kernel32: Add a special case to EnumProcessModules for the local process.

LLVM's libunwind uses EnumProcessModules for locating .eh_frame sections when unwinding dwarf exceptions (used on i686). When running wine in docker (without adding custom additional permissions), EnumProcessModules currently fails as it uses ReadProcessMemory, which requires the SYS_PTRACE capability. The current implementation also is slower than necessary (by a couple orders of magnituide), for accessing the current process. Currently, unwinding 10000 exception throws with libunwind on i686 takes 24 seconds when run in wine, while it runs in less than 0.1 second with this patch. Signed-off-by: Martin Storsjo <martin@martin.st> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

kernel32: Add a special case to EnumProcessModules for the local process.
fbda8db3 · Martin Storsjo · Alexandre Julliard · fef1d403 · fbda8db3
Commit fbda8db3 authored Oct 30, 2019 by Martin Storsjo Committed by Alexandre Julliard Nov 04, 2019
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module.c dlls/kernel32/module.c +34 -0

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--- a/dlls/kernel32/module.c
+++ b/dlls/kernel32/module.c
@@ -555,6 +555,40 @@ BOOL WINAPI K32EnumProcessModules(HANDLE process, HMODULE *lphModule,
    DWORD size = 0;
    INT ret;

+    if (process == GetCurrentProcess())
+    {
+        PPEB_LDR_DATA ldr_data = NtCurrentTeb()->Peb->LdrData;
+        PLIST_ENTRY head = &ldr_data->InLoadOrderModuleList;
+        PLIST_ENTRY entry = head->Flink;
+
+        if (cb && !lphModule)
+        {
+            SetLastError(ERROR_NOACCESS);
+            return FALSE;
+        }
+        while (entry != head)
+        {
+            PLDR_MODULE table_entry = (PLDR_MODULE)
+                ((PBYTE)entry - offsetof(LDR_MODULE, InLoadOrderModuleList));
+            if (cb >= sizeof(HMODULE))
+            {
+                *lphModule++ = table_entry->BaseAddress;
+                cb -= sizeof(HMODULE);
+            }
+            size += sizeof(HMODULE);
+            entry = entry->Flink;
+        }
+
+        if (!needed)
+        {
+            SetLastError(ERROR_NOACCESS);
+            return FALSE;
+        }
+        *needed = size;
+
+        return TRUE;
+    }
+
    if (!init_module_iterator(&iter, process))
        return FALSE;