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newlib/winsup/cygwin/dll_init.cc

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/* dll_init.cc
Copyright 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
2007, 2008, 2009, 2010, 2011 Red Hat, Inc.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#include "winsup.h"
#include "cygerrno.h"
#include "perprocess.h"
#include "sync.h"
#include "dll_init.h"
#include "environ.h"
#include "security.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include "pinfo.h"
#include "cygtls.h"
#include "exception.h"
#include <wchar.h>
#include <sys/reent.h>
#include <assert.h>
extern void __stdcall check_sanity_and_sync (per_process *);
dll_list dlls;
muto dll_list::protect;
static bool dll_global_dtors_recorded;
/* Run destructors for all DLLs on exit. */
void
dll_global_dtors ()
{
/* Don't attempt to call destructors if we're still in fork processing
since that likely means fork is failing and everything will not have been
set up. */
if (in_forkee)
return;
int recorded = dll_global_dtors_recorded;
dll_global_dtors_recorded = false;
if (recorded && dlls.start.next)
for (dll *d = dlls.end; d != &dlls.start; d = d->prev)
d->run_dtors ();
}
/* Run all constructors associated with a dll */
void
per_module::run_ctors ()
{
void (**pfunc)() = ctors;
/* Run ctors backwards, so skip the first entry and find how many
there are, then run them. */
if (pfunc)
{
int i;
for (i = 1; pfunc[i]; i++);
for (int j = i - 1; j > 0; j--)
(pfunc[j]) ();
}
}
/* Run all destructors associated with a dll */
void
per_module::run_dtors ()
{
void (**pfunc)() = dtors;
while (*++pfunc)
(*pfunc) ();
}
/* Initialize an individual DLL */
int
dll::init ()
{
int ret = 1;
/* This should be a no-op. Why didn't we just import this variable? */
if (!p.envptr)
p.envptr = &__cygwin_environ;
else if (*(p.envptr) != __cygwin_environ)
*(p.envptr) = __cygwin_environ;
/* Don't run constructors or the "main" if we've forked. */
if (!in_forkee)
{
/* global contructors */
p.run_ctors ();
/* entry point of dll (use main of per_process with null args...) */
if (p.main)
ret = p.main (0, 0, 0);
}
return ret;
}
/* Look for a dll based on name */
dll *
dll_list::operator[] (const PWCHAR name)
{
dll *d = &start;
while ((d = d->next) != NULL)
if (!wcscasecmp (name, d->name))
return d;
return NULL;
}
#define RETRIES 1000
/* Allocate space for a dll struct. */
dll *
dll_list::alloc (HINSTANCE h, per_process *p, dll_type type)
{
WCHAR name[NT_MAX_PATH];
DWORD namelen = GetModuleFileNameW (h, name, sizeof (name));
guard (true);
/* Already loaded? */
dll *d = dlls[name];
if (d)
{
if (!in_forkee)
d->count++; /* Yes. Bump the usage count. */
d->p = p;
}
else
{
/* FIXME: Change this to new at some point. */
d = (dll *) cmalloc (HEAP_2_DLL, sizeof (*d) + (namelen * sizeof (*name)));
/* Now we've allocated a block of information. Fill it in with the supplied
info about this DLL. */
d->count = 1;
wcscpy (d->name, name);
d->handle = h;
d->has_dtors = true;
d->p = p;
d->type = type;
if (end == NULL)
end = &start; /* Point to "end" of dll chain. */
end->next = d; /* Standard linked list stuff. */
d->next = NULL;
d->prev = end;
