[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;
};

struct my_sect_info {
	long scnhdr_fofs;
	long sect_fofs;
	long reloc_fofs;
	uint8_t *data;
	long size;
	RELOC *relocs;
	long reloc_cnt;
};

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,
	struct my_sect_info *sect_i,
	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++) {
		sect_i->scnhdr_fofs = ftell(f);

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

		if (scnhdr.s_size != 0) {
			text_scnum = s + 1;
			break;
		}
	}
	my_assert(s < hdr.f_nscns, 1);

#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_i->data = malloc(scnhdr.s_size);
	my_assert_not(sect_i->data, NULL);
	ret = fread(sect_i->data, 1, scnhdr.s_size, f);
	my_assert(ret, scnhdr.s_size);

	sect_i->sect_fofs = scnhdr.s_scnptr;
	sect_i->size = scnhdr.s_size;

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

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

	sect_i->reloc_cnt = scnhdr.s_nreloc;
	sect_i->reloc_fofs = scnhdr.s_relptr;

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

	if (symtab_out == NULL || sym_cnt == NULL)
		return;

	// 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;
}

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;
}

static void fill_int3(unsigned char *d, int len)
{
	while (len-- > 0) {
		if (*d == 0xcc)
			break;
		*d++ = 0xcc;
	}
}

int main(int argc, char *argv[])
{
	struct my_sect_info s_text_obj, s_text_exe;
	struct my_symtab *syms_obj = NULL;
	long sym_cnt_obj;
	FILE *f_obj, *f_exe;
	unsigned int base = 0, addr, end;
	SCNHDR tmphdr;
	long sztext_cmn;
	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, &s_text_obj, &syms_obj, &sym_cnt_obj);
	parse_headers(f_exe, &base, &s_text_exe, NULL, NULL);

	sztext_cmn = s_text_obj.size;
	if (sztext_cmn > s_text_exe.size)
		sztext_cmn = s_text_exe.size;

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

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

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

	for (i = 0; i < sztext_cmn; i++)
	{
		if (s_text_obj.data[i] == s_text_exe.data[i])
			continue;

		left = sztext_cmn - i;

		if (s_text_exe.data[i] == 0xcc) { // padding
			if (handle_pad(s_text_obj.data + i,
			    s_text_exe.data + i, left))
				continue;
		}

		ret = check_equiv(s_text_obj.data + i, s_text_exe.data + i, left);
		if (ret >= 0) {
			i += ret;
			continue;
		}

		printf("%x: %02x vs %02x\n", base + i,
			s_text_obj.data[i], s_text_exe.data[i]);
		goto out;
	}

	// fill removed funcs with 'int3'
	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 : s_text_obj.size;
		if (addr >= s_text_obj.size || end > s_text_obj.size) {
			printf("addr OOR: %x-%x '%s'\n", addr, end,
				syms_obj[i].name);
			goto out;
		}
		fill_int3(s_text_obj.data + addr, end - addr);
	}

	// remove relocs
	for (i = 0; i < s_text_obj.reloc_cnt; i++) {
		addr = s_text_obj.relocs[i].r_vaddr;
		if (addr > s_text_obj.size - 4) {
			printf("reloc addr OOR: %x\n", addr);
			goto out;
		}
		if (*(unsigned int *)(s_text_obj.data + addr) == 0xcccccccc) {
			memmove(&s_text_obj.relocs[i],
				&s_text_obj.relocs[i + 1],
				(s_text_obj.reloc_cnt - i - 1)
				 * sizeof(s_text_obj.relocs[0]));
			i--;
			s_text_obj.reloc_cnt--;
		}
	}

	// patch .text
	ret = fseek(f_obj, s_text_obj.sect_fofs, SEEK_SET);
	my_assert(ret, 0);
	ret = fwrite(s_text_obj.data, 1, s_text_obj.size, f_obj);
	my_assert(ret, s_text_obj.size);

