[ia32rtools.git] / tools / cmpmrg_text.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/coff.h>
#include <assert.h>
#include <stdint.h>

#include "my_assert.h"

/* http://www.delorie.com/djgpp/doc/coff/ */

typedef struct {
  unsigned short f_magic;         /* magic number             */
  unsigned short f_nscns;         /* number of sections       */
  unsigned int   f_timdat;        /* time & date stamp        */
  unsigned int   f_symptr;        /* file pointer to symtab   */
  unsigned int   f_nsyms;         /* number of symtab entries */
  unsigned short f_opthdr;        /* sizeof(optional hdr)     */
  unsigned short f_flags;         /* flags                    */
} FILHDR;

typedef struct {
  unsigned short magic;          /* type of file                         */
  unsigned short vstamp;         /* version stamp                        */
  unsigned int   tsize;          /* text size in bytes, padded to FW bdry*/
  unsigned int   dsize;          /* initialized data    "  "             */
  unsigned int   bsize;          /* uninitialized data  "  "             */
  unsigned int   entry;          /* entry pt.                            */
  unsigned int   text_start;     /* base of text used for this file      */
  unsigned int   data_start;     /* base of data used for this file      */
} AOUTHDR;

typedef struct {
  char           s_name[8];  /* section name                     */
  unsigned int   s_paddr;    /* physical address, aliased s_nlib */
  unsigned int   s_vaddr;    /* virtual address                  */
  unsigned int   s_size;     /* section size                     */
  unsigned int   s_scnptr;   /* file ptr to raw data for section */
  unsigned int   s_relptr;   /* file ptr to relocation           */
  unsigned int   s_lnnoptr;  /* file ptr to line numbers         */
  unsigned short s_nreloc;   /* number of relocation entries     */
  unsigned short s_nlnno;    /* number of line number entries    */
  unsigned int   s_flags;    /* flags                            */
} SCNHDR;

typedef struct {
  unsigned int  r_vaddr;   /* address of relocation      */
  unsigned int  r_symndx;  /* symbol we're adjusting for */
  unsigned short r_type;    /* type of relocation         */
} __attribute__((packed)) RELOC;

typedef struct {
  union {
    char e_name[E_SYMNMLEN];
    struct {
      unsigned int e_zeroes;
      unsigned int e_offset;
    } e;
  } e;
  unsigned int e_value;
  short e_scnum;
  unsigned short e_type;
  unsigned char e_sclass;
  unsigned char e_numaux;
} __attribute__((packed)) SYMENT;

#define C_EXT 2

struct my_symtab {
  unsigned int addr;
  unsigned int fpos; // for patching
  char *name;
};

static int symt_cmp(const void *p1_, const void *p2_)
{
	const struct my_symtab *p1 = p1_, *p2 = p2_;
	return p1->addr - p2->addr;
}

void parse_headers(FILE *f, unsigned int *base_out,
	long *sect_ofs, uint8_t **sect_data, long *sect_sz,
	RELOC **relocs, long *reloc_cnt,
	struct my_symtab **symtab_out, long *sym_cnt)
{
	struct my_symtab *symt_o = NULL;
	char *stringtab = NULL;
	unsigned int base = 0;
	int text_scnum = 0;
	long filesize;
	char symname[9];
	long opthdr_pos;
	long reloc_size;
	FILHDR hdr;
	AOUTHDR opthdr;
	SCNHDR scnhdr;
	SYMENT syment;
	int i, s, val;
	int ret;
	
	ret = fseek(f, 0, SEEK_END);
	my_assert(ret, 0);

	filesize = ftell(f);

	ret = fseek(f, 0, SEEK_SET);
	my_assert(ret, 0);

	ret = fread(&hdr, 1, sizeof(hdr), f);
	my_assert(ret, sizeof(hdr));

	if (hdr.f_magic == 0x5a4d) // MZ
	{
		ret = fseek(f, 0x3c, SEEK_SET);
		my_assert(ret, 0);
		ret = fread(&val, 1, sizeof(val), f);
		my_assert(ret, sizeof(val));

		ret = fseek(f, val, SEEK_SET);
		my_assert(ret, 0);
		ret = fread(&val, 1, sizeof(val), f);
		my_assert(ret, sizeof(val));
		my_assert(val, 0x4550); // PE

		// should be COFF now
		ret = fread(&hdr, 1, sizeof(hdr), f);
		my_assert(ret, sizeof(hdr));
	}

	my_assert(hdr.f_magic, COFF_I386MAGIC);

	if (hdr.f_opthdr != 0)
	{
		opthdr_pos = ftell(f);

		if (hdr.f_opthdr < sizeof(opthdr))
			my_assert(1, 0);

		ret = fread(&opthdr, 1, sizeof(opthdr), f);
		my_assert(ret, sizeof(opthdr));
		my_assert(opthdr.magic, COFF_ZMAGIC);

		//printf("text_start: %x\n", opthdr.text_start);

		if (hdr.f_opthdr > sizeof(opthdr)) {
			ret = fread(&base, 1, sizeof(base), f);
			my_assert(ret, sizeof(base));
			//printf("base: %x\n", base);
		}
		ret = fseek(f, opthdr_pos + hdr.f_opthdr, SEEK_SET);
		my_assert(ret, 0);
	}

