<feed xmlns='http://www.w3.org/2005/Atom'>
<title>delta/git.git/compat/mingw.h, branch es/worktree-add</title>
<subtitle>github.com: git/git.git
</subtitle>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/'/>
<entry>
<title>mingw.h: add dummy functions for sigset_t operations</title>
<updated>2014-09-22T20:41:52+00:00</updated>
<author>
<name>Johannes Sixt</name>
<email>j6t@kdbg.org</email>
</author>
<published>2014-09-22T18:24:34+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=4e6d207c45e6f5c13b38c4a200f0d3339f88ad34'/>
<id>4e6d207c45e6f5c13b38c4a200f0d3339f88ad34</id>
<content type='text'>
Windows does not have POSIX-like signals, and so we ignore all
operations on the non-existent signal mask machinery.

Do not turn sigemptyset into a function, but leave it a macro that
erases the code in the argument because it is used to set sa_mask
of a struct sigaction, but our dummy in mingw.h does not have that
member.

Signed-off-by: Johannes Sixt &lt;j6t@kdbg.org&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Windows does not have POSIX-like signals, and so we ignore all
operations on the non-existent signal mask machinery.

Do not turn sigemptyset into a function, but leave it a macro that
erases the code in the argument because it is used to set sa_mask
of a struct sigaction, but our dummy in mingw.h does not have that
member.

Signed-off-by: Johannes Sixt &lt;j6t@kdbg.org&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'sk/mingw-uni-fix-more'</title>
<updated>2014-07-30T21:21:09+00:00</updated>
<author>
<name>Junio C Hamano</name>
<email>gitster@pobox.com</email>
</author>
<published>2014-07-30T21:21:09+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=385e171a5b56dabbe33dbef6f88e8f934a6cacda'/>
<id>385e171a5b56dabbe33dbef6f88e8f934a6cacda</id>
<content type='text'>
Most of these are battle-tested in msysgit and are needed to
complete what has been merged to 'master' already.

* sk/mingw-uni-fix-more:
  Win32: enable color output in Windows cmd.exe
  Win32: patch Windows environment on startup
  Win32: keep the environment sorted
  Win32: use low-level memory allocation during initialization
  Win32: reduce environment array reallocations
  Win32: don't copy the environment twice when spawning child processes
  Win32: factor out environment block creation
  Win32: unify environment function names
  Win32: unify environment case-sensitivity
  Win32: fix environment memory leaks
  Win32: Unicode environment (incoming)
  Win32: Unicode environment (outgoing)
  Revert "Windows: teach getenv to do a case-sensitive search"
  tests: do not pass iso8859-1 encoded parameter
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Most of these are battle-tested in msysgit and are needed to
complete what has been merged to 'master' already.

* sk/mingw-uni-fix-more:
  Win32: enable color output in Windows cmd.exe
  Win32: patch Windows environment on startup
  Win32: keep the environment sorted
  Win32: use low-level memory allocation during initialization
  Win32: reduce environment array reallocations
  Win32: don't copy the environment twice when spawning child processes
  Win32: factor out environment block creation
  Win32: unify environment function names
  Win32: unify environment case-sensitivity
  Win32: fix environment memory leaks
  Win32: Unicode environment (incoming)
  Win32: Unicode environment (outgoing)
  Revert "Windows: teach getenv to do a case-sensitive search"
  tests: do not pass iso8859-1 encoded parameter
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'sk/mingw-uni-fix'</title>
<updated>2014-07-21T18:18:50+00:00</updated>
<author>
<name>Junio C Hamano</name>
<email>gitster@pobox.com</email>
</author>
<published>2014-07-21T18:18:50+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=80e85754e08da9999f7b7ab956465150aebcf44d'/>
<id>80e85754e08da9999f7b7ab956465150aebcf44d</id>
<content type='text'>
* sk/mingw-uni-fix:
  Win32: Unicode file name support (dirent)
  Win32: Unicode file name support (except dirent)
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* sk/mingw-uni-fix:
  Win32: Unicode file name support (dirent)
  Win32: Unicode file name support (except dirent)
</pre>
</div>
</content>
</entry>
<entry>
<title>Win32: don't copy the environment twice when spawning child processes</title>
<updated>2014-07-21T16:32:49+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>blees@dcon.de</email>
</author>
<published>2014-07-17T15:38:01+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=77734da241f97607eea8f2bb55e0e19937e918d4'/>
<id>77734da241f97607eea8f2bb55e0e19937e918d4</id>
<content type='text'>
When spawning child processes via start_command(), the environment and all
environment entries are copied twice. First by make_augmented_environ /
copy_environ to merge with child_process.env. Then a second time by
make_environment_block to create a sorted environment block string as
required by CreateProcess.

