mirror of https://github.com/0intro/libelf
744 lines
12 KiB
C
744 lines
12 KiB
C
#include <stdio.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 <inttypes.h>
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#include "bele.h"
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#include "elf.h"
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#include "dat.h"
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#include "fns.h"
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static int verbose;
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typedef struct Data Data;
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typedef struct Class Class;
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struct Data {
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int type;
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char *name;
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unsigned int (*get8)(void*, uint8_t*);
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unsigned int (*get16)(void*, uint16_t*);
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unsigned int (*get32)(void*, uint32_t*);
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unsigned int (*get64)(void*, uint64_t*);
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};
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struct Class {
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int type;
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char *name;
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int ehsize;
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int shentsize;
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int phentsize;
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int (*readelfehdr)(FILE*, Fhdr*);
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int (*readelfshdr)(FILE*, Fhdr*);
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int (*readelfphdr)(FILE*, Fhdr*);
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int (*readelfstrndx)(FILE*, Fhdr*);
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};
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static int readelf32ehdr(FILE*, Fhdr*);
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static int readelf32shdr(FILE*, Fhdr*);
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static int readelf32phdr(FILE*, Fhdr*);
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static int readelf32strndx(FILE*, Fhdr*);
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static int readelf64ehdr(FILE*, Fhdr*);
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static int readelf64shdr(FILE*, Fhdr*);
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static int readelf64phdr(FILE*, Fhdr*);
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static int readelf64strndx(FILE*, Fhdr*);
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static Data data[] = {
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{
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ELFDATANONE,
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"invalid",
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NULL,
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NULL,
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NULL,
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NULL
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},
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{
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ELFDATA2LSB,
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"little-endian",
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le8get,
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le16get,
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le32get,
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le64get
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},
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{
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ELFDATA2MSB,
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"big-endian",
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be8get,
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be16get,
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be32get,
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be64get
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}
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};
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static Class class[] = {
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{
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ELFCLASSNONE,
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"invalid",
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0,
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0,
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0,
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NULL,
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NULL,
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NULL,
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NULL,
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},
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{
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ELFCLASS32,
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"32-bit",
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sizeof(Elf32_Ehdr),
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sizeof(Elf32_Shdr),
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sizeof(Elf32_Phdr),
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readelf32ehdr,
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readelf32shdr,
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readelf32phdr,
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readelf32strndx,
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},
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{
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ELFCLASS64,
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"64-bit",
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sizeof(Elf64_Ehdr),
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sizeof(Elf64_Shdr),
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sizeof(Elf64_Phdr),
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readelf64ehdr,
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readelf64shdr,
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readelf64phdr,
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readelf64strndx,
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}
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};
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/*
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* Read ELF32 Header
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*/
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static int
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readelf32ehdr(FILE *f, Fhdr *fp)
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{
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uint8_t buf[Eh32sz];
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Elf32_Ehdr e;
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uint8_t *p;
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p = buf;
