[PATCH v2 0/3] Really fix the isatty() problem on Windows

My previous fix may have fixed running the new t/t6030-bisect-porcelain.sh script that tested the new bisect--helper, which in turn used isatty() to determine whether it was running interactively and was fooled by being redirected to /dev/null.

But it not only broke paging when running in a CMD window, due to testing in the wrong worktree I also missed that it broke paging in Git for Windows 2.x' Git Bash (i.e. a MinTTY terminal emulator).

Let's use this opportunity to actually clean up the entire isatty() mess once and for all, as part of the problem was introduced by a clever hack that messes with internals of the Microsoft C runtime, and which changed recently, so it was not such a clever hack to begin with.

Happily, one of my colleagues had to address that latter problem recently when he was tasked to make Git compile with Microsoft Visual C (the rationale: debugging facilities of Visual Studio are really outstanding, try them if you get a chance).

And incidentally, replacing the previous hack with the clean, new solution, which specifies explicitly for the file descriptors 0, 1 and 2 whether we detected an MSYS2 pseudo-tty, whether we detected a real Win32 Console, and whether we had to swap out a real Win32 Console for a pipe to allow child processes to inherit it.

While at it (or, actually, more like: as I already made this part of v1 by mistake), upstream the patch carried in Git for Windows that supports color when running Git for Windows in Cygwin terminals.

Changes since v1:

- rebased onto master

- unsquashed 2/3 which was improperly snuck in before,

- noted that Beat Bolli tested this (see
  https://github.com/git-for-windows/git/issues/997#issuecomment-268764693)

- fixed the confusing commit message by using Junio's suggested
  replacement

- added the missing white space between ">=" and "0"

Alan Davies (1):
  mingw: fix colourization on Cygwin pseudo terminals

Jeff Hostetler (1):
  mingw: replace isatty() hack

Johannes Schindelin (1):
  mingw: adjust is_console() to work with stdin

 compat/winansi.c | 198 +++++++++++++++++++++++--------------------------------
 1 file changed, 84 insertions(+), 114 deletions(-)

base-commit: 1d1bdafd64266e5ee3bd46c6965228f32e4022ea
Published-As: https://github.com/dscho/git/releases/tag/mingw-isatty-fixup-v2
Fetch-It-Via: git fetch https://github.com/dscho/git mingw-isatty-fixup-v2

Interdiff vs v1:

 diff --git a/compat/winansi.c b/compat/winansi.c
 index f51a2856d2..477209fce7 100644
 --- a/compat/winansi.c
 +++ b/compat/winansi.c
 @@ -108,7 +108,7 @@ static int is_console(int fd)
  	} else if (!GetConsoleScreenBufferInfo(hcon, &sbi))
  		return 0;
  
 -	if (fd >=0 && fd <= 2)
 +	if (fd >= 0 && fd <= 2)
  		fd_is_interactive[fd] |= FD_CONSOLE;
  
  	/* initialize attributes */
 @@ -555,7 +555,8 @@ static void detect_msys_tty(int fd)
  
  #endif
  
 -/* Wrapper for isatty().  Most calls in the main git code
 +/*
 + * Wrapper for isatty().  Most calls in the main git code
   * call isatty(1 or 2) to see if the instance is interactive
   * and should: be colored, show progress, paginate output.
   * We lie and give results for what the descriptor WAS at
 @@ -565,7 +566,7 @@ static void detect_msys_tty(int fd)
  #undef isatty
  int winansi_isatty(int fd)
  {
 -	if (fd >=0 && fd <= 2)
 +	if (fd >= 0 && fd <= 2)
  		return fd_is_interactive[fd] != 0;
  	return isatty(fd);
  }