	// patch relocs
	ret = fseek(f_obj, s_text_obj.reloc_fofs, SEEK_SET);
	my_assert(ret, 0);
	ret = fwrite(s_text_obj.relocs, sizeof(s_text_obj.relocs[0]),
		s_text_obj.reloc_cnt, f_obj);
	my_assert(ret, s_text_obj.reloc_cnt);

	ret = fseek(f_obj, s_text_obj.scnhdr_fofs, SEEK_SET);
	my_assert(ret, 0);
	ret = fread(&tmphdr, 1, sizeof(tmphdr), f_obj);
	my_assert(ret, sizeof(tmphdr));

	tmphdr.s_nreloc = s_text_obj.reloc_cnt;

	ret = fseek(f_obj, s_text_obj.scnhdr_fofs, SEEK_SET);
	my_assert(ret, 0);
	ret = fwrite(&tmphdr, 1, sizeof(tmphdr), f_obj);
	my_assert(ret, sizeof(tmphdr));

	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
572a6bea	75	struct my_sect_info {
	76	long scnhdr_fofs;
	77	long sect_fofs;
	78	long reloc_fofs;
	79	uint8_t *data;
	80	long size;
	81	RELOC *relocs;
	82	long reloc_cnt;
	83	};
	84
e86c9ee6	85	static int symt_cmp(const void p1_, const void p2_)
	86	{
	87	const struct my_symtab p1 = p1_, p2 = p2_;
	88	return p1->addr - p2->addr;
	89	}
	90
cfd23479	91	void parse_headers(FILE f, unsigned int base_out,
572a6bea	92	struct my_sect_info *sect_i,
e86c9ee6	93	struct my_symtab *symtab_out, long sym_cnt)
cfd23479	94	{
e86c9ee6	95	struct my_symtab *symt_o = NULL;
e86c9ee6	96	char *stringtab = NULL;
cfd23479	97	unsigned int base = 0;
e86c9ee6	98	int text_scnum = 0;
	99	long filesize;
	100	char symname[9];
cfd23479	101	long opthdr_pos;
	102	long reloc_size;
	103	FILHDR hdr;
	104	AOUTHDR opthdr;
	105	SCNHDR scnhdr;
e86c9ee6	106	SYMENT syment;
e86c9ee6	107	int i, s, val;
cfd23479	108	int ret;
cfd23479	109
e86c9ee6	110	ret = fseek(f, 0, SEEK_END);
	111	my_assert(ret, 0);
	112
	113	filesize = ftell(f);
	114
	115	ret = fseek(f, 0, SEEK_SET);
	116	my_assert(ret, 0);
	117
cfd23479	118	ret = fread(&hdr, 1, sizeof(hdr), f);
	119	my_assert(ret, sizeof(hdr));
	120
	121	if (hdr.f_magic == 0x5a4d) // MZ
	122	{
	123	ret = fseek(f, 0x3c, SEEK_SET);
	124	my_assert(ret, 0);
	125	ret = fread(&val, 1, sizeof(val), f);
	126	my_assert(ret, sizeof(val));
	127
	128	ret = fseek(f, val, SEEK_SET);
	129	my_assert(ret, 0);
	130	ret = fread(&val, 1, sizeof(val), f);
	131	my_assert(ret, sizeof(val));
	132	my_assert(val, 0x4550); // PE
	133
	134	// should be COFF now
	135	ret = fread(&hdr, 1, sizeof(hdr), f);
	136	my_assert(ret, sizeof(hdr));
	137	}
	138
	139	my_assert(hdr.f_magic, COFF_I386MAGIC);
	140
	141	if (hdr.f_opthdr != 0)
	142	{
	143	opthdr_pos = ftell(f);
	144
	145	if (hdr.f_opthdr < sizeof(opthdr))
	146	my_assert(1, 0);
	147
	148	ret = fread(&opthdr, 1, sizeof(opthdr), f);
	149	my_assert(ret, sizeof(opthdr));
	150	my_assert(opthdr.magic, COFF_ZMAGIC);
