373 lines
12 KiB
C
373 lines
12 KiB
C
/* pseudo-reloc.c
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Contributed by Egor Duda <deo@logos-m.ru>
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Modified by addition of runtime_pseudo_reloc version 2
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by Kai Tietz <kai.tietz@onevision.com>
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THIS SOFTWARE IS NOT COPYRIGHTED
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This source code is offered for use in the public domain. You may
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use, modify or distribute it freely.
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This code is distributed in the hope that it will be useful but
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WITHOUT ANY WARRANTY. ALL WARRENTIES, EXPRESS OR IMPLIED ARE HEREBY
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DISCLAMED. This includes but is not limited to warrenties of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#include <windows.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#if defined(__CYGWIN__)
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#include <wchar.h>
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#include <ntdef.h>
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#include <stdarg.h>
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#include <sys/cygwin.h>
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/* copied from winsup.h */
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# define NO_COPY __attribute__((nocommon)) __attribute__((section(".data_cygwin_nocopy")))
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/* custom status code: */
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#define STATUS_ILLEGAL_DLL_PSEUDO_RELOCATION ((NTSTATUS) 0xe0000269)
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#else
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# define NO_COPY
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#endif
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extern char __RUNTIME_PSEUDO_RELOC_LIST__;
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extern char __RUNTIME_PSEUDO_RELOC_LIST_END__;
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extern char _image_base__;
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/* v1 relocation is basically:
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* *(base + .target) += .addend
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* where (base + .target) is always assumed to point
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* to a DWORD (4 bytes).
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*/
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typedef struct {
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DWORD addend;
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DWORD target;
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} runtime_pseudo_reloc_item_v1;
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/* v2 relocation is more complex. In effect, it is
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* *(base + .target) += *(base + .sym) - (base + .sym)
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* with care taken in both reading, sign extension, and writing
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* because .flags may indicate that (base + .target) may point
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* to a BYTE, WORD, DWORD, or QWORD (w64).
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*/
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typedef struct {
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DWORD sym;
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DWORD target;
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DWORD flags;
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} runtime_pseudo_reloc_item_v2;
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typedef struct {
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DWORD magic1;
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DWORD magic2;
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DWORD version;
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} runtime_pseudo_reloc_v2;
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#if defined(__CYGWIN__)
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#define SHORT_MSG_BUF_SZ 128
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/* This function is used to print short error messages
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* to stderr, which may occur during DLL initialization
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* while fixing up 'pseudo' relocations. This early, we
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* may not be able to use cygwin stdio functions, so we
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* use the win32 WriteFile api. This should work with both
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* normal win32 console IO handles, redirected ones, and
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* cygwin ptys.
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*/
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static BOOL
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__print_reloc_error (const char *fmt, ...)
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{
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char buf[SHORT_MSG_BUF_SZ];
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wchar_t module[MAX_PATH];
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char * posix_module = NULL;
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BOOL rVal = FALSE;
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static const char * UNKNOWN_MODULE = "<unknown module>: ";
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DWORD len;
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DWORD done;
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va_list args;
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HANDLE errh = GetStdHandle (STD_ERROR_HANDLE);
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ssize_t modulelen = GetModuleFileNameW (NULL, module, sizeof (module));
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if (errh == INVALID_HANDLE_VALUE)
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return FALSE;
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if (modulelen > 0)
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posix_module = cygwin_create_path (CCP_WIN_W_TO_POSIX, module);
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va_start (args, fmt);
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len = (DWORD) vsnprintf (buf, SHORT_MSG_BUF_SZ, fmt, args);
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va_end (args);
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buf[SHORT_MSG_BUF_SZ-1] = '\0'; /* paranoia */
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if (posix_module)
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{
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rVal = WriteFile (errh, (PCVOID)posix_module,
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strlen(posix_module), &done, NULL) &&
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WriteFile (errh, (PCVOID)": ", 2, &done, NULL) &&
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WriteFile (errh, (PCVOID)buf, len, &done, NULL);
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free (posix_module);
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}
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else
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{
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rVal = WriteFile (errh, (PCVOID)UNKNOWN_MODULE,
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sizeof(UNKNOWN_MODULE), &done, NULL) &&
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WriteFile (errh, (PCVOID)buf, len, &done, NULL);
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}
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return rVal;
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}
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#endif /* __CYGWIN__ */
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/* This function temporarily marks the page containing addr
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* writable, before copying len bytes from *src to *addr, and
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* then restores the original protection settings to the page.