end = d;
tot++;
if (type == DLL_LOAD)
loaded_dlls++;
}
guard (false);
assert (p->envptr != NULL);
return d;
}
dll *
dll_list::find (void *retaddr)
{
MEMORY_BASIC_INFORMATION m;
if (!VirtualQuery (retaddr, &m, sizeof m))
return NULL;
HMODULE h = (HMODULE) m.AllocationBase;
dll *d = &start;
while ((d = d->next))
if (d->handle == h)
break;
return d;
}
/* Detach a DLL from the chain. */
void
dll_list::detach (void *retaddr)
{
dll *d;
/* Don't attempt to call destructors if we're still in fork processing
since that likely means fork is failing and everything will not have been
set up. */
if (!myself || in_forkee)
return;
guard (true);
if ((d = find (retaddr)))
{
if (d->count <= 0)
system_printf ("WARNING: trying to detach an already detached dll ...");
if (--d->count == 0)
{
/* Ensure our exception handler is enabled for destructors */
exception protect;
/* Call finalize function if we are not already exiting */
if (!exit_state)
__cxa_finalize (d);
d->run_dtors ();
d->prev->next = d->next;
if (d->next)
d->next->prev = d->prev;
if (d->type == DLL_LOAD)
loaded_dlls--;
if (end == d)
end = d->prev;
cfree (d);
}
}
guard (false);
}
/* Initialization for all linked DLLs, called by dll_crt0_1. */
void
dll_list::init ()
{
/* Walk the dll chain, initializing each dll */
dll *d = &start;
dll_global_dtors_recorded = d->next != NULL;
while ((d = d->next))
d->init ();
}
#define A64K (64 * 1024)
/* Mark every memory address up to "here" as reserved. This may force
Windows NT to load a DLL in the next available, lowest slot. */
static void
reserve_upto (const PWCHAR name, DWORD here)
{
DWORD size;
MEMORY_BASIC_INFORMATION mb;
for (DWORD start = 0x10000; start < here; start += size)
if (!VirtualQuery ((void *) start, &mb, sizeof (mb)))
size = A64K;
else
{
size = A64K * ((mb.RegionSize + A64K - 1) / A64K);
start = A64K * (((DWORD) mb.BaseAddress + A64K - 1) / A64K);
if (start + size > here)
size = here - start;
if (mb.State == MEM_FREE &&
!VirtualAlloc ((void *) start, size, MEM_RESERVE, PAGE_NOACCESS))
api_fatal ("couldn't allocate memory %p(%d) for '%W' alignment, %E\n",
start, size, name);
}
}
/* Release all of the memory previously allocated by "upto" above.
Note that this may also free otherwise reserved memory. If that becomes
a problem, we'll have to keep track of the memory that we reserve above. */
static void
release_upto (const PWCHAR name, DWORD here)
{
DWORD size;
MEMORY_BASIC_INFORMATION mb;
for (DWORD start = 0x10000; start < here; start += size)
if (!VirtualQuery ((void *) start, &mb, sizeof (mb)))
size = 64 * 1024;
else
{
size = mb.RegionSize;
if (!(mb.State == MEM_RESERVE && mb.AllocationProtect == PAGE_NOACCESS
&& (((void *) start < cygheap->user_heap.base
|| (void *) start > cygheap->user_heap.top)
&& ((void *) start < (void *) cygheap
|| (void *) start
> (void *) ((char *) cygheap + CYGHEAPSIZE)))))
continue;
if (!VirtualFree ((void *) start, 0, MEM_RELEASE))
api_fatal ("couldn't release memory %p(%d) for '%W' alignment, %E\n",
start, size, name);
}
}
/* 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++)
{
/* See if DLL will load in proper place. If so, free it and reload
it the right way.