	// note: assuming first non-empty one is .text ..
	for (s = 0; s < hdr.f_nscns; s++) {
		ret = fread(&scnhdr, 1, sizeof(scnhdr), f);
		my_assert(ret, sizeof(scnhdr));

		if (scnhdr.s_size != 0) {
			text_scnum = s + 1;
			break;
		}
	}

#if 0
	printf("f_nsyms:  %x\n", hdr.f_nsyms);
	printf("s_name:   '%s'\n", scnhdr.s_name);
	printf("s_vaddr:  %x\n", scnhdr.s_vaddr);
	printf("s_size:   %x\n", scnhdr.s_size);
	//printf("s_scnptr: %x\n", scnhdr.s_scnptr);
	printf("s_nreloc: %x\n", scnhdr.s_nreloc);
	printf("--\n");
#endif

	ret = fseek(f, scnhdr.s_scnptr, SEEK_SET);
	my_assert(ret, 0);

	*sect_data = malloc(scnhdr.s_size);
	my_assert_not(*sect_data, NULL);
	ret = fread(*sect_data, 1, scnhdr.s_size, f);
	my_assert(ret, scnhdr.s_size);

	*sect_ofs = scnhdr.s_scnptr;
	*sect_sz = scnhdr.s_size;

	// relocs
	ret = fseek(f, scnhdr.s_relptr, SEEK_SET);
	my_assert(ret, 0);

	reloc_size = scnhdr.s_nreloc * sizeof((*relocs)[0]);
	*relocs = malloc(reloc_size + 1);
	my_assert_not(*relocs, NULL);
	ret = fread(*relocs, 1, reloc_size, f);
	my_assert(ret, reloc_size);

	*reloc_cnt = scnhdr.s_nreloc;

	// symtab
	if (hdr.f_nsyms != 0) {
		symname[8] = 0;

		symt_o = malloc(hdr.f_nsyms * sizeof(symt_o[0]) + 1);
		my_assert_not(symt_o, NULL);

		ret = fseek(f, hdr.f_symptr
				+ hdr.f_nsyms * sizeof(syment), SEEK_SET);
		my_assert(ret, 0);
		ret = fread(&i, 1, sizeof(i), f);
		my_assert(ret, sizeof(i));
		my_assert((unsigned int)i < filesize, 1);

		stringtab = malloc(i);
		my_assert_not(stringtab, NULL);
		memset(stringtab, 0, 4);
		ret = fread(stringtab + 4, 1, i - 4, f);
		my_assert(ret, i - 4);

		ret = fseek(f, hdr.f_symptr, SEEK_SET);
		my_assert(ret, 0);
	}

	for (i = s = 0; i < hdr.f_nsyms; i++) {
		long pos = ftell(f);

		ret = fread(&syment, 1, sizeof(syment), f);
		my_assert(ret, sizeof(syment));

		strncpy(symname, syment.e.e_name, 8);
		//printf("%3d %2d %08x '%s'\n", syment.e_sclass,
		//	syment.e_scnum, syment.e_value, symname);

		if (syment.e_scnum != text_scnum || syment.e_sclass != C_EXT)
			continue;

		symt_o[s].addr = syment.e_value;
		symt_o[s].fpos = pos;
		if (syment.e.e.e_zeroes == 0)
			symt_o[s].name = stringtab + syment.e.e.e_offset;
		else
			symt_o[s].name = strdup(symname);
		s++;

		if (syment.e_numaux) {
			ret = fseek(f, syment.e_numaux * sizeof(syment),
				    SEEK_CUR);
			my_assert(ret, 0);
			i += syment.e_numaux;
		}
	}

	if (symt_o != NULL)
		qsort(symt_o, s, sizeof(symt_o[0]), symt_cmp);

	*sym_cnt = s;
	*symtab_out = symt_o;

	// seek to .text start
	ret = fseek(f, scnhdr.s_scnptr, SEEK_SET);
	my_assert(ret, 0);

	if (base != 0 && base_out != NULL)
		*base_out = base + scnhdr.s_vaddr;
}

static int handle_pad(uint8_t *d_obj, uint8_t *d_exe, int maxlen)
{
	static const uint8_t p7[7] = { 0x8d, 0xa4, 0x24, 0x00, 0x00, 0x00, 0x00 };
	static const uint8_t p6[6] = { 0x8d, 0x9b, 0x00, 0x00, 0x00, 0x00 };
	static const uint8_t p5[5] = { 0x05, 0x00, 0x00, 0x00, 0x00 };
	static const uint8_t p4[4] = { 0x8d, 0x64, 0x24, 0x00 };
	static const uint8_t p3[3] = { 0x8d, 0x49, 0x00 };
	static const uint8_t p2[2] = { 0x8b, 0xff };
	static const uint8_t p1[1] = { 0x90 };
	int len;
	int i;

	for (i = 0; i < maxlen; i++)
		if (d_exe[i] != 0xcc)
			break;

	for (len = i; len > 0; )
	{
		i = len;
		if (i > 7)
			i = 7;

		switch (i) {
		#define CASE(x) \
		case sizeof(p ## x): \
			if (memcmp(d_obj, p ## x, sizeof(p ## x))) \
				return 0; \
			memset(d_obj, 0xcc, sizeof(p ## x)); \
			break;
		CASE(7)
		CASE(6)
		CASE(5)
		CASE(4)
		CASE(3)
		CASE(2)
		CASE(1)
		default:
			printf("%s: unhandled len: %d\n", __func__, len);
			return 0;
		#undef CASE
		}

