From f5f594c2ff906aabdfb440d032687569231c5d98 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 21 Feb 2023 15:21:03 +0100 Subject: [PATCH] amend! Avoid sharing cygheaps across Cygwin versions Avoid sharing cygheaps across Cygwin versions It frequently leads to problems when trying, say, to call from Git for Windows' Bash into Cygwin's or MSYS2's, merely because sharing that data is pretty finicky. For example, using the Git for Windows that is current at time of writing, trying to call MSYS2's Bash from Git for Windows' Bash fails somewhere in `_cmalloc()`, without any error message, and with the rather misleading exit code 127 (a code which is reserved to indicate that a command was not found). Let's just treat these as completely incompatible with one another, by virtue of using a different `CHILD_INFO_MAGIC` constant. Let's take the msys2-runtime commit as the tell-tale whether two MSYS2 runtime versions are compatible with each other. To support building in the MSYS2-packages repository (where we do not check out the `msys2-runtime` but instead check out Cygwin and apply patches on top), let's accept a hard-coded commit hash as `./configure` option. One consequence is that spawned MSYS processes using a different MSYS2 runtime will not be visible as such to the parent process, i.e. they cannot share any resources such as pseudo terminals. But that's okay, they are simply treated as if they were regular Win32 programs. This should also help the scenario where interactions between two different versions of Git for Windows lead to those infamous `cygheap base mismatch detected` problems mentioned e.g. in https://github.com/git-for-windows/git/issues/4255 Note: We have to use a very rare form of encoding the brackets in the `expr` calls: quadrigraphs (for a thorough explanation, see https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.70/html_node/Quadrigraphs.html#Quadrigraphs). This is necessary because it is apparently impossible in `configure.ac` files to encode brackets otherwise. Signed-off-by: Johannes Schindelin --- winsup/configure.ac | 28 ++++++++++++++++++++++++++++ winsup/cygwin/Makefile.am | 3 +++ winsup/cygwin/dcrt0.cc | 2 +- winsup/cygwin/sigproc.cc | 2 +- 4 files changed, 33 insertions(+), 2 deletions(-) diff --git a/winsup/configure.ac b/winsup/configure.ac index ca2b8c0748..cfb0bbf279 100644 --- a/winsup/configure.ac +++ b/winsup/configure.ac @@ -57,6 +57,34 @@ AC_CHECK_TOOL(RANLIB, ranlib, ranlib) AC_CHECK_TOOL(STRIP, strip, strip) AC_CHECK_TOOL(WINDRES, windres, windres) +# Record msys2-runtime commit +AC_ARG_WITH([msys2-runtime-commit], + [AS_HELP_STRING([--with-msys2-runtime-commit=COMMIT], + [indicate the msys2-runtime commit corresponding to this build])], + [MSYS2_RUNTIME_COMMIT=$withval], [MSYS2_RUNTIME_COMMIT=yes]) +case "$MSYS2_RUNTIME_COMMIT" in +no) + MSYS2_RUNTIME_COMMIT= + MSYS2_RUNTIME_COMMIT_HEX=0 + ;; +yes|auto) + if MSYS2_RUNTIME_COMMIT="$(git --git-dir="$srcdir/../.git" rev-parse HEAD)" + then + MSYS2_RUNTIME_COMMIT_HEX="0x$(expr "$MSYS2_RUNTIME_COMMIT" : '\(.\{,8\}\)')ull" + else + AC_MSG_WARN([Could not determine msys2-runtime commit"]) + MSYS2_RUNTIME_COMMIT= + MSYS2_RUNTIME_COMMIT_HEX=0 + fi + ;; +*) + expr "$MSYS2_RUNTIME_COMMIT" : '@<:@0-9a-f@:>@\{6,64\}$' || + AC_MSG_ERROR([Invalid commit name: "$MSYS2_RUNTIME_COMMIT"]) + MSYS2_RUNTIME_COMMIT_HEX="0x$(expr "$MSYS2_RUNTIME_COMMIT" : '\(.\{,8\}\)')ull" + ;; +esac +AC_SUBST(MSYS2_RUNTIME_COMMIT_HEX) + AC_ARG_ENABLE(debugging, [ --enable-debugging Build a cygwin DLL which has more consistency checking for debugging], [case "${enableval}" in diff --git a/winsup/cygwin/Makefile.am b/winsup/cygwin/Makefile.am index 01666e1cf4..695ebeb7c7 100644 --- a/winsup/cygwin/Makefile.am +++ b/winsup/cygwin/Makefile.am @@ -17,6 +17,9 @@ if TARGET_X86_64 COMMON_CFLAGS+=-mcmodel=small endif +VERSION_CFLAGS = -DMSYS2_RUNTIME_COMMIT_HEX="@MSYS2_RUNTIME_COMMIT_HEX@" +COMMON_CFLAGS += $(VERSION_CFLAGS) + AM_CFLAGS=$(cflags_common) $(COMMON_CFLAGS) AM_CXXFLAGS=$(cxxflags_common) $(COMMON_CFLAGS) -fno-threadsafe-statics diff --git a/winsup/cygwin/dcrt0.cc b/winsup/cygwin/dcrt0.cc index 45f3b0f905..d354eab7dc 100644 --- a/winsup/cygwin/dcrt0.cc +++ b/winsup/cygwin/dcrt0.cc @@ -545,7 +545,7 @@ get_cygwin_startup_info () child_info *res = (child_info *) si.lpReserved2; if (si.cbReserved2 < EXEC_MAGIC_SIZE || !res - || res->intro != PROC_MAGIC_GENERIC || res->magic != (CHILD_INFO_MAGIC ^ CYGWIN_VERSION_DLL_COMBINED)) + || res->intro != PROC_MAGIC_GENERIC || res->magic != (CHILD_INFO_MAGIC ^ MSYS2_RUNTIME_COMMIT_HEX)) { strace.activate (false); res = NULL; diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc index 65dc523ca5..782c0d97cd 100644 --- a/winsup/cygwin/sigproc.cc +++ b/winsup/cygwin/sigproc.cc @@ -817,7 +817,7 @@ int child_info::retry_count = 0; by fork/spawn/exec. */ child_info::child_info (unsigned in_cb, child_info_types chtype, bool need_subproc_ready): - cb (in_cb), intro (PROC_MAGIC_GENERIC), magic (CHILD_INFO_MAGIC ^ CYGWIN_VERSION_DLL_COMBINED), + cb (in_cb), intro (PROC_MAGIC_GENERIC), magic (CHILD_INFO_MAGIC ^ MSYS2_RUNTIME_COMMIT_HEX), type (chtype), cygheap (::cygheap), cygheap_max (::cygheap_max), flag (0), retry (child_info::retry_count), rd_proc_pipe (NULL), wr_proc_pipe (NULL), sigmask (_my_tls.sigmask)