It stinks that we can't invert the order of the initial LoadLibrary
and FreeLibrary since Microsoft documentation seems to imply that
should do what we want. However, once a library is loaded as
above, the second LoadLibrary will not execute its startup code
unless it is first unloaded. */
HMODULE h = LoadLibraryExW (d->name, NULL, DONT_RESOLVE_DLL_REFERENCES);
if (!h)
system_printf ("can't reload %W, %E", d->name);
else
{
FreeLibrary (h);
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);
if (preferred_block)
release_at (d->name, preferred_block);
preferred_block = 0;
}
if (h == d->handle)
break; /* Success */
if (i > 0)
/* We tried once to relocate the dll and it failed. */
api_fatal ("unable to remap %W to same address as parent: %p != %p",
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 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;
}
struct dllcrt0_info
{
HMODULE h;
per_process *p;
int res;
dllcrt0_info (HMODULE h0, per_process *p0): h (h0), p (p0) {}
};
extern "C" int
dll_dllcrt0 (HMODULE h, per_process *p)
{
dllcrt0_info x (h, p);
if (_my_tls.isinitialized ())
dll_dllcrt0_1 (&x);
else
_my_tls.call ((DWORD (*) (void *, void *)) dll_dllcrt0_1, &x);
return x.res;
}
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;
if (p == NULL)
p = &__cygwin_user_data;
else
{
*(p->impure_ptr_ptr) = __cygwin_user_data.impure_ptr;
_pei386_runtime_relocator (p);
}
bool linked = !in_forkee && !cygwin_finished_initializing;
/* Broken DLLs built against Cygwin versions 1.7.0-49 up to 1.7.0-57
override the cxx_malloc pointer in their DLL initialization code,
when loaded either statically or dynamically. Because this leaves
a stale pointer into demapped memory space if the DLL is unloaded
by a call to dlclose, we prevent this happening for dynamically
loaded DLLS in dlopen by saving and restoring cxx_malloc around
the call to LoadLibrary, which invokes the DLL's startup sequence.
Modern DLLs won't even attempt to override the pointer when loaded
statically, but will write their overrides directly into the
struct it points to. With all modern DLLs, this will remain the
default_cygwin_cxx_malloc struct in cxx.cc, but if any broken DLLs
are in the mix they will have overridden the pointer and subsequent
overrides will go into their embedded cxx_malloc structs. This is
almost certainly not a problem as they can never be unloaded, but
if we ever did want to do anything about it, we could check here to
see if the pointer had been altered in the early parts of the DLL's
startup, and if so copy back the new overrides and reset it here.
However, that's just a note for the record; at the moment, we can't
see any need to worry about this happening. */
/* Partially initialize Cygwin guts for non-cygwin apps. */
if (dynamically_loaded && user_data->magic_biscuit == 0)
dll_crt0 (p);
else
check_sanity_and_sync (p);
dll_type type;
/* If this function is called before cygwin has finished
initializing, then the DLL must be a cygwin-aware DLL
that was explicitly linked into the program rather than
a dlopened DLL. */
if (linked)
type = DLL_LINK;
else
{
type = DLL_LOAD;
dlls.reload_on_fork = 1;
}
/* Allocate and initialize space for the DLL. */
dll *d = dlls.alloc (h, p, type);
/* If d == NULL, then something is broken.
Otherwise, if we've finished initializing, it's ok to
initialize the DLL. If we haven't finished initializing,
it may not be safe to call the dll's "main" since not
all of cygwin's internal structures may have been set up. */
if (!d || (!linked && !d->init ()))
res = -1;
else
res = (DWORD) d;
}
/* OBSOLETE: This function is obsolete and will go away in the
future. Cygwin can now handle being loaded from a noncygwin app
using the same entry point. */
extern "C" int
dll_noncygwin_dllcrt0 (HMODULE h, per_process *p)
{
return dll_dllcrt0 (h, p);
}
extern "C" void
cygwin_detach_dll (dll *)
{
HANDLE retaddr;
if (_my_tls.isinitialized ())
retaddr = (void *) _my_tls.retaddr ();
else
retaddr = __builtin_return_address (0);
dlls.detach (retaddr);
}
extern "C" void
dlfork (int val)
{
dlls.reload_on_fork = val;
}
/* Called from various places to update all of the individual
ideas of the environ block. Explain to me again why we didn't
just import __cygwin_environ? */
void __stdcall
update_envptrs ()
{
for (dll *d = dlls.istart (DLL_ANY); d; d = dlls.inext ())
if (*(d->p.envptr) != __cygwin_environ)
*(d->p.envptr) = __cygwin_environ;
*main_environ = __cygwin_environ;
}
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