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-rw-r--r--libbutl/buildfile4
-rw-r--r--libbutl/process.cxx172
2 files changed, 121 insertions, 55 deletions
diff --git a/libbutl/buildfile b/libbutl/buildfile
index a55311c..e860638 100644
--- a/libbutl/buildfile
+++ b/libbutl/buildfile
@@ -80,9 +80,9 @@ libs{butl}: cxx.export.poptions += -DLIBBUTL_SHARED
if ($cxx.target.class == "windows")
{
if ($cxx.target.system == "mingw32")
- cxx.libs += -lpsapi
+ cxx.libs += -limagehlp
else
- cxx.libs += psapi.lib
+ cxx.libs += imagehlp.lib
}
else
cxx.libs += -lpthread
diff --git a/libbutl/process.cxx b/libbutl/process.cxx
index 49e11bb..641866e 100644
--- a/libbutl/process.cxx
+++ b/libbutl/process.cxx
@@ -13,7 +13,7 @@
#else
# include <libbutl/win32-utility.hxx>
-# include <psapi.h> // EnumProcessModules(), etc
+# include "imagehlp.h" // ImageLoad(), etc (PE insepction for MSYS2 detect).
# include <io.h> // _get_osfhandle(), _close()
# include <stdlib.h> // _MAX_PATH
@@ -28,6 +28,7 @@
# define STDERR_FILENO 2
# endif // _MSC_VER
+# include <map>
# include <cstdlib> // getenv(), __argv[]
# include <libbutl/small-vector.hxx>
@@ -906,6 +907,10 @@ namespace butl
small_vector<HANDLE, 3> handles_;
};
+ // Protected by process_spawn_mutex. See below for the gory details.
+ //
+ static map<string, bool> detect_msys_cache_;
+
process::
process (const char* cwd,
const process_path& pp, const char* args[],
@@ -1166,14 +1171,111 @@ namespace butl
// some time.
//
// One way to improve this implementation is to only do it for MSYS2-
- // based programs by checking (using EnumProcessModules()) if the
- // process loaded the msys-2.0.dll. With this improvement we can then
- // wait longer and try harder.
+ // based programs. This way we can then wait longer and try harder. We
+ // first used EnumProcessModules() to see if the process loaded the
+ // msys-2.0.dll but that proved racy. Now we examine the PE executable's
+ // import list.
//
- optional<bool>& msys = msys_; // Absent if we don't know.
- msys = nullopt;
- for (size_t ret (0); ret != (msys ? 40 : 20); ++ret)
+ // Notes:
+ //
+ // 1. The ImageLoad() API is not thread-safe so we do this while holding
+ // process_spawn_mutex.
+ //
+ // 2. We can only load an image of the same width as us (32/64-bit).
+ //
+ // 3. If something goes wrong (width mismatch, failed to load, etc),
+ // then we assume it is MSYS for safety. Better run slow than not run
+ // at all, right?
+ //
+ auto detect_msys = [] (const char* p) -> bool
+ {
+ auto deleter = [] (LOADED_IMAGE* p)
+ {
+ if (p != nullptr)
+ ImageUnload (p);
+ };
+
+ unique_ptr<LOADED_IMAGE, void (*)(LOADED_IMAGE*)> img (
+ ImageLoad (p, nullptr), deleter);
+
+ if (img == nullptr)
+ return true;
+
+ if (img->FileHeader->OptionalHeader.NumberOfRvaAndSizes < 2)
+ return false;
+
+ auto rva_to_ptr = [&img] (DWORD rva) -> const void*
+ {
+ const IMAGE_NT_HEADERS* nh (img->FileHeader);
+ const BYTE* base (img->MappedAddress);
+
+ auto rva_to_sh = [nh] (DWORD rva) -> const IMAGE_SECTION_HEADER*
+ {
+ const IMAGE_SECTION_HEADER* s (IMAGE_FIRST_SECTION (nh));
+
+ for (WORD i (0); i < nh->FileHeader.NumberOfSections; ++i, ++s)
+ {
+ DWORD v (s->Misc.VirtualSize);
+ if (v == 0)
+ v = s->SizeOfRawData;
+
+ // Is the RVA within this section?
