Commit Graph

225 Commits

Author SHA1 Message Date
Johannes Schindelin
a53306c284 mingw: support spawning programs containing spaces in their names
The CreateProcessW() function does not really support spaces in its
first argument, lpApplicationName. But it supports passing NULL as
lpApplicationName, which makes it figure out the application from the
(possibly quoted) first argument of lpCommandLine.

Let's use that trick (if we are certain that the first argument matches
the executable's path) to support launching programs whose path contains
spaces.

This fixes https://github.com/git-for-windows/git/issue/692

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:15 +01:00
Johannes Schindelin
0d1dec3713 Merge pull request #773 from jeffhostetler/vs2015
Build with VS2015
2017-10-29 16:46:14 +01:00
Johannes Schindelin
6b89e4dd98 Merge branch 'program-data-config'
This branch introduces support for reading the "Windows-wide" Git
configuration from `%PROGRAMDATA%\Git\config`. As these settings are
intended to be shared between *all* Git-related software, that config
file takes an even lower precedence than `$(prefix)/etc/gitconfig`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:14 +01:00
Johannes Schindelin
a780849800 Merge 'mingw-getcwd' into HEAD 2017-10-29 16:46:14 +01:00
Johannes Schindelin
2327e72e43 Merge pull request #443 from kblees/kb/nanosecond-file-times-v2.5.3
nanosecond file times for v2.5.3
2017-10-29 16:46:14 +01:00
Johannes Schindelin
33e7576327 Merge pull request #156 from kblees/kb/symlinks
Symlink support
2017-10-29 16:46:13 +01:00
Johannes Schindelin
201fb3081b Merge 'fix-externals' into HEAD 2017-10-29 16:46:13 +01:00
Johannes Schindelin
781b83bd63 Merge 'msys2' into HEAD
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:13 +01:00
Johannes Schindelin
caf209e5d1 msvc: provide a main() wrapper similar to mingw_main()
The MINGW version of the main() wrapper gets away with declaring symbols
that were intentionally not exported. However, some of these symbols do
not actually exist in MSVC's UCRT.

So let's add an MSVC version of the main() wrapper that uses wmain() and
imports the UNICODE argv and environment. While at it, we pass our UTF-8
version of ARGV to the real main -- rather than overwriting __argv as is
done in the MINGW Version.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
2017-10-29 16:46:09 +01:00
Jeff Hostetler
91bf4ac600 msvc: do not pretend to support all signals
This special-cases various signals that are not supported on Windows,
such as SIGPIPE. These cause the UCRT to throw asserts (at least in
debug mode).

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
2017-10-29 16:46:09 +01:00
Jeff Hostetler
bd44697fb2 msvc: mark a variable as non-const
VS2015 complains when using a const pointer in memcpy()/free().

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
2017-10-29 16:46:09 +01:00
Jeff Hostetler
158cb45587 msvc: convert environment from/to UTF-16 on the fly
This adds MSVC versions of getenv() and friends. These take UTF-8
arguments and return UTF-8 values, but use the UNICODE versions
of the CRT routines.  This avoids the need to write to __environ
(which is only visible if you statically link to the CRT).  This
also avoids the CP_ACP conversions performed inside the CRT.
It also avoids various memory leaks and problems.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
2017-10-29 16:46:09 +01:00
Philip Oakley
f97feb7f77 msvc: fix the declaration of the _REPARSE_DATA_BUFFER structure
GCC and MSVC disagree about using the GCC extension _ANONYMOUS_UNION.
Simply skip that offending keyword when compiling with MSVC.

Signed-off-by: Philip Oakley <philipoakley@iee.org>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:09 +01:00
Johannes Schindelin
e51d266e8e Merge branch 'redirect-std-handles'
This topic branch introduces a highly-experimental feature allowing to
override stdin/stdout/stderr by setting environment variables e.g. to
named pipes, solving a problem in highly multi-threaded applications
where inheritable handles could cause blocked Git operations.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:08 +01:00
Anton Serbulov
af72872ec3 mingw: fix getcwd when the parent directory cannot be queried
`GetLongPathName()` function may fail when it is unable to query
the parent directory of a path component to determine the long name
for that component. It happens, because of it uses `FindFirstFile()`
function for each next short part of path. The `FindFirstFile()`
requires `List Directory` and `Synchronize` desired access for a calling
process.

