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/* Copyright (c) 2012-2013 Zeex
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#if defined _MSC_VER
#if defined SUBHOOK_X86
typedef __int32 intptr_t;
#elif defined SUBHOOK_X86_64
typedef __int64 intptr_t;
#endif
#else
#include <stdint.h>
#endif
#include "subhook.h"
#include "subhook_private.h"
#define JMP_OPCODE 0xE9
static const unsigned char jmp_opcode = JMP_OPCODE;
static const unsigned char jmp_instr[] = { JMP_OPCODE, 0x0, 0x0, 0x0, 0x0 };
struct subhook_x86 {
struct subhook _;
unsigned char code[sizeof(jmp_instr)];
};
SUBHOOK_EXPORT subhook_t SUBHOOK_API subhook_new() {
struct subhook_x86 *hook;
if ((hook = calloc(1, sizeof(*hook))) == NULL)
return NULL;
return (subhook_t)hook;
}
SUBHOOK_EXPORT void SUBHOOK_API subhook_free(subhook_t hook) {
free(hook);
}
SUBHOOK_EXPORT int SUBHOOK_API subhook_install(subhook_t hook) {
void *src;
void *dst;
intptr_t offset;
if (subhook_is_installed(hook))
return -EINVAL;
src = subhook_get_src(hook);
dst = subhook_get_dst(hook);
subhook_unprotect(src, sizeof(jmp_instr));
memcpy(((struct subhook_x86 *)hook)->code, src, sizeof(jmp_instr));
memcpy(src, &jmp_instr, sizeof(jmp_instr));
offset = (intptr_t)dst - ((intptr_t)src + sizeof(jmp_instr));
memcpy((void *)((intptr_t)src + sizeof(jmp_opcode)), &offset,
sizeof(jmp_instr) - sizeof(jmp_opcode));
hook->installed = 1;
return 0;
}
SUBHOOK_EXPORT int SUBHOOK_API subhook_remove(subhook_t hook) {
if (!subhook_is_installed(hook))
return -EINVAL;
memcpy(subhook_get_src(hook), ((struct subhook_x86 *)hook)->code,
sizeof(jmp_instr));
hook->installed = 0;
return 0;
}
SUBHOOK_EXPORT void *SUBHOOK_API subhook_read_dst(void *src) {
unsigned char opcode;
intptr_t src_addr = (intptr_t)src;
intptr_t dst_addr;
intptr_t *target;
memcpy(&opcode, src, sizeof(opcode));
if (opcode != jmp_opcode)
return NULL;
memcpy(&target, (void *)(src_addr + sizeof(jmp_opcode)), sizeof(*target));
dst_addr = *target + src_addr + sizeof(jmp_instr);
return (void *)dst_addr;
}
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