object generation: added mdso_objgen_symfn().

1 files changed, 226 insertions, 0 deletions

diff --git a/src/object/mdso_objgen_symfn.c b/src/object/mdso_objgen_symfn.c
new file mode 100644
index 0000000..5644f4c
--- /dev/null
+++ b/src/object/mdso_objgen_symfn.c
@@ -0,0 +1,226 @@
+/****************************************************************/
+/*  mdso: midipix dso scavenger                                 */
+/*  Copyright (C) 2015--2017  Z. Gilboa                         */
+/*  Released under GPLv2 and GPLv3; see COPYING.MDSO.           */
+/****************************************************************/
+
+#include <stdio.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <mdso/mdso.h>
+#include "mdso_object_impl.h"
+#include "mdso_errinfo_impl.h"
+#include "perk_consts.h"
+#include "perk_structs.h"
+
+static const unsigned char jmp_code_i386[16] = {
+	0xff,0x25,
+	0x0,0x0,0x0,0x0,
+	0x90,0x90,
+	0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0
+};
+
+static const unsigned char jmp_code_amd64[16] = {
+	0xff,0x24,0x25,
+	0x0,0x0,0x0,0x0,
+	0x90,
+	0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90
+};
+
+struct mdso_symfn_code {
+	unsigned char 	code[16];
+};
+
+struct mdso_symfn_object {
+	struct pe_raw_coff_object_hdr	hdr;
+	struct pe_raw_sec_hdr		sec[1];
+	struct mdso_symfn_code		cod[1];
+	struct pe_raw_coff_reloc	rel[1];
+	struct pe_raw_coff_symbol	sym[7];
+	struct pe_raw_coff_strtbl	cst;
+};
+
+int mdso_objgen_symfn(
+	const struct mdso_driver_ctx *	dctx,
+	const char *			sym,
+	FILE *				fout,
+	struct mdso_object *		vobj)
+{
+	struct mdso_symfn_object *	symfn;
+	struct pe_raw_coff_symbol *	symrec;
+	const unsigned char *		code;
+	unsigned char *			mark;
+	struct pe_aux_rec_section *	aux;
+	size_t				buflen;
+	uint32_t			symlen;
+	uint32_t			cstlen;
+	uint32_t			objlen;
+	uint32_t			aattr;
+	uint32_t			sattr;
+	uint16_t			oattr;
+	uint16_t			machine;
+	uint16_t			reltype;
+	uint32_t			relrva;
+	uint32_t			reloff;
+	uint32_t			symoff;
+	uint32_t			cstoff;
+	uint32_t			codoff;
+	uint32_t			datoff;
+
+	if ((buflen = strlen(sym)) > 1024*1024)
+		return MDSO_CUSTOM_ERROR(dctx,MDSO_ERR_INVALID_DATA);
+
+	symlen = (uint32_t)buflen;
+	cstlen = (3 * symlen) + 32;
+	objlen = sizeof(*symfn) + cstlen;
+
+	if (vobj && vobj->addr && (vobj->size < objlen))
+		return MDSO_BUFFER_ERROR(dctx);
+
+	if (vobj && !vobj->addr) {
+		vobj->size = objlen;
+		return 0;
+	}
+
+	if (vobj)
+		symfn = (struct mdso_symfn_object *)vobj->addr;
+
+	else if (!(symfn = calloc(1,objlen)))
+		return MDSO_SYSTEM_ERROR(dctx);
+
+	if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
+		code    = jmp_code_amd64;
+		aattr   = PE_IMAGE_SCN_ALIGN_16BYTES;
+		machine = PE_IMAGE_FILE_MACHINE_AMD64;
+		reltype = PE_IMAGE_REL_AMD64_ADDR32;
+		relrva  = 3;
+	} else {
+		code    = jmp_code_i386;
+		aattr   = PE_IMAGE_SCN_ALIGN_4BYTES;
+		machine = PE_IMAGE_FILE_MACHINE_I386;
+		reltype = PE_IMAGE_REL_I386_DIR32;
+		relrva  = 2;
+	}
+
+	sattr  = aattr;
+	sattr |= PE_IMAGE_SCN_MEM_READ;
+	sattr |= PE_IMAGE_SCN_MEM_EXECUTE;
+	sattr |= PE_IMAGE_SCN_CNT_CODE;
+
+	oattr  = PE_IMAGE_FILE_LINE_NUMS_STRIPPED;
+	reloff = offsetof(struct mdso_symfn_object,rel);
+	symoff = offsetof(struct mdso_symfn_object,sym);
+	codoff = offsetof(struct mdso_symfn_object,cod);