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fseek(f, 0, SEEK_SET);
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if (fread(p, fp->ehsize, 1, f) != 1)
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return -1;
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memmove(&e.ident, p, sizeof(e.ident));
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p += sizeof(e.ident);
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p += fp->get16(p, &e.type);
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p += fp->get16(p, &e.machine);
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p += fp->get32(p, &e.version);
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p += fp->get32(p, &e.entry);
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p += fp->get32(p, &e.phoff);
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p += fp->get32(p, &e.shoff);
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p += fp->get32(p, &e.flags);
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p += fp->get16(p, &e.ehsize);
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p += fp->get16(p, &e.phentsize);
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p += fp->get16(p, &e.phnum);
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p += fp->get16(p, &e.shentsize);
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p += fp->get16(p, &e.shnum);
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p += fp->get16(p, &e.shstrndx);
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if (verbose)
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printelf32ehdr(&e, fp);
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if (e.type != ET_REL && e.type != ET_EXEC) {
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fprintf(stderr, "unsupported file type %d\n", e.type);
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return -1;
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}
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if (fp->ehsize != e.ehsize) {
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fprintf(stderr, "ehsize mismatch; want %u; got %u\n", fp->ehsize, e.ehsize);
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return -1;
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}
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if (fp->shentsize != e.shentsize) {
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fprintf(stderr, "shentsize mismatch; want %u; got %u\n", fp->ehsize, e.ehsize);
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return -1;
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}
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if (fp->phentsize != e.phentsize) {
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fprintf(stderr, "phentsize mismatch; want %u; got %u\n", fp->ehsize, e.ehsize);
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return -1;
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}
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fp->type = e.type;
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fp->machine = e.machine;
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fp->version = e.version;
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fp->entry = e.entry;
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fp->shoff = e.shoff;
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fp->phoff = e.phoff;
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fp->phnum = e.phnum;
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fp->shnum = e.shnum;
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fp->shstrndx = e.shstrndx;
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return p - buf;
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}
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/*
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* Read ELF64 Header
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*/
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static int
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readelf64ehdr(FILE *f, Fhdr *fp)
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{
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uint8_t buf[Eh64sz];
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Elf64_Ehdr e;
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uint8_t *p;
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p = buf;
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fseek(f, 0, SEEK_SET);
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if (fread(p, fp->ehsize , 1, f) != 1)
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return -1;
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memmove(&e.ident, p, sizeof(e.ident));
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p += sizeof(e.ident);
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p += fp->get16(p, &e.type);
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p += fp->get16(p, &e.machine);
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p += fp->get32(p, &e.version);
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p += fp->get64(p, &e.entry);
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p += fp->get64(p, &e.phoff);
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p += fp->get64(p, &e.shoff);
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p += fp->get32(p, &e.flags);
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p += fp->get16(p, &e.ehsize);
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p += fp->get16(p, &e.phentsize);
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p += fp->get16(p, &e.phnum);
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p += fp->get16(p, &e.shentsize);
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p += fp->get16(p, &e.shnum);
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p += fp->get16(p, &e.shstrndx);
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if (verbose)
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printelf64ehdr(&e, fp);
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if (e.type != ET_REL && e.type != ET_EXEC) {
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fprintf(stderr, "unsupported file type %d\n", e.type);
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return -1;
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}
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if (fp->ehsize != e.ehsize) {
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fprintf(stderr, "ehsize mismatch; want %u; got %u\n", fp->ehsize, e.ehsize);
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return -1;
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}
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if (fp->shentsize != e.shentsize) {
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fprintf(stderr, "shentsize mismatch; want %u; got %u\n", fp->ehsize, e.ehsize);
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return -1;
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}
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if (fp->phentsize != e.phentsize) {
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fprintf(stderr, "phentsize mismatch; want %u; got %u\n", fp->ehsize, e.ehsize);
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return -1;
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}