	151
2c605b97	152	//printf("text_start: %x\n", opthdr.text_start);
cfd23479	153
	154	if (hdr.f_opthdr > sizeof(opthdr)) {
	155	ret = fread(&base, 1, sizeof(base), f);
	156	my_assert(ret, sizeof(base));
2c605b97	157	//printf("base: %x\n", base);
cfd23479	158	}
	159	ret = fseek(f, opthdr_pos + hdr.f_opthdr, SEEK_SET);
	160	my_assert(ret, 0);
	161	}
	162
e86c9ee6	163	// note: assuming first non-empty one is .text ..
cfd23479	164	for (s = 0; s < hdr.f_nscns; s++) {
572a6bea	165	sect_i->scnhdr_fofs = ftell(f);
572a6bea	166
cfd23479	167	ret = fread(&scnhdr, 1, sizeof(scnhdr), f);
	168	my_assert(ret, sizeof(scnhdr));
	169
e86c9ee6	170	if (scnhdr.s_size != 0) {
e86c9ee6	171	text_scnum = s + 1;
cfd23479	172	break;
e86c9ee6	173	}
cfd23479	174	}
572a6bea	175	my_assert(s < hdr.f_nscns, 1);
cfd23479	176
2c605b97	177	#if 0
e86c9ee6	178	printf("f_nsyms: %x\n", hdr.f_nsyms);
cfd23479	179	printf("s_name: '%s'\n", scnhdr.s_name);
	180	printf("s_vaddr: %x\n", scnhdr.s_vaddr);
	181	printf("s_size: %x\n", scnhdr.s_size);
e86c9ee6	182	//printf("s_scnptr: %x\n", scnhdr.s_scnptr);
cfd23479	183	printf("s_nreloc: %x\n", scnhdr.s_nreloc);
cfd23479	184	printf("--\n");
2c605b97	185	#endif
cfd23479	186
	187	ret = fseek(f, scnhdr.s_scnptr, SEEK_SET);
	188	my_assert(ret, 0);
	189
572a6bea	190	sect_i->data = malloc(scnhdr.s_size);
	191	my_assert_not(sect_i->data, NULL);
	192	ret = fread(sect_i->data, 1, scnhdr.s_size, f);
cfd23479	193	my_assert(ret, scnhdr.s_size);
cfd23479	194
572a6bea	195	sect_i->sect_fofs = scnhdr.s_scnptr;
572a6bea	196	sect_i->size = scnhdr.s_size;
cfd23479	197
e86c9ee6	198	// relocs
cfd23479	199	ret = fseek(f, scnhdr.s_relptr, SEEK_SET);
	200	my_assert(ret, 0);
	201
572a6bea	202	reloc_size = scnhdr.s_nreloc * sizeof(sect_i->relocs[0]);
	203	sect_i->relocs = malloc(reloc_size + 1);
	204	my_assert_not(sect_i->relocs, NULL);
	205	ret = fread(sect_i->relocs, 1, reloc_size, f);
cfd23479	206	my_assert(ret, reloc_size);
cfd23479	207
572a6bea	208	sect_i->reloc_cnt = scnhdr.s_nreloc;
	209	sect_i->reloc_fofs = scnhdr.s_relptr;
	210
	211	if (base != 0 && base_out != NULL)
	212	*base_out = base + scnhdr.s_vaddr;
	213
	214	if (symtab_out == NULL \|\| sym_cnt == NULL)
	215	return;
cfd23479	216
e86c9ee6	217	// symtab
	218	if (hdr.f_nsyms != 0) {
	219	symname[8] = 0;
	220
	221	symt_o = malloc(hdr.f_nsyms * sizeof(symt_o[0]) + 1);
	222	my_assert_not(symt_o, NULL);
	223
	224	ret = fseek(f, hdr.f_symptr
	225	+ hdr.f_nsyms * sizeof(syment), SEEK_SET);
	226	my_assert(ret, 0);
	227	ret = fread(&i, 1, sizeof(i), f);
	228	my_assert(ret, sizeof(i));
