The userdiff structures may be initialized either statically on the
stack or dynamically via configuration keys. In the latter case we end
up leaking memory because we didn't have any infrastructure to discern
those strings which have been allocated statically and those which have
been allocated dynamically.
Refactor the code such that we have two pointers for each of these
strings: one that holds the value as accessed by other subsystems, and
one that points to the same string in case it has been allocated. Like
this, we can safely free the second pointer and thus plug those memory
leaks.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git diff --exit-code --ext-diff" learned to take the exit status
of the external diff driver into account when deciding the exit
status of the overall "git diff" invocation when configured to do
so.
* rs/diff-exit-code-with-external-diff:
diff: let external diffs report that changes are uninteresting
userdiff: add and use struct external_diff
t4020: test exit code with external diffs
The options --exit-code and --quiet instruct git diff to indicate
whether it found any significant changes by exiting with code 1 if it
did and 0 if there were none. Currently this doesn't work if external
diff programs are involved, as we have no way to learn what they found.
Add that ability in the form of the new configuration options
diff.trustExitCode and diff.<driver>.trustExitCode and the environment
variable GIT_EXTERNAL_DIFF_TRUST_EXIT_CODE. They pair with the config
options diff.external and diff.<driver>.command and the environment
variable GIT_EXTERNAL_DIFF, respectively.
The new options are off by default, keeping the old behavior. Enabling
them indicates that the external diff returns exit code 1 if it finds
significant changes and 0 if it doesn't, like diff(1).
The name of the new options is taken from the git difftool and mergetool
options of similar purpose. (There they enable passing on the exit code
of a diff tool and to infer whether a merge done by a merge tool is
successful.)
The new feature sets the diff flag diff_from_contents in
diff_setup_done() if we need the exit code and are allowed to call
external diffs. This disables the optimization that avoids calling the
program with --quiet. Add it back by skipping the call if the external
diff is not able to report empty diffs. We can only do that check after
evaluating the file-specific attributes in run_external_diff().
If we do run the external diff with --quiet, send its output to
/dev/null.
I considered checking the output of the external diff to check whether
its empty. It was added as 11be65cfa4 (diff: fix --exit-code with
external diff, 2024-05-05) and quickly reverted, as it does not work
with external diffs that do not write to stdout. There's no reason why
a graphical diff tool would even need to write anything there at all.
I also considered using a non-zero exit code for empty diffs, which
could be done without adding new configuration options. We'd need to
disable the optimization that allows git diff --quiet to skip calling
external diffs, though -- that might be quite surprising if graphical
diff programs are involved. And assigning the opposite meaning of the
exit codes compared to diff(1) and git diff --exit-code to the external
diff can cause unnecessary confusion.
Suggested-by: Phillip Wood <phillip.wood123@gmail.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Wrap the string specifying the external diff command in a new struct to
simplify adding attributes, which the next patch will do.
Make sure external_diff() still returns NULL if neither the environment
variable GIT_EXTERNAL_DIFF nor the configuration option diff.external is
set, to continue allowing its use in a boolean context.
Use a designated initializer for the default builtin userdiff driver to
adjust to the type change of the second struct member. Spelling out
only the non-zero members improves readability as a nice side-effect.
No functional change intended.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There are multiple cases where we intentionally leak config strings:
- `struct gpg_format` is used to track programs that can be used for
signing commits, either via gpg(1), gpgsm(1) or ssh-keygen(1). The
user can override the commands via several config variables. As the
array is populated once, only, and the struct memers are never
written to or free'd.
- `struct ll_merge_driver` is used to track merge drivers. Same as
with the GPG format, these drivers are populated once and then
reused. Its data is never written to or free'd, either.
- `struct userdiff_funcname` and `struct userdiff_driver` can be
configured via `diff.<driver>.*` to add additional drivers. Again,
these have a global lifetime and are never written to or free'd.
All of these are intentionally kept alive and are never written to.