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fp->type = e.type;
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fp->machine = e.machine;
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fp->version = e.version;
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fp->entry = e.entry;
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fp->shoff = e.shoff;
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fp->phoff = e.phoff;
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fp->phnum = e.phnum;
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fp->shnum = e.shnum;
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fp->shstrndx = e.shstrndx;
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return p - buf;
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}
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/*
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* Unpack ELF32 Section Header
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*/
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int
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unpackelf32shdr(uint8_t *buf, int len, Elf32_Shdr *sh, Fhdr *fp)
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{
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uint8_t *p;
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if (len < Sh32sz)
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return -1;
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p = buf;
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p += fp->get32(p, &sh->name);
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p += fp->get32(p, &sh->type);
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p += fp->get32(p, &sh->flags);
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p += fp->get32(p, &sh->addr);
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p += fp->get32(p, &sh->offset);
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p += fp->get32(p, &sh->size);
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p += fp->get32(p, &sh->link);
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p += fp->get32(p, &sh->info);
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p += fp->get32(p, &sh->addralign);
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p += fp->get32(p, &sh->entsize);
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return p - buf;
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}
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/*
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* Read ELF32 Section Header
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*/
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static int
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readelf32shdr(FILE *f, Fhdr *fp)
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{
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uint8_t buf[Sh32sz];
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Elf32_Shdr sh;
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if (fread(buf, fp->shentsize, 1, f) != 1)
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return -1;
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if (unpackelf32shdr(buf, sizeof(buf), &sh, fp) < 0)
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return -1;
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fp->name = sh.name;
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fp->offset = sh.offset;
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fp->size = sh.size;
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if (verbose)
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printelf32shdr(&sh, fp);
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return 0;
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}
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/*
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* Unpack ELF32 Program Header
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*/
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int
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unpackelf32phdr(uint8_t *buf, int len, Elf32_Phdr *ph, Fhdr *fp)
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{
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uint8_t *p;
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if (len < Ph32sz)
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return -1;
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p = buf;
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p += fp->get32(p, &ph->type);
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p += fp->get32(p, &ph->offset);
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p += fp->get32(p, &ph->vaddr);
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p += fp->get32(p, &ph->paddr);
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p += fp->get32(p, &ph->filesz);
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p += fp->get32(p, &ph->memsz);
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p += fp->get32(p, &ph->flags);
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p += fp->get32(p, &ph->align);
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return p - buf;
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}
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/*
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* Read ELF32 Program Header
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*/
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static int
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readelf32phdr(FILE *f, Fhdr *fp)
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{
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uint8_t buf[Ph32sz];
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Elf32_Phdr ph;
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if (fread(buf, fp->phentsize, 1, f) != 1)
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return -1;
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if (unpackelf32phdr(buf, sizeof(buf), &ph, fp) < 0)
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return -1;
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if (verbose)
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printelf32phdr(&ph, fp);
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return 0;
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}
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/*
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* Unpack ELF64 Section Header
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*/
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int
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unpackelf64shdr(uint8_t *buf, int len, Elf64_Shdr *sh, Fhdr *fp)
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{
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uint8_t *p;
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if (len < Sh64sz)
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return -1;
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p = buf;
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p += fp->get32(p, &sh->name);
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p += fp->get32(p, &sh->type);
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p += fp->get64(p, &sh->flags);
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p += fp->get64(p, &sh->addr);
