diff options
Diffstat (limited to 'winsup/cygwin/dll_init.cc')
| -rw-r--r-- | winsup/cygwin/dll_init.cc | 72 |
1 files changed, 61 insertions, 11 deletions
diff --git a/winsup/cygwin/dll_init.cc b/winsup/cygwin/dll_init.cc index 122055722..5ee2f0036 100644 --- a/winsup/cygwin/dll_init.cc +++ b/winsup/cygwin/dll_init.cc @@ -78,7 +78,7 @@ dll::init () /* This should be a no-op. Why didn't we just import this variable? */ if (!p.envptr) p.envptr = &__cygwin_environ; - else + else if (*(p.envptr) != __cygwin_environ) *(p.envptr) = __cygwin_environ; /* Don't run constructors or the "main" if we've forked. */ @@ -257,12 +257,44 @@ release_upto (const PWCHAR name, DWORD here) } } +/* Mark one page at "here" as reserved. This may force + Windows NT to load a DLL elsewhere. */ +static DWORD +reserve_at (const PWCHAR name, DWORD here) +{ + DWORD size; + MEMORY_BASIC_INFORMATION mb; + + if (!VirtualQuery ((void *) here, &mb, sizeof (mb))) + size = 64 * 1024; + + if (mb.State != MEM_FREE) + return 0; + + size = mb.RegionSize; + if (!VirtualAlloc ((void *) here, size, MEM_RESERVE, PAGE_NOACCESS)) + api_fatal ("couldn't allocate memory %p(%d) for '%W' alignment, %E\n", + here, size, name); + return here; +} + +/* Release the memory previously allocated by "reserve_at" above. */ +static void +release_at (const PWCHAR name, DWORD here) +{ + if (!VirtualFree ((void *) here, 0, MEM_RELEASE)) + api_fatal ("couldn't release memory %p for '%W' alignment, %E\n", + here, name); +} + /* Reload DLLs after a fork. Iterates over the list of dynamically loaded DLLs and attempts to load them in the same place as they were loaded in the parent. */ void dll_list::load_after_fork (HANDLE parent) { + DWORD preferred_block = 0; + for (dll *d = &dlls.start; (d = d->next) != NULL; ) if (d->type == DLL_LOAD) for (int i = 0; i < 2; i++) @@ -284,10 +316,18 @@ dll_list::load_after_fork (HANDLE parent) if (h == d->handle) h = LoadLibraryW (d->name); } + /* If we reached here on the second iteration of the for loop then there is a lot of memory to release. */ if (i > 0) - release_upto (d->name, (DWORD) d->handle); + { + release_upto (d->name, (DWORD) d->handle); + + if (preferred_block) + release_at (d->name, preferred_block); + preferred_block = 0; + } + if (h == d->handle) break; /* Success */ @@ -297,11 +337,20 @@ dll_list::load_after_fork (HANDLE parent) d->name, d->handle, h); /* Dll loaded in the wrong place. Dunno why this happens but it - always seems to happen when there are multiple DLLs attempting to - load into the same address space. In the "forked" process, the - second DLL always loads into a different location. So, block all - of the memory up to the new load address and try again. */ + always seems to happen when there are multiple DLLs with the + same base address. In the "forked" process, the relocated DLL + may load at a different address. So, block all of the memory up + to the relocated load address and try again. */ reserve_upto (d->name, (DWORD) d->handle); + + /* Also, if the DLL loaded at a higher address than wanted (probably + it's base address), reserve the memory at that address. This can + happen if it couldn't load at the preferred base in the parent, but + can in the child, due to differences in the load ordering. + Block memory at it's preferred address and try again. */ + if ((DWORD) h > (DWORD) d->handle) + preferred_block = reserve_at (d->name, (DWORD) h); + } in_forkee = false; } @@ -311,7 +360,7 @@ struct dllcrt0_info HMODULE h; per_process *p; int res; - dllcrt0_info (HMODULE h0, per_process *p0): h(h0), p(p0) {} + dllcrt0_info (HMODULE h0, per_process *p0): h (h0), p (p0) {} }; extern "C" int @@ -329,9 +378,9 @@ dll_dllcrt0 (HMODULE h, per_process *p) void dll_dllcrt0_1 (VOID *x) { - HMODULE& h = ((dllcrt0_info *)x)->h; - per_process*& p = ((dllcrt0_info *)x)->p; - int& res = ((dllcrt0_info *)x)->res; + HMODULE& h = ((dllcrt0_info *) x)->h; + per_process*& p = ((dllcrt0_info *) x)->p; + int& res = ((dllcrt0_info *) x)->res; if (p == NULL) p = &__cygwin_user_data; @@ -431,6 +480,7 @@ void __stdcall update_envptrs () { for (dll *d = dlls.istart (DLL_ANY); d; d = dlls.inext ()) - *(d->p.envptr) = __cygwin_environ; + if (*(d->p.envptr) != __cygwin_environ) + *(d->p.envptr) = __cygwin_environ; *main_environ = __cygwin_environ; } |