Move the merge logic to make_environment_block so that we only need to copy
the environment once. This changes semantics of the env parameter: it now
expects a delta (such as child_process.env) rather than a full environment.
This is not a problem as the parameter is only used by start_command()
(all other callers previously passed char **environ, and now pass NULL).

The merge logic no longer xstrdup()s the environment strings, so do_putenv
must not free them. Add a parameter to distinguish this from normal putenv.

Remove the now unused make_augmented_environ / free_environ API.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When spawning child processes via start_command(), the environment and all
environment entries are copied twice. First by make_augmented_environ /
copy_environ to merge with child_process.env. Then a second time by
make_environment_block to create a sorted environment block string as
required by CreateProcess.

Move the merge logic to make_environment_block so that we only need to copy
the environment once. This changes semantics of the env parameter: it now
expects a delta (such as child_process.env) rather than a full environment.
This is not a problem as the parameter is only used by start_command()
(all other callers previously passed char **environ, and now pass NULL).

The merge logic no longer xstrdup()s the environment strings, so do_putenv
must not free them. Add a parameter to distinguish this from normal putenv.

Remove the now unused make_augmented_environ / free_environ API.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Win32: fix environment memory leaks</title>
<updated>2014-07-21T16:32:49+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>blees@dcon.de</email>
</author>
<published>2014-07-17T15:37:57+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=e96942e821dec273b884fec378cc2a97a7f5d689'/>
<id>e96942e821dec273b884fec378cc2a97a7f5d689</id>
<content type='text'>
All functions that modify the environment have memory leaks.

Disable gitunsetenv in the Makefile and use env_setenv (via mingw_putenv)
instead (this frees removed environment entries).

Move xstrdup from env_setenv to make_augmented_environ, so that
mingw_putenv no longer copies the environment entries (according to POSIX
[1], "the string [...] shall become part of the environment"). This also
fixes the memory leak in gitsetenv, which expects a POSIX compliant putenv.

[1] http://pubs.opengroup.org/onlinepubs/009695399/functions/putenv.html

Note: This patch depends on taking control of char **environ and having
our own mingw_putenv (both introduced in "Win32: Unicode environment
(incoming)").

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
All functions that modify the environment have memory leaks.

Disable gitunsetenv in the Makefile and use env_setenv (via mingw_putenv)
instead (this frees removed environment entries).

Move xstrdup from env_setenv to make_augmented_environ, so that
mingw_putenv no longer copies the environment entries (according to POSIX
[1], "the string [...] shall become part of the environment"). This also
fixes the memory leak in gitsetenv, which expects a POSIX compliant putenv.

[1] http://pubs.opengroup.org/onlinepubs/009695399/functions/putenv.html

Note: This patch depends on taking control of char **environ and having
our own mingw_putenv (both introduced in "Win32: Unicode environment
(incoming)").

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Win32: Unicode environment (incoming)</title>
<updated>2014-07-21T16:32:48+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>blees@dcon.de</email>
</author>
<published>2014-07-17T15:37:56+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=b729f98fa50b10cfba7cbf3f37a0ac255e1fbdcd'/>
<id>b729f98fa50b10cfba7cbf3f37a0ac255e1fbdcd</id>
<content type='text'>
Convert environment from UTF-16 to UTF-8 on startup.

No changes to getenv() are necessary, as the MSVCRT version is implemented
on top of char **environ.

