode, then reads the file block by block using ext4_bread() and copies the data to the output buffer. Signed-off-by: Simon Glass <sjg@chromium.org> Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com> --- fs/ext4l/interface.c | 64 +++++++++++++++++++++++++++++ fs/fs_legacy.c | 2 +- include/ext4l.h | 13 ++++++ test/fs/ext4l.c | 38 +++++++++++++++++ test/py/tests/test_fs/test_ext4l.py | 7 ++++ 5 files changed, 123 insertions(+), 1 deletion(-) diff --git a/fs/ext4l/interface.c b/fs/ext4l/interface.c index 17648a59077..34e659cd28b 100644 --- a/fs/ext4l/interface.c +++ b/fs/ext4l/interface.c @@ -663,6 +663,70 @@ int ext4l_size(const char *filename, loff_t *sizep) return 0; } +int ext4l_read(const char *filename, void *buf, loff_t offset, loff_t len, + loff_t *actread) +{ + uint copy_len, blk_off, blksize; + loff_t bytes_left, file_size; + struct buffer_head *bh; + struct inode *inode; + ext4_lblk_t block; + char *dst; + int ret; + + *actread = 0; + + ret = ext4l_resolve_path(filename, &inode); + if (ret) { + printf("** File not found %s **\n", filename); + return ret; + } + + file_size = inode->i_size; + if (offset >= file_size) + return 0; + + /* If len is 0, read the whole file from offset */ + if (!len) + len = file_size - offset; + + /* Clamp to file size */ + if (offset + len > file_size) + len = file_size - offset; + + blksize = inode->i_sb->s_blocksize; + bytes_left = len; + dst = buf; + + while (bytes_left > 0) { + /* Calculate logical block number and offset within block */ + block = offset / blksize; + blk_off = offset % blksize; + + /* Read the block */ + bh = ext4_bread(NULL, inode, block, 0); + if (IS_ERR(bh)) + return PTR_ERR(bh); + if (!bh) + return -EIO; + + /* Calculate how much to copy from this block */ + copy_len = blksize - blk_off; + if (copy_len > bytes_left) + copy_len = bytes_left; + + memcpy(dst, bh->b_data + blk_off, copy_len); + brelse(bh); + + dst += copy_len; + offset += copy_len; + bytes_left -= copy_len; + *actread += copy_len; + } + + return 0; +} + void ext4l_close(void) { if (ext4l_open_dirs > 0) diff --git a/fs/fs_legacy.c b/fs/fs_legacy.c index 5edc35c4cdb..27a2d7be220 100644 --- a/fs/fs_legacy.c +++ b/fs/fs_legacy.c @@ -268,7 +268,7 @@ static struct fstype_info fstypes[] = { .ls = ext4l_ls, .exists = ext4l_exists, .size = ext4l_size, - .read = fs_read_unsupported, + .read = ext4l_read, .write = fs_write_unsupported, .uuid = fs_uuid_unsupported, .opendir = ext4l_opendir, diff --git a/include/ext4l.h b/include/ext4l.h index 6fee701f335..643060ee44c 100644 --- a/include/ext4l.h +++ b/include/ext4l.h @@ -55,6 +55,19 @@ int ext4l_exists(const char *filename); */ int ext4l_size(const char *filename, loff_t *sizep); +/** + * ext4l_read() - Read data from a file + * + * @filename: Path to file + * @buf: Buffer to read data into + * @offset: Byte offset to start reading from + * @len: Number of bytes to read (0 = read entire file from offset) + * @actread: Returns actual bytes read + * Return: 0 on success, negative on error + */ +int ext4l_read(const char *filename, void *buf, loff_t offset, loff_t len, + loff_t *actread); + /** * ext4l_get_uuid() - Get the filesystem UUID * diff --git a/test/fs/ext4l.c b/test/fs/ext4l.c index f58a91893cc..1bea9186d5a 100644 --- a/test/fs/ext4l.c +++ b/test/fs/ext4l.c @@ -257,3 +257,41 @@ static int fs_test_ext4l_size_norun(struct unit_test_state *uts) } FS_TEST_ARGS(fs_test_ext4l_size_norun, UTF_SCAN_FDT | UTF_CONSOLE | UTF_MANUAL, { "fs_image", UT_ARG_STR }); + +/** + * fs_test_ext4l_read_norun() - Test ext4l_read function + * + * Verifies that ext4l can read file contents. + * + * Arguments: + * fs_image: Path to the ext4 filesystem image + */ +static int fs_test_ext4l_read_norun(struct unit_test_state *uts) +{ + const char *fs_image = ut_str(EXT4L_ARG_IMAGE); + loff_t actread; + char buf[32]; + + ut_assertnonnull(fs_image); + ut_assertok(run_commandf("host bind 0 %s", fs_image)); + ut_assertok(fs_set_blk_dev("host", "0", FS_TYPE_ANY)); + + /* Read the test file - contains "hello world\n" (12 bytes) */ + memset(buf, '\0', sizeof(buf)); + ut_assertok(ext4l_read("/testfile.txt", buf, 0, 0, &actread)); + ut_asserteq(12, actread); + ut_asserteq_str("hello world\n", buf); + + /* Test partial read with offset */ + memset(buf, '\0', sizeof(buf)); + ut_assertok(ext4l_read("/testfile.txt", buf, 6, 5, &actread)); + ut_asserteq(5, actread); + ut_asserteq_str("world", buf); + + /* Verify read returns error for non-existent path */ + ut_asserteq(-ENOENT, ext4l_read("/no/such/file", buf, 0, 10, &actread)); + + return 0; +} +FS_TEST_ARGS(fs_test_ext4l_read_norun, UTF_SCAN_FDT | UTF_CONSOLE | UTF_MANUAL, + { "fs_image", UT_ARG_STR }); diff --git a/test/py/tests/test_fs/test_ext4l.py b/test/py/tests/test_fs/test_ext4l.py index 922fa37a7d8..4064a6c53ff 100644 --- a/test/py/tests/test_fs/test_ext4l.py +++ b/test/py/tests/test_fs/test_ext4l.py @@ -110,3 +110,10 @@ class TestExt4l: output = ubman.run_command( f'ut -f fs fs_test_ext4l_size_norun fs_image={ext4_image}') assert 'failures: 0' in output + + def test_read(self, ubman, ext4_image): + """Test that ext4l can read file contents.""" + with ubman.log.section('Test ext4l read'): + output = ubman.run_command( + f'ut -f fs fs_test_ext4l_read_norun fs_image={ext4_image}') + assert 'failures: 0' in output -- 2.43.0