		len -= i;
		d_obj += i;
	}

	return 1;
}

struct equiv_opcode {
	signed char len;
	signed char ofs;
	short cmp_rm;
	uint8_t v_masm[8];
	uint8_t v_masm_mask[8];
	uint8_t v_msvc[8];
	uint8_t v_msvc_mask[8];
} equiv_ops[] = {
	// cmp    $0x11,%ax
	{ 4, -1, 0,
	 { 0x66,0x83,0xf8,0x03 }, { 0xff,0xff,0xff,0x00 },
	 { 0x66,0x3d,0x03,0x00 }, { 0xff,0xff,0x00,0xff }, },
	// lea    -0x1(%ebx,%eax,1),%esi // op mod/rm sib offs
	// mov, test, imm grp 1
	{ 3, -2, 1,
	 { 0x8d,0x74,0x03 }, { 0xf0,0x07,0xc0 },
	 { 0x8d,0x74,0x18 }, { 0xf0,0x07,0xc0 }, },
	// movzbl 0x58f24a(%eax,%ecx,1),%eax
	{ 4, -3, 1,
	 { 0x0f,0xb6,0x84,0x08 }, { 0xff,0xff,0x07,0xc0 },
	 { 0x0f,0xb6,0x84,0x01 }, { 0xff,0xff,0x07,0xc0 }, },
	// inc/dec
	{ 3, -2, 1,
	 { 0xfe,0x4c,0x03 }, { 0xfe,0xff,0xc0 },
	 { 0xfe,0x4c,0x18 }, { 0xfe,0xff,0xc0 }, },
	// cmp
	{ 3, -2, 1,
	 { 0x38,0x0c,0x0c }, { 0xff,0xff,0xc0 },
	 { 0x38,0x0c,0x30 }, { 0xff,0xff,0xc0 }, },
	// test   %dl,%bl
	{ 2, -1, 1,
	 { 0x84,0xd3 }, { 0xfe,0xc0 },
	 { 0x84,0xda }, { 0xfe,0xc0 }, },
	// cmp	  r,r/m vs rm/r
	{ 2, 0, 1,
	 { 0x3a,0xca }, { 0xff,0xc0 },
	 { 0x38,0xd1 }, { 0xff,0xc0 }, },
	// rep + 66 prefix
	{ 2, 0, 0,
	 { 0xf3,0x66 }, { 0xfe,0xff },
	 { 0x66,0xf3 }, { 0xff,0xfe }, },
	// fadd   st, st(0) vs st(0), st
	{ 2, 0, 0,
	 { 0xd8,0xc0 }, { 0xff,0xf7 },
	 { 0xdc,0xc0 }, { 0xff,0xf7 }, },

	// broad filters (may take too much..)
	// testb  $0x4,0x1d(%esi,%eax,1)
	// movb, push, ..
	{ 3, -2, 1,
	 { 0xf6,0x44,0x06 }, { 0x00,0x07,0xc0 },
	 { 0xf6,0x44,0x30 }, { 0x00,0x07,0xc0 }, },
};

static int cmp_mask(uint8_t *d, uint8_t *expect, uint8_t *mask, int len)
{
	int i;

	for (i = 0; i < len; i++)
		if ((d[i] & mask[i]) != (expect[i] & mask[i]))
			return 1;

	return 0;
}

static int check_equiv(uint8_t *d_obj, uint8_t *d_exe, int maxlen)
{
	uint8_t vo, ve, vo2, ve2;
	int i, jo, je;
	int len, ofs;

	for (i = 0; i < sizeof(equiv_ops) / sizeof(equiv_ops[0]); i++)
	{
		struct equiv_opcode *op = &equiv_ops[i];

		len = op->len;
		if (maxlen < len)
			continue;

		ofs = op->ofs;
		if (cmp_mask(d_obj + ofs, op->v_masm,
			     op->v_masm_mask, len))
			continue;
		if (cmp_mask(d_exe + ofs, op->v_msvc,
			     op->v_msvc_mask, len))
			continue;

		jo = je = 0;
		d_obj += ofs;
		d_exe += ofs;
		while (1)
		{
			for (; jo < len; jo++)
				if (op->v_masm_mask[jo] != 0xff)
					break;
			for (; je < len; je++)
				if (op->v_msvc_mask[je] != 0xff)
					break;

			if ((jo == len && je != len) || (jo != len && je == len)) {
				printf("invalid equiv_ops\n");
				return -1;
			}
			if (jo == len)
				return len + ofs - 1; // matched

