/*
 * "elfsubr.c"
 *
 */
#include <libelf.h>
#include <string.h>
#include "elfsubr.h"

int
sym_val64(Elf *elf, char *sym_name, __uint64_t *value)
{
	/* this static is here so that if the same file is repeatedly checked,
	   the code isn't repeated */
	static Elf *oldelf = NULL;
	static Elf_Scn *symtab_scn;
	static Elf64_Shdr *symtab_shdr;

	Elf64_Sym *symtab;
	int symtab_size, i;

	/* see if we have correct symtab */
	if (elf != oldelf) {
		symtab_scn = find_section(elf, ".symtab");
		symtab_shdr = elf64_getshdr(symtab_scn);
	}

	symtab = (Elf64_Sym *)(elf_getdata(symtab_scn, NULL)->d_buf);
	symtab_size = (int) ((elf_getdata(symtab_scn, NULL)->d_size)
			     / sizeof(Elf64_Sym));

	/* keep looking at entries until the right one is found */
	for(i = 0; i < symtab_size; i++)
		if (strcmp(sym_name,
		    elf_strptr(elf, symtab_shdr->sh_link, symtab[i].st_name))
		    == 0)
			break;

	if (i == symtab_size)
		return 1;

	*value = symtab[i].st_value;
	return 0;
}

int
sym_val32(Elf *elf, char *sym_name, __uint32_t *value)
{
	/* this static is here so that if the same file is repeatedly checked,
	   the code isn't repeated */
	static Elf *oldelf = NULL;
	static Elf_Scn *symtab_scn;
	static Elf32_Shdr *symtab_shdr;

	Elf32_Sym *symtab;
	int symtab_size, i;

	/* see if we have correct symtab */
	if (elf != oldelf) {
		symtab_scn = find_section(elf, ".symtab");
		symtab_shdr = elf32_getshdr(symtab_scn);
	}

	symtab = (Elf32_Sym *)(elf_getdata(symtab_scn, NULL)->d_buf);
	symtab_size = (int ) ((elf_getdata(symtab_scn, NULL)->d_size)
			      / sizeof(Elf32_Sym));

	/* keep looking at entries until the right one is found */
	for(i = 0; i < symtab_size; i++)
		if (strcmp(sym_name,
		    elf_strptr(elf, symtab_shdr->sh_link, symtab[i].st_name))
		    == 0)
			break;

	if (i == symtab_size)
		return 1;

	*value = symtab[i].st_value;
	return 0;
}

int
elf_type(Elf *elf)
{
	/* these statics are here so that if the same file is repeatedly
	   checked, the code isn't repeated */
	static Elf *oldelf = NULL;
	static int oldtype;

	if (elf == oldelf)
		return(oldtype);
	/* otherwise do calculations */
	else
	{
		unsigned char MipsElf32Ident[EI_NIDENT] = {
			0x7f, 'E', 'L', 'F',
			ELFCLASS32, ELFDATA2MSB, EV_CURRENT,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
		};
		unsigned char MipsElf64Ident[EI_NIDENT] = {
			0x7f, 'E', 'L', 'F',
			ELFCLASS64, ELFDATA2MSB, EV_CURRENT,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
		};
		char *elf_ident;

		oldelf = elf;
		if ((elf_ident = elf_getident(elf, NULL)) == NULL)
			return((oldtype = ELF_NONE));

		if (memcmp(MipsElf32Ident, elf_ident, EI_NIDENT) == 0)
			return((oldtype = ELF_MIPS32));
		else if (memcmp(MipsElf64Ident, elf_ident, EI_NIDENT) == 0)
			return((oldtype = ELF_MIPS64));
		else
			return((oldtype = ELF_UNKNOWN));
	}
}





/*
 * returns section with the name of scn_name, & puts its header in shdr64 or
 * shdr32 based on elf's file type
 *
 */
Elf_Scn *
find_section(Elf *elf, char *scn_name)
{
	Elf64_Ehdr *ehdr64;
	Elf32_Ehdr *ehdr32;
	Elf_Scn *scn = NULL;
	Elf64_Shdr *shdr64;
	Elf32_Shdr *shdr32;

	if (elf_type(elf) == ELF_MIPS64) {
		if ((ehdr64 = elf64_getehdr(elf)) == NULL)
			return(NULL);
		do {
			if ((scn = elf_nextscn(elf, scn)) == NULL)
				break;
			if ((shdr64 = elf64_getshdr(scn)) == NULL)
				return(NULL);
		} while (strcmp(scn_name, elf_strptr(elf, ehdr64->e_shstrndx,
							  shdr64->sh_name)));
	}
	else if (elf_type(elf) == ELF_MIPS32) {
		if ((ehdr32 = elf32_getehdr(elf)) == NULL)
			return(NULL);
		do {
			if ((scn = elf_nextscn(elf, scn)) == NULL)
				break;
			if ((shdr32 = elf32_getshdr(scn)) == NULL)
				return(NULL);
		} while (strcmp(scn_name, elf_strptr(elf, ehdr32->e_shstrndx,
							  shdr32->sh_name)));
	}
	else
		scn = NULL;

	return(scn);	
}