However, putenv / _wputenv from MSVCRT no longer work, for two reasons:
1. they try to keep environ, _wenviron and the Win32 process environment
in sync, using the default system encoding instead of UTF-8 to convert
between charsets
2. msysgit and MSVCRT use different allocators, memory allocated in git
cannot be freed by the CRT and vice versa

Implement mingw_putenv using the env_setenv helper function from the
environment merge code.

Note that in case of memory allocation failure, putenv now dies with error
message (due to xrealloc) instead of failing with ENOMEM. As git assumes
setenv / putenv to always succeed, this prevents it from continuing with
incorrect settings.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Convert environment from UTF-16 to UTF-8 on startup.

No changes to getenv() are necessary, as the MSVCRT version is implemented
on top of char **environ.

However, putenv / _wputenv from MSVCRT no longer work, for two reasons:
1. they try to keep environ, _wenviron and the Win32 process environment
in sync, using the default system encoding instead of UTF-8 to convert
between charsets
2. msysgit and MSVCRT use different allocators, memory allocated in git
cannot be freed by the CRT and vice versa

Implement mingw_putenv using the env_setenv helper function from the
environment merge code.

Note that in case of memory allocation failure, putenv now dies with error
message (due to xrealloc) instead of failing with ENOMEM. As git assumes
setenv / putenv to always succeed, this prevents it from continuing with
incorrect settings.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MinGW: fix compile error due to missing ELOOP</title>
<updated>2014-07-16T17:42:49+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>karsten.blees@gmail.com</email>
</author>
<published>2014-07-15T22:53:27+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=e0a064a10749a8039f28e9bd3de0ffb5cf99e678'/>
<id>e0a064a10749a8039f28e9bd3de0ffb5cf99e678</id>
<content type='text'>
MinGW and MSVC before 2010 don't define ELOOP, use EMLINK (aka "Too many
links") instead.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Reviewed-by: Jonathan Nieder &lt;jrnieder@gmail.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
MinGW and MSVC before 2010 don't define ELOOP, use EMLINK (aka "Too many
links") instead.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Reviewed-by: Jonathan Nieder &lt;jrnieder@gmail.com&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Win32: Unicode file name support (except dirent)</title>
<updated>2014-07-15T18:19:08+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>blees@dcon.de</email>
</author>
<published>2012-03-15T17:21:28+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=85faec9d3acd8bb20e26e2d3386f7d3708d02fca'/>
<id>85faec9d3acd8bb20e26e2d3386f7d3708d02fca</id>
<content type='text'>
Replaces Windows "ANSI" APIs dealing with file- or path names with their
Unicode equivalent, adding UTF-8/UTF-16LE conversion as necessary.

The dirent API (opendir/readdir/closedir) is updated in a separate commit.

Adds trivial wrappers for access, chmod and chdir.

Adds wrapper for mktemp (needed for both mkstemp and mkdtemp).

The simplest way to convert a repository with legacy-encoded (e.g. Cp1252)
file names to UTF-8 ist to checkout with an old msysgit version and
"git add --all &amp; git commit" with the new version.

Includes a fix for bug reported by John Chen:
On Windows XP (not Win7), directories cannot be deleted while a find handle
is open, causing "Deletion of directory '...' failed. Should I try again?"
prompts.

Prior to this commit, these failures were silently ignored due to
strbuf_free in is_dir_empty resetting GetLastError to ERROR_SUCCESS.

Close the find handle in is_dir_empty so that git doesn't block deletion
of the directory even after all other applications have released it.

Reported-by: John Chen &lt;john0312@gmail.com&gt;
Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replaces Windows "ANSI" APIs dealing with file- or path names with their
Unicode equivalent, adding UTF-8/UTF-16LE conversion as necessary.

The dirent API (opendir/readdir/closedir) is updated in a separate commit.

Adds trivial wrappers for access, chmod and chdir.

Adds wrapper for mktemp (needed for both mkstemp and mkdtemp).

The simplest way to convert a repository with legacy-encoded (e.g. Cp1252)
file names to UTF-8 ist to checkout with an old msysgit version and
"git add --all &amp; git commit" with the new version.

Includes a fix for bug reported by John Chen:
On Windows XP (not Win7), directories cannot be deleted while a find handle
is open, causing "Deletion of directory '...' failed. Should I try again?"
prompts.

