b4054e7706
(putmem): Make static. (get_export): Ditto. (rvadelta): Ditto. Don't assume that a section which ends where the import_rva begins is the import list. * child_info.h: Update copyright. * fork.cc: Ditto.
238 lines
6.5 KiB
C++
238 lines
6.5 KiB
C++
/* hookapi.cc
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Copyright 2005, 2006 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 "cygerrno.h"
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#include "security.h"
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#include "path.h"
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#include "fhandler.h"
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#include "dtable.h"
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#include "cygheap.h"
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#include <stdlib.h>
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#include <imagehlp.h>
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#include <alloca.h>
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#define rva(coerce, base, addr) (coerce) ((char *) (base) + (addr))
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#define rvacyg(coerce, addr) rva (coerce, cygwin_hmodule, addr)
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struct function_hook
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{
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const char *name; // Function name, e.g. "DirectDrawCreateEx".
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const void *hookfn; // Address of your function.
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void *origfn; // Stored by HookAPICalls, the address of the original function.
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};
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/* Given an HMODULE, returns a pointer to the PE header */
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static PIMAGE_NT_HEADERS
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PEHeaderFromHModule (HMODULE hModule)
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{
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PIMAGE_NT_HEADERS pNTHeader;
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if (PIMAGE_DOS_HEADER(hModule) ->e_magic != IMAGE_DOS_SIGNATURE)
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pNTHeader = NULL;
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else
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{
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pNTHeader = PIMAGE_NT_HEADERS (PBYTE (hModule)
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+ PIMAGE_DOS_HEADER (hModule) ->e_lfanew);
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if (pNTHeader->Signature != IMAGE_NT_SIGNATURE)
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pNTHeader = NULL;
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}
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return pNTHeader;
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}
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static long
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rvadelta (PIMAGE_NT_HEADERS pnt, DWORD import_rva)
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{
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PIMAGE_SECTION_HEADER section = (PIMAGE_SECTION_HEADER) (pnt + 1);
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for (int i = 0; i < pnt->FileHeader.NumberOfSections; i++)
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if (section[i].VirtualAddress <= import_rva
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&& (section[i].VirtualAddress + section[i].Misc.VirtualSize) > import_rva)
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// if (strncasematch ((char *) section[i].Name, ".idata", IMAGE_SIZEOF_SHORT_NAME))
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return section[i].VirtualAddress - section[i].PointerToRawData;
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return -1;
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}
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static void *
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putmem (PIMAGE_THUNK_DATA pi, const void *hookfn)
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{
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DWORD ofl;
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if (!VirtualProtect (pi, sizeof (PVOID), PAGE_READWRITE, &ofl) )
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return NULL;
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void *origfn = (void *) pi->u1.Function;
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pi->u1.Function = (DWORD) hookfn;
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VirtualProtect (pi, sizeof (PVOID), ofl, &ofl);
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return origfn;
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}
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/* Builds stubs for and redirects the IAT for one DLL (pImportDesc) */
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static bool
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RedirectIAT (function_hook& fh, PIMAGE_IMPORT_DESCRIPTOR pImportDesc,
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HMODULE hm)
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{
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// If no import names table, we can't redirect this, so bail
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if (pImportDesc->OriginalFirstThunk == 0)
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return false;
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/* import address table */
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PIMAGE_THUNK_DATA pt = rva (PIMAGE_THUNK_DATA, hm, pImportDesc->FirstThunk);
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/* import names table */
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PIMAGE_THUNK_DATA pn = rva (PIMAGE_THUNK_DATA, hm, pImportDesc->OriginalFirstThunk);
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/* Scan through the IAT, completing the stubs and redirecting the IAT
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entries to point to the stubs. */
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for (PIMAGE_THUNK_DATA pi = pt; pn->u1.Ordinal; pi++, pn++)
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{
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if (IMAGE_SNAP_BY_ORDINAL (pn->u1.Ordinal) )
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continue;
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/* import by name */
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PIMAGE_IMPORT_BY_NAME pimp = rva (PIMAGE_IMPORT_BY_NAME, hm, pn->u1.AddressOfData);
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if (strcmp (fh.name, (char *) pimp->Name) == 0)
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{
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fh.origfn = putmem (pi, fh.hookfn);
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if (!fh.origfn)
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return false;
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hook_chain *hc;
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for (hc = &cygheap->hooks; hc->next; hc = hc->next)
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continue;
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hc->next = (hook_chain *) cmalloc (HEAP_1_HOOK, sizeof (hook_chain));
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hc->next->loc = (void **) pi;
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hc->next->func = fh.hookfn;
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hc->next->next = NULL;
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break;
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}
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}
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return true;
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}
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static void
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get_export (function_hook& fh)
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{