			// var byte
			vo = d_obj[jo] & ~op->v_masm_mask[jo];
			ve = d_exe[je] & ~op->v_msvc_mask[je];
			if (op->cmp_rm && op->v_masm_mask[jo] == 0xc0) {
				vo2 = vo >> 3;
				vo &= 7;
				ve2 = ve & 7;
				ve >>= 3;
				if (vo != ve || vo2 != ve2)
					return -1;
			}
			else {
				if (vo != ve)
					return -1;
			}

			jo++;
			je++;
		}
	}

	return -1;
}

int main(int argc, char *argv[])
{
	FILE *f_obj, *f_exe;
	long text_ofs_obj, text_ofs_exe;
	long sztext_obj, sztext_exe, sztext_cmn;
	RELOC *relocs_obj, *relocs_exe;
	long reloc_cnt_obj, reloc_cnt_exe;
	struct my_symtab *syms_obj, *syms_exe;
	long sym_cnt_obj, sym_cnt_exe;
	uint8_t *d_obj, *d_exe;
	unsigned int base = 0, addr, end;
	int retval = 1;
	int left;
	int ret;
	int i;

	if (argc != 3) {
		printf("usage:\n%s <a_obj> <exe>\n", argv[0]);
		return 1;
	}

	f_obj = fopen(argv[1], "r+b");
	if (f_obj == NULL) {
		fprintf(stderr, "%s", argv[1]);
		perror("");
		return 1;
	}

	f_exe = fopen(argv[2], "r");
	if (f_exe == NULL) {
		fprintf(stderr, "%s", argv[2]);
		perror("");
		return 1;
	}

	parse_headers(f_obj, NULL, &text_ofs_obj, &d_obj, &sztext_obj,
		&relocs_obj, &reloc_cnt_obj, &syms_obj, &sym_cnt_obj);
	parse_headers(f_exe, &base, &text_ofs_exe, &d_exe, &sztext_exe,
		&relocs_exe, &reloc_cnt_exe, &syms_exe, &sym_cnt_exe);

	sztext_cmn = sztext_obj;
	if (sztext_cmn > sztext_exe)
		sztext_cmn = sztext_exe;

	if (sztext_cmn == 0) {
		printf("bad .text size(s): %ld, %ld\n",
			sztext_obj, sztext_exe);
		return 1;
	}

	for (i = 0; i < reloc_cnt_obj; i++)
	{
		unsigned int a = relocs_obj[i].r_vaddr;
		//printf("%04x %08x\n", relocs_obj[i].r_type, a);

		switch (relocs_obj[i].r_type) {
		case 0x06: // RELOC_ADDR32
		case 0x14: // RELOC_REL32
			// must preserve stored val,
			// so trash d_exe so that cmp passes
			memcpy(d_exe + a, d_obj + a, 4);
			break;
		default:
			printf("unknown reloc %x @%08x/%08x\n",
				relocs_obj[i].r_type, a, base + a);
			return 1;
		}
	}

	for (i = 0; i < sztext_cmn; i++)
	{
		if (d_obj[i] == d_exe[i])
			continue;

		left = sztext_cmn - i;

		if (d_exe[i] == 0xcc) { // padding
			if (handle_pad(d_obj + i, d_exe + i, left))
				continue;
		}

		ret = check_equiv(d_obj + i, d_exe + i, left);
		if (ret >= 0) {
			i += ret;
			continue;
		}

		printf("%x: %02x vs %02x\n", base + i, d_obj[i], d_exe[i]);
		goto out;
	}

	for (i = 0; i < sym_cnt_obj; i++) {
		if (strncmp(syms_obj[i].name, "rm_", 3))
			continue;

		addr = syms_obj[i].addr;
		end = (i < sym_cnt_obj - 1)
			? syms_obj[i + 1].addr : sztext_obj;
		if (addr >= sztext_obj || end > sztext_obj) {
			printf("addr OOR: %x-%x '%s'\n", addr, end,
				syms_obj[i].name);
			goto out;
		}
		memset(d_obj + addr, 0xcc, end - addr);
	}

	// parse_headers has set pos to .text
	ret = fwrite(d_obj, 1, sztext_obj, f_obj);
	my_assert(ret, sztext_obj);

	fclose(f_obj);
	fclose(f_exe);

