In a push to polish Git for Windows more, we are moving away from
scripts toward proper binaries.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The Git wrapper does one thing, and does it well: setting up the
environment required to run Git and its scripts, and then hand off to
another program.
We already do this for the Git executable itself; in Git for Windows'
context, we have exactly the same need also when calling the Git Bash or
Git CMD. However, both are tied to what particular shell environment you
use, though: MSys or MSys2 (or whatever else cunning developers make
work for them). This means that the Git Bash and Git CMD need to be
compiled in the respective context (e.g. when compiling the
mingw-w64-git package in the MSys2 context).
Happily, Windows offers a way to configure compiled executables:
resources. So let's just look whether the current executable has a
string resource and use it as the command-line to execute after the
environment is set up. To support MSys2's Git Bash better (where
`mintty` should, but might not, be available), we verify whether the
specified executable exists, and keep looking for string resources if it
does not.
For even more flexibility, we expand environment variables specified as
`@@<VARIABLE-NAME>@@`, and for convenience `@@EXEPATH@@` expands into
the directory in which the executable resides.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The intention of this change was to make it easier for the Git for
Windows installer, or for power Git users, to change the command-line
launched when executing Git Bash. The idea was to allow reconfiguring
the Git Bash to run different terminals than MSys2's default, mintty.
However, the comments this commit got let no room for misunderstanding:
at least three developers who gained trust by being active in the Git
for Windows offered their vetoes.
RIP, resource editor.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Instead of making it possible to change the .exe icon of git-bash.exe or
git-cmd.exe, this change was compared to adding the option to format USB
drives.
Let's get rid of this change, therefore, before real people are harmed.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Otherwise the output of Git commands cannot be caught by, say, Git GUI
(because it is running detached from any console, which would make
`git.exe` inherit the standard handles implicitly).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
As we already allow changing text resources, it is a very small step to
allow changing the `.exe` icon, too.
So let's just do it.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
To allow the Git wrapper to replace the `git-bash.bat` script (which
would always open the Win32 console, even if the user wants to use a
different terminal emulator), we need to offer a way to configure
*which* command-line to run.
We need to recompile the git-wrapper with the `-mwindows` flag to
declare that this is a GUI program (not a console program). Having to
recompile it anyway, let's put the new code in a conditionally compiled
section so that the builtins (for which we use the git-wrapper, too) do
not need to carry around that code.
To configure the command-line, we use a way that is very typical for
Windows: resources. Windows resources are data that are stored inside
.exe files, but can be changed *after* compilation. Therefore, this
facility is *exactly* what we want: we can easily copy the .exe to the
new name `git-bash.exe`, configure that executable to run the Bash, and
then copy it again to the new name `git-cmd.exe` and configure that
executable to run `cmd.exe` instead.
For even more flexibility, we expand environment variables specified as
`@@<VARIABLE-NAME>@@`, and for convenience `@@EXEPATH@@` expands into
the directory in which the executable resides.
Sadly, an executable cannot configure itself: the `.exe` file is locked
while the process is running. This means we have to have a separate
executable to edit the resources anyway, so let's just enhance the Git
wrapper *itself*: when copied to the new name `edit-res.exe`, it can
edit other copies of the Git wrapper like so:
edit-res.exe git-cmd.exe command '@@COMSPEC@@ /K'
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
We are about to use the Git wrapper to call the Git Bash of Git for
Windows. All the wrapper needs to do for that is to set up the
environment variables, use the home directory as working directory and
then hand off to a user-specified command-line.
We prepare the existing code for this change by introducing flags to set
up the environment variables, to launch a non-Git program, and to use
the home directory as working directory.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
The original purpose of the Git wrapper is to run from inside Git for
Windows' /cmd/ directory, to allow setting up some environment variables
before Git is allowed to take over.
Due to differences in the file system layout, MSys2 requires some
changes for that to work.
In addition, we must take care to set the `MSYSTEM` environment variable
to `MINGW32` or `MINGW64`, respectively, to allow MSys2 to be configured
correctly in case Git launches a shell or Perl script.
We also need to change the `TERM` variable to `cygwin` instead of
`msys`, otherwise the pager `less.exe` (spawned e.g. by `git log`) will
simply crash with a message similar to this one:
1 [main] less 9832 cygwin_exception::open_stackdumpfile:
Dumping stack trace to less.exe.stackdump
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Prepare to prefix the command-line with non-builtins. We are now using
the Git wrapper to call non-Git programs, too.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This was originally 'pull request #330 from ethomson/poll_inftim' in
msysgit/git.
poll: honor the timeout on Win32
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
These fixes were necessary for Sverre Rabbelier's remote-hg to work,
but for some magic reason they are not necessary for the current
remote-hg. Makes you wonder how that one gets away with it.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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>
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>
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>
The `git_terminal_prompt()` function expects the terminal window to be
attached to a Win32 Console. However, this is not the case with terminal
windows other than `cmd.exe`'s, e.g. with MSys2's own `mintty`.
