Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 1 | // Copyright 2009 The Go Authors. All rights reserved. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // DWARF debug information entry parser. |
| 6 | // An entry is a sequence of data items of a given format. |
| 7 | // The first word in the entry is an index into what DWARF |
| 8 | // calls the ``abbreviation table.'' An abbreviation is really |
| 9 | // just a type descriptor: it's an array of attribute tag/value format pairs. |
| 10 | |
| 11 | package dwarf |
| 12 | |
| 13 | import ( |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 14 | "encoding/binary" |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 15 | "errors" |
| 16 | "strconv" |
| 17 | ) |
| 18 | |
| 19 | // a single entry's description: a sequence of attributes |
| 20 | type abbrev struct { |
| 21 | tag Tag |
| 22 | children bool |
| 23 | field []afield |
| 24 | } |
| 25 | |
| 26 | type afield struct { |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 27 | attr Attr |
| 28 | fmt format |
| 29 | class Class |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 30 | val int64 // for formImplicitConst |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 31 | } |
| 32 | |
| 33 | // a map from entry format ids to their descriptions |
| 34 | type abbrevTable map[uint32]abbrev |
| 35 | |
| 36 | // ParseAbbrev returns the abbreviation table that starts at byte off |
| 37 | // in the .debug_abbrev section. |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame] | 38 | func (d *Data) parseAbbrev(off uint64, vers int) (abbrevTable, error) { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 39 | if m, ok := d.abbrevCache[off]; ok { |
| 40 | return m, nil |
| 41 | } |
| 42 | |
| 43 | data := d.abbrev |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame] | 44 | if off > uint64(len(data)) { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 45 | data = nil |
| 46 | } else { |
| 47 | data = data[off:] |
| 48 | } |
| 49 | b := makeBuf(d, unknownFormat{}, "abbrev", 0, data) |
| 50 | |
| 51 | // Error handling is simplified by the buf getters |
| 52 | // returning an endless stream of 0s after an error. |
| 53 | m := make(abbrevTable) |
| 54 | for { |
| 55 | // Table ends with id == 0. |
| 56 | id := uint32(b.uint()) |
| 57 | if id == 0 { |
| 58 | break |
| 59 | } |
| 60 | |
| 61 | // Walk over attributes, counting. |
| 62 | n := 0 |
| 63 | b1 := b // Read from copy of b. |
| 64 | b1.uint() |
| 65 | b1.uint8() |
| 66 | for { |
| 67 | tag := b1.uint() |
| 68 | fmt := b1.uint() |
| 69 | if tag == 0 && fmt == 0 { |
| 70 | break |
| 71 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 72 | if format(fmt) == formImplicitConst { |
| 73 | b1.int() |
| 74 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 75 | n++ |
| 76 | } |
| 77 | if b1.err != nil { |
| 78 | return nil, b1.err |
| 79 | } |
| 80 | |
| 81 | // Walk over attributes again, this time writing them down. |
| 82 | var a abbrev |
| 83 | a.tag = Tag(b.uint()) |
| 84 | a.children = b.uint8() != 0 |
| 85 | a.field = make([]afield, n) |
| 86 | for i := range a.field { |
| 87 | a.field[i].attr = Attr(b.uint()) |
| 88 | a.field[i].fmt = format(b.uint()) |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 89 | a.field[i].class = formToClass(a.field[i].fmt, a.field[i].attr, vers, &b) |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 90 | if a.field[i].fmt == formImplicitConst { |
| 91 | a.field[i].val = b.int() |
| 92 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 93 | } |
| 94 | b.uint() |
| 95 | b.uint() |
| 96 | |
| 97 | m[id] = a |
| 98 | } |
| 99 | if b.err != nil { |
| 100 | return nil, b.err |
| 101 | } |
| 102 | d.abbrevCache[off] = m |
| 103 | return m, nil |
| 104 | } |
| 105 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 106 | // attrIsExprloc indicates attributes that allow exprloc values that |