	retval = 0;
out:
	return retval;
}
Commit	Line	Data
cfd23479	1	#include <stdio.h>
	2	#include <stdlib.h>
	3	#include <string.h>
	4	#include <linux/coff.h>
	5	#include <assert.h>
	6	#include <stdint.h>
	7
ede51255	8	#include "my_assert.h"
ede51255	9
cfd23479	10	/* http://www.delorie.com/djgpp/doc/coff/ */
	11
	12	typedef struct {
	13	unsigned short f_magic; /* magic number */
	14	unsigned short f_nscns; /* number of sections */
	15	unsigned int f_timdat; /* time & date stamp */
	16	unsigned int f_symptr; /* file pointer to symtab */
	17	unsigned int f_nsyms; /* number of symtab entries */
	18	unsigned short f_opthdr; /* sizeof(optional hdr) */
	19	unsigned short f_flags; /* flags */
	20	} FILHDR;
	21
	22	typedef struct {
	23	unsigned short magic; /* type of file */
	24	unsigned short vstamp; /* version stamp */
	25	unsigned int tsize; /* text size in bytes, padded to FW bdry*/
	26	unsigned int dsize; /* initialized data " " */
	27	unsigned int bsize; /* uninitialized data " " */
	28	unsigned int entry; /* entry pt. */
	29	unsigned int text_start; /* base of text used for this file */
	30	unsigned int data_start; /* base of data used for this file */
	31	} AOUTHDR;
	32
	33	typedef struct {
	34	char s_name[8]; /* section name */
	35	unsigned int s_paddr; /* physical address, aliased s_nlib */
	36	unsigned int s_vaddr; /* virtual address */
	37	unsigned int s_size; /* section size */
	38	unsigned int s_scnptr; /* file ptr to raw data for section */
	39	unsigned int s_relptr; /* file ptr to relocation */
	40	unsigned int s_lnnoptr; /* file ptr to line numbers */
	41	unsigned short s_nreloc; /* number of relocation entries */
	42	unsigned short s_nlnno; /* number of line number entries */
	43	unsigned int s_flags; /* flags */
	44	} SCNHDR;
	45
	46	typedef struct {
	47	unsigned int r_vaddr; /* address of relocation */
	48	unsigned int r_symndx; /* symbol we're adjusting for */
	49	unsigned short r_type; /* type of relocation */
	50	} __attribute__((packed)) RELOC;
	51
e86c9ee6	52	typedef struct {
	53	union {
	54	char e_name[E_SYMNMLEN];
	55	struct {
	56	unsigned int e_zeroes;
	57	unsigned int e_offset;
	58	} e;
	59	} e;
	60	unsigned int e_value;
	61	short e_scnum;
	62	unsigned short e_type;
	63	unsigned char e_sclass;
	64	unsigned char e_numaux;
	65	} __attribute__((packed)) SYMENT;
	66
	67	#define C_EXT 2
	68
	69	struct my_symtab {
	70	unsigned int addr;
	71	unsigned int fpos; // for patching
	72	char *name;
	73	};
	74
e86c9ee6	75	static int symt_cmp(const void p1_, const void p2_)
	76	{
	77	const struct my_symtab p1 = p1_, p2 = p2_;
	78	return p1->addr - p2->addr;
	79	}
	80
cfd23479	81	void parse_headers(FILE f, unsigned int base_out,
cfd23479	82	long sect_ofs, uint8_t sect_data, long sect_sz,
e86c9ee6	83	RELOC *relocs, long reloc_cnt,
e86c9ee6	84	struct my_symtab *symtab_out, long sym_cnt)
cfd23479	85	{
e86c9ee6	86	struct my_symtab *symt_o = NULL;
e86c9ee6	87	char *stringtab = NULL;
cfd23479	88	unsigned int base = 0;
e86c9ee6	89	int text_scnum = 0;
	90	long filesize;
	91	char symname[9];
cfd23479	92	long opthdr_pos;
	93	long reloc_size;
	94	FILHDR hdr;
	95	AOUTHDR opthdr;
	96	SCNHDR scnhdr;
e86c9ee6	97	SYMENT syment;
e86c9ee6	98	int i, s, val;
cfd23479	99	int ret;
cfd23479	100
e86c9ee6	101	ret = fseek(f, 0, SEEK_END);
	102	my_assert(ret, 0);
	103
	104	filesize = ftell(f);
	105
	106	ret = fseek(f, 0, SEEK_SET);
	107	my_assert(ret, 0);
	108
cfd23479	109	ret = fread(&hdr, 1, sizeof(hdr), f);
	110	my_assert(ret, sizeof(hdr));
	111
	112	if (hdr.f_magic == 0x5a4d) // MZ
	113	{
	114	ret = fseek(f, 0x3c, SEEK_SET);
	115	my_assert(ret, 0);
	116	ret = fread(&val, 1, sizeof(val), f);
	117	my_assert(ret, sizeof(val));
	118
	119	ret = fseek(f, val, SEEK_SET);
	120	my_assert(ret, 0);
	121	ret = fread(&val, 1, sizeof(val), f);
	122	my_assert(ret, sizeof(val));