Prior to this commit, these failures were silently ignored due to
strbuf_free in is_dir_empty resetting GetLastError to ERROR_SUCCESS.

Close the find handle in is_dir_empty so that git doesn't block deletion
of the directory even after all other applications have released it.

Reported-by: John Chen &lt;john0312@gmail.com&gt;
Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Win32: fix broken pipe detection</title>
<updated>2014-06-10T20:32:59+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>blees@dcon.de</email>
</author>
<published>2012-03-01T20:53:54+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=fcd428f4a952a19d7553a9447fd4fa3c3584c6e6'/>
<id>fcd428f4a952a19d7553a9447fd4fa3c3584c6e6</id>
<content type='text'>
As of "Win32: Thread-safe windows console output", git-log no longer
terminates when the pager process dies. This is due to disabling buffering
for the replaced stdout / stderr streams. Git-log will periodically fflush
stdout (see write_or_die.c/mayble_flush_or_die()), but with no buffering,
this is a NOP that always succeeds (so we never detect the EPIPE error).

Exchange the original console handles with our console thread pipe handles
by accessing the internal MSVCRT data structures directly (which are
exposed via __pioinfo for some reason).

Implement this with minimal assumptions about the actual data structure to
make it work with different (hopefully even future) MSVCRT versions.

While messing with internal data structures is ugly, this patch solves the
problem at the source instead of adding more workarounds. We no longer need
the special winansi_isatty override, and the limitations documented in
"Win32: Thread-safe windows console output" are gone (i.e. fdopen(1/2)
returns unbuffered streams now, and isatty() for duped console file
descriptors works as expected).

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As of "Win32: Thread-safe windows console output", git-log no longer
terminates when the pager process dies. This is due to disabling buffering
for the replaced stdout / stderr streams. Git-log will periodically fflush
stdout (see write_or_die.c/mayble_flush_or_die()), but with no buffering,
this is a NOP that always succeeds (so we never detect the EPIPE error).

Exchange the original console handles with our console thread pipe handles
by accessing the internal MSVCRT data structures directly (which are
exposed via __pioinfo for some reason).

Implement this with minimal assumptions about the actual data structure to
make it work with different (hopefully even future) MSVCRT versions.

While messing with internal data structures is ugly, this patch solves the
problem at the source instead of adding more workarounds. We no longer need
the special winansi_isatty override, and the limitations documented in
"Win32: Thread-safe windows console output" are gone (i.e. fdopen(1/2)
returns unbuffered streams now, and isatty() for duped console file
descriptors works as expected).

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Win32: Thread-safe windows console output</title>
<updated>2014-06-10T20:32:59+00:00</updated>
<author>
<name>Karsten Blees</name>
<email>blees@dcon.de</email>
</author>
<published>2012-01-14T21:24:19+00:00</published>
<link rel='alternate' type='text/html' href='http://91.123.203.49/cgit/delta/git.git/commit/?id=eac14f8909d986a38d9eab4a7f926af41dd64a4f'/>
<id>eac14f8909d986a38d9eab4a7f926af41dd64a4f</id>
<content type='text'>
Winansi.c has many static variables that are accessed and modified from
the [v][f]printf / fputs functions overridden in the file. This may cause
multi threaded git commands that print to the console to produce corrupted
output or even crash.

Additionally, winansi.c doesn't override all functions that can be used to
print to the console (e.g. fwrite, write, fputc are missing), so that ANSI
escapes don't work properly for some git commands (e.g. git-grep).

Instead of doing ANSI emulation in just a few wrapped functions on top of
the IO API, let's plug into the IO system and take advantage of the thread
safety inherent to the IO system.

Redirect stdout and stderr to a pipe if they point to the console. A
background thread reads from the pipe, handles ANSI escape sequences and
UTF-8 to UTF-16 conversion, then writes to the console.

The pipe-based stdout and stderr replacements must be set to unbuffered, as
MSVCRT doesn't support line buffering and fully buffered streams are
inappropriate for console output.