In case of lacking such permission for some part of path,
the `GetLongPathName()` returns 0 as result and `GetLastError()`
returns ERROR_ACCESS_DENIED.

`GetFinalPathNameByHandle()` function can help in such cases, because
it requires `Read Attributes` and `Synchronize` desired access to the
target path only.

The `GetFinalPathNameByHandle()` function was introduced on
`Windows Server 2008/Windows Vista`. So we need to load it dynamically.

`CreateFile()` parameters:
    `lpFileName` = path to the current directory
    `dwDesiredAccess` = 0 (it means `Read Attributes` and `Synchronize`)
    `dwShareMode` = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE
                    (it prevents `Sharing Violation`)
    `lpSecurityAttributes` = NULL (default security attributes)
    `dwCreationDisposition` = OPEN_EXISTING
                              (required to obtain a directory handle)
    `dwFlagsAndAttributes` = FILE_FLAG_BACKUP_SEMANTICS
                             (required to obtain a directory handle)
    `hTemplateFile` = NULL (when opening an existing file or directory,
                            `CreateFile` ignores this parameter)

The string that is returned by `GetFinalPathNameByHandle()` function
uses the \\?\ syntax. To skip the prefix and convert backslashes
to slashes, the `normalize_ntpath()` mingw function will be used.

Note: `GetFinalPathNameByHandle()` function returns a final path.
It is the path that is returned when a path is fully resolved.
For example, for a symbolic link named "C:\tmp\mydir" that points to
"D:\yourdir", the final path would be "D:\yourdir".

Signed-off-by: Anton Serbulov <aserbulov@plesk.com>
2017-10-29 16:46:07 +01:00
Johannes Schindelin
249006649b Windows: add support for a Windows-wide configuration
Between the libgit2 and the Git for Windows project, there has been a
discussion how we could share Git configuration to avoid duplication (or
worse: skew).

Earlier, libgit2 was nice enough to just re-use Git for Windows'

	C:\Program Files (x86)\Git\etc\gitconfig

but with the upcoming Git for Windows 2.x, there would be more paths to
search, as we will have 64-bit and 32-bit versions, and the
corresponding config files will be in %PROGRAMFILES%\Git\mingw64\etc and
...\mingw32\etc, respectively.

Worse: there are portable Git for Windows versions out there which live
in totally unrelated directories, still.

Therefore we came to a consensus to use `%PROGRAMDATA%\Git\config` as the
location for shared Git settings that are of wider interest than just Git
for Windows.

On XP, there is no %PROGRAMDATA%, therefore we need to use
"%ALLUSERSPROFILE%\Application Data\Git\config" in those setups.

Of course, the configuration in `%PROGRAMDATA%\Git\config` has the
widest reach, therefore it must take the lowest precedence, i.e. Git for
Windows can still override settings in its `etc/gitconfig` file.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:07 +01:00
Johannes Schindelin
77ba836789 mingw: ensure getcwd() reports the correct case
When switching the current working directory, say, in PowerShell, it is
quite possible to use a different capitalization than the one that is
recorded on disk. While doing the same in `cmd.exe` adjusts the
capitalization magically, that does not happen in PowerShell so that
`getcwd()` returns the current directory in a different way than is
recorded on disk.

Typically this creates no problems except when you call

	git log .

in a subdirectory called, say, "GIT/" but you switched to "Git/" and
your `getcwd()` reports the latter, then Git won't understand that you
wanted to see the history as per the `GIT/` subdirectory but it thinks you
wanted to see the history of some directory that may have existed in the
past (but actually never did).

So let's be extra careful to adjust the capitalization of the current
directory before working with it.