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*
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* Using this function eliminates the requirement with older
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* pseudo-reloc implementations, that sections containing
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* pseudo-relocs (such as .text and .rdata) be permanently
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* marked writable. This older behavior sabotaged any memory
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* savings achieved by shared libraries on win32 -- and was
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* slower, too. However, on cygwin as of binutils 2.20 the
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* .text section is still marked writable, and the .rdata section
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* is folded into the (writable) .data when --enable-auto-import.
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*/
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static void
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__write_memory (void *addr,const void *src,size_t len)
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{
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MEMORY_BASIC_INFORMATION b;
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DWORD oldprot;
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SIZE_T memsz;
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if (!len)
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return;
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memsz = VirtualQuery (addr, &b, sizeof(b));
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#if defined(__CYGWIN__)
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/* CYGWIN: If error, print error message and die. */
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if (memsz == 0)
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{
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__print_reloc_error (
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"error while loading shared libraries: bad address specified 0x%08x.\n",
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addr);
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cygwin_internal (CW_EXIT_PROCESS,
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STATUS_ILLEGAL_DLL_PSEUDO_RELOCATION,
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1);
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}
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#else
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/* MINGW: If error, die. assert() may print error message when !NDEBUG */
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assert (memsz);
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#endif
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/* Temporarily allow write access to read-only protected memory. */
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if (b.Protect != PAGE_EXECUTE_READWRITE && b.Protect != PAGE_READWRITE)
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VirtualProtect (b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE,
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&oldprot);
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/* write the data. */
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memcpy (addr, src, len);
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/* Restore original protection. */
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if (b.Protect != PAGE_EXECUTE_READWRITE && b.Protect != PAGE_READWRITE)
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VirtualProtect (b.BaseAddress, b.RegionSize, oldprot, &oldprot);
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}
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#define RP_VERSION_V1 0
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#define RP_VERSION_V2 1
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static void
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do_pseudo_reloc (void * start, void * end, void * base)
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{
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ptrdiff_t addr_imp, reldata;
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ptrdiff_t reloc_target = (ptrdiff_t) ((char *)end - (char*)start);
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runtime_pseudo_reloc_v2 *v2_hdr = (runtime_pseudo_reloc_v2 *) start;
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runtime_pseudo_reloc_item_v2 *r;
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/* A valid relocation list will contain at least one entry, and
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* one v1 data structure (the smallest one) requires two DWORDs.
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* So, if the relocation list is smaller than 8 bytes, bail.
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*/
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if (reloc_target < 8)
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return;
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/* Check if this is the old pseudo relocation version. */
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/* There are two kinds of v1 relocation lists:
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* 1) With a (v2-style) version header. In this case, the
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* first entry in the list is a 3-DWORD structure, with
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* value:
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* { 0, 0, RP_VERSION_V1 }
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* In this case, we skip to the next entry in the list,
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* knowing that all elements after the head item can
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* be cast to runtime_pseudo_reloc_item_v1.
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* 2) Without a (v2-style) version header. In this case, the
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* first element in the list IS an actual v1 relocation
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* record, which is two DWORDs. Because there will never
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* be a case where a v1 relocation record has both
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* addend == 0 and target == 0, this case will not be
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* confused with the prior one.
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* All current binutils, when generating a v1 relocation list,
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* use the second (e.g. original) form -- that is, without the
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* v2-style version header.
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*/
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if (reloc_target >= 12
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&& v2_hdr->magic1 == 0 && v2_hdr->magic2 == 0
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&& v2_hdr->version == RP_VERSION_V1)
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{
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/* We have a list header item indicating that the rest
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* of the list contains v1 entries. Move the pointer to
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* the first true v1 relocation record. By definition,
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* that v1 element will not have both addend == 0 and
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* target == 0 (and thus, when interpreted as a
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* runtime_pseudo_reloc_v2, it will not have both
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* magic1 == 0 and magic2 == 0).