+ //
+ if (rva >= s->VirtualAddress && rva < s->VirtualAddress + v)
+ return s;
+ }
+
+ return nullptr;
+ };
+
+ if (const IMAGE_SECTION_HEADER* sh = rva_to_sh (rva))
+ {
+ ptrdiff_t o (sh->VirtualAddress - sh->PointerToRawData);
+ return base - o + rva;
+ }
+ else
+ return nullptr;
+ };
+
+ auto imp (
+ static_cast<const IMAGE_IMPORT_DESCRIPTOR*> (
+ rva_to_ptr (
+ img->FileHeader->OptionalHeader.DataDirectory[1].VirtualAddress)));
+
+ if (imp == nullptr)
+ return true;
+
+ for (; imp->Name != 0 || imp->TimeDateStamp != 0; ++imp)
+ {
+ if (auto name = static_cast<const char*> (rva_to_ptr (imp->Name)))
+ {
+ if (casecmp (name, "msys-2.0.dll") == 0)
+ return true;
+ }
+ }
+
+ return false;
+ };
+
+ bool msys (false);
+ if (batch == nullptr)
+ {
+ string p (pp.effect_string ());
+ auto i (detect_msys_cache_.find (p));
+
+ if (i == detect_msys_cache_.end ())
+ {
+ msys = detect_msys (p.c_str ());
+ detect_msys_cache_.emplace (move (p), msys);
+ }
+ else
+ msys = i->second;
+ }
+
+ msys_ = msys; //@@ TMP
+
+ for (size_t ret (0); ret != 40; ++ret)
{
if (!CreateProcess (
batch != nullptr ? batch : pp.effect_string (),
@@ -1190,56 +1292,20 @@ namespace butl
auto_handle (pi.hThread).reset (); // Close.
- // Detect if this is an MSYS2 process by checking if the process has
- // loaded msys-2.0.dll.
- //
- DWORD wait (300);
-
- if (!msys)
+ if (msys)
{
- // Wait a bit for the process to load its DLLs.
+ // Wait a bit and check if the process has terminated. If it is
+ // still running then we assume all is good. Otherwise, retry if
+ // this is the DLL initialization error.
//
- if (WaitForSingleObject (pi.hProcess, 100) == WAIT_TIMEOUT)
- {
- wait -= 100;
-
- DWORD mn;
- HMODULE ms[32]; // Normally it is one of the first.
-
- if (EnumProcessModules (pi.hProcess, ms, sizeof (ms), &mn))
- {
- for (DWORD i (0); !msys && i != mn / sizeof (HMODULE); ++i)
- {
- char p[_MAX_PATH + 1];
- if (GetModuleFileNameExA (pi.hProcess, ms[i], p, sizeof (p)))
- {
- size_t n (strlen (p));
- if (n >= 12 && casecmp (p + n - 12, "msys-2.0.dll") == 0)
- msys = true;
- }
- }
-
- if (!msys)
- msys = false;
- }
- // EnumProcessModules() failed (presumably because the process has
- // already exited), fall through.
- }
- // Process exited, fall through.
+ DWORD s;
+ if (WaitForSingleObject (pi.hProcess, 250) == WAIT_OBJECT_0 &&
+ GetExitCodeProcess (pi.hProcess, &s) &&
+ s == STATUS_DLL_INIT_FAILED)
+ continue;
}
- if (msys && !*msys)
- break;
-
- // Wait a bit longer and check if the process has terminated. If it is
- // still running then we assume all is good. Otherwise, retry if this
- // is the DLL initialization error.
- //
- DWORD s;
- if (WaitForSingleObject (pi.hProcess, wait) != WAIT_OBJECT_0 ||
- !GetExitCodeProcess (pi.hProcess, &s) ||
- s != STATUS_DLL_INIT_FAILED)
- break;
+ break;
}
} // Revert handles back to non-inheritable and release the lock.