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1 | /* Read ELF (Executable and Linking Format) object files for GDB. |
2 | Copyright (C) 1991 Free Software Foundation, Inc. | |
3 | Written by Fred Fish at Cygnus Support. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
20 | ||
21 | /************************************************************************ | |
22 | * * | |
23 | * NOTICE * | |
24 | * * | |
25 | * This file is still under construction. When it is complete, this * | |
26 | * notice will be removed. Until then, direct any questions or changes * | |
27 | * to Fred Fish at Cygnus Support (fnf@cygint) * | |
28 | * * | |
29 | * FIXME Still needs support for shared libraries. * | |
30 | * FIXME Still needs support for core files. * | |
31 | * FIXME The ".debug" and ".line" section names are hardwired. * | |
32 | * FIXME Still needs support ELF symbol tables (as distinct * | |
33 | * from DWARF support). Can use them to build the misc * | |
34 | * function vector at least. This is fairly trivial once * | |
35 | * bfd is extended to handle ELF symbol tables. * | |
36 | * * | |
37 | ************************************************************************/ | |
38 | ||
39 | #include <stdio.h> | |
40 | ||
41 | #include "defs.h" | |
42 | #include "param.h" | |
43 | #include "elf-common.h" | |
44 | #include "elf-external.h" | |
45 | #include "elf-internal.h" | |
46 | #include "bfd.h" | |
47 | #include "symfile.h" | |
48 | #include "symtab.h" | |
49 | #include "ansidecl.h" | |
50 | ||
51 | extern int EXFUN(strcmp, (CONST char *a, CONST char *b)); | |
52 | #define STREQ(a,b) (strcmp((a),(b))==0) | |
53 | ||
54 | struct elfinfo { | |
55 | unsigned int dboffset; /* Offset to dwarf debug section */ | |
56 | unsigned int dbsize; /* Size of dwarf debug section */ | |
57 | unsigned int lnoffset; /* Offset to dwarf line number section */ | |
58 | unsigned int lnsize; /* Size of dwarf line number section */ | |
59 | }; | |
60 | ||
61 | /* FIXME - crude hack to resolve undefined global. This function is | |
62 | part of support for corefiles, which is not yet implemented. */ | |
63 | ||
64 | unsigned int | |
65 | DEFUN(register_addr, (regno, blockend), | |
66 | int regno AND | |
67 | int blockend) | |
68 | { | |
69 | error ("Fetching registers from corefiles unimplemented."); | |
70 | } | |
71 | ||
72 | /* We are called once per section from elf_symfile_read. We | |
73 | need to examine each section we are passed, check to see | |
74 | if it is something we are interested in processing, and | |
75 | if so, stash away some access information for the section. | |
76 | ||
77 | For now we recognize the dwarf debug information sections and | |
78 | line number sections from matching their section names. The | |
79 | ELF definition is no real help here since it has no direct | |
80 | knowledge of DWARF (by design, so any debugging format can be | |
81 | used). | |
82 | ||
83 | FIXME: The section names should not be hardwired strings. */ | |
84 | ||
85 | static void | |
86 | DEFUN(elf_locate_sections, (abfd, sectp, ei), | |
87 | bfd *abfd AND | |
88 | asection *sectp AND | |
89 | struct elfinfo *ei) | |
90 | { | |
91 | if (STREQ (sectp -> name, ".debug")) | |
92 | { | |
93 | ei -> dboffset = sectp -> filepos; | |
94 | ei -> dbsize = sectp -> size; | |
95 | } | |
96 | else if (STREQ (sectp -> name, ".line")) | |
97 | { | |
98 | ei -> lnoffset = sectp -> filepos; | |
99 | ei -> lnsize = sectp -> size; | |
100 | } | |
101 | } | |
102 | ||
103 | /* Scan and build partial symbols for a symbol file. | |
104 | We have been initialized by a call to elf_symfile_init, which | |
105 | currently does nothing. | |
106 | ||
107 | ADDR is the address relative to which the symbols in it are (e.g. | |
108 | the base address of the text segment). | |
109 | ||
110 | MAINLINE is true if we are reading the main symbol | |
111 | table (as opposed to a shared lib or dynamically loaded file). | |
112 | ||
113 | This function only does the minimum work necessary for letting the | |
114 | user "name" things symbolically; it does not read the entire symtab. | |
