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f4382c45 TT |
1 | /* Low-level DWARF 2 reading code |
2 | ||
88b9d363 | 3 | Copyright (C) 1994-2022 Free Software Foundation, Inc. |
f4382c45 TT |
4 | |
5 | Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology, | |
6 | Inc. with support from Florida State University (under contract | |
7 | with the Ada Joint Program Office), and Silicon Graphics, Inc. | |
8 | Initial contribution by Brent Benson, Harris Computer Systems, Inc., | |
9 | based on Fred Fish's (Cygnus Support) implementation of DWARF 1 | |
10 | support. | |
11 | ||
12 | This file is part of GDB. | |
13 | ||
14 | This program is free software; you can redistribute it and/or modify | |
15 | it under the terms of the GNU General Public License as published by | |
16 | the Free Software Foundation; either version 3 of the License, or | |
17 | (at your option) any later version. | |
18 | ||
19 | This program is distributed in the hope that it will be useful, | |
20 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
22 | GNU General Public License for more details. | |
23 | ||
24 | You should have received a copy of the GNU General Public License | |
25 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
26 | ||
27 | #ifndef GDB_DWARF2_LEB_H | |
28 | #define GDB_DWARF2_LEB_H | |
29 | ||
30 | /* Read dwarf information from a buffer. */ | |
31 | ||
32 | static inline unsigned int | |
33 | read_1_byte (bfd *abfd, const gdb_byte *buf) | |
34 | { | |
35 | return bfd_get_8 (abfd, buf); | |
36 | } | |
37 | ||
38 | static inline int | |
39 | read_1_signed_byte (bfd *abfd, const gdb_byte *buf) | |
40 | { | |
41 | return bfd_get_signed_8 (abfd, buf); | |
42 | } | |
43 | ||
44 | static inline unsigned int | |
45 | read_2_bytes (bfd *abfd, const gdb_byte *buf) | |
46 | { | |
47 | return bfd_get_16 (abfd, buf); | |
48 | } | |
49 | ||
50 | static inline int | |
51 | read_2_signed_bytes (bfd *abfd, const gdb_byte *buf) | |
52 | { | |
53 | return bfd_get_signed_16 (abfd, buf); | |
54 | } | |
55 | ||
56 | /* Read the next three bytes (little-endian order) as an unsigned integer. */ | |
57 | static inline unsigned int | |
58 | read_3_bytes (bfd *abfd, const gdb_byte *buf) | |
59 | { | |
93f9561e | 60 | return bfd_get_24 (abfd, buf); |
f4382c45 TT |
61 | } |
62 | ||
63 | static inline unsigned int | |
64 | read_4_bytes (bfd *abfd, const gdb_byte *buf) | |
65 | { | |
66 | return bfd_get_32 (abfd, buf); | |
67 | } | |
68 | ||
69 | static inline int | |
70 | read_4_signed_bytes (bfd *abfd, const gdb_byte *buf) | |
71 | { | |
72 | return bfd_get_signed_32 (abfd, buf); | |
73 | } | |
74 | ||
75 | static inline ULONGEST | |
76 | read_8_bytes (bfd *abfd, const gdb_byte *buf) | |
77 | { | |
78 | return bfd_get_64 (abfd, buf); | |
79 | } | |
80 | ||
81 | extern LONGEST read_signed_leb128 (bfd *, const gdb_byte *, unsigned int *); | |
82 | ||
83 | extern ULONGEST read_unsigned_leb128 (bfd *, const gdb_byte *, unsigned int *); | |
84 | ||
4075cb26 TT |
85 | /* Read the initial length from a section. The (draft) DWARF 3 |
86 | specification allows the initial length to take up either 4 bytes | |
87 | or 12 bytes. If the first 4 bytes are 0xffffffff, then the next 8 | |
88 | bytes describe the length and all offsets will be 8 bytes in length | |
89 | instead of 4. | |
90 | ||
91 | An older, non-standard 64-bit format is also handled by this | |
92 | function. The older format in question stores the initial length | |
93 | as an 8-byte quantity without an escape value. Lengths greater | |
94 | than 2^32 aren't very common which means that the initial 4 bytes | |
95 | is almost always zero. Since a length value of zero doesn't make | |
96 | sense for the 32-bit format, this initial zero can be considered to | |
97 | be an escape value which indicates the presence of the older 64-bit | |
98 | format. As written, the code can't detect (old format) lengths | |
99 | greater than 4GB. If it becomes necessary to handle lengths | |
100 | somewhat larger than 4GB, we could allow other small values (such | |
101 | as the non-sensical values of 1, 2, and 3) to also be used as | |
102 | escape values indicating the presence of the old format. | |
103 | ||
104 | The value returned via bytes_read should be used to increment the | |
105 | relevant pointer after calling read_initial_length(). | |
106 | ||
107 | [ Note: read_initial_length() and read_offset() are based on the | |
108 | document entitled "DWARF Debugging Information Format", revision | |
109 | 3, draft 8, dated November 19, 2001. This document was obtained | |
110 | from: | |
111 | ||
112 | http://reality.sgiweb.org/davea/dwarf3-draft8-011125.pdf | |
113 | ||
114 | This document is only a draft and is subject to change. (So beware.) | |
115 | ||
116 | Details regarding the older, non-standard 64-bit format were | |
117 | determined empirically by examining 64-bit ELF files produced by | |
118 | the SGI toolchain on an IRIX 6.5 machine. | |
119 | ||
120 | - Kevin, July 16, 2002 | |
121 | ] */ | |
122 | extern LONGEST read_initial_length (bfd *abfd, const gdb_byte *buf, | |
123 | unsigned int *bytes_read, | |
124 | bool handle_nonstd = true); | |
125 | ||
24aa364d TT |
126 | /* Read an offset from the data stream. */ |
127 | extern LONGEST read_offset (bfd *abfd, const gdb_byte *buf, | |
128 | unsigned int offset_size); | |
129 | ||
9f66ff1c TT |
130 | static inline const gdb_byte * |
131 | read_n_bytes (bfd *abfd, const gdb_byte *buf, unsigned int size) | |
132 | { | |
133 | /* If the size of a host char is 8 bits, we can return a pointer | |
134 | to the buffer, otherwise we have to copy the data to a buffer | |
135 | allocated on the temporary obstack. */ | |
136 | gdb_assert (HOST_CHAR_BIT == 8); | |
137 | return buf; | |
138 | } | |
139 | ||
140 | static inline const char * | |
141 | read_direct_string (bfd *abfd, const gdb_byte *buf, | |
142 | unsigned int *bytes_read_ptr) | |
143 | { | |
144 | /* If the size of a host char is 8 bits, we can return a pointer | |
145 | to the string, otherwise we have to copy the string to a buffer | |
146 | allocated on the temporary obstack. */ | |
147 | gdb_assert (HOST_CHAR_BIT == 8); | |
148 | if (*buf == '\0') | |
149 | { | |
150 | *bytes_read_ptr = 1; | |
151 | return NULL; | |
152 | } | |
153 | *bytes_read_ptr = strlen ((const char *) buf) + 1; | |
154 | return (const char *) buf; | |
155 | } | |
156 | ||
f4382c45 | 157 | #endif /* GDB_DWARF2_LEB_H */ |