Blame src/object/mdso_objgen_symfn.c

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/****************************************************************/
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/*  mdso: midipix dso scavenger                                 */
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/*  Copyright (C) 2015--2017  Z. Gilboa                         */
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/*  Released under GPLv2 and GPLv3; see COPYING.MDSO.           */
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/****************************************************************/
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#include <stdio.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <mdso/mdso.h>
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#include "mdso_object_impl.h"
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#include "mdso_errinfo_impl.h"
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#include "perk_consts.h"
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#include "perk_structs.h"
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static const unsigned char jmp_code_i386[16] = {
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	0xff,0x25,
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	0x0,0x0,0x0,0x0,
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	0x90,0x90,
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	0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0
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};
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static const unsigned char jmp_code_amd64[16] = {
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	0xff,0x24,0x25,
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	0x0,0x0,0x0,0x0,
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	0x90,
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	0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90
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};
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struct mdso_symfn_code {
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	unsigned char 	code[16];
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};
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struct mdso_symfn_object {
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	struct pe_raw_coff_object_hdr	hdr;
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	struct pe_raw_sec_hdr		sec[1];
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	struct mdso_symfn_code		cod[1];
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	struct pe_raw_coff_reloc	rel[1];
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	struct pe_raw_coff_symbol	sym[7];
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	struct pe_raw_coff_strtbl	cst;
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};
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int mdso_objgen_symfn(
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	const struct mdso_driver_ctx *	dctx,
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	const char *			sym,
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	FILE *				fout,
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	struct mdso_object *		vobj)
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{
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	struct mdso_symfn_object *	symfn;
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	struct pe_raw_coff_symbol *	symrec;
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	const unsigned char *		code;
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	unsigned char *			mark;
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	struct pe_aux_rec_section *	aux;
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	size_t				buflen;
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	uint32_t			symlen;
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	uint32_t			cstlen;
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	uint32_t			objlen;
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	uint32_t			aattr;
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	uint32_t			sattr;
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	uint16_t			oattr;
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	uint16_t			machine;
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	uint16_t			reltype;
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	uint32_t			relrva;
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	uint32_t			reloff;
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	uint32_t			symoff;
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	uint32_t			cstoff;
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	uint32_t			codoff;
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	uint32_t			datoff;
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	if ((buflen = strlen(sym)) > 1024*1024)
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		return MDSO_CUSTOM_ERROR(dctx,MDSO_ERR_INVALID_DATA);
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	symlen = (uint32_t)buflen;
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	cstlen = (3 * symlen) + 32;
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	objlen = sizeof(*symfn) + cstlen;
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	if (vobj && vobj->addr && (vobj->size < objlen))
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		return MDSO_BUFFER_ERROR(dctx);
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	if (vobj && !vobj->addr) {
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		vobj->size = objlen;
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		return 0;
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	}
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	if (vobj)
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		symfn = (struct mdso_symfn_object *)vobj->addr;
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	else if (!(symfn = calloc(1,objlen)))
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		return MDSO_SYSTEM_ERROR(dctx);
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	if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
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		code    = jmp_code_amd64;
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		aattr   = PE_IMAGE_SCN_ALIGN_16BYTES;
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		machine = PE_IMAGE_FILE_MACHINE_AMD64;
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		reltype = PE_IMAGE_REL_AMD64_ADDR32;
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		relrva  = 3;
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	} else {
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		code    = jmp_code_i386;
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		aattr   = PE_IMAGE_SCN_ALIGN_4BYTES;
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		machine = PE_IMAGE_FILE_MACHINE_I386;
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		reltype = PE_IMAGE_REL_I386_DIR32;
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		relrva  = 2;
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	}
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	sattr  = aattr;
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	sattr |= PE_IMAGE_SCN_MEM_READ;
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	sattr |= PE_IMAGE_SCN_MEM_EXECUTE;
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	sattr |= PE_IMAGE_SCN_CNT_CODE;
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	oattr  = PE_IMAGE_FILE_LINE_NUMS_STRIPPED;
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	reloff = offsetof(struct mdso_symfn_object,rel);
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	symoff = offsetof(struct mdso_symfn_object,sym);
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	codoff = offsetof(struct mdso_symfn_object,cod);