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*/
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v2_hdr++;
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}
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if (v2_hdr->magic1 != 0 || v2_hdr->magic2 != 0)
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{
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/*************************
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* Handle v1 relocations *
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*************************/
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runtime_pseudo_reloc_item_v1 * o;
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for (o = (runtime_pseudo_reloc_item_v1 *) v2_hdr;
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o < (runtime_pseudo_reloc_item_v1 *)end;
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o++)
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{
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DWORD newval;
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reloc_target = (ptrdiff_t) base + o->target;
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newval = (*((DWORD*) reloc_target)) + o->addend;
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__write_memory ((void *) reloc_target, &newval, sizeof(DWORD));
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}
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return;
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}
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/* If we got this far, then we have relocations of version 2 or newer */
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/* Check if this is a known version. */
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if (v2_hdr->version != RP_VERSION_V2)
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{
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#if defined(__CYGWIN__)
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/* CYGWIN: Print error message and die, even when !DEBUGGING */
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__print_reloc_error (
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"error while loading shared libraries: invalid pseudo_reloc version %d.\n",
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(int) v2_hdr->version);
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cygwin_internal (CW_EXIT_PROCESS,
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STATUS_ILLEGAL_DLL_PSEUDO_RELOCATION,
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1);
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#else
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# if defined(DEBUG)
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/* MINGW: Don't die; just return to caller. If DEBUG, print error message. */
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fprintf (stderr, "internal mingw runtime error:"
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"psuedo_reloc version %d is unknown to this runtime.\n",
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(int) v2_hdr->version);
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# endif
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#endif
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return;
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}
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/*************************
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* Handle v2 relocations *
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*************************/
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/* Walk over header. */
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r = (runtime_pseudo_reloc_item_v2 *) &v2_hdr[1];
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for (; r < (runtime_pseudo_reloc_item_v2 *) end; r++)
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{
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/* location where new address will be written */
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reloc_target = (ptrdiff_t) base + r->target;
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/* get sym pointer. It points either to the iat entry
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* of the referenced element, or to the stub function.
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*/
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addr_imp = (ptrdiff_t) base + r->sym;
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addr_imp = *((ptrdiff_t *) addr_imp);
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/* read existing relocation value from image, casting to the
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* bitsize indicated by the 8 LSBs of flags. If the value is
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* negative, manually sign-extend to ptrdiff_t width. Raise an
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* error if the bitsize indicated by the 8 LSBs of flags is not
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* supported.
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*/
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switch ((r->flags & 0xff))
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{
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case 8:
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reldata = (ptrdiff_t) (*((unsigned char *)reloc_target));
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if ((reldata & 0x80) != 0)
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reldata |= ~((ptrdiff_t) 0xff);
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break;
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case 16:
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reldata = (ptrdiff_t) (*((unsigned short *)reloc_target));
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if ((reldata & 0x8000) != 0)
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reldata |= ~((ptrdiff_t) 0xffff);
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break;
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case 32:
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reldata = (ptrdiff_t) (*((unsigned int *)reloc_target));
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#ifdef _WIN64
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if ((reldata & 0x80000000) != 0)
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reldata |= ~((ptrdiff_t) 0xffffffff);
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#endif
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break;
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#ifdef _WIN64
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case 64:
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reldata = (ptrdiff_t) (*((unsigned long long *)reloc_target));
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break;
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#endif
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default:
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reldata=0;
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#if defined(__CYGWIN__)
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/* Print error message and die, even when !DEBUGGING */
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__print_reloc_error (
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"error while loading shared libraries: unknown pseudo_reloc bit size %d.\n",
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(int) (r->flags & 0xff));
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cygwin_internal (CW_EXIT_PROCESS,
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STATUS_ILLEGAL_DLL_PSEUDO_RELOCATION,
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1);
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#else
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# ifdef DEBUG
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/* MINGW: If error, don't die; just print message if DEBUG */
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fprintf(stderr, "internal mingw runtime error: "
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"unknown pseudo_reloc bit size %d\n",
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(int) (r->flags & 0xff));
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# endif
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#endif
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break;
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}
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/* Adjust the relocation value */
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reldata -= ((ptrdiff_t) base + r->sym);
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reldata += addr_imp;
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/* Write the new relocation value back to *reloc_target */
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switch ((r->flags & 0xff))
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{
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case 8:
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__write_memory ((void *) reloc_target, &reldata, 1);
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break;
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case 16:
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__write_memory ((void *) reloc_target, &reldata, 2);
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break;
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case 32:
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__write_memory ((void *) reloc_target, &reldata, 4);
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break;
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#ifdef _WIN64
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case 64:
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__write_memory ((void *) reloc_target, &reldata, 8);
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break;
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#endif
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}
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}
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}
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void
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_pei386_runtime_relocator ()
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{
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static NO_COPY int was_init = 0;
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if (was_init)
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return;
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++was_init;
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do_pseudo_reloc (&__RUNTIME_PSEUDO_RELOC_LIST__,
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&__RUNTIME_PSEUDO_RELOC_LIST_END__,
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&_image_base__);
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}
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