ltrace-elf.h revision 439ab5bfac8588e52c77e22c96fb397787512d0e 
1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2006,2010,2012,2013 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2010 Zachary T Welch
5 * Copyright (C) 2001,2004,2007,2009 Juan Cespedes
6 * Copyright (C) 2006 Ian Wienand
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
21 * 02110-1301 USA
22 */
23
24#ifndef LTRACE_ELF_H
25#define LTRACE_ELF_H
26
27#include <gelf.h>
28#include <stdlib.h>
29
30#include "forward.h"
31#include "sysdep.h"
32
33/* XXX Ok, the original idea was to separate the low-level ELF data
34 * from the abstract "struct library" object, but we use some of the
35 * following extensively in the back end.  Not all though.  So what we
36 * use should be move to struct library, and the rest of this
37 * structure maybe could be safely hidden in .c.  How to integrate the
38 * arch-specific bits into struct library is unclear as of now.  */
39struct ltelf {
40	int fd;
41	Elf *elf;
42	GElf_Ehdr ehdr;
43	Elf_Data *dynsym;
44	size_t dynsym_count;
45	const char *dynstr;
46	GElf_Addr plt_addr;
47	GElf_Word plt_flags;
48	size_t plt_size;
49	Elf_Data *relplt;
50	Elf_Data *plt_data;
51	size_t relplt_count;
52	Elf_Data *symtab;
53	const char *strtab;
54	const char *soname;
55	size_t symtab_count;
56	Elf_Data *opd;
57	GElf_Addr *opd_addr;
58	size_t opd_size;
59	GElf_Addr dyn_addr;
60	size_t dyn_sz;
61	size_t relplt_size;
62	GElf_Addr bias;
63	GElf_Addr entry_addr;
64	GElf_Addr base_addr;
65	struct arch_ltelf_data arch;
66};
67
68int open_elf(struct ltelf *lte, const char *filename);
69void do_close_elf(struct ltelf *lte);
70
71/* XXX is it possible to put breakpoints in VDSO and VSYSCALL
72 * pseudo-libraries?  For now we assume that all libraries can be
73 * opened via a filesystem.  BASE is ignored for ET_EXEC files.  */
74int ltelf_read_library(struct library *lib, struct process *proc,
75		       const char *filename, GElf_Addr bias);
76
77/* Create a library object representing the main binary.  The entry
78 * point address is stored to *ENTRYP.  */
79struct library *ltelf_read_main_binary(struct process *proc, const char *path);
80
81/* Create a default PLT entry.  This can be used instead (or in
82 * addition to) returning PLT_DEFAULT from arch_elf_add_plt_entry.
83 * RET shall be initialized, the created symbol will be added to the
84 * beginning of the linked list at *RET.  This function doesn't add
85 * the symbol to LTE.  arch_elf_add_plt_entry has the chance to adjust
86 * symbol internals to its liking, and then return either PLT_DEFAULT
87 * or PLT_OK.  */
88int default_elf_add_plt_entry(struct process *proc, struct ltelf *lte,
89			      const char *a_name, GElf_Rela *rela, size_t ndx,
90			      struct library_symbol **ret);
91
92/* The base implementation of backend.h (arch_get_sym_info).
93 * See backend.h for details.  */
94int elf_get_sym_info(struct ltelf *lte, const char *filename,
95		     size_t sym_index, GElf_Rela *rela, GElf_Sym *sym);
96
97Elf_Data *elf_loaddata(Elf_Scn *scn, GElf_Shdr *shdr);
98
99/* The following three look for sections based on various criteria.
100 * They return 0 if there was no error, or a negative value if there
101 * was.  If the section was found, it is returned in *TGT_SEC, and the
102 * header is stored te TGT_SHDR.  If it wasn't found, *TGT_SEC is set
103 * to NULL.  */
104int elf_get_section_covering(struct ltelf *lte, GElf_Addr addr,
105			     Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr);
106int elf_get_section_type(struct ltelf *lte, GElf_Word type,
107			 Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr);
108int elf_get_section_named(struct ltelf *lte, const char *name,
109			  Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr);
110
111/* Read, respectively, 1, 2, 4, or 8 bytes from Elf data at given
112 * OFFSET, and store it in *RETP.  Returns 0 on success or a negative
113 * value if there's not enough data.  */
114int elf_read_u8(Elf_Data *data, GElf_Xword offset, uint8_t *retp);
115int elf_read_u16(Elf_Data *data, GElf_Xword offset, uint16_t *retp);
116int elf_read_u32(Elf_Data *data, GElf_Xword offset, uint32_t *retp);
117int elf_read_u64(Elf_Data *data, GElf_Xword offset, uint64_t *retp);
118
119/* These are same as above, but update *OFFSET with the width
120 * of read datum.  */
121int elf_read_next_u8(Elf_Data *data, GElf_Xword *offset, uint8_t *retp);
122int elf_read_next_u16(Elf_Data *data, GElf_Xword *offset, uint16_t *retp);
123int elf_read_next_u32(Elf_Data *data, GElf_Xword *offset, uint32_t *retp);
124int elf_read_next_u64(Elf_Data *data, GElf_Xword *offset, uint64_t *retp);
125
126#if __WORDSIZE == 32
127#define PRI_ELF_ADDR		PRIx32
128#define GELF_ADDR_CAST(x)	(void *)(uint32_t)(x)
129#else
130#define PRI_ELF_ADDR		PRIx64
131#define GELF_ADDR_CAST(x)	(void *)(x)
132#endif
133
134#endif
135