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PIMAGE_DOS_HEADER pdh = (PIMAGE_DOS_HEADER) cygwin_hmodule;
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if (pdh->e_magic != IMAGE_DOS_SIGNATURE)
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return;
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PIMAGE_NT_HEADERS pnt = (PIMAGE_NT_HEADERS) ((char *) pdh + pdh->e_lfanew);
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if (pnt->Signature != IMAGE_NT_SIGNATURE || pnt->FileHeader.SizeOfOptionalHeader == 0)
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return;
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PIMAGE_EXPORT_DIRECTORY pexp =
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rvacyg (PIMAGE_EXPORT_DIRECTORY,
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pnt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress);
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if (!pexp)
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return;
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PDWORD pfuncs = rvacyg (PDWORD, pexp->AddressOfFunctions);
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PDWORD pnames = rvacyg (PDWORD, pexp->AddressOfNames);
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for (DWORD i = 0; i < pexp->NumberOfNames; i++)
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if (strcmp (fh.name, rvacyg (char *, pnames[i])) == 0)
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{
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fh.origfn = rvacyg (void *, pfuncs[i]);
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break;
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}
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}
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static const char *
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makename (const char *name, char *&buf, int& i, int inc)
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{
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i += inc;
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static const char *testers[] = {"NOTUSED", "64", "32"};
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if (i < 0 || i >= (int) (sizeof (testers) / sizeof (testers[0])))
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return NULL;
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if (i)
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{
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__small_sprintf (buf, "_%s%s", name, testers[i]);
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name = buf;
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}
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return name;
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}
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// Top level routine to find the EXE's imports, and redirect them
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void *
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hook_or_detect_cygwin (const char *name, const void *fn, WORD& subsys)
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{
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HMODULE hm = fn ? GetModuleHandle (NULL) : (HMODULE) name;
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PIMAGE_NT_HEADERS pExeNTHdr = PEHeaderFromHModule (hm);
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if (!pExeNTHdr)
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return false;
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subsys = pExeNTHdr->OptionalHeader.Subsystem;
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DWORD importRVA = pExeNTHdr->OptionalHeader.DataDirectory
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[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress;
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if (!importRVA)
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return false;
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long delta = fn ? 0 : rvadelta (pExeNTHdr, importRVA);
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if (delta < 0)
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return false;
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// Convert imports RVA to a usable pointer
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PIMAGE_IMPORT_DESCRIPTOR pdfirst = rva (PIMAGE_IMPORT_DESCRIPTOR, hm, importRVA - delta);
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function_hook fh;
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fh.origfn = NULL;
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fh.hookfn = fn;
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char *buf = (char *) alloca (strlen (name) + sizeof ("_64"));
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int i;
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// Iterate through each import descriptor, and redirect if appropriate
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for (PIMAGE_IMPORT_DESCRIPTOR pd = pdfirst; pd->FirstThunk; pd++)
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{
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if (!strcasematch (rva (PSTR, hm, pd->Name - delta), "cygwin1.dll"))
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continue;
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if (!fn)
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return (void *) "found it"; // just checking if executable used cygwin1.dll
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i = -1;
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while (!fh.origfn && (fh.name = makename (name, buf, i, 1)))
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RedirectIAT (fh, pd, hm);
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if (fh.origfn)
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break;
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}
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while (!fh.origfn && (fh.name = makename (name, buf, i, -1)))
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get_export (fh);
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return fh.origfn;
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}
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void
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ld_preload ()
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{
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char *p = getenv ("LD_PRELOAD");
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if (!p)
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return;
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char *s = (char *) alloca (strlen (p) + 1);
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strcpy (s, p);
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char *here = NULL;
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for (p = strtok_r (s, ":\t\n", &here); p; p = strtok_r (NULL, ":\t\n", &here))
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{
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path_conv lib (p);
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if (!LoadLibrary (lib))
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{
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__seterrno ();
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api_fatal ("error while loading shared libraries: %s: "
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"cannot open shared object file: %s", p,
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strerror (get_errno ()));
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}
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}
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}
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void
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fixup_hooks_after_fork ()
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{
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for (hook_chain *hc = &cygheap->hooks; (hc = hc->next); )
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putmem ((PIMAGE_THUNK_DATA) hc->loc, hc->func);
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}
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