The Android Open Source Project | 441f72d | 2009-03-03 19:29:28 -0800 | [diff] [blame^] | 1 | /* Advance to next CU header. |
| 2 | Copyright (C) 2002, 2003, 2004 Red Hat, Inc. |
| 3 | Written by Ulrich Drepper <drepper@redhat.com>, 2002. |
| 4 | |
| 5 | This program is Open Source software; you can redistribute it and/or |
| 6 | modify it under the terms of the Open Software License version 1.0 as |
| 7 | published by the Open Source Initiative. |
| 8 | |
| 9 | You should have received a copy of the Open Software License along |
| 10 | with this program; if not, you may obtain a copy of the Open Software |
| 11 | License version 1.0 from http://www.opensource.org/licenses/osl.php or |
| 12 | by writing the Open Source Initiative c/o Lawrence Rosen, Esq., |
| 13 | 3001 King Ranch Road, Ukiah, CA 95482. */ |
| 14 | |
| 15 | #ifdef HAVE_CONFIG_H |
| 16 | # include <config.h> |
| 17 | #endif |
| 18 | |
| 19 | #include <libdwP.h> |
| 20 | |
| 21 | |
| 22 | int |
| 23 | dwarf_nextcu (dwarf, off, next_off, header_sizep, abbrev_offsetp, |
| 24 | address_sizep, offset_sizep) |
| 25 | Dwarf *dwarf; |
| 26 | Dwarf_Off off; |
| 27 | Dwarf_Off *next_off; |
| 28 | size_t *header_sizep; |
| 29 | Dwarf_Off *abbrev_offsetp; |
| 30 | uint8_t *address_sizep; |
| 31 | uint8_t *offset_sizep; |
| 32 | { |
| 33 | /* Maybe there has been an error before. */ |
| 34 | if (dwarf == NULL) |
| 35 | return -1; |
| 36 | |
| 37 | /* If we reached the end before don't do anything. */ |
| 38 | if (off == (Dwarf_Off) -1l |
| 39 | /* Make sure there is enough space in the .debug_info section |
| 40 | for at least the initial word. We cannot test the rest since |
| 41 | we don't know yet whether this is a 64-bit object or not. */ |
| 42 | || unlikely (off + 4 >= dwarf->sectiondata[IDX_debug_info]->d_size)) |
| 43 | { |
| 44 | *next_off = (Dwarf_Off) -1l; |
| 45 | return 1; |
| 46 | } |
| 47 | |
| 48 | /* This points into the .debug_info section to the beginning of the |
| 49 | CU entry. */ |
| 50 | char *bytes = (char *) dwarf->sectiondata[IDX_debug_info]->d_buf + off; |
| 51 | |
| 52 | /* The format of the CU header is described in dwarf2p1 7.5.1: |
| 53 | |
| 54 | 1. A 4-byte or 12-byte unsigned integer representing the length |
| 55 | of the .debug_info contribution for that compilation unit, not |
| 56 | including the length field itself. In the 32-bit DWARF format, |
| 57 | this is a 4-byte unsigned integer (which must be less than |
| 58 | 0xffffff00); in the 64-bit DWARF format, this consists of the |
| 59 | 4-byte value 0xffffffff followed by an 8-byte unsigned integer |
| 60 | that gives the actual length (see Section 7.4). |
| 61 | |
| 62 | 2. A 2-byte unsigned integer representing the version of the |
| 63 | DWARF information for that compilation unit. For DWARF Version |
| 64 | 2.1, the value in this field is 2. |
| 65 | |
| 66 | 3. A 4-byte or 8-byte unsigned offset into the .debug_abbrev |
| 67 | section. This offset associates the compilation unit with a |
| 68 | particular set of debugging information entry abbreviations. In |
| 69 | the 32-bit DWARF format, this is a 4-byte unsigned length; in |
| 70 | the 64-bit DWARF format, this is an 8-byte unsigned length (see |
| 71 | Section 7.4). |
| 72 | |
| 73 | 4. A 1-byte unsigned integer representing the size in bytes of |
| 74 | an address on the target architecture. If the system uses |
| 75 | segmented addressing, this value represents the size of the |
| 76 | offset portion of an address. */ |
| 77 | uint64_t length = read_4ubyte_unaligned_inc (dwarf, bytes); |
| 78 | size_t offset_size = 4; |
| 79 | if (length == 0xffffffffu) |
| 80 | offset_size = 8; |
| 81 | |
| 82 | /* Now we know how large the header is. Note the trick in the |
| 83 | computation. If the offset_size is 4 the '- 4' term undoes the |
| 84 | '2 *'. If offset_size is 8 this term computes the size of the |
| 85 | escape value plus the 8 byte offset. */ |
| 86 | if (unlikely (off + 2 * offset_size - 4 + sizeof (uint16_t) |
| 87 | + offset_size + sizeof (uint8_t) |
| 88 | >= dwarf->sectiondata[IDX_debug_info]->d_size)) |
| 89 | { |
| 90 | *next_off = -1; |
| 91 | return 1; |
| 92 | } |
| 93 | |
| 94 | if (length == 0xffffffffu) |
| 95 | /* This is a 64-bit DWARF format. */ |
| 96 | length = read_8ubyte_unaligned_inc (dwarf, bytes); |
| 97 | |
| 98 | /* Read the version stamp. Always a 16-bit value. |
| 99 | XXX Do we need the value? */ |
| 100 | read_2ubyte_unaligned_inc (dwarf, bytes); |
| 101 | |
| 102 | /* Get offset in .debug_abbrev. Note that the size of the entry |
| 103 | depends on whether this is a 32-bit or 64-bit DWARF definition. */ |
| 104 | uint64_t abbrev_offset; |
| 105 | if (offset_size == 4) |
| 106 | abbrev_offset = read_4ubyte_unaligned_inc (dwarf, bytes); |
| 107 | else |
| 108 | abbrev_offset = read_8ubyte_unaligned_inc (dwarf, bytes); |
| 109 | if (abbrev_offsetp != NULL) |
| 110 | *abbrev_offsetp = abbrev_offset; |
| 111 | |
| 112 | /* The address size. Always an 8-bit value. */ |
| 113 | uint8_t address_size = *bytes++; |
| 114 | if (address_sizep != NULL) |
| 115 | *address_sizep = address_size; |
| 116 | |
| 117 | /* Store the offset size. */ |
| 118 | if (offset_sizep != NULL) |
| 119 | *offset_sizep = offset_size; |
| 120 | |
| 121 | /* Store the header length. */ |
| 122 | if (header_sizep != NULL) |
| 123 | *header_sizep = (bytes |
| 124 | - ((char *) dwarf->sectiondata[IDX_debug_info]->d_buf |
| 125 | + off)); |
| 126 | |
| 127 | /* See above for an explanation of the trick in this formula. */ |
| 128 | *next_off = off + 2 * offset_size - 4 + length; |
| 129 | |
| 130 | return 0; |
| 131 | } |