	229	my_assert((unsigned int)i < filesize, 1);
	230
	231	stringtab = malloc(i);
	232	my_assert_not(stringtab, NULL);
	233	memset(stringtab, 0, 4);
	234	ret = fread(stringtab + 4, 1, i - 4, f);
	235	my_assert(ret, i - 4);
	236
	237	ret = fseek(f, hdr.f_symptr, SEEK_SET);
	238	my_assert(ret, 0);
	239	}
	240
	241	for (i = s = 0; i < hdr.f_nsyms; i++) {
	242	long pos = ftell(f);
	243
	244	ret = fread(&syment, 1, sizeof(syment), f);
	245	my_assert(ret, sizeof(syment));
	246
	247	strncpy(symname, syment.e.e_name, 8);
	248	//printf("%3d %2d %08x '%s'\n", syment.e_sclass,
	249	// syment.e_scnum, syment.e_value, symname);
	250
	251	if (syment.e_scnum != text_scnum \|\| syment.e_sclass != C_EXT)
	252	continue;
	253
	254	symt_o[s].addr = syment.e_value;
	255	symt_o[s].fpos = pos;
	256	if (syment.e.e.e_zeroes == 0)
	257	symt_o[s].name = stringtab + syment.e.e.e_offset;
	258	else
	259	symt_o[s].name = strdup(symname);
	260	s++;
	261
	262	if (syment.e_numaux) {
	263	ret = fseek(f, syment.e_numaux * sizeof(syment),
	264	SEEK_CUR);
	265	my_assert(ret, 0);
	266	i += syment.e_numaux;
	267	}
	268	}
	269
	270	if (symt_o != NULL)
	271	qsort(symt_o, s, sizeof(symt_o[0]), symt_cmp);
	272
	273	*sym_cnt = s;
	274	*symtab_out = symt_o;
cfd23479	275	}
	276
	277	static int handle_pad(uint8_t d_obj, uint8_t d_exe, int maxlen)
	278	{
	279	static const uint8_t p7[7] = { 0x8d, 0xa4, 0x24, 0x00, 0x00, 0x00, 0x00 };
	280	static const uint8_t p6[6] = { 0x8d, 0x9b, 0x00, 0x00, 0x00, 0x00 };
	281	static const uint8_t p5[5] = { 0x05, 0x00, 0x00, 0x00, 0x00 };
	282	static const uint8_t p4[4] = { 0x8d, 0x64, 0x24, 0x00 };
	283	static const uint8_t p3[3] = { 0x8d, 0x49, 0x00 };
	284	static const uint8_t p2[2] = { 0x8b, 0xff };
	285	static const uint8_t p1[1] = { 0x90 };
	286	int len;
	287	int i;
	288
	289	for (i = 0; i < maxlen; i++)
	290	if (d_exe[i] != 0xcc)
	291	break;
	292
	293	for (len = i; len > 0; )
	294	{
	295	i = len;
	296	if (i > 7)
	297	i = 7;
	298
	299	switch (i) {
	300	#define CASE(x) \
	301	case sizeof(p ## x): \
	302	if (memcmp(d_obj, p ## x, sizeof(p ## x))) \
	303	return 0; \
	304	memset(d_obj, 0xcc, sizeof(p ## x)); \
	305	break;
	306	CASE(7)
	307	CASE(6)
	308	CASE(5)
	309	CASE(4)
	310	CASE(3)
	311	CASE(2)
	312	CASE(1)
	313	default:
	314	printf("%s: unhandled len: %d\n", __func__, len);
	315	return 0;
	316	#undef CASE
	317	}
	318
	319	len -= i;
	320	d_obj += i;
	321	}
	322
	323	return 1;
	324	}
	325
	326	struct equiv_opcode {
	327	signed char len;
	328	signed char ofs;
	329	short cmp_rm;
	330	uint8_t v_masm[8];
	331	uint8_t v_masm_mask[8];
	332	uint8_t v_msvc[8];