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p += fp->get64(p, &sh->offset);
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p += fp->get64(p, &sh->size);
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p += fp->get32(p, &sh->link);
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p += fp->get32(p, &sh->info);
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p += fp->get64(p, &sh->addralign);
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p += fp->get64(p, &sh->entsize);
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return p - buf;
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}
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/*
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* Read ELF64 Section Header
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*/
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static int
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readelf64shdr(FILE *f, Fhdr *fp)
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{
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uint8_t buf[Sh64sz];
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Elf64_Shdr sh;
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if (fread(buf, fp->shentsize, 1, f) != 1)
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return -1;
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if (unpackelf64shdr(buf, sizeof(buf), &sh, fp) < 0)
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return -1;
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fp->name = sh.name;
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fp->offset = sh.offset;
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fp->size = sh.size;
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if (verbose)
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printelf64shdr(&sh, fp);
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return 0;
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}
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/*
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* Unpack ELF64 Program Header
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*/
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int
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unpackelf64phdr(uint8_t *buf, int len, Elf64_Phdr *ph, Fhdr *fp)
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{
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uint8_t *p;
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if (len < Ph64sz)
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return -1;
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p = buf;
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p += fp->get32(p, &ph->type);
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p += fp->get32(p, &ph->flags);
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p += fp->get64(p, &ph->offset);
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p += fp->get64(p, &ph->vaddr);
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p += fp->get64(p, &ph->paddr);
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p += fp->get64(p, &ph->filesz);
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p += fp->get64(p, &ph->memsz);
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p += fp->get64(p, &ph->align);
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return p - buf;
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}
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/*
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* Read ELF64 Program Header
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*/
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static int
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readelf64phdr(FILE *f, Fhdr *fp)
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{
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uint8_t buf[Ph64sz];
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Elf64_Phdr ph;
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if (fread(buf, fp->phentsize, 1, f) != 1)
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return -1;
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if (unpackelf64phdr(buf, sizeof(buf), &ph, fp) < 0)
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return -1;
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if (verbose)
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printelf64phdr(&ph, fp);
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return 0;
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}
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/*
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* Read ELF ident
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*/
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int
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readident(FILE *f, Fhdr *fp)
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{
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uint8_t buf[EI_NIDENT];
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unsigned int i;
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uint8_t *p;
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fseek(f, 0, SEEK_SET);
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p = buf;
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if (fread(p, EI_NIDENT, 1, f) != 1)
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return -1;
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p += EI_NIDENT;
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if (buf[EI_MAG0] != ELFMAG0)
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return -1;
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if (buf[EI_MAG1] != ELFMAG1)
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return -1;
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if (buf[EI_MAG2] != ELFMAG2)
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return -1;
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if (buf[EI_MAG3] != ELFMAG3)
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return -1;
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if(buf[EI_VERSION] != EV_CURRENT) {
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fprintf(stderr, "unsupported file version %d\n", buf[EI_VERSION]);
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return -1;
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}
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for (i = 0; i < nelem(class); i++) {
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if (buf[EI_CLASS] != class[i].type)
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continue;
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if (class[i].readelfehdr == NULL)
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return -1;
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fp->readelfehdr = class[i].readelfehdr;
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fp->readelfshdr = class[i].readelfshdr;
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fp->readelfphdr = class[i].readelfphdr;
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fp->readelfstrndx = class[i].readelfstrndx;
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fp->ehsize = class[i].ehsize;