Reported by a few PowerShell power users ;-)

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:07 +01:00
Johannes Schindelin
b6ba8e0b07 Merge 'default-ident' into HEAD 2017-10-29 16:46:07 +01:00
Karsten Blees
0416e75066 Win32: implement nanosecond-precision file times
We no longer use any of MSVCRT's stat-functions, so there's no need to
stick to a CRT-compatible 'struct stat' either.

Define and use our own POSIX-2013-compatible 'struct stat' with nanosecond-
precision file times.

Note: Due to performance issues when using git variants with different file
time resolutions, this patch does *not* yet enable nanosecond precision in
the Makefile (use 'make USE_NSEC=1').

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:06 +01:00
lchiocca
98c9bb484b The stat() function should be independent of core.symlinks
The contract for the stat() and lstat() function is:
> stat():  stats the file pointed to by path and fills in buf.
> lstat(): is identical to stat(), except that if path is a symbolic link,
>          then the link itself is stat-ed, not the file that it refers to.

stat() should always return the statistics of the file or directory a
symbolic link is pointing to. The lstat() function is used to get the
stats for the symlink. Hence the check should not be there.

Signed-off-by: Loris Chiocca <loris@chiocca.ch>
2017-10-29 16:46:06 +01:00
Karsten Blees
984d91c696 Win32: replace MSVCRT's fstat() with a Win32-based implementation
fstat() is the only stat-related CRT function for which we don't have a
full replacement yet (and thus the only reason to stick with MSVCRT's
'struct stat' definition).

Fully implement fstat(), in preparation of implementing a POSIX 2013
compatible 'struct stat' with nanosecond-precision file times.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:06 +01:00
Johannes Schindelin
f51f074d8e mingw: keep trailing slashes for _wchdir() and readlink()
This is needed so that `_wchdir()` can be used with drive root
directories, e.g. C:\ (`_wchdir("C:")` fails to switch the directory
to the root directory).

This fixes https://github.com/msysgit/git/issues/359 (in Git for Windows
2.x only, though).

Likewise, `readlink()`'s semantics require a trailing slash for symbolic
links pointing to directories. Otherwise all checked out symbolic links
pointing to directories would be marked as modified even directly after a
fresh clone.

This fixes https://github.com/git-for-windows/git/issues/210

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:06 +01:00
Karsten Blees
5fdff93f50 Win32: symlink: add support for symlinks to directories
Symlinks on Windows have a flag that indicates whether the target is a file
or a directory. Symlinks of wrong type simply don't work. This even affects
core Win32 APIs (e.g. DeleteFile() refuses to delete directory symlinks).

However, CreateFile() with FILE_FLAG_BACKUP_SEMANTICS doesn't seem to care.
Check the target type by first creating a tentative file symlink, opening
it, and checking the type of the resulting handle. If it is a directory,
recreate the symlink with the directory flag set.

It is possible to create symlinks before the target exists (or in case of
symlinks to symlinks: before the target type is known). If this happens,
create a tentative file symlink and postpone the directory decision: keep
a list of phantom symlinks to be processed whenever a new directory is
created in mingw_mkdir().

Limitations: This algorithm may fail if a link target changes from file to
directory or vice versa, or if the target directory is created in another
process.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:06 +01:00
Karsten Blees
ffb00f3947 Win32: implement basic symlink() functionality (file symlinks only)
Implement symlink() that always creates file symlinks. Fails with ENOSYS
if symlinks are disabled or unsupported.

Note: CreateSymbolicLinkW() was introduced with symlink support in Windows
Vista. For compatibility with Windows XP, we need to load it dynamically
and fail gracefully if it isnt's available.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:06 +01:00
Karsten Blees
1a827be4b2 Win32: implement readlink()
Implement readlink() by reading NTFS reparse points. Works for symlinks
and directory junctions. If symlinks are disabled, fail with ENOSYS.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:06 +01:00
Karsten Blees
c820258d01 Win32: mingw_chdir: change to symlink-resolved directory
If symlinks are enabled, resolve all symlinks when changing directories,
as required by POSIX.

