From 56edfefb9718f72bd45093e0efd76bd88645fa89 Mon Sep 17 00:00:00 2001 From: David Oberhollenzer Date: Sun, 18 Sep 2022 16:04:24 +0200 Subject: block writer: move block comaprison to utility function Slightly modify the byte-for-byte comparison function to compare an arbitrary range in a file and move it to libutil. Instead of calling it for each block in the block writer, simply let it check an entire range in the block writer and compute the range position/size of the reference ahead, before looking for potential matches. Signed-off-by: David Oberhollenzer --- lib/util/Makemodule.am | 1 + lib/util/file_cmp.c | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) create mode 100644 lib/util/file_cmp.c (limited to 'lib/util') diff --git a/lib/util/Makemodule.am b/lib/util/Makemodule.am index b65ebda..830a338 100644 --- a/lib/util/Makemodule.am +++ b/lib/util/Makemodule.am @@ -13,6 +13,7 @@ libutil_a_SOURCES += lib/util/mkdir_p.c libutil_a_SOURCES += lib/util/canonicalize_name.c libutil_a_SOURCES += lib/util/filename_sane.c libutil_a_SOURCES += lib/util/source_date_epoch.c +libutil_a_SOURCES += lib/util/file_cmp.c libutil_a_CFLAGS = $(AM_CFLAGS) libutil_a_CPPFLAGS = $(AM_CPPFLAGS) diff --git a/lib/util/file_cmp.c b/lib/util/file_cmp.c new file mode 100644 index 0000000..2aa0cc2 --- /dev/null +++ b/lib/util/file_cmp.c @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: LGPL-3.0-or-later */ +/* + * file_cmp.c + * + * Copyright (C) 2019 David Oberhollenzer + */ +#include "config.h" + +#include "util/util.h" +#include "sqfs/io.h" + +#include + +int check_file_range_equal(sqfs_file_t *file, void *scratch, size_t scratch_sz, + sqfs_u64 loc_a, sqfs_u64 loc_b, sqfs_u64 size) +{ + sqfs_u8 *ptr_a = scratch, *ptr_b = ptr_a + scratch_sz / 2; + int ret; + + while (size > 0) { + size_t diff = scratch_sz / 2; + diff = (sqfs_u64)diff > size ? size : diff; + + ret = file->read_at(file, loc_a, ptr_a, diff); + if (ret != 0) + return ret; + + ret = file->read_at(file, loc_b, ptr_b, diff); + if (ret != 0) + return ret; + + if (memcmp(ptr_a, ptr_b, diff) != 0) + return 1; + + size -= diff; + loc_a += diff; + loc_b += diff; + } + + return 0; +} -- cgit v1.2.3