Non-cmd terminals such as `mintty` still have to have a Win32 Console
to be proper console programs, but have to hide the Win32 Console to
be able to provide more flexibility (such as being resizeable not only
vertically but also horizontally). By writing to that Win32 Console,
`git_terminal_prompt()` manages only to send the prompt to nowhere and
to wait for input from a Console to which the user has no access.
This commit introduces a function specifically to support `mintty` -- or
other terminals that are compatible with MSys2's `/dev/tty` emulation. We
use the `TERM` environment variable as an indicator for that: if the value
starts with "xterm" (such as `mintty`'s "xterm_256color"), we prefer to
let `xterm_prompt()` handle the user interaction.
To handle the case when standard input/output are redirected – as is the
case when pushing via HTTPS: `git-remote-https`' standard input and
output are pipes from/to the main Git executable – we make use of the
`MSYS_TTY_HANDLES` environment variable that was introduced to
fix another bug in MSys2-based Git: this environment variable contains
the Win32 `HANDLE`s of the standard input, output and error as originally
passed from MSys2 to the Git executable, enclosed within space
characters, skipping handles that do not refer to the terminal window
(e.g. when they were redirected). We will only use those handles when
that environment variable lists all three handles because then we can be
100% certain that we are running inside a terminal window, and that we
know exactly which Win32 handles to use to communicate with it.
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: nalla <nalla@hamal.uberspace.de>
Ensure that when passing a pipe, the gnulib poll replacement will not
return 0 before the timeout has passed.
Not obeying the timeout (and merely returning 0) causes pathological
behavior when preparing a packfile for a repository and taking a
long time to do so. If poll were to return 0 immediately, this would
cause keep-alives to get sent as quickly as possible until the packfile
was created. Such deviance from the standard would cause megabytes (or
more) of keep-alive packets to be sent.
GetTickCount is used as it is efficient, stable and monotonically
increasing. (Neither GetSystemTime nor QueryPerformanceCounter have
all three of these properties.)
This reduces the disk footprint of a full Git for Windows setup
dramatically because on Windows, one cannot assume that hard links are
supported.
The net savings are calculated easily: the 32-bit `git.exe` file weighs
in with 7662 kB while the `git-wrapper.exe` file (modified to serve as a
drop-in replacement for builtins) weighs a scant 21 kB. At this point,
there are 109 builtins which results in a total of 813 MB disk space
being freed up by this commit.
Yes, that is really more than half a gigabyte.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Git started out as a bunch of separate commands, in the true Unix spirit.
Over time, more and more functionality was shared between the different
Git commands, though, so it made sense to introduce the notion of
"builtins": programs that are actually integrated into the main Git
executable.
These builtins can be called in two ways: either by specifying a
subcommand as the first command-line argument, or -- for backwards
compatibility -- by calling the Git executable hardlinked to a filename
of the form "git-<subcommand>". Example: the "log" command can be called
via "git log <parameters>" or via "git-log <parameters>". The latter
form is actually deprecated and only supported for scripts; calling
"git-log" interactively will not even work by default because the
libexec/git-core/ directory is not in the PATH.
All of this is well and groovy as long as hard links are supported.
Sadly, this is not the case in general on Windows. So it actually hurts
quite a bit when you have to fall back to copying all of git.exe's
currently 7.5MB 109 times, just for backwards compatibility.
The simple solution would be to install really trivial shell script
wrappers in place of the builtins:
for builtin in $BUILTINS
do
rm git-$builtin.exe
printf '#!/bin/sh\nexec git %s "$@"\n' $builtin > git-builtin
chmod a+x git-builtin
done
This method would work -- even on Windows because Git for Windows ships a
full-fledged Bash. However, the Windows Bash comes at a price: it needs to
spin up a full-fledged POSIX emulation layer everytime it starts.
Therefore, the shell script solution would incur a significant performance
penalty.
The best solution the Git for Windows team could come up with is to extend
the Git wrapper -- that is needed to call Git from cmd.exe anyway, and
that weighs in with a scant 19KB -- to also serve as a drop-in replacement
for the builtins so that the following workaround is satisfactory:
for builtin in $BUILTINS
do
cp git-wrapper.exe git-$builtin.exe
done
This commit allows for this, by extending the module file parsing to
turn builtin command names like `git-log.exe ...` into calls to the main
Git executable: `git.exe log ...`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This prepares the wrapper for modifications to serve as a drop-in
replacement for the builtins.
This commit's diff is best viewed with the `-w` flag.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
We take care to embed the manifest, too, because we will modify the
wrapper in the next few commits to serve as a drop-in replacement for
the built-ins, i.e. we will want to call the wrapper under names such
as 'git-patch-id.exe', too.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