	123	my_assert(val, 0x4550); // PE
	124
	125	// should be COFF now
	126	ret = fread(&hdr, 1, sizeof(hdr), f);
	127	my_assert(ret, sizeof(hdr));
	128	}
	129
	130	my_assert(hdr.f_magic, COFF_I386MAGIC);
	131
	132	if (hdr.f_opthdr != 0)
	133	{
	134	opthdr_pos = ftell(f);
	135
	136	if (hdr.f_opthdr < sizeof(opthdr))
	137	my_assert(1, 0);
	138
	139	ret = fread(&opthdr, 1, sizeof(opthdr), f);
	140	my_assert(ret, sizeof(opthdr));
	141	my_assert(opthdr.magic, COFF_ZMAGIC);
	142
2c605b97	143	//printf("text_start: %x\n", opthdr.text_start);
cfd23479	144
	145	if (hdr.f_opthdr > sizeof(opthdr)) {
	146	ret = fread(&base, 1, sizeof(base), f);
	147	my_assert(ret, sizeof(base));
2c605b97	148	//printf("base: %x\n", base);
cfd23479	149	}
	150	ret = fseek(f, opthdr_pos + hdr.f_opthdr, SEEK_SET);
	151	my_assert(ret, 0);
	152	}
	153
e86c9ee6	154	// note: assuming first non-empty one is .text ..
cfd23479	155	for (s = 0; s < hdr.f_nscns; s++) {
	156	ret = fread(&scnhdr, 1, sizeof(scnhdr), f);
	157	my_assert(ret, sizeof(scnhdr));
	158
e86c9ee6	159	if (scnhdr.s_size != 0) {
e86c9ee6	160	text_scnum = s + 1;
cfd23479	161	break;
e86c9ee6	162	}
cfd23479	163	}
cfd23479	164
2c605b97	165	#if 0
e86c9ee6	166	printf("f_nsyms: %x\n", hdr.f_nsyms);
cfd23479	167	printf("s_name: '%s'\n", scnhdr.s_name);
	168	printf("s_vaddr: %x\n", scnhdr.s_vaddr);
	169	printf("s_size: %x\n", scnhdr.s_size);
e86c9ee6	170	//printf("s_scnptr: %x\n", scnhdr.s_scnptr);
cfd23479	171	printf("s_nreloc: %x\n", scnhdr.s_nreloc);
cfd23479	172	printf("--\n");
2c605b97	173	#endif
cfd23479	174
	175	ret = fseek(f, scnhdr.s_scnptr, SEEK_SET);
	176	my_assert(ret, 0);
	177
	178	*sect_data = malloc(scnhdr.s_size);
	179	my_assert_not(*sect_data, NULL);
	180	ret = fread(*sect_data, 1, scnhdr.s_size, f);
	181	my_assert(ret, scnhdr.s_size);
	182
	183	*sect_ofs = scnhdr.s_scnptr;
	184	*sect_sz = scnhdr.s_size;
	185
e86c9ee6	186	// relocs
cfd23479	187	ret = fseek(f, scnhdr.s_relptr, SEEK_SET);
	188	my_assert(ret, 0);
	189
	190	reloc_size = scnhdr.s_nreloc * sizeof((*relocs)[0]);
	191	*relocs = malloc(reloc_size + 1);
	192	my_assert_not(*relocs, NULL);
	193	ret = fread(*relocs, 1, reloc_size, f);
	194	my_assert(ret, reloc_size);
	195
	196	*reloc_cnt = scnhdr.s_nreloc;
	197
e86c9ee6	198	// symtab
	199	if (hdr.f_nsyms != 0) {
	200	symname[8] = 0;
	201
	202	symt_o = malloc(hdr.f_nsyms * sizeof(symt_o[0]) + 1);
	203	my_assert_not(symt_o, NULL);
	204
	205	ret = fseek(f, hdr.f_symptr
	206	+ hdr.f_nsyms * sizeof(syment), SEEK_SET);
	207	my_assert(ret, 0);
	208	ret = fread(&i, 1, sizeof(i), f);
	209	my_assert(ret, sizeof(i));
	210	my_assert((unsigned int)i < filesize, 1);
	211
	212	stringtab = malloc(i);
	213	my_assert_not(stringtab, NULL);
	214	memset(stringtab, 0, 4);
	215	ret = fread(stringtab + 4, 1, i - 4, f);
	216	my_assert(ret, i - 4);
	217
	218	ret = fseek(f, hdr.f_symptr, SEEK_SET);
	219	my_assert(ret, 0);
	220	}
	221
	222	for (i = s = 0; i < hdr.f_nsyms; i++) {
	223	long pos = ftell(f);
	224
	225	ret = fread(&syment, 1, sizeof(syment), f);
	226	my_assert(ret, sizeof(syment));
	227
	228	strncpy(symname, syment.e.e_name, 8);
	229	//printf("%3d %2d %08x '%s'\n", syment.e_sclass,
	230	// syment.e_scnum, syment.e_value, symname);
	231
	232	if (syment.e_scnum != text_scnum \|\| syment.e_sclass != C_EXT)
	233	continue;
	234
	235	symt_o[s].addr = syment.e_value;
	236	symt_o[s].fpos = pos;
	237	if (syment.e.e.e_zeroes == 0)
	238	symt_o[s].name = stringtab + syment.e.e.e_offset;
	239	else
	240	symt_o[s].name = strdup(symname);
	241	s++;
	242
	243	if (syment.e_numaux) {
	244	ret = fseek(f, syment.e_numaux * sizeof(syment),
	245	SEEK_CUR);
	246	my_assert(ret, 0);
	247	i += syment.e_numaux;
	248	}
	249	}
	250
	251	if (symt_o != NULL)
	252	qsort(symt_o, s, sizeof(symt_o[0]), symt_cmp);
	253
	254	*sym_cnt = s;
	255	*symtab_out = symt_o;
	256
2c605b97	257	// seek to .text start