Note: Git's real_path() function bases its link resolution algorithm on
this property of chdir(). Unfortunately, the current directory on Windows
is limited to only MAX_PATH (260) characters. Therefore using symlinks and
long paths in combination may be problematic.

Note: GetFinalPathNameByHandleW() was introduced with symlink support in
Windows Vista. Thus, for compatibility with Windows XP, we need to load it
dynamically and behave gracefully if it isnt's available.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
6c9e248421 Win32: mingw_rename: support renaming symlinks
MSVCRT's _wrename() cannot rename symlinks over existing files: it returns
success without doing anything. Newer MSVCR*.dll versions probably do not
have this problem: according to CRT sources, they just call MoveFileEx()
with the MOVEFILE_COPY_ALLOWED flag.

Get rid of _wrename() and call MoveFileEx() with proper error handling.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
e90d4b341a Win32: mingw_unlink: support symlinks to directories
_wunlink() / DeleteFileW() refuses to delete symlinks to directories. If
_wunlink() fails with ERROR_ACCESS_DENIED, try _wrmdir() as well.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
100b051b9b Win32: add symlink-specific error codes
Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
1d457db578 Win32: change default of 'core.symlinks' to false
Symlinks on Windows don't work the same way as on Unix systems. E.g. there
are different types of symlinks for directories and files, creating
symlinks requires administrative privileges etc.

By default, disable symlink support on Windows. I.e. users explicitly have
to enable it with 'git config [--system|--global] core.symlinks true'.

The test suite ignores system / global config files. Allow testing *with*
symlink support by checking if native symlinks are enabled in MSys2 (via
'MSYS=winsymlinks:nativestrict').

Reminder: This would need to be changed if / when we find a way to run the
test suite in a non-MSys-based shell (e.g. dash).

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
f8e41db38a Win32: factor out retry logic
The retry pattern is duplicated in three places. It also seems to be too
hard to use: mingw_unlink() and mingw_rmdir() duplicate the code to retry,
and both of them do so incompletely. They also do not restore errno if the
user answers 'no'.

Introduce a retry_ask_yes_no() helper function that handles retry with
small delay, asking the user, and restoring errno.

mingw_unlink: include _wchmod in the retry loop (which may fail if the
file is locked exclusively).

mingw_rmdir: include special error handling in the retry loop.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
047e128819 Win32: lstat(): return adequate stat.st_size for symlinks
Git typically doesn't trust the stat.st_size member of symlinks (e.g. see
strbuf_readlink()). However, some functions take shortcuts if st_size is 0
(e.g. diff_populate_filespec()).

In mingw_lstat() and fscache_lstat(), make sure to return an adequate size.

The extra overhead of opening and reading the reparse point to calculate
the exact size is not necessary, as git doesn't rely on the value anyway.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Johannes Schindelin
40b59862f1 Win32: teach fscache and dirent about symlinks
Move S_IFLNK detection to file_attr_to_st_mode() and reuse it in fscache.

Implement DT_LNK detection in dirent.c and the fscache readdir version.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
87114b2513 Win32: let mingw_lstat() error early upon problems with reparse points
When obtaining lstat information for reparse points, we need to call
FindFirstFile() in addition to GetFileInformationEx() to obtain the type
of the reparse point (symlink, mount point etc.). However, currently there
is no error handling whatsoever if FindFirstFile() fails.

Call FindFirstFile() before modifying the stat *buf output parameter and
error out if the call fails.

Note: The FindFirstFile() return value includes all the data that we get
from GetFileAttributesEx(), so we could replace GetFileAttributesEx() with
FindFirstFile(). We don't do that because GetFileAttributesEx() is about
twice as fast for single files. I.e. we only pay the extra cost of calling
FindFirstFile() in the rare case that we encounter a reparse point.

Note: The indentation of the remaining reparse point code will be fixed in
the next patch.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
56212fdf9e Win32: remove separate do_lstat() function
With the new mingw_stat() implementation, do_lstat() is only called from
mingw_lstat() (with follow == 0). Remove the extra function and the old
mingw_stat()-specific (follow == 1) logic.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
df26965b24 Win32: implement stat() with symlink support
With respect to symlinks, the current stat() implementation is almost the
same as lstat(): except for the file type (st_mode & S_IFMT), it returns
information about the link rather than the target.