Due to the byte-oriented pipe, ANSI escape sequences and multi-byte UTF-8
sequences can no longer be expected to arrive in one piece. Replace the
string-based ansi_emulate() with a simple stateful parser (this also fixes
colored diff hunk headers, which were broken as of commit 2efcc977).

Override isatty to return true for the pipes redirecting to the console.

Exec/spawn obtain the original console handle to pass to the next process
via winansi_get_osfhandle().

All other overrides are gone, the default stdio implementations work as
expected with the piped stdout/stderr descriptors.

Global variables are either initialized on startup (single threaded) or
exclusively modified by the background thread. Threads communicate through
the pipe, no further synchronization is necessary.

The background thread is terminated by disonnecting the pipe after flushing
the stdio and pipe buffers. This doesn't work for anonymous pipes (created
via CreatePipe), as DisconnectNamedPipe only works on the read end, which
discards remaining data. Thus we have to setup the pipe manually, with the
write end beeing the server (opened with CreateNamedPipe) and the read end
the client (opened with CreateFile).

Limitations: doesn't track reopened or duped file descriptors, i.e.:
- fdopen(1/2) returns fully buffered streams
- dup(1/2), dup2(1/2) returns normal pipe descriptors (i.e. isatty() =
  false, winansi_get_osfhandle won't return the original console handle)

Currently, only the git-format-patch command uses xfdopen(xdup(1)) (see
"realstdout" in builtin/log.c), but works well with these limitations.

Many thanks to Atsushi Nakagawa &lt;atnak@chejz.com&gt; for suggesting and
reviewing the thread-exit-mechanism.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Winansi.c has many static variables that are accessed and modified from
the [v][f]printf / fputs functions overridden in the file. This may cause
multi threaded git commands that print to the console to produce corrupted
output or even crash.

Additionally, winansi.c doesn't override all functions that can be used to
print to the console (e.g. fwrite, write, fputc are missing), so that ANSI
escapes don't work properly for some git commands (e.g. git-grep).

Instead of doing ANSI emulation in just a few wrapped functions on top of
the IO API, let's plug into the IO system and take advantage of the thread
safety inherent to the IO system.

Redirect stdout and stderr to a pipe if they point to the console. A
background thread reads from the pipe, handles ANSI escape sequences and
UTF-8 to UTF-16 conversion, then writes to the console.

The pipe-based stdout and stderr replacements must be set to unbuffered, as
MSVCRT doesn't support line buffering and fully buffered streams are
inappropriate for console output.

Due to the byte-oriented pipe, ANSI escape sequences and multi-byte UTF-8
sequences can no longer be expected to arrive in one piece. Replace the
string-based ansi_emulate() with a simple stateful parser (this also fixes
colored diff hunk headers, which were broken as of commit 2efcc977).

Override isatty to return true for the pipes redirecting to the console.

Exec/spawn obtain the original console handle to pass to the next process
via winansi_get_osfhandle().

All other overrides are gone, the default stdio implementations work as
expected with the piped stdout/stderr descriptors.

Global variables are either initialized on startup (single threaded) or
exclusively modified by the background thread. Threads communicate through
the pipe, no further synchronization is necessary.

The background thread is terminated by disonnecting the pipe after flushing
the stdio and pipe buffers. This doesn't work for anonymous pipes (created
via CreatePipe), as DisconnectNamedPipe only works on the read end, which
discards remaining data. Thus we have to setup the pipe manually, with the
write end beeing the server (opened with CreateNamedPipe) and the read end
the client (opened with CreateFile).

Limitations: doesn't track reopened or duped file descriptors, i.e.:
- fdopen(1/2) returns fully buffered streams
- dup(1/2), dup2(1/2) returns normal pipe descriptors (i.e. isatty() =
  false, winansi_get_osfhandle won't return the original console handle)

Currently, only the git-format-patch command uses xfdopen(xdup(1)) (see
"realstdout" in builtin/log.c), but works well with these limitations.

Many thanks to Atsushi Nakagawa &lt;atnak@chejz.com&gt; for suggesting and
reviewing the thread-exit-mechanism.

Signed-off-by: Karsten Blees &lt;blees@dcon.de&gt;
Signed-off-by: Stepan Kasal &lt;kasal@ucw.cz&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</pre>
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