1 /* Low-level DWARF 2 reading code 2 3 Copyright (C) 1994-2024 Free Software Foundation, Inc. 4 5 Adapted by Gary Funck (gary (at) 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 { 60 return bfd_get_24 (abfd, buf); 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 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); 125 126 /* Read an offset from the data stream. */ 127 extern LONGEST read_offset (bfd *abfd, const gdb_byte *buf, 128 unsigned int offset_size); 129 130 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 } 156 157 #endif /* GDB_DWARF2_LEB_H */ 158
Indexes created Mon Mar 02 05:31:46 UTC 2026