Implement stat by opening the file with as little permissions as possible
and calling GetFileInformationByHandle on it. This way, all link resoltion
is handled by the Windows file system layer.

If symlinks are disabled, use lstat() as before, but fail with ELOOP if a
symlink would have to be resolved.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Karsten Blees
fd1470edeb Win32: don't call GetFileAttributes twice in mingw_lstat()
GetFileAttributes cannot handle paths with trailing dir separator. The
current [l]stat implementation calls GetFileAttributes twice if the path
has trailing slashes (first with the original path passed to [l]stat, and
and a second time with a path copy with trailing '/' removed).

With Unicode conversion, we get the length of the path for free and also
have a (wide char) buffer that can be modified.

Remove trailing directory separators before calling the Win32 API.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:46:05 +01:00
Johannes Schindelin
71f2bc71c8 mingw: use domain information for default email
When a user is registered in a Windows domain, it is really easy to
obtain the email address. So let's do that.

Suggested by Lutz Roeder.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:04 +01:00
Johannes Schindelin
6a7c76b9f6 getpwuid(mingw): provide a better default for the user name
We do have the excellent GetUserInfoEx() function to obtain more
detailed information of the current user (if the user is part of a
Windows domain); Let's use it.

Suggested by Lutz Roeder.

To avoid the cost of loading Secur32.dll (even lazily, loading DLLs
takes a non-neglibile amount of time), we use the established technique
to load DLLs only when, and if, needed.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:04 +01:00
Johannes Schindelin
4a80215c87 getpwuid(mingw): initialize the structure only once
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:04 +01:00
Johannes Schindelin
abbccc47a4 mingw: simplify loading the CreadHardLinkW() function
We introduced helper macros to simplify loading functions dynamically.
Might just as well use them.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:46:04 +01:00
Johannes Schindelin
d16bf9c2ee Merge 'default-ident' into HEAD 2017-10-29 16:46:04 +01:00
Adam Roben
8736dca960 Make non-.exe externals work again
7ebac8cb94 made launching of .exe
externals work when installed in Unicode paths. But it broke launching
of non-.exe externals, no matter where they were installed. We now
correctly maintain the UTF-8 and UTF-16 paths in tandem in lookup_prog.

This fixes t5526, among others.

Signed-off-by: Adam Roben <adam@roben.org>
2017-10-29 16:45:51 +01:00
Adam Roben
958df13cf9 Fix launching of externals from Unicode paths
If Git were installed in a path containing non-ASCII characters,
commands such as git-am and git-submodule, which are implemented as
externals, would fail to launch with the following error:

> fatal: 'am' appears to be a git command, but we were not
> able to execute it. Maybe git-am is broken?

This was due to lookup_prog not being Unicode-aware. It was somehow
missed in 2ee5a1a14a.

Note that the only problem in this function was calling
GetFileAttributes instead of GetFileAttributesW. The calls to access()
were fine because access() is a macro which resolves to mingw_access,
which already handles Unicode correctly. But I changed lookup_prog to
use _waccess directly so that we only convert the path to UTF-16 once.

Signed-off-by: Adam Roben <adam@roben.org>
2017-10-29 16:45:51 +01:00
Johannes Schindelin
6df2edd405 mingw: load system libraries the recommended way
When we access IPv6-related functions, we load the corresponding system
library using the `LoadLibrary()` function, which is not the recommended
way to load system libraries.

In practice, it does not make a difference: the `ws2_32.dll` library
containing the IPv6 functions is already loaded into memory, so
LoadLibrary() simply reuses the already-loaded library.

Still, recommended way is recommended way, so let's use that instead.

While at it, also adjust the code in contrib/ that loads system libraries.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:45:49 +01:00
Karsten Blees
841fb6da85 mingw: initialize HOME on startup
HOME initialization was historically duplicated in many different places,
including /etc/profile, launch scripts such as git-bash.vbs and gitk.cmd,
and (although slightly broken) in the git-wrapper.

