[PATCH] Do not adjust mtime timezone on Windows

[Joel Brobecker]

Hi Tom,

On Thu, Sep 03, 2020 at 11:02:44AM -0600, Tom Tromey wrote:
> PR win32/25302 notes that gdb will crash when trying to "run" even a
> simple program on Windows.  The essential bug here is that the BFD
> cache can easily be corrupted -- I have sent a separate patch for
> that.
> 
> The particular reason that the cache is corrupted on Windows is that
> gnulib overrides "stat" to make it do timezone adjustment -- but BFD
> does not use this version of stat.  The difference here triggers the
> latent cache bug, but can also cause other bugs as well; in particular
> it can cause spurious warnings about source files being newer.
> 
> This patch simply removes the stat override on mingw, making gnulib
> and BFD agree.
> 
> I tested this by backing out the local AdaCore changes to work around
> this bug and then verifying that I could reproduce it.  Then, I
> applied this patch and verified that "run" works again.
> 
> gnulib/ChangeLog
> 2020-09-03  Tom Tromey  <tromey@adacore.com>
> 
> 	PR win32/25302:
> 	* update-gnulib.sh: Apply stat patch.
> 	* patches/0001-use-windows-stat: New file.
> 	* import/m4/stat.m4: Update.
> 	* configure: Rebuild.

Thanks for helping us with this patch.

This looks good to me. We will want this patch in before
we create the gdb-10-branch, but let's give people a few
more days to comment if they'd like -- let's say, if by
Thursday, we haven't received comments, then we push it.

Thanks again!


> ---
>  gnulib/ChangeLog                     |  8 ++++++++
>  gnulib/configure                     |  3 +--
>  gnulib/import/m4/stat.m4             |  2 +-
>  gnulib/patches/0001-use-windows-stat | 13 +++++++++++++
>  gnulib/update-gnulib.sh              |  2 ++
>  5 files changed, 25 insertions(+), 3 deletions(-)
>  create mode 100644 gnulib/patches/0001-use-windows-stat
> 
> diff --git a/gnulib/configure b/gnulib/configure
> index fa2feb5ea9a..5c6add6e371 100644
> --- a/gnulib/configure
> +++ b/gnulib/configure
> @@ -26907,8 +26907,7 @@ $as_echo "#define ssize_t int" >>confdefs.h
>  
>    case "$host_os" in
>      mingw*)
> -                  REPLACE_STAT=1
> -      ;;
> +                        ;;
>      *)
>                          { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether stat handles trailing slashes on files" >&5
>  $as_echo_n "checking whether stat handles trailing slashes on files... " >&6; }
> diff --git a/gnulib/import/m4/stat.m4 b/gnulib/import/m4/stat.m4
> index 46e9abceee7..8ef355f9407 100644
> --- a/gnulib/import/m4/stat.m4
> +++ b/gnulib/import/m4/stat.m4
> @@ -15,7 +15,7 @@ AC_DEFUN([gl_FUNC_STAT],
>      mingw*)
>        dnl On this platform, the original stat() returns st_atime, st_mtime,
>        dnl st_ctime values that are affected by the time zone.
> -      REPLACE_STAT=1
> +      dnl REPLACE_STAT=1
>        ;;
>      *)
>        dnl AIX 7.1, Solaris 9, mingw64 mistakenly succeed on stat("file/").
> diff --git a/gnulib/patches/0001-use-windows-stat b/gnulib/patches/0001-use-windows-stat
> new file mode 100644
> index 00000000000..adf9638858d
> --- /dev/null
> +++ b/gnulib/patches/0001-use-windows-stat
> @@ -0,0 +1,13 @@
> +diff --git a/gnulib/import/m4/stat.m4 b/gnulib/import/m4/stat.m4
> +index 46e9abceee7..8ef355f9407 100644
> +--- a/gnulib/import/m4/stat.m4
> ++++ b/gnulib/import/m4/stat.m4
> +@@ -15,7 +15,7 @@ AC_DEFUN([gl_FUNC_STAT],
> +     mingw*)
> +       dnl On this platform, the original stat() returns st_atime, st_mtime,
> +       dnl st_ctime values that are affected by the time zone.
> +-      REPLACE_STAT=1
> ++      dnl REPLACE_STAT=1
> +       ;;
> +     *)
> +       dnl AIX 7.1, Solaris 9, mingw64 mistakenly succeed on stat("file/").
> diff --git a/gnulib/update-gnulib.sh b/gnulib/update-gnulib.sh
> index b9cc7d8f353..ac5e3d56a29 100755
> --- a/gnulib/update-gnulib.sh
> +++ b/gnulib/update-gnulib.sh
> @@ -173,6 +173,8 @@ apply_patches ()
>      fi
>  }
>  
> +apply_patches "patches/0001-use-windows-stat"
> +
>  # Regenerate all necessary files...
>  aclocal &&
>  autoconf &&
> -- 
> 2.26.2

-- 
Joel