| 107 | // are encoded as block values in DWARF 2 and 3. See DWARF 4, Figure |
| 108 | // 20. |
| 109 | var attrIsExprloc = map[Attr]bool{ |
| 110 | AttrLocation: true, |
| 111 | AttrByteSize: true, |
| 112 | AttrBitOffset: true, |
| 113 | AttrBitSize: true, |
| 114 | AttrStringLength: true, |
| 115 | AttrLowerBound: true, |
| 116 | AttrReturnAddr: true, |
| 117 | AttrStrideSize: true, |
| 118 | AttrUpperBound: true, |
| 119 | AttrCount: true, |
| 120 | AttrDataMemberLoc: true, |
| 121 | AttrFrameBase: true, |
| 122 | AttrSegment: true, |
| 123 | AttrStaticLink: true, |
| 124 | AttrUseLocation: true, |
| 125 | AttrVtableElemLoc: true, |
| 126 | AttrAllocated: true, |
| 127 | AttrAssociated: true, |
| 128 | AttrDataLocation: true, |
| 129 | AttrStride: true, |
| 130 | } |
| 131 | |
| 132 | // attrPtrClass indicates the *ptr class of attributes that have |
| 133 | // encoding formSecOffset in DWARF 4 or formData* in DWARF 2 and 3. |
| 134 | var attrPtrClass = map[Attr]Class{ |
| 135 | AttrLocation: ClassLocListPtr, |
| 136 | AttrStmtList: ClassLinePtr, |
| 137 | AttrStringLength: ClassLocListPtr, |
| 138 | AttrReturnAddr: ClassLocListPtr, |
| 139 | AttrStartScope: ClassRangeListPtr, |
| 140 | AttrDataMemberLoc: ClassLocListPtr, |
| 141 | AttrFrameBase: ClassLocListPtr, |
| 142 | AttrMacroInfo: ClassMacPtr, |
| 143 | AttrSegment: ClassLocListPtr, |
| 144 | AttrStaticLink: ClassLocListPtr, |
| 145 | AttrUseLocation: ClassLocListPtr, |
| 146 | AttrVtableElemLoc: ClassLocListPtr, |
| 147 | AttrRanges: ClassRangeListPtr, |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 148 | // The following are new in DWARF 5. |
| 149 | AttrStrOffsetsBase: ClassStrOffsetsPtr, |
| 150 | AttrAddrBase: ClassAddrPtr, |
| 151 | AttrRnglistsBase: ClassRngListsPtr, |
| 152 | AttrLoclistsBase: ClassLocListPtr, |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 153 | } |
| 154 | |
| 155 | // formToClass returns the DWARF 4 Class for the given form. If the |
| 156 | // DWARF version is less then 4, it will disambiguate some forms |
| 157 | // depending on the attribute. |
| 158 | func formToClass(form format, attr Attr, vers int, b *buf) Class { |
| 159 | switch form { |
| 160 | default: |
| 161 | b.error("cannot determine class of unknown attribute form") |
| 162 | return 0 |
| 163 | |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 164 | case formIndirect: |
| 165 | return ClassUnknown |
| 166 | |
| 167 | case formAddr, formAddrx, formAddrx1, formAddrx2, formAddrx3, formAddrx4: |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 168 | return ClassAddress |
| 169 | |
| 170 | case formDwarfBlock1, formDwarfBlock2, formDwarfBlock4, formDwarfBlock: |
| 171 | // In DWARF 2 and 3, ClassExprLoc was encoded as a |
| 172 | // block. DWARF 4 distinguishes ClassBlock and |
| 173 | // ClassExprLoc, but there are no attributes that can |
| 174 | // be both, so we also promote ClassBlock values in |
| 175 | // DWARF 4 that should be ClassExprLoc in case |
| 176 | // producers get this wrong. |
| 177 | if attrIsExprloc[attr] { |
| 178 | return ClassExprLoc |
| 179 | } |
| 180 | return ClassBlock |
| 181 | |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 182 | case formData1, formData2, formData4, formData8, formSdata, formUdata, formData16, formImplicitConst: |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 183 | // In DWARF 2 and 3, ClassPtr was encoded as a |
| 184 | // constant. Unlike ClassExprLoc/ClassBlock, some |
| 185 | // DWARF 4 attributes need to distinguish Class*Ptr |
| 186 | // from ClassConstant, so we only do this promotion |
| 187 | // for versions 2 and 3. |
| 188 | if class, ok := attrPtrClass[attr]; vers < 4 && ok { |
| 189 | return class |
| 190 | } |
| 191 | return ClassConstant |
| 192 | |
| 193 | case formFlag, formFlagPresent: |
| 194 | return ClassFlag