Even unrelated projects such as GitExtensions and TortoiseGit need to
implement the same logic to be able to call git directly.

Initialize HOME in git's own startup code so that we can eventually retire
all the duplicate initialization code.

Signed-off-by: Karsten Blees <blees@dcon.de>
2017-10-29 16:45:49 +01:00
Johannes Schindelin
6b74c74350 mingw: HOT FIX: work around environment issues -- again
This developer should really, really have known better. The fact that we
are changing the environment in ways for which the MSVCRT is not
prepared for is bad enough. But then this developer followed the request
to re-enable nedmalloc -- despite the prediction that it would cause an
access violation, predicting it in the same message as the request to
re-enable nedmalloc, no less!

To paper over the issue until the time when this developer finds the
time to re-design the Unicode environment handling from scratch, let's
hope that cURL is the only library we are using that *may* set an
environment variable using MSVCRT's putenv() after we fscked the
environment up.

Note: this commit can serve as no source of pride to anyone, certainly
not yours truly. It is necessary as a quick and pragmatic stop gap,
though, to prevent worse problems.

Note: cURL manages to set the variable CHARSET when nedmalloc is *not*
enabled, without causing an access violation. In that case, it sets it
successfully to the value "cp" + GetACP() (hence it is our choice, too,
cURL may need it, Git does not):

	https://github.com/bagder/curl/blob/aa5808b5/lib/easy.c#L157-L162

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:45:49 +01:00
Johannes Schindelin
509ef05f1d mingw: be *very* wary about outside environment changes
The environment is modified in most surprising circumstances, and not
all of them are under Git's control. For example, calling
curl_global_init() on Windows will ensure that the CHARSET variable is
set, adding one if necessary.

While the previous commit worked around crashes triggered by such
outside changes of the environment by relaxing the requirement that the
environment be terminated by a NULL pointer, the other assumption made
by `mingw_getenv()` and `mingw_putenv()` is that the environment is
sorted, for efficient lookup via binary search.

Let's make real sure that our environment is intact before querying or
modifying it, and reinitialize our idea of the environment if necessary.

With this commit, before working on the environment we look briefly for
indicators that the environment was modified outside of our control, and
to ensure that it is terminated with a NULL pointer and sorted again in
that case.

Note: the indicators are maybe not sufficient. For example, when a
variable is removed, it will not be noticed. It might also be a problem
if outside changes to the environment result in a modified `environ`
pointer: it is unclear whether such a modification could result in a
problem when `mingw_putenv()` needs to `realloc()` the environment
buffer.

For the moment, however, the current fix works well enough, so let's
only face the potential problems when (and if!) they occur.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:45:49 +01:00
Johannes Schindelin
001fccf412 mingw: be more defensive when making the environment block
Outside of our Windows-specific code, the end of the environment can be
marked also by a pointer to a NUL character, not only by a NULL pointer
as our code assumed so far.

That led to a buffer overrun in `make_environment_block()` when running
`git-remote-https` in `mintty` (because `curl_global_init()` added the
`CHARSET` environment variable *outside* of `mingw_putenv()`, ending the
environment in a pointer to an empty string).

Side note for future debugging on Windows: when running programs in
`mintty`, the standard input/output/error is not connected to a Win32
Console, but instead is pipe()d. That means that even stderr may not be
written completely before a crash, but has to be fflush()ed explicitly.
For example, when debugging crashes, the developer should insert an
`fflush(stderr);` at the end of the `error()` function defined in
usage.c.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:45:49 +01:00
Johannes Schindelin
102ed8c878 UTF-8 environment: be a little bit more defensive
It is unlikely that we have an empty environment, ever, but *if* we do,
when `environ_size - 1` is passed to `bsearchenv()` it is misinterpreted
as a real large integer.

To make the code truly defensive, refuse to do anything at all if the
size is negative (which should not happen, of course).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2017-10-29 16:45:49 +01:00