	333	uint8_t v_msvc_mask[8];
	334	} equiv_ops[] = {
	335	// cmp $0x11,%ax
	336	{ 4, -1, 0,
	337	{ 0x66,0x83,0xf8,0x03 }, { 0xff,0xff,0xff,0x00 },
	338	{ 0x66,0x3d,0x03,0x00 }, { 0xff,0xff,0x00,0xff }, },
339	// lea -0x1(%ebx,%eax,1),%esi // op mod/rm sib offs
340	// mov, test, imm grp 1
341	{ 3, -2, 1,
342	{ 0x8d,0x74,0x03 }, { 0xf0,0x07,0xc0 },
343	{ 0x8d,0x74,0x18 }, { 0xf0,0x07,0xc0 }, },
344	// movzbl 0x58f24a(%eax,%ecx,1),%eax
345	{ 4, -3, 1,
346	{ 0x0f,0xb6,0x84,0x08 }, { 0xff,0xff,0x07,0xc0 },
347	{ 0x0f,0xb6,0x84,0x01 }, { 0xff,0xff,0x07,0xc0 }, },
348	// inc/dec
349	{ 3, -2, 1,
350	{ 0xfe,0x4c,0x03 }, { 0xfe,0xff,0xc0 },
351	{ 0xfe,0x4c,0x18 }, { 0xfe,0xff,0xc0 }, },
352	// cmp
353	{ 3, -2, 1,
354	{ 0x38,0x0c,0x0c }, { 0xff,0xff,0xc0 },
355	{ 0x38,0x0c,0x30 }, { 0xff,0xff,0xc0 }, },
356	// test %dl,%bl
357	{ 2, -1, 1,
358	{ 0x84,0xd3 }, { 0xfe,0xc0 },
359	{ 0x84,0xda }, { 0xfe,0xc0 }, },
360	// cmp r,r/m vs rm/r
361	{ 2, 0, 1,
362	{ 0x3a,0xca }, { 0xff,0xc0 },
363	{ 0x38,0xd1 }, { 0xff,0xc0 }, },
364	// rep + 66 prefix
365	{ 2, 0, 0,
366	{ 0xf3,0x66 }, { 0xfe,0xff },
367	{ 0x66,0xf3 }, { 0xff,0xfe }, },
368	// fadd st, st(0) vs st(0), st
369	{ 2, 0, 0,
370	{ 0xd8,0xc0 }, { 0xff,0xf7 },
371	{ 0xdc,0xc0 }, { 0xff,0xf7 }, },
372
373	// broad filters (may take too much..)
374	// testb $0x4,0x1d(%esi,%eax,1)
375	// movb, push, ..
376	{ 3, -2, 1,
377	{ 0xf6,0x44,0x06 }, { 0x00,0x07,0xc0 },
378	{ 0xf6,0x44,0x30 }, { 0x00,0x07,0xc0 }, },
379	};
380
381	static int cmp_mask(uint8_t d, uint8_t expect, uint8_t *mask, int len)
382	{
383	int i;
384
385	for (i = 0; i < len; i++)
386	if ((d[i] & mask[i]) != (expect[i] & mask[i]))
387	return 1;
388
389	return 0;
390	}
391
392	static int check_equiv(uint8_t d_obj, uint8_t d_exe, int maxlen)
393	{
394	uint8_t vo, ve, vo2, ve2;
395	int i, jo, je;
396	int len, ofs;
397
398	for (i = 0; i < sizeof(equiv_ops) / sizeof(equiv_ops[0]); i++)
399	{
400	struct equiv_opcode *op = &equiv_ops[i];
401
402	len = op->len;
403	if (maxlen < len)
404	continue;
405
406	ofs = op->ofs;
407	if (cmp_mask(d_obj + ofs, op->v_masm,
408	op->v_masm_mask, len))
409	continue;
410	if (cmp_mask(d_exe + ofs, op->v_msvc,
411	op->v_msvc_mask, len))
412	continue;
413
414	jo = je = 0;
415	d_obj += ofs;
416	d_exe += ofs;
417	while (1)
418	{
419	for (; jo < len; jo++)
420	if (op->v_masm_mask[jo] != 0xff)
421	break;
422	for (; je < len; je++)
423	if (op->v_msvc_mask[je] != 0xff)
424	break;
425
426	if ((jo == len && je != len) \|\| (jo != len && je == len)) {
427	printf("invalid equiv_ops\n");
428	return -1;
429	}
430	if (jo == len)
