library.h revision 29add4fdf852b10ddd22cac0d1390f6d01577bc2 
1/*
2 * This file is part of ltrace.
3 * Copyright (C) 2012 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2006 Paul Gilliam
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation; either version 2 of the
9 * License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful, but
12 * WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
19 * 02110-1301 USA
20 */
21
22#ifndef _LIBRARY_H_
23#define _LIBRARY_H_
24
25#include <stdint.h>
26#include <gelf.h> // XXX
27
28struct Process;
29struct library;
30
31enum toplt {
32	LS_TOPLT_NONE = 0,	/* PLT not used for this symbol. */
33	LS_TOPLT_EXEC,		/* PLT for this symbol is executable. */
34	LS_TOPLT_POINT		/* PLT for this symbol is a non-executable. */
35};
36
37/* We should in general be able to trace 64-bit processes with 32-bit
38 * ltrace.  (At least PPC has several PTRACE requests related to
39 * tracing 64-on-32, so presumably it should be possible.)  But ltrace
40 * is currently hopelessly infested with using void* for host address.
41 * So keep with it, for now.  */
42typedef void *target_address_t;
43
44struct library_symbol {
45	struct library_symbol *next;
46	struct library *lib;
47	const char *name;
48	target_address_t enter_addr;
49	enum toplt plt_type;
50	char needs_init;
51	char is_weak;
52	char own_name;
53};
54
55/* Init LIBSYM.  NAME will be freed when LIBSYM is destroyed if
56 * OWN_NAME.  */
57/* XXX note that we shouldn't use GElf_Addr for ADDR either.  The fact
58 * that Elf is used is a back-end detail.  At least ltrace pretends
59 * that it would like to be cross-platform like that one day.  */
60void library_symbol_init(struct library_symbol *libsym, struct library *lib,
61			 GElf_Addr addr, const char *name, int own_name,
62			 enum toplt type_of_plt, int is_weak);
63
64/* Copy library symbol SYM into the area pointed-to by RETP.  Return 0
65 * on success or a negative value on failure.  */
66int library_symbol_clone(struct library_symbol *retp,
67			 struct library_symbol *sym);
68
69/* Destroy library symbol.  This essentially just frees name if it's
70 * owned.  It doesn't free the memory associated with SYM pointer
71 * itself.  Returns 0 on success or a negative value in case of an
72 * error (which would be an out of memory condition).  */
73void library_symbol_destroy(struct library_symbol *sym);
74
75/* Compare two library symbols.  Returns a negative value, 0, or a
76 * positive value, much like strcmp.  The function compares symbol
77 * addresses, and if those are equal, it compares symbol names.  If
78 * those are equal, too, the symbols are considered equal.  */
79int library_symbol_cmp(struct library_symbol *a, struct library_symbol *b);
80
81/* A function that can be used as library_each_symbol callback.  Looks
82 * for a symbol SYM for which library_symbol_cmp(SYM, STANDARD)
83 * returns 0.  */
84enum callback_status library_symbol_equal_cb(struct library_symbol *libsym,
85					     void *standard);
86
87/* XXX we might consider sharing libraries across processes.  Things
88 * like libc will be opened by every single process, no point cloning
89 * these everywhere.  But for now, keep the ownership structure
90 * simple.  */
91struct library {
92	struct library *next;
93
94	/* Address where the library is mapped.  Two library objects
95	 * are considered equal, if they have the same base.  */
96	target_address_t base;
97
98	/* Absolute address of the entry point.  Useful for main
99	 * binary, though I the value might be useful for the dynamic
100	 * linker, too (in case we ever want to do early process
101	 * tracing).  */
102	target_address_t entry;
103
104	/* Symbols associated with the library.  */
105	struct library_symbol *symbols;
106	const char *name;
107	char own_name;
108};
109
110/* Init LIB.  NAME will be freed when LIB is destroyed if
111 * OWN_NAME.  */
112void library_init(struct library *lib, const char *name, int own_name);
113
114/* Initialize RETP to a library identical to LIB.  Symbols are not
115 * shared, but copied over.  Returns 0 on success and a negative value
116 * in case of failure.  */
117int library_clone(struct library *retp, struct library *lib);
118
119/* Destroy library.  Doesn't free LIB itself.  */
120void library_destroy(struct library *lib);
121
122/* Set library name.  Frees the old name if necessary.  */
123void library_set_name(struct library *lib, const char *new_name, int own_name);
124
125/* Iterate through list of symbols of library LIB.  Restarts are
126 * supported via START (see each_process for details of iteration
127 * interface).  */
128struct library_symbol *library_each_symbol
129	(struct library *lib, struct library_symbol *start,
130	 enum callback_status (*cb)(struct library_symbol *, void *),
131	 void *data);
132
133/* Add a new symbol SYM to LIB.  SYM is assumed owned, we need to
134 * overwrite SYM->next.  */
135void library_add_symbol(struct library *lib, struct library_symbol *sym);
136
137/* A function that can be used as proc_each_library callback.  Looks
138 * for a library with the name passed in DATA.  PROC is ignored.  */
139enum callback_status library_named_cb(struct Process *proc,
140				      struct library *lib, void *name);
141
142/* A function that can be used as proc_each_library callback.  Looks
143 * for a library with given base.
144 *
145 * NOTE: The base is passed as a POINTER to target_address_t (that
146 * because in general, target_address_t doesn't fit in void*). */
147enum callback_status library_with_base_cb(struct Process *proc,
148					  struct library *lib, void *basep);
149
150#endif /* _LIBRARY_H_ */
151