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2022-02-16xdiff: handle allocation failure in patience diffLibravatar Phillip Wood1-5/+12
Other users of libxdiff such as libgit2 need to be able to handle allocation failures. As NULL is a valid return value the function signature is changed to be able report allocation failures. Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-16xdiff: fix a memory leakLibravatar Phillip Wood1-4/+0
Although the patience and histogram algorithms initialize the environment they do not free it if there is an error. In contrast for the Myers algorithm the environment is initalized in xdl_do_diff() and it is freed if there is an error. Fix this by always initializing the environment in xdl_do_diff() and freeing it there if there is an error. Remove the comment in do_patience_diff() about the environment being freed by xdl_diff() as it is not accurate because (a) xdl_diff() does not do that if there is an error and (b) xdl_diff() is not the only caller. Reported-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-14Merge branch 'pw/patience-diff-clean-up'Libravatar Junio C Hamano1-11/+3
Code clean-up. * pw/patience-diff-clean-up: patience diff: remove unused variable patience diff: remove unnecessary string comparisons
2021-05-05patience diff: remove unused variableLibravatar Phillip Wood1-3/+0
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-05patience diff: remove unnecessary string comparisonsLibravatar Phillip Wood1-8/+3
xdl_prepare_env() calls xdl_classify_record() which arranges for the hashes of non-matching lines to be different so lines can be tested for equality by comparing just their hashes. This reduces the time taken to calculate the diff of v2.28.0 to v2.29.0 by ~3-4%. Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-20merge-base, xdiff: zero out xpparam_t structuresLibravatar Michał Kępień1-0/+2
xpparam_t structures are usually zero-initialized before their specific fields are assigned to, but there are three locations in the tree where that does not happen. Add the missing memset() calls in order to make initialization of xpparam_t structures consistent tree-wide and to prevent stack garbage from being used as field values. Signed-off-by: Michał Kępień <michal@isc.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-07-28xdiff: remove duplicate headers from xpatience.cLibravatar Carlo Marcelo Arenas Belón1-2/+0
92b7de93fb (Implement the patience diff algorithm, 2009-01-07) added them but were already part of xinclude.h Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-28diff: support anchoring line(s)Libravatar Jonathan Tan1-5/+37
Teach diff a new algorithm, one that attempts to prevent user-specified lines from appearing as a deletion or addition in the end result. The end user can use this by specifying "--anchored=<text>" one or more times when using Git commands like "diff" and "show". Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-11-09Replace Free Software Foundation address in license noticesLibravatar Todd Zullinger1-2/+2
The mailing address for the FSF has changed over the years. Rather than updating the address across all files, refer readers to gnu.org, as the GNU GPL documentation now suggests for license notices. The mailing address is retained in the full license files (COPYING and LGPL-2.1). The old address is still present in t/diff-lib/COPYING. This is intentional, as the file is used in tests and the contents are not expected to change. Signed-off-by: Todd Zullinger <tmz@pobox.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-10-10cleanup: fix possible overflow errors in binary searchLibravatar Derrick Stolee1-1/+1
A common mistake when writing binary search is to allow possible integer overflow by using the simple average: mid = (min + max) / 2; Instead, use the overflow-safe version: mid = min + (max - min) / 2; This translation is safe since the operation occurs inside a loop conditioned on "min < max". The included changes were found using the following git grep: git grep '/ *2;' '*.c' Making this cleanup will prevent future review friction when a new binary search is contructed based on existing code. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-11diff: fix a double off-by-one with --ignore-space-at-eolLibravatar Johannes Schindelin1-1/+1
When comparing two lines, ignoring any whitespace at the end, we first try to match as many bytes as possible and break out of the loop only upon mismatch, to let the remainder be handled by the code shared with the other whitespace-ignoring code paths. When comparing the bytes, however, we incremented the counters always, even if the bytes did not match. And because we fall through to the space-at-eol handling at that point, it is as if that mismatch never happened. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-02-19xdiff: PATIENCE/HISTOGRAM are not independent option bitsLibravatar Junio C Hamano1-1/+1
Because the default Myers, patience and histogram algorithms cannot be in effect at the same time, XDL_PATIENCE_DIFF and XDL_HISTOGRAM_DIFF are not independent bits. Instead of wasting one bit per algorithm, define a few macros to access the few bits they occupy and update the code that access them. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-07-07xdiff/xpatience: factor out fall-back-diff functionLibravatar Tay Ray Chuan1-25/+2
This is in preparation for the histogram diff algorithm, which will also re-use much of the code to call the default Meyers diff algorithm. Signed-off-by: Tay Ray Chuan <rctay89@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-07Implement the patience diff algorithmLibravatar Johannes Schindelin1-0/+381
The patience diff algorithm produces slightly more intuitive output than the classic Myers algorithm, as it does not try to minimize the number of +/- lines first, but tries to preserve the lines that are unique. To this end, it first determines lines that are unique in both files, then the maximal sequence which preserves the order (relative to both files) is extracted. Starting from this initial set of common lines, the rest of the lines is handled recursively, with Myers' algorithm as a fallback when the patience algorithm fails (due to no common unique lines). This patch includes memory leak fixes by Pierre Habouzit. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>