431	return len + ofs - 1; // matched
432
433	// var byte
434	vo = d_obj[jo] & ~op->v_masm_mask[jo];
435	ve = d_exe[je] & ~op->v_msvc_mask[je];
436	if (op->cmp_rm && op->v_masm_mask[jo] == 0xc0) {
437	vo2 = vo >> 3;
438	vo &= 7;
439	ve2 = ve & 7;
440	ve >>= 3;
441	if (vo != ve \|\| vo2 != ve2)
442	return -1;
443	}
444	else {
445	if (vo != ve)
446	return -1;
447	}
448
449	jo++;
450	je++;
451	}
452	}
453
454	return -1;
455	}
456
572a6bea	457	static void fill_int3(unsigned char *d, int len)
	458	{
	459	while (len-- > 0) {
	460	if (*d == 0xcc)
	461	break;
	462	*d++ = 0xcc;
	463	}
	464	}
	465
cfd23479	466	int main(int argc, char *argv[])
cfd23479	467	{
572a6bea	468	struct my_sect_info s_text_obj, s_text_exe;
	469	struct my_symtab *syms_obj = NULL;
	470	long sym_cnt_obj;
cfd23479	471	FILE f_obj, f_exe;
2c605b97	472	unsigned int base = 0, addr, end;
572a6bea	473	SCNHDR tmphdr;
572a6bea	474	long sztext_cmn;
cfd23479	475	int retval = 1;
	476	int left;
	477	int ret;
	478	int i;
	479
	480	if (argc != 3) {
e86c9ee6	481	printf("usage:\n%s <a_obj> <exe>\n", argv[0]);
cfd23479	482	return 1;
	483	}
	484
	485	f_obj = fopen(argv[1], "r+b");
	486	if (f_obj == NULL) {
	487	fprintf(stderr, "%s", argv[1]);
	488	perror("");
	489	return 1;
	490	}
	491
	492	f_exe = fopen(argv[2], "r");
	493	if (f_exe == NULL) {
e86c9ee6	494	fprintf(stderr, "%s", argv[2]);
cfd23479	495	perror("");
	496	return 1;
	497	}
	498
572a6bea	499	parse_headers(f_obj, NULL, &s_text_obj, &syms_obj, &sym_cnt_obj);
572a6bea	500	parse_headers(f_exe, &base, &s_text_exe, NULL, NULL);
cfd23479	501
572a6bea	502	sztext_cmn = s_text_obj.size;
	503	if (sztext_cmn > s_text_exe.size)
	504	sztext_cmn = s_text_exe.size;
cfd23479	505
	506	if (sztext_cmn == 0) {
	507	printf("bad .text size(s): %ld, %ld\n",
572a6bea	508	s_text_obj.size, s_text_exe.size);
cfd23479	509	return 1;
	510	}
	511
572a6bea	512	for (i = 0; i < s_text_obj.reloc_cnt; i++)
cfd23479	513	{
572a6bea	514	unsigned int a = s_text_obj.relocs[i].r_vaddr;
572a6bea	515	//printf("%04x %08x\n", s_text_obj.relocs[i].r_type, a);
cfd23479	516
572a6bea	517	switch (s_text_obj.relocs[i].r_type) {
2c605b97	518	case 0x06: // RELOC_ADDR32
	519	case 0x14: // RELOC_REL32
	520	// must preserve stored val,
572a6bea	521	// so trash exe so that cmp passes
572a6bea	522	memcpy(s_text_exe.data + a, s_text_obj.data + a, 4);
cfd23479	523	break;
cfd23479	524	default:
2c605b97	525	printf("unknown reloc %x @%08x/%08x\n",
572a6bea	526	s_text_obj.relocs[i].r_type, a, base + a);
cfd23479	527	return 1;
	528	}
	529	}
	530
	531	for (i = 0; i < sztext_cmn; i++)
	532	{