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fp->shentsize = class[i].shentsize;
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fp->phentsize = class[i].phentsize;
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break;
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}
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if (i == nelem(class))
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return -1;
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for (i = 0; i < nelem(data); i++) {
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if (buf[EI_DATA] != data[i].type)
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continue;
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if (data[i].get8 == NULL)
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return -1;
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fp->get8 = data[i].get8;
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fp->get16 = data[i].get16;
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fp->get32 = data[i].get32;
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fp->get64 = data[i].get64;
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break;
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}
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if (i == nelem(data))
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return -1;
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fp->class = buf[EI_CLASS];
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fp->data = buf[EI_DATA];
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fp->elfversion = buf[EI_VERSION];
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fp->osabi = buf[EI_OSABI];
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fp->abiversion = buf[EI_ABIVERSION];
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return p - buf;
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}
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/*
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* Read ELF Section Headers
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*/
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int
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readelfshdrs(FILE *f, Fhdr *fp)
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{
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unsigned int i;
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fseek(f, fp->shoff, SEEK_SET);
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for (i = 0; i < fp->shnum; i++) {
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if (fp->readelfshdr(f, fp) < 0)
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return -1;
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}
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return 0;
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}
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/*
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* Read ELF Program Headers
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*/
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int
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readelfphdrs(FILE *f, Fhdr *fp)
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{
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unsigned int i;
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fseek(f, fp->phoff, SEEK_SET);
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for (i = 0; i < fp->phnum; i++) {
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if (fp->readelfphdr(f, fp) < 0)
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return -1;
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}
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return 0;
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}
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/*
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* Read ELF32 String Table
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*/
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static int
|
|
readelf32strndx(FILE *f, Fhdr *fp)
|
|
{
|
|
uint8_t buf[Sh32sz];
|
|
Elf32_Shdr sh;
|
|
|
|
fseek(f, fp->shoff + fp->shstrndx * fp->shentsize, SEEK_SET);
|
|
|
|
if (fread(buf, fp->shentsize, 1, f) != 1)
|
|
return -1;
|
|
|
|
if (unpackelf32shdr(buf, sizeof(buf), &sh, fp) < 0)
|
|
return -1;
|
|
|
|
fp->offset = sh.offset;
|
|
fp->strndxsize = sh.size;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Read ELF64 String Table
|
|
*/
|
|
static int
|
|
readelf64strndx(FILE *f, Fhdr *fp)
|
|
{
|
|
uint8_t buf[Sh64sz];
|
|
Elf64_Shdr sh;
|
|
|
|
fseek(f, fp->shoff + fp->shstrndx * fp->shentsize, SEEK_SET);
|
|
|
|
if (fread(buf, fp->shentsize, 1, f) != 1)
|
|
return -1;
|
|
|
|
if (unpackelf64shdr(buf, sizeof(buf), &sh, fp) < 0)
|
|
return -1;
|
|
|
|
fp->offset = sh.offset;
|
|
fp->strndxsize = sh.size;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static uint8_t*
|
|
newsection(FILE *f, uint64_t offset, uint64_t size)
|
|
{
|
|
uint8_t *sect;
|
|
|
|
sect = malloc(size);
|
|
if (sect == NULL)
|
|
return NULL;
|
|
|
|
fseek(f, offset, SEEK_SET);
|
|
|
|
if (fread(sect, size, 1, f) != 1) {
|
|
free(sect);
|
|
return NULL;
|
|
}
|
|
|
|
return sect;
|
|
}
|
|
|
|
/*
|
|
* Read ELF String Table
|
|
*/
|
|
static int
|
|
readelfstrndx(FILE *f, Fhdr *fp)
|
|
{
|
|
if (fp->shstrndx == SHN_UNDEF) {
|
|
fprintf(stderr, "missing string table\n");
|
|
return -1;
|
|
}
|
|
|
|
if (fp->readelfstrndx(f, fp) < 0)
|
|
return -1;
|
|
|
|
fp->strndx = newsection(f, fp->offset, fp->strndxsize);
|
|
if (fp->strndx == NULL)
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Get string from index in String Table
|
|
*/
|
|
char* getstr(Fhdr *fp, uint32_t i)
|
|
{
|
|
if (fp->strndx == NULL)
|
|
return NULL;
|
|
|
|
if (i >= fp->strndxsize)
|
|
return NULL;
|
|
|
|
return (char*)&fp->strndx[i];
|
|
}
|
|
|
|
/*
|
|
* Read ELF Section Headers
|
|
*/
|
|
uint8_t*
|
|
readelfsect(FILE *f, char *name, Fhdr *fp)
|
|
{
|
|
unsigned int i;
|
|
char *n;
|
|
|
|
fseek(f, fp->shoff, SEEK_SET);
|
|
|
|
for (i = 0; i < fp->shnum; i++) {
|
|
if (fp->readelfshdr(f, fp) < 0)
|
|
return NULL;
|
|
n = getstr(fp, fp->name);
|
|
if (n == NULL)
|
|
return NULL;
|
|
if (strcmp(n, name) == 0)
|
|
return newsection(f, fp->offset, fp->size);
|
|
}
|
|
|
|
fprintf(stderr, "section %s not found\n", name);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Read ELF File
|
|
*/
|
|
int
|
|
readelf(FILE *f, Fhdr *fp)
|
|
{
|
|
memset(fp, 0, sizeof(*fp));
|
|
|
|
if (readident(f, fp) < 0)
|
|
return -1;
|
|
|
|
if (fp->readelfehdr(f, fp) < 0)
|
|
return -1;
|
|
|
|
if (readelfstrndx(f, fp) < 0)
|
|
return -1;
|
|
|
|
if (readelfshdrs(f, fp) < 0)
|
|
return -1;
|
|
|
|
if (readelfphdrs(f, fp) < 0)
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Read ELF Section
|
|
*/
|
|
uint8_t*
|
|
readelfsection(FILE *f, char *name, uint64_t *size, Fhdr *fp)
|
|
{
|
|
uint8_t *sect;
|
|
|
|
memset(fp, 0, sizeof(*fp));
|
|
|
|
if (readident(f, fp) < 0)
|
|
return NULL;
|
|
|
|
if (fp->readelfehdr(f, fp) < 0)
|
|
return NULL;
|
|
|
|
if (readelfstrndx(f, fp) < 0)
|
|
return NULL;
|
|
|
|
sect = readelfsect(f, name, fp);
|
|
if (sect == NULL)
|
|
return NULL;
|
|
|
|
*size = fp->size;
|
|
|
|
return sect;
|
|
}
|
|
|
|
|
|
void
|
|
freeelf(Fhdr *fp)
|
|
{
|
|
if (fp->strndx != NULL)
|
|
free(fp->strndx);
|
|
}
|