115 | Instead, it reads the external and static symbols and puts them in partial | |
116 | symbol tables. When more extensive information is requested of a | |
117 | file, the corresponding partial symbol table is mutated into a full | |
118 | fledged symbol table by going back and reading the symbols | |
119 | for real. The function dwarf_psymtab_to_symtab() is the function that | |
120 | does this for DWARF symbols. */ | |
121 | ||
122 | static void | |
123 | DEFUN(elf_symfile_read, (sf, addr, mainline), | |
124 | struct sym_fns *sf AND | |
125 | CORE_ADDR addr AND | |
126 | int mainline) | |
127 | { | |
128 | bfd *abfd = sf -> sym_bfd; | |
129 | struct elfinfo ei; | |
130 | ||
131 | bfd_map_over_sections (abfd, elf_locate_sections, &ei); | |
132 | if (ei.dboffset && ei.lnoffset) | |
133 | { | |
134 | addr = 0; /* FIXME: force address base to zero for now */ | |
135 | dwarf_build_psymtabs (fileno ((FILE *)(abfd -> iostream)), | |
136 | bfd_get_filename (abfd), | |
137 | addr, mainline, | |
138 | ei.dboffset, ei.dbsize, | |
139 | ei.lnoffset, ei.lnsize); | |
140 | } | |
141 | if (!partial_symtab_list) | |
142 | { | |
143 | wrap_here (""); | |
144 | printf_filtered ("(no debugging symbols found)..."); | |
145 | wrap_here (""); | |
146 | } | |
147 | } | |
148 | ||
149 | /* Initialize anything that needs initializing when a completely new symbol | |
150 | file is specified (not just adding some symbols from another file, e.g. a | |
151 | shared library). | |
152 | ||
153 | For now at least, we have nothing in particular to do, so this function is | |
154 | just a stub. */ | |
155 | ||
156 | static void | |
157 | DEFUN_VOID (elf_new_init) | |
158 | { | |
159 | } | |
160 | ||
161 | /* ELF specific initialization routine for reading symbols. | |
162 | ||
163 | It is passed a pointer to a struct sym_fns which contains, among other | |
164 | things, the BFD for the file whose symbols are being read, and a slot for | |
165 | a pointer to "private data" which we can fill with goodies. | |
166 | ||
167 | For now at least, we have nothing in particular to do, so this function is | |
168 | just a stub. */ | |
169 | ||
170 | static void | |
171 | DEFUN(elf_symfile_init, (sf), | |
172 | struct sym_fns *sf) | |
173 | { | |
174 | } | |
175 | ||
176 | \f | |
177 | /* Register that we are able to handle ELF object file formats and DWARF | |
178 | debugging formats. | |
179 | ||
180 | Unlike other object file formats, where the debugging information format | |
181 | is implied by the object file format, the ELF object file format and the | |
182 | DWARF debugging information format are two distinct, and potentially | |
183 | separate entities. I.E. it is perfectly possible to have ELF objects | |
184 | with debugging formats other than DWARF. And it is conceivable that the | |
185 | DWARF debugging format might be used with another object file format, | |
186 | like COFF, by simply using COFF's custom section feature. | |
187 | ||
188 | GDB, and to a lesser extent BFD, should support the notion of separate | |
189 | object file formats and debugging information formats. For now, we just | |
190 | use "elf" in the same sense as "a.out" or "coff", to imply both the ELF | |
191 | object file format and the DWARF debugging format. */ | |
192 | ||
193 | static struct sym_fns elf_sym_fns = { | |
194 | "elf", /* sym_name: name or name prefix of BFD target type */ | |
195 | 3, /* sym_namelen: number of significant sym_name chars */ | |
196 | elf_new_init, /* sym_new_init: init anything gbl to entire symtab */ | |
197 | elf_symfile_init, /* sym_init: read initial info, setup for sym_read() */ | |
198 | elf_symfile_read, /* sym_read: read a symbol file into symtab */ | |
199 | NULL, /* sym_bfd: accessor for symbol file being read */ | |
200 | NULL, /* sym_private: sym_init & sym_read shared info */ | |
201 | NULL /* next: pointer to next struct sym_fns */ | |
202 | }; | |
203 | ||
204 | void | |
205 | DEFUN_VOID (_initialize_elfread) | |
206 | { | |
207 | add_symtab_fns (&elf_sym_fns); | |
208 | } |