572a6bea	533	if (s_text_obj.data[i] == s_text_exe.data[i])
cfd23479	534	continue;
	535
	536	left = sztext_cmn - i;
	537
572a6bea	538	if (s_text_exe.data[i] == 0xcc) { // padding
	539	if (handle_pad(s_text_obj.data + i,
	540	s_text_exe.data + i, left))
cfd23479	541	continue;
	542	}
	543
572a6bea	544	ret = check_equiv(s_text_obj.data + i, s_text_exe.data + i, left);
cfd23479	545	if (ret >= 0) {
	546	i += ret;
	547	continue;
	548	}
	549
572a6bea	550	printf("%x: %02x vs %02x\n", base + i,
572a6bea	551	s_text_obj.data[i], s_text_exe.data[i]);
cfd23479	552	goto out;
	553	}
	554
572a6bea	555	// fill removed funcs with 'int3'
2c605b97	556	for (i = 0; i < sym_cnt_obj; i++) {
	557	if (strncmp(syms_obj[i].name, "rm_", 3))
	558	continue;
	559
	560	addr = syms_obj[i].addr;
	561	end = (i < sym_cnt_obj - 1)
572a6bea	562	? syms_obj[i + 1].addr : s_text_obj.size;
572a6bea	563	if (addr >= s_text_obj.size \|\| end > s_text_obj.size) {
2c605b97	564	printf("addr OOR: %x-%x '%s'\n", addr, end,
	565	syms_obj[i].name);
	566	goto out;
	567	}
572a6bea	568	fill_int3(s_text_obj.data + addr, end - addr);
	569	}
	570
	571	// remove relocs
	572	for (i = 0; i < s_text_obj.reloc_cnt; i++) {
	573	addr = s_text_obj.relocs[i].r_vaddr;
	574	if (addr > s_text_obj.size - 4) {
	575	printf("reloc addr OOR: %x\n", addr);
	576	goto out;
	577	}
	578	if ((unsigned int )(s_text_obj.data + addr) == 0xcccccccc) {
	579	memmove(&s_text_obj.relocs[i],
	580	&s_text_obj.relocs[i + 1],
	581	(s_text_obj.reloc_cnt - i - 1)
	582	* sizeof(s_text_obj.relocs[0]));
	583	i--;
	584	s_text_obj.reloc_cnt--;
	585	}
2c605b97	586	}
2c605b97	587
572a6bea	588	// patch .text
	589	ret = fseek(f_obj, s_text_obj.sect_fofs, SEEK_SET);
	590	my_assert(ret, 0);
	591	ret = fwrite(s_text_obj.data, 1, s_text_obj.size, f_obj);
	592	my_assert(ret, s_text_obj.size);
	593
	594	// patch relocs
	595	ret = fseek(f_obj, s_text_obj.reloc_fofs, SEEK_SET);
	596	my_assert(ret, 0);
	597	ret = fwrite(s_text_obj.relocs, sizeof(s_text_obj.relocs[0]),
	598	s_text_obj.reloc_cnt, f_obj);
	599	my_assert(ret, s_text_obj.reloc_cnt);
	600
	601	ret = fseek(f_obj, s_text_obj.scnhdr_fofs, SEEK_SET);
	602	my_assert(ret, 0);
	603	ret = fread(&tmphdr, 1, sizeof(tmphdr), f_obj);
	604	my_assert(ret, sizeof(tmphdr));
	605
	606	tmphdr.s_nreloc = s_text_obj.reloc_cnt;
	607
	608	ret = fseek(f_obj, s_text_obj.scnhdr_fofs, SEEK_SET);
	609	my_assert(ret, 0);
	610	ret = fwrite(&tmphdr, 1, sizeof(tmphdr), f_obj);
	611	my_assert(ret, sizeof(tmphdr));
2c605b97	612
	613	fclose(f_obj);
	614	fclose(f_exe);
	615
	616	retval = 0;
cfd23479	617	out:
	618	return retval;
	619	}