From a4222dbca4d1974f246f688d5f780a1d5f22c51a Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Mon, 30 Jan 2023 23:22:22 +0100 Subject: [PATCH] Avoid sharing cygheaps across Cygwin versions It frequently leads to problems when trying, say, to call from MSYS2's Bash into Cygwin's or Git for Windows', merely because sharing that data is pretty finicky. For example, using the MSYS2' Bash using the MSYS2 runtime version that is current at time of writing, trying to call Cygwin's programs fails in manners like this: $ /c/cygwin64/bin/uname -r 0 [main] uname (9540) child_copy: cygheap read copy failed, 0x800000000..0x800010BE0, done 0, windows pid 9540, Win32 error 6 680 [main] uname 880 C:\cygwin64\bin\uname.exe: *** fatal error - couldn't create signal pipe, Win32 error 5 with the rather misleading exit code 127 (a code which is reserved to indicate that a command was not found). Let's just treat the MSYS2 runtime and the Cygwin runtime as completely incompatible with one another, by virtue of using a different magic constant than merely `CHILD_INFO_MAGIC`. By using the msys2-runtime commit to modify that magic constant, we can even spawn programs using a different MSYS2 runtime (such as Git for Windows') because the commit serves 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. 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 to encode brackets in `configure.ac` files 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 59b77fe3ed..368a1dbd91 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, [AS_HELP_STRING([--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 ec782dc6b9..038ae5a824 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 a5b82b0e01..db79042c8c 100644 --- a/winsup/cygwin/dcrt0.cc +++ b/winsup/cygwin/dcrt0.cc @@ -530,7 +530,7 @@ 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) + || 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 fd3291c1bc..3d3f38fef9 100644 --- a/winsup/cygwin/sigproc.cc +++ b/winsup/cygwin/sigproc.cc @@ -811,7 +811,7 @@ int child_info::retry_count = 0; child_info::child_info (unsigned in_cb, child_info_types chtype, bool need_subproc_ready): msv_count (0), cb (in_cb), intro (PROC_MAGIC_GENERIC), - magic (CHILD_INFO_MAGIC), type (chtype), cygheap (::cygheap), + 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) {