From: Jeremy Drake <cyg...@jdrake.com>
This was already used in the FAST_CWD check, and could be used in a
couple other places.
I found the "emulated"/process value returned from the function largely
useless, so I did not cache it. It is useless because, as the docs say,
it is set to IMAGE_FILE_MACHINE_UNKNOWN (0) if the process is not
running under WOW64, but Microsoft also doesn't consider x64-on-ARM64 to
be WOW64, so it is set to 0 regardless if the process is ARM64 or x64.
You can tell the difference via
GetProcessInformation(ProcessMachineTypeInfo), but for the current
process even that's overkill: what we really want to know is the
IMAGE_FILE_MACHINE_* constant for the Cygwin dll itself, which is
conveniently located in memory already, so make an accessor function to
access that. (It could also be cached in a member variable for a
simpler accessor, and looked up in init).
Signed-off-by: Jeremy Drake <cyg...@jdrake.com>
---
v2: rename current_module_machine to cygwin_machine, adjust comment and
remove ifdefs from fallback case when IsWow64Process2 fails.
winsup/cygwin/local_includes/wincap.h | 3 +++
winsup/cygwin/path.cc | 6 ++----
winsup/cygwin/wincap.cc | 22 ++++++++++++++++++++++
3 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/winsup/cygwin/local_includes/wincap.h
b/winsup/cygwin/local_includes/wincap.h
index c14872787c..c4554b7a51 100644
--- a/winsup/cygwin/local_includes/wincap.h
+++ b/winsup/cygwin/local_includes/wincap.h
@@ -42,6 +42,7 @@ class wincapc
RTL_OSVERSIONINFOEXW version;
char osnam[40];
const void *caps;
+ USHORT host_mach;
bool _is_server;
public:
@@ -61,6 +62,8 @@ public:
{ return (size_t) system_info.dwAllocationGranularity; }
const char *osname () const { return osnam; }
const DWORD build_number () const { return version.dwBuildNumber; }
+ const USHORT host_machine () const { return host_mach; }
+ const USHORT cygwin_machine () const;
#define IMPLEMENT(cap) cap() const { return ((wincaps *) this->caps)->cap; }
diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 5cfcbc0f2f..869383c836 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -4617,14 +4617,12 @@ find_fast_cwd_pointer ()
static fcwd_access_t **
find_fast_cwd ()
{
- USHORT emulated, hosted;
fcwd_access_t **f_cwd_ptr;
- /* First check if we're running in WOW64 on ARM64 emulating AMD64. Skip
+ /* First check if we're running on an ARM64 system. Skip
fetching FAST_CWD pointer as long as there's no solution for finding
it on that system. */
- if (IsWow64Process2 (GetCurrentProcess (), &emulated, &hosted)
- && hosted == IMAGE_FILE_MACHINE_ARM64)
+ if (wincap.host_machine () == IMAGE_FILE_MACHINE_ARM64)
return NULL;
/* Fetch the pointer but don't set the global fast_cwd_ptr yet. First
diff --git a/winsup/cygwin/wincap.cc b/winsup/cygwin/wincap.cc
index 30d9c14e8d..5fd657487d 100644
--- a/winsup/cygwin/wincap.cc
+++ b/winsup/cygwin/wincap.cc
@@ -238,6 +238,8 @@ wincapc wincap __attribute__((section
(".cygwin_dll_common"), shared));
void
wincapc::init ()
{
+ USHORT emul_mach;
+
if (caps)
return; // already initialized
@@ -282,4 +284,24 @@ wincapc::init ()
__small_sprintf (osnam, "NT-%d.%d", version.dwMajorVersion,
version.dwMinorVersion);
+
+ if (!IsWow64Process2 (GetCurrentProcess (), &emul_mach, &host_mach))
+ {
+ /* If IsWow64Process2 succeeded, it filled in host_mach. Assume the only
+ way it fails for the current process is that we're running on an OS
+ version where it's not implemented yet. As such, the only realistic
+ option for host_mach is AMD64 */
+ host_mach = IMAGE_FILE_MACHINE_AMD64;
+ }
+}
+
+extern const IMAGE_DOS_HEADER
+dosheader __asm__ ("__image_base__");
+
+const USHORT
+wincapc::cygwin_machine () const
+{
+ PIMAGE_NT_HEADERS ntheader = (PIMAGE_NT_HEADERS)((LPBYTE) &dosheader
+ + dosheader.e_lfanew);
+ return ntheader->FileHeader.Machine;
}
--
2.47.0.windows.2