	258	ret = fseek(f, scnhdr.s_scnptr, SEEK_SET);
	259	my_assert(ret, 0);
	260
e86c9ee6	261	if (base != 0 && base_out != NULL)
cfd23479	262	*base_out = base + scnhdr.s_vaddr;
	263	}
	264
	265	static int handle_pad(uint8_t d_obj, uint8_t d_exe, int maxlen)
	266	{
	267	static const uint8_t p7[7] = { 0x8d, 0xa4, 0x24, 0x00, 0x00, 0x00, 0x00 };
	268	static const uint8_t p6[6] = { 0x8d, 0x9b, 0x00, 0x00, 0x00, 0x00 };
	269	static const uint8_t p5[5] = { 0x05, 0x00, 0x00, 0x00, 0x00 };
	270	static const uint8_t p4[4] = { 0x8d, 0x64, 0x24, 0x00 };
	271	static const uint8_t p3[3] = { 0x8d, 0x49, 0x00 };
	272	static const uint8_t p2[2] = { 0x8b, 0xff };
	273	static const uint8_t p1[1] = { 0x90 };
	274	int len;
	275	int i;
	276
	277	for (i = 0; i < maxlen; i++)
	278	if (d_exe[i] != 0xcc)
	279	break;
	280
	281	for (len = i; len > 0; )
	282	{
	283	i = len;
	284	if (i > 7)
	285	i = 7;
	286
	287	switch (i) {
	288	#define CASE(x) \
	289	case sizeof(p ## x): \
	290	if (memcmp(d_obj, p ## x, sizeof(p ## x))) \
	291	return 0; \
	292	memset(d_obj, 0xcc, sizeof(p ## x)); \
	293	break;
	294	CASE(7)
	295	CASE(6)
	296	CASE(5)
	297	CASE(4)
	298	CASE(3)
	299	CASE(2)
	300	CASE(1)
	301	default:
	302	printf("%s: unhandled len: %d\n", __func__, len);
	303	return 0;
	304	#undef CASE
	305	}
	306
	307	len -= i;
	308	d_obj += i;
	309	}
	310
	311	return 1;
	312	}
	313
	314	struct equiv_opcode {
	315	signed char len;
	316	signed char ofs;
	317	short cmp_rm;
	318	uint8_t v_masm[8];
	319	uint8_t v_masm_mask[8];
	320	uint8_t v_msvc[8];
	321	uint8_t v_msvc_mask[8];
	322	} equiv_ops[] = {
	323	// cmp $0x11,%ax
	324	{ 4, -1, 0,
	325	{ 0x66,0x83,0xf8,0x03 }, { 0xff,0xff,0xff,0x00 },
326	{ 0x66,0x3d,0x03,0x00 }, { 0xff,0xff,0x00,0xff }, },
327	// lea -0x1(%ebx,%eax,1),%esi // op mod/rm sib offs
328	// mov, test, imm grp 1
329	{ 3, -2, 1,
330	{ 0x8d,0x74,0x03 }, { 0xf0,0x07,0xc0 },
331	{ 0x8d,0x74,0x18 }, { 0xf0,0x07,0xc0 }, },
332	// movzbl 0x58f24a(%eax,%ecx,1),%eax
333	{ 4, -3, 1,
334	{ 0x0f,0xb6,0x84,0x08 }, { 0xff,0xff,0x07,0xc0 },
335	{ 0x0f,0xb6,0x84,0x01 }, { 0xff,0xff,0x07,0xc0 }, },
336	// inc/dec
337	{ 3, -2, 1,
338	{ 0xfe,0x4c,0x03 }, { 0xfe,0xff,0xc0 },
339	{ 0xfe,0x4c,0x18 }, { 0xfe,0xff,0xc0 }, },
340	// cmp
341	{ 3, -2, 1,
342	{ 0x38,0x0c,0x0c }, { 0xff,0xff,0xc0 },
343	{ 0x38,0x0c,0x30 }, { 0xff,0xff,0xc0 }, },
344	// test %dl,%bl
345	{ 2, -1, 1,
346	{ 0x84,0xd3 }, { 0xfe,0xc0 },
347	{ 0x84,0xda }, { 0xfe,0xc0 }, },
348	// cmp r,r/m vs rm/r
349	{ 2, 0, 1,
350	{ 0x3a,0xca }, { 0xff,0xc0 },
351	{ 0x38,0xd1 }, { 0xff,0xc0 }, },
352	// rep + 66 prefix
353	{ 2, 0, 0,
354	{ 0xf3,0x66 }, { 0xfe,0xff },
355	{ 0x66,0xf3 }, { 0xff,0xfe }, },
356	// fadd st, st(0) vs st(0), st
357	{ 2, 0, 0,
358	{ 0xd8,0xc0 }, { 0xff,0xf7 },
359	{ 0xdc,0xc0 }, { 0xff,0xf7 }, },
360
361	// broad filters (may take too much..)
362	// testb $0x4,0x1d(%esi,%eax,1)
363	// movb, push, ..
364	{ 3, -2, 1,
365	{ 0xf6,0x44,0x06 }, { 0x00,0x07,0xc0 },
366	{ 0xf6,0x44,0x30 }, { 0x00,0x07,0xc0 }, },
367	};
368
369	static int cmp_mask(uint8_t d, uint8_t expect, uint8_t *mask, int len)
370	{
371	int i;
372
373	for (i = 0; i < len; i++)
374	if ((d[i] & mask[i]) != (expect[i] & mask[i]))
375	return 1;
376
377	return 0;
378	}
379
380	static int check_equiv(uint8_t d_obj, uint8_t d_exe, int maxlen)
381	{
382	uint8_t vo, ve, vo2, ve2;
383	int i, jo, je;
384	int len, ofs;
385
386	for (i = 0; i < sizeof(equiv_ops) / sizeof(equiv_ops[0]); i++)
387	{
388	struct equiv_opcode *op = &equiv_ops[i];
389
390	len = op->len;
391	if (maxlen < len)
392	continue;
393
394	ofs = op->ofs;
395	if (cmp_mask(d_obj + ofs, op->v_masm,
396	op->v_masm_mask, len))
397	continue;
398	if (cmp_mask(d_exe + ofs, op->v_msvc,
399	op->v_msvc_mask, len))
400	continue;
401
402	jo = je = 0;
403	d_obj += ofs;
404	d_exe += ofs;
405	while (1)
406	{