Furthermore, all of these are being assigned both string constants in
some places, and allocated strings in other places. This will cause
warnings once we enable `-Wwrite-strings`, so let's mark the respective
fields as `const char *` and cast away the constness when assigning
those values.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The out parameter of `git_config_string()` is a `const char **` even
though we transfer ownership of memory to the caller. This is quite
misleading and has led to many memory leaks all over the place. Adapt
the parameter to instead be `char **`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The userdiff regexp patterns for various filetypes that are built
into the system have been updated to avoid triggering regexp errors
from UTF-8 aware regex engines.
* rs/userdiff-multibyte-regex:
userdiff: support regexec(3) with multi-byte support
Since 1819ad327b (grep: fix multibyte regex handling under macOS,
2022-08-26) we use the system library for all regular expression
matching on macOS, not just for git grep. It supports multi-byte
strings and rejects invalid multi-byte characters.
This broke all built-in userdiff word regexes in UTF-8 locales because
they all include such invalid bytes in expressions that are intended to
match multi-byte characters without explicit support for that from the
regex engine.
"|[^[:space:]]|[\xc0-\xff][\x80-\xbf]+" is added to all built-in word
regexes to match a single non-space or multi-byte character. The \xNN
characters are invalid if interpreted as UTF-8 because they have their
high bit set, which indicates they are part of a multi-byte character,
but they are surrounded by single-byte characters.
Replace that expression with "|[^[:space:]]" if the regex engine
supports multi-byte matching, as there is no need to have an explicit
range for multi-byte characters then. Check for that capability at
runtime, because it depends on the locale and thus on environment
variables. Construct the full replacement expression at build time
and just switch it in if necessary to avoid string manipulation and
allocations at runtime.
Additionally the word regex for tex contains the expression
"[a-zA-Z0-9\x80-\xff]+" with a similarly invalid range. The best
replacement with only valid characters that I can come up with is
"([a-zA-Z0-9]|[^\x01-\x7f])+". Unlike the original it matches NUL
characters, though. Assuming that tex files usually don't contain NUL
this should be acceptable.
Reported-by: D. Ben Knoble <ben.knoble@gmail.com>
Reported-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It can be useful to specify diff algorithms per file type. For example,
one may want to use the minimal diff algorithm for .json files, another
for .c files, etc.
The diff machinery already checks attributes for a diff driver. Teach
the diff driver parser a new type "algorithm" to look for in the
config, which will be used if a driver has been specified through the
attributes.
Enforce precedence of the diff algorithm by favoring the command line
option, then looking at the driver attributes & config combination, then
finally the diff.algorithm config.
To enforce precedence order, use a new `ignore_driver_algorithm` member
during options parsing to indicate the diff algorithm was set via command
line args.
Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Refactor the userdiff_find_by_namelen() function so that a new
for_each_userdiff_driver() API function does most of the work.
This will be useful for the same reason we've got other for_each_*()
API functions as part of various APIs, and will be used in a follow-up
commit.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
[jc: squashed in missing forward decl in userdiff.h found by Ramsay]
Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The memory allocation scheme for the textconv interface is a
bit tricky, and not well documented. It was originally
designed as an internal part of diff.c (matching
fill_mmfile), but gradually was made public.
Refactoring it is difficult, but we can at least improve the
situation by documenting the intended flow and enforcing it
with an in-code assertion.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This function actually does two things:
1. Load the userdiff driver for the filespec.
2. Decide whether the driver has a textconv component, and
initialize the textconv cache if applicable.
Only part (1) requires the filespec object, and some callers
may not have a filespec at all. So let's split them it into
two functions, and put part (2) with the userdiff code,
which is a better fit.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Running a textconv filter can take a long time. It's
particularly bad for a large file which needs to be spooled
to disk, but even for small files, the fork+exec overhead
can add up for something like "git log -p".
This patch uses the notes-cache mechanism to keep a fast
cache of textconv output. Caches are stored in
refs/notes/textconv/$x, where $x is the userdiff driver
defined in gitattributes.
Caching is enabled only if diff.$x.cachetextconv is true.