+	cstoff = offsetof(struct pe_raw_coff_strtbl,cst_data);
+	datoff = 0;
+
+	/* coff object header */
+	mdso_obj_write_short(symfn->hdr.cfh_machine,machine);
+	mdso_obj_write_short(symfn->hdr.cfh_num_of_sections,1);
+	mdso_obj_write_long(symfn->hdr.cfh_ptr_to_sym_tbl,symoff);
+	mdso_obj_write_long(symfn->hdr.cfh_num_of_syms,7);
+	mdso_obj_write_short(symfn->hdr.cfh_characteristics,oattr);
+
+	/* .text section header */
+	memcpy(symfn->sec[0].sh_name,".text",5);
+	mdso_obj_write_long(symfn->sec[0].sh_size_of_raw_data,16);
+	mdso_obj_write_long(symfn->sec[0].sh_ptr_to_raw_data,codoff);
+	mdso_obj_write_long(symfn->sec[0].sh_ptr_to_relocs,reloff);
+	mdso_obj_write_short(symfn->sec[0].sh_num_of_relocs,1);
+	mdso_obj_write_long(symfn->sec[0].sh_characteristics,sattr);
+
+	/* .text section content */
+	memcpy(symfn->cod,code,16);
+
+	/* .text relocation record */
+	mdso_obj_write_long(symfn->rel[0].rel_sym,6);
+	mdso_obj_write_long(symfn->rel[0].rel_rva,relrva);
+	mdso_obj_write_short(symfn->rel[0].rel_type,reltype);
+
+	/* coff string table */
+	mdso_obj_write_long(symfn->cst.cst_size,cstlen);
+
+	/* coff symbol table */
+	symrec = symfn->sym;
+	mark   = symfn->cst.cst_data;
+
+	/* coff symbol: .file */
+	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_FILE;
+	symrec[0].cs_num_of_aux_symbols[0] = 1;
+
+	mdso_obj_write_short(&symrec[0].cs_section_number[0],PE_IMAGE_SYM_DEBUG);
+	mdso_obj_write_long(&symrec[1].cs_name[4],cstoff+datoff);
+
+	memcpy(symrec[0].cs_name,".file",5);
+	memcpy(&mark[0],"__",2);
+	memcpy(&mark[2],sym,symlen);
+	memcpy(&mark[2+symlen],"_sym_fn.s",9);
+
+	datoff += 12 + symlen;
+	mark   += 12 + symlen;
+	symrec += 2;
+
+	/* coff symbol: .text */
+	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_STATIC;
+	symrec[0].cs_num_of_aux_symbols[0] = 1;
+
+	mdso_obj_write_short(symrec[0].cs_section_number,1);
+	memcpy(symrec[0].cs_name,".text",5);
+
+	aux = (struct pe_aux_rec_section *)&symrec[1];
+	mdso_obj_write_long(aux->aux_size,relrva+4);
+	mdso_obj_write_short(aux->aux_num_of_relocs,1);
+
+	datoff += 0;
+	mark   += 0;
+	symrec += 2;
+
+	/* coff symbol: sym */
+	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_EXTERNAL;
+	symrec[0].cs_num_of_aux_symbols[0] = 1;
+
+	mdso_obj_write_short(symrec[0].cs_type,PE_IMAGE_SYM_DTYPE_FUNCTION<<8);
+	mdso_obj_write_short(symrec[0].cs_section_number,1);
+	mdso_obj_write_long(&symrec[0].cs_name[4],cstoff+datoff);
+
+	if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
+		memcpy(&mark[0],sym,symlen);
+	} else {
+		memcpy(&mark[1],sym,symlen);
+		mark[0] = '_';
+		datoff++;
+		mark++;
+	}
+
+	datoff += 1 + symlen;
+	mark   += 1 + symlen;
+	symrec += 2;
+
+	/* coff symbol: __imp_sym */
+	symrec[0].cs_storage_class[0] = PE_IMAGE_SYM_CLASS_EXTERNAL;
+	symrec[0].cs_num_of_aux_symbols[0] = 0;
+
+	mdso_obj_write_short(symrec[0].cs_section_number,0);
+	mdso_obj_write_long(&symrec[0].cs_name[4],cstoff+datoff);
+
+	if (dctx->cctx->drvflags & MDSO_DRIVER_QUAD_PTR) {
+		memcpy(&mark[0],"__imp_",6);
+		memcpy(&mark[6],sym,symlen);
+	} else {
+		memcpy(&mark[0],"__imp_",6);
+		memcpy(&mark[7],sym,symlen);
+		mark[6] = '_';
+		datoff++;
+		mark++;
+	}
+
+	/* tada */
+	if (fout)
+		if (fwrite(symfn,objlen,1,fout) == 0)
+			return MDSO_FILE_ERROR(dctx);
+
+	return 0;
+}