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/*
* Copyright (C) 2014 Google, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef ELFPARSING_H
#define ELFPARSING_H
#include "elf.h"
#include "common.h"
struct parsed_elf {
Elf64_Ehdr ehdr;
Elf64_Phdr *phdr;
Elf64_Shdr *shdr;
/*
* The relocs array contains pointers to arrays of relocation
* structures. Each index into the relocs array corresponds to its
* corresponding section index. i.e. if a section i is of type SHT_REL
* or SHT_RELA then the corresponding index into the relocs array will
* contain the associated relocations. Otherwise thee entry will be
* NULL.
*/
Elf64_Rela **relocs;
/*
* Similarly to the relocs array the strtabs array consists of an
* array of pointers where each entry represents a potential struct
* buffer pointer. Only setions of type SHT_STRTAB will have a non-NULL
* entry.
*/
struct buffer **strtabs;
/* Parsed symbols. */
Elf64_Sym *syms;
};
#define ELF_PARSE_PHDR (1 << 0)
#define ELF_PARSE_SHDR (1 << 1)
#define ELF_PARSE_RELOC (1 << 2)
#define ELF_PARSE_STRTAB (1 << 3)
#define ELF_PARSE_SYMTAB (1 << 4)
#define ELF_PARSE_ALL (-1)
/*
* Parse an ELF file contained within provide struct buffer. The ELF header
* is always parsed while the flags value containing the ELF_PARSE_* values
* determine if other parts of the ELF file will be parsed as well.
* Returns 0 on success, < 0 error.
*/
int parse_elf(const struct buffer *pinput, struct parsed_elf *pelf, int flags);
/*
* Clean up memory associated with parsed_elf.
*/
void parsed_elf_destroy(struct parsed_elf *pelf);
int
elf_headers(const struct buffer *pinput,
Elf64_Ehdr *ehdr,
Elf64_Phdr **pphdr,
Elf64_Shdr **pshdr);
/* ELF writing support. */
struct elf_writer;
/*
* Initialize a 64-bit ELF header provided the inputs. While the structure
* is a 64-bit header one can specify a 32-bit machine. The 64-bit version
* is just used as a common structure. If one wants to specify the entry
* point, for example, the caller can set it after filling in the common
* bits. The machine, nbits, and endian values should be from the ELF
* definitions (e.g. EM_386, ELFCLASS32, and ELFDATA2LSB) found in elf.h
* with no endian conversion required.
*/
void elf_init_eheader(Elf64_Ehdr *ehdr, int machine, int nbits, int endian);
/*
* Initialize a new ELF writer. Default machine type, endianness, etc is
* copied from the passed in Elf64_Ehdr. Returns NULL on failure, valid
* pointer on success.
*/
struct elf_writer *elf_writer_init(const Elf64_Ehdr *ehdr);
/*
* Clean up any internal state represented by ew. Aftewards the elf_writer
* is invalid.
* It is safe to call elf_writer_destroy with ew as NULL. It returns without
* performing any action.
*/
void elf_writer_destroy(struct elf_writer *ew);
/*
* Add a section to the ELF file. Section type, flags, and memsize are
* maintained from the passed in Elf64_Shdr. The buffer represents the
* content of the section while the name is the name of section itself.
* Returns < 0 on error, 0 on success.
*/
int elf_writer_add_section(struct elf_writer *ew, const Elf64_Shdr *shdr,
struct buffer *contents, const char *name);
/* Add an absolute symbol to the ELF file returning < 0 on error, index of
* symbol otherwise. */
int elf_writer_add_symbol(struct elf_writer *ew, const char *name,
const char *section_name,
Elf64_Addr value, Elf64_Word size,
int binding, int type);
/* Add an absolute relocation referencing the provided symbol name. Returns < 0
* on error, 0 on success. */
int elf_writer_add_rel(struct elf_writer *ew, const char *sym, Elf64_Addr addr);
/*
* Serialize the ELF file to the output buffer. Return < 0 on error,
* 0 on success.
*/
int elf_writer_serialize(struct elf_writer *ew, struct buffer *out);
/*
* Calculate the loadable program's file size footprint. Returns < 0 on error,
* 0 on success.
*/
int elf_program_file_size(const struct buffer *input, size_t *file_size);
#endif /* ELFPARSING_H */
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