In my test repo, on a commit with 45 jpg and avi files
changed and a textconv to show their exif tags:
[before]
$ time git show >/dev/null
real 0m13.724s
user 0m12.057s
sys 0m1.624s
[after, first run]
$ git config diff.mfo.cachetextconv true
$ time git show >/dev/null
real 0m14.252s
user 0m12.197s
sys 0m1.800s
[after, subsequent runs]
$ time git show >/dev/null
real 0m0.352s
user 0m0.148s
sys 0m0.200s
So for a slight (3.8%) cost on the first run, we achieve an
almost 40x speed up on subsequent runs.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Make the --color-words splitting regular expression configurable via
the diff driver's 'wordregex' attribute. The user can then set the
driver on a file in .gitattributes. If a regex is given on the
command line, it overrides the driver's setting.
We also provide built-in regexes for the languages that already had
funcname patterns, and add an appropriate diff driver entry for C/++.
(The patterns are designed to run UTF-8 sequences into a single chunk
to make sure they remain readable.)
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffs that have been produced with textconv almost certainly
cannot be applied, so we want to be careful not to generate
them in things like format-patch.
This introduces a new diff options, ALLOW_TEXTCONV, which
controls this behavior. It is off by default, but is
explicitly turned on for the "log" family of commands, as
well as the "diff" porcelain (but not diff-* plumbing).
Because both text conversion and external diffing are
controlled by these diff options, we can get rid of the
"plumbing versus porcelain" distinction when reading the
config. This was an attempt to control the same thing, but
suffered from being too coarse-grained.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When diffing binary files, it is sometimes nice to see the
differences of a canonical text form rather than either a
binary patch or simply "binary files differ."
Until now, the only option for doing this was to define an
external diff command to perform the diff. This was a lot of
work, since the external command needed to take care of
doing the diff itself (including mode changes), and lost the
benefit of git's colorization and other options.
This patch adds a text conversion option, which converts a
file to its canonical format before performing the diff.
This is less flexible than an arbitrary external diff, but
is much less work to set up. For example:
$ echo '*.jpg diff=exif' >>.gitattributes
$ git config diff.exif.textconv exiftool
$ git config diff.exif.binary false
allows one to see jpg diffs represented by the text output
of exiftool.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The "diff" gitattribute is somewhat overloaded right now. It
can say one of three things:
1. this file is definitely binary, or definitely not
(i.e., diff or !diff)
2. this file should use an external diff engine (i.e.,
diff=foo, diff.foo.command = custom-script)
3. this file should use particular funcname patterns
(i.e., diff=foo, diff.foo.(x?)funcname = some-regex)
Most of the time, there is no conflict between these uses,
since using one implies that the other is irrelevant (e.g.,
an external diff engine will decide for itself whether the
file is binary).
However, there is at least one conflicting situation: there
is no way to say "use the regular rules to determine whether
this file is binary, but if we do diff it textually, use
this funcname pattern." That is, currently setting diff=foo
indicates that the file is definitely text.
This patch introduces a "binary" config option for a diff
driver, so that one can explicitly set diff.foo.binary. We
default this value to "don't know". That is, setting a diff
attribute to "foo" and using "diff.foo.funcname" will have
no effect on the binaryness of a file. To get the current
behavior, one can set diff.foo.binary to true.
This patch also has one additional advantage: it cleans up
the interface to the userdiff code a bit. Before, calling
code had to know more about whether attributes were false,
true, or unset to determine binaryness. Now that binaryness
is a property of a driver, we can represent these situations
just by passing back a driver struct.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Both sets of code assume that one specifies a diff profile
as a gitattribute via the "diff=foo" attribute. They then
pull information about that profile from the config as
diff.foo.*.
The code for each is currently completely separate from the
other, which has several disadvantages:
- there is duplication as we maintain code to create and
search the separate lists of external drivers and
funcname patterns
- it is difficult to add new profile options, since it is
unclear where they should go
- the code is difficult to follow, as we rely on the
"check if this file is binary" code to find the funcname
pattern as a side effect. This is the first step in
refactoring the binary-checking code.
This patch factors out these diff profiles into "userdiff"
drivers. A file with "diff=foo" uses the "foo" driver, which
is specified by a single struct.
Note that one major difference between the two pieces of
code is that the funcname patterns are always loaded,
whereas external drivers are loaded only for the "git diff"
porcelain; the new code takes care to retain that situation.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
