git-commit-vandalism/compat
Torsten Bögershausen 5c327502db MacOS: precompose_argv_prefix()
The following sequence leads to a "BUG" assertion running under MacOS:

  DIR=git-test-restore-p
  Adiarnfd=$(printf 'A\314\210')
  DIRNAME=xx${Adiarnfd}yy
  mkdir $DIR &&
  cd $DIR &&
  git init &&
  mkdir $DIRNAME &&
  cd $DIRNAME &&
  echo "Initial" >file &&
  git add file &&
  echo "One more line" >>file &&
  echo y | git restore -p .

 Initialized empty Git repository in /tmp/git-test-restore-p/.git/
 BUG: pathspec.c:495: error initializing pathspec_item
 Cannot close git diff-index --cached --numstat
 [snip]

The command `git restore` is run from a directory inside a Git repo.
Git needs to split the $CWD into 2 parts:
The path to the repo and "the rest", if any.
"The rest" becomes a "prefix" later used inside the pathspec code.

As an example, "/path/to/repo/dir-inside-repå" would determine
"/path/to/repo" as the root of the repo, the place where the
configuration file .git/config is found.

The rest becomes the prefix ("dir-inside-repå"), from where the
pathspec machinery expands the ".", more about this later.
If there is a decomposed form, (making the decomposing visible like this),
"dir-inside-rep°a" doesn't match "dir-inside-repå".

Git commands need to:

 (a) read the configuration variable "core.precomposeunicode"
 (b) precocompose argv[]
 (c) precompose the prefix, if there was any

The first commit,
76759c7dff "git on Mac OS and precomposed unicode"
addressed (a) and (b).

The call to precompose_argv() was added into parse-options.c,
because that seemed to be a good place when the patch was written.

Commands that don't use parse-options need to do (a) and (b) themselfs.

The commands `diff-files`, `diff-index`, `diff-tree` and `diff`
learned (a) and (b) in
commit 90a78b83e0 "diff: run arguments through precompose_argv"

Branch names (or refs in general) using decomposed code points
resulting in decomposed file names had been fixed in
commit 8e712ef6fc "Honor core.precomposeUnicode in more places"

The bug report from above shows 2 things:
- more commands need to handle precomposed unicode
- (c) should be implemented for all commands using pathspecs

Solution:
precompose_argv() now handles the prefix (if needed), and is renamed into
precompose_argv_prefix().

Inside this function the config variable core.precomposeunicode is read
into the global variable precomposed_unicode, as before.
This reading is skipped if precomposed_unicode had been read before.

The original patch for preocomposed unicode, 76759c7dff, placed
precompose_argv() into parse-options.c

Now add it into git.c::run_builtin() as well.  Existing precompose
calls in diff-files.c and others may become redundant, and if we
audit the callflows that reach these places to make sure that they
can never be reached without going through the new call added to
run_builtin(), we might be able to remove these existing ones.

But in this commit, we do not bother to do so and leave these
precompose callsites as they are.  Because precompose() is
idempotent and can be called on an already precomposed string
safely, this is safer than removing existing calls without fully
vetting the callflows.

There is certainly room for cleanups - this change intends to be a bug fix.
Cleanups needs more tests in e.g. t/t3910-mac-os-precompose.sh, and should
be done in future commits.

[1] git-bugreport-2021-01-06-1209.txt (git can't deal with special characters)
[2] https://lore.kernel.org/git/A102844A-9501-4A86-854D-E3B387D378AA@icloud.com/

Reported-by: Daniel Troger <random_n0body@icloud.com>
Helped-By: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-02-03 14:09:37 -08:00
..
nedmalloc Fix spelling errors in no-longer-updated-from-upstream modules 2019-11-10 16:00:55 +09:00
poll mingw: workaround for hangs when sending STDIN 2020-02-27 14:23:29 -08:00
regex compat/regex: move stdlib.h up in inclusion chain 2020-04-27 11:21:16 -07:00
vcbuild ci(vs-build): stop passing the iconv library location explicitly 2020-12-04 12:03:15 -08:00
win32 run-command: trigger PATH lookup properly on Cygwin 2020-03-27 11:06:17 -07:00
access.c git-compat-util: work around for access(X_OK) under root 2019-04-25 17:49:44 +09:00
apple-common-crypto.h imap-send: use HMAC() function provided by OpenSSL 2016-04-08 11:45:47 -07:00
basename.c compat/basename.c: provide a dirname() compatibility function 2016-01-12 10:40:54 -08:00
bswap.h compat/bswap.h: don't assume MSVC is little-endian 2020-11-11 11:24:47 -08:00
compiler.h bugreport: add compiler info 2020-04-16 15:23:42 -07:00
fileno.c git-compat-util: work around for access(X_OK) under root 2019-04-25 17:49:44 +09:00
fopen.c git_fopen: fix a sparse 'not declared' warning 2017-05-26 12:33:55 +09:00
hstrerror.c compat/hstrerror: convert sprintf to snprintf 2015-09-25 10:18:18 -07:00
inet_ntop.c compat/inet_ntop: fix off-by-one in inet_ntop4 2015-09-25 10:18:18 -07:00
inet_pton.c
memmem.c
mingw.c Merge branch 'jh/mingw-unlink' 2020-08-19 16:14:53 -07:00
mingw.h compat/mingw.h: drop extern from function declaration 2020-10-07 09:55:20 -07:00
mkdir.c
mkdtemp.c
mmap.c compat: make sure git_mmap is not expected to write 2018-10-25 18:51:03 +09:00
msvc.c
msvc.h msvc: add pragmas for common warnings 2019-06-25 10:46:57 -07:00
obstack.c compat/obstack: fix -Wcast-function-type warnings 2019-01-17 11:13:38 -08:00
obstack.h obstack: avoid computing offsets from NULL pointer 2020-01-28 23:13:25 -08:00
pread.c
precompose_utf8.c MacOS: precompose_argv_prefix() 2021-02-03 14:09:37 -08:00
precompose_utf8.h MacOS: precompose_argv_prefix() 2021-02-03 14:09:37 -08:00
qsort_s.c compat: add qsort_s() 2017-01-23 11:02:34 -08:00
setenv.c use st_add and st_mult for allocation size computation 2016-02-22 14:51:09 -08:00
sha1-chunked.c sha1: allow limiting the size of the data passed to SHA1_Update() 2015-11-05 10:35:11 -08:00
sha1-chunked.h sha1: allow limiting the size of the data passed to SHA1_Update() 2015-11-05 10:35:11 -08:00
snprintf.c MSVC: vsnprintf in Visual Studio 2015 doesn't need SNPRINTF_SIZE_CORR any more 2016-03-30 11:13:01 -07:00
stat.c compat: convert modes to use portable file type values 2014-12-04 11:58:36 -08:00
strcasestr.c
strdup.c compat: move strdup(3) replacement to its own file 2016-09-07 10:41:45 -07:00
strlcpy.c
strtoimax.c
strtoumax.c
terminal.c strvec: convert more callers away from argv_array name 2020-07-28 15:02:18 -07:00
terminal.h terminal: add a new function to read a single keystroke 2020-01-15 12:06:17 -08:00
unsetenv.c Revert "compat/unsetenv.c: Fix a sparse warning" 2013-07-21 15:09:56 -07:00
win32.h mingw: rename WIN32 cpp macro to GIT_WINDOWS_NATIVE 2013-05-08 12:14:35 -07:00
win32mmap.c mmap(win32): avoid expensive fstat() call 2016-04-22 15:01:16 -07:00
winansi.c mingw: work around incorrect standard handles 2019-11-23 11:17:01 +09:00