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	cstoff = offsetof(struct pe_raw_coff_strtbl,cst_data);
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	datoff = 0;
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	/* coff object header */
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	mdso_obj_write_short(symfn->hdr.cfh_machine,machine);
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	mdso_obj_write_short(symfn->hdr.cfh_num_of_sections,1);
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	mdso_obj_write_long(symfn->hdr.cfh_ptr_to_sym_tbl,symoff);
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	mdso_obj_write_long(symfn->hdr.cfh_num_of_syms,7);
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	mdso_obj_write_short(symfn->hdr.cfh_characteristics,oattr);
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	/* .text section header */
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	memcpy(symfn->sec[0].sh_name,".text",5);
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	mdso_obj_write_long(symfn->sec[0].sh_size_of_raw_data,16);
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	mdso_obj_write_long(symfn->sec[0].sh_ptr_to_raw_data,codoff);
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	mdso_obj_write_long(symfn->sec[0].sh_ptr_to_relocs,reloff);
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	mdso_obj_write_short(symfn->sec[0].sh_num_of_relocs,1);
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	mdso_obj_write_long(symfn->sec[0].sh_characteristics,sattr);
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	/* .text section content */
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	memcpy(symfn->cod,code,16);
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	/* .text relocation record */
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	mdso_obj_write_long(symfn->rel[0].rel_sym,6);
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	mdso_obj_write_long(symfn->rel[0].rel_rva,relrva);
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	mdso_obj_write_short(symfn->rel[0].rel_type,reltype);
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	/* coff string table */
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	mdso_obj_write_long(symfn->cst.cst_size,cstlen);
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	/* coff symbol table */
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	symrec = symfn->sym;
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	mark   = symfn->cst.cst_data;
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	/* coff symbol: .file */
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	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_FILE;
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	symrec[0].cs_num_of_aux_symbols[0] = 1;
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	mdso_obj_write_short(&symrec[0].cs_section_number[0],PE_IMAGE_SYM_DEBUG);
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	mdso_obj_write_long(&symrec[1].cs_name[4],cstoff+datoff);
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	memcpy(symrec[0].cs_name,".file",5);
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	memcpy(&mark[0],".",1);
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	memcpy(&mark[1],sym,symlen);
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	memcpy(&mark[1+symlen],"_symfn.s",8);
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	datoff += 10 + symlen;
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	mark   += 10 + symlen;
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	symrec += 2;
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	/* coff symbol: .text */
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	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_STATIC;
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	symrec[0].cs_num_of_aux_symbols[0] = 1;
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	mdso_obj_write_short(symrec[0].cs_section_number,1);
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	memcpy(symrec[0].cs_name,".text",5);
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	aux = (struct pe_aux_rec_section *)&symrec[1];
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	mdso_obj_write_long(aux->aux_size,relrva+4);
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	mdso_obj_write_short(aux->aux_num_of_relocs,1);
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	datoff += 0;
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	mark   += 0;
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	symrec += 2;
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	/* coff symbol: sym */
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	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_EXTERNAL;
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	symrec[0].cs_num_of_aux_symbols[0] = 1;
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	mdso_obj_write_short(symrec[0].cs_type,PE_IMAGE_SYM_DTYPE_FUNCTION<<8);
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	mdso_obj_write_short(symrec[0].cs_section_number,1);
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	mdso_obj_write_long(&symrec[0].cs_name[4],cstoff+datoff);
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	if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
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		memcpy(&mark[0],sym,symlen);
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	} else {
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		memcpy(&mark[1],sym,symlen);
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		mark[0] = '_';
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		datoff++;
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		mark++;
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	}
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	datoff += 1 + symlen;
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	mark   += 1 + symlen;
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	symrec += 2;
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	/* coff symbol: __imp_sym */
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	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_EXTERNAL;
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	symrec[0].cs_num_of_aux_symbols[0] = 0;
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	mdso_obj_write_short(symrec[0].cs_section_number,0);
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	mdso_obj_write_long(&symrec[0].cs_name[4],cstoff+datoff);
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	if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
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		memcpy(&mark[0],"__imp_",6);
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		memcpy(&mark[6],sym,symlen);
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	} else {
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		memcpy(&mark[0],"__imp_",6);
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		memcpy(&mark[7],sym,symlen);
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		mark[6] = '_';
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		datoff++;
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		mark++;
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	}
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	/* tada */
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	if (fout)
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		if (fwrite(symfn,objlen,1,fout) == 0)
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			return MDSO_FILE_ERROR(dctx);
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	if (!vobj)
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		free(symfn);
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	return 0;
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}