113 lines
2.9 KiB
C++
113 lines
2.9 KiB
C++
/* init.cc
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Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Red Hat, Inc.
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This file is part of Cygwin.
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This software is a copyrighted work licensed under the terms of the
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Cygwin license. Please consult the file "CYGWIN_LICENSE" for
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details. */
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#include "winsup.h"
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#include <stdlib.h>
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#include "thread.h"
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#include "perprocess.h"
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#include "cygthread.h"
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#include "cygtls.h"
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int NO_COPY dynamically_loaded;
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static char *search_for = (char *) cygthread::stub;
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static unsigned threadfunc_ix __attribute__((section ("cygwin_dll_common"), shared)) = 0;
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DWORD tls_func;
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HANDLE sync_startup;
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#define OLDFUNC_OFFSET -1
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static void WINAPI
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threadfunc_fe (VOID *arg)
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{
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_cygtls::call ((DWORD (*) (void *, void *)) (((char **) _tlsbase)[OLDFUNC_OFFSET]), arg);
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}
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static DWORD WINAPI
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calibration_thread (VOID *arg)
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{
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ExitThread (0);
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}
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/* We need to know where the OS stores the address of the thread function
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on the stack so that we can intercept the call and insert some tls
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stuff on the stack. This function starts a known calibration thread.
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When it starts, a call will be made to dll_entry which will call munge_threadfunc
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looking for the calibration thread offset on the stack. This offset will
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be stored and used by all executing cygwin processes. */
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void
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prime_threads ()
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{
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if (!threadfunc_ix)
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{
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DWORD id;
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search_for = (char *) calibration_thread;
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sync_startup = CreateThread (NULL, 0, calibration_thread, 0, 0, &id);
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}
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}
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/* If possible, redirect the thread entry point to a cygwin routine which
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adds tls stuff to the stack. */
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static void
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munge_threadfunc ()
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{
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char **ebp = (char **) __builtin_frame_address (0);
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if (!threadfunc_ix)
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{
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for (char **peb = ebp; peb < (char **) _tlsbase; peb++)
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if (*peb == search_for)
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{
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threadfunc_ix = peb - ebp;
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goto foundit;
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}
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#ifdef DEBUGGING_HARD
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system_printf ("non-fatal warning: unknown thread! search_for %p, cygthread::stub %p, calibration_thread %p, possible func offset %p",
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search_for, cygthread::stub, calibration_thread, ebp[137]);
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#endif
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try_to_debug ();
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return;
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}
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foundit:
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char *threadfunc = ebp[threadfunc_ix];
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if (threadfunc == (char *) calibration_thread)
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/* no need for the overhead */;
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else
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{
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ebp[threadfunc_ix] = (char *) threadfunc_fe;
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((char **) _tlsbase)[OLDFUNC_OFFSET] = threadfunc;
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// TlsSetValue (tls_func, (void *) threadfunc);
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}
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}
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extern void __stdcall dll_crt0_0 ();
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extern "C" int WINAPI
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dll_entry (HANDLE h, DWORD reason, void *static_load)
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{
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switch (reason)
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{
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case DLL_PROCESS_ATTACH:
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prime_threads ();
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dynamically_loaded = (static_load == NULL);
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dll_crt0_0 ();
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break;
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case DLL_PROCESS_DETACH:
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break;
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case DLL_THREAD_ATTACH:
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munge_threadfunc ();
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break;
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case DLL_THREAD_DETACH:
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_my_tls.remove (0);
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break;
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}
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return 1;
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}
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