407	for (; jo < len; jo++)
408	if (op->v_masm_mask[jo] != 0xff)
409	break;
410	for (; je < len; je++)
411	if (op->v_msvc_mask[je] != 0xff)
412	break;
413
414	if ((jo == len && je != len) \|\| (jo != len && je == len)) {
415	printf("invalid equiv_ops\n");
416	return -1;
417	}
418	if (jo == len)
419	return len + ofs - 1; // matched
420
421	// var byte
422	vo = d_obj[jo] & ~op->v_masm_mask[jo];
423	ve = d_exe[je] & ~op->v_msvc_mask[je];
424	if (op->cmp_rm && op->v_masm_mask[jo] == 0xc0) {
425	vo2 = vo >> 3;
426	vo &= 7;
427	ve2 = ve & 7;
428	ve >>= 3;
429	if (vo != ve \|\| vo2 != ve2)
430	return -1;
431	}
432	else {
433	if (vo != ve)
434	return -1;
435	}
436
437	jo++;
438	je++;
439	}
440	}
441
442	return -1;
443	}
444
445	int main(int argc, char *argv[])
446	{
447	FILE f_obj, f_exe;
448	long text_ofs_obj, text_ofs_exe;
449	long sztext_obj, sztext_exe, sztext_cmn;
450	RELOC relocs_obj, relocs_exe;
e86c9ee6	451	long reloc_cnt_obj, reloc_cnt_exe;
	452	struct my_symtab syms_obj, syms_exe;
	453	long sym_cnt_obj, sym_cnt_exe;
cfd23479	454	uint8_t d_obj, d_exe;
2c605b97	455	unsigned int base = 0, addr, end;
cfd23479	456	int retval = 1;
	457	int left;
	458	int ret;
	459	int i;
	460
	461	if (argc != 3) {
e86c9ee6	462	printf("usage:\n%s <a_obj> <exe>\n", argv[0]);
cfd23479	463	return 1;
	464	}
	465
	466	f_obj = fopen(argv[1], "r+b");
	467	if (f_obj == NULL) {
	468	fprintf(stderr, "%s", argv[1]);
	469	perror("");
	470	return 1;
	471	}
	472
	473	f_exe = fopen(argv[2], "r");
	474	if (f_exe == NULL) {
e86c9ee6	475	fprintf(stderr, "%s", argv[2]);
cfd23479	476	perror("");
	477	return 1;
	478	}
	479
e86c9ee6	480	parse_headers(f_obj, NULL, &text_ofs_obj, &d_obj, &sztext_obj,
e86c9ee6	481	&relocs_obj, &reloc_cnt_obj, &syms_obj, &sym_cnt_obj);
cfd23479	482	parse_headers(f_exe, &base, &text_ofs_exe, &d_exe, &sztext_exe,
e86c9ee6	483	&relocs_exe, &reloc_cnt_exe, &syms_exe, &sym_cnt_exe);
cfd23479	484
	485	sztext_cmn = sztext_obj;
	486	if (sztext_cmn > sztext_exe)
	487	sztext_cmn = sztext_exe;
cfd23479	488
	489	if (sztext_cmn == 0) {
	490	printf("bad .text size(s): %ld, %ld\n",
	491	sztext_obj, sztext_exe);
	492	return 1;
	493	}
	494
e86c9ee6	495	for (i = 0; i < reloc_cnt_obj; i++)
cfd23479	496	{
	497	unsigned int a = relocs_obj[i].r_vaddr;
	498	//printf("%04x %08x\n", relocs_obj[i].r_type, a);
	499
	500	switch (relocs_obj[i].r_type) {
2c605b97	501	case 0x06: // RELOC_ADDR32
	502	case 0x14: // RELOC_REL32
	503	// must preserve stored val,
	504	// so trash d_exe so that cmp passes
	505	memcpy(d_exe + a, d_obj + a, 4);
cfd23479	506	break;
cfd23479	507	default:
2c605b97	508	printf("unknown reloc %x @%08x/%08x\n",
2c605b97	509	relocs_obj[i].r_type, a, base + a);
cfd23479	510	return 1;
	511	}
	512	}
	513
	514	for (i = 0; i < sztext_cmn; i++)
	515	{
	516	if (d_obj[i] == d_exe[i])
	517	continue;
	518
	519	left = sztext_cmn - i;
	520
	521	if (d_exe[i] == 0xcc) { // padding
	522	if (handle_pad(d_obj + i, d_exe + i, left))
	523	continue;
	524	}
	525
	526	ret = check_equiv(d_obj + i, d_exe + i, left);
	527	if (ret >= 0) {
	528	i += ret;
	529	continue;
	530	}
	531
	532	printf("%x: %02x vs %02x\n", base + i, d_obj[i], d_exe[i]);
	533	goto out;
	534	}
	535
2c605b97	536	for (i = 0; i < sym_cnt_obj; i++) {
	537	if (strncmp(syms_obj[i].name, "rm_", 3))
	538	continue;
	539
	540	addr = syms_obj[i].addr;
	541	end = (i < sym_cnt_obj - 1)
	542	? syms_obj[i + 1].addr : sztext_obj;
	543	if (addr >= sztext_obj \|\| end > sztext_obj) {
	544	printf("addr OOR: %x-%x '%s'\n", addr, end,
	545	syms_obj[i].name);
	546	goto out;
	547	}
	548	memset(d_obj + addr, 0xcc, end - addr);
	549	}
	550
	551	// parse_headers has set pos to .text
	552	ret = fwrite(d_obj, 1, sztext_obj, f_obj);
	553	my_assert(ret, sztext_obj);
	554
	555	fclose(f_obj);
	556	fclose(f_exe);
	557
	558	retval = 0;
cfd23479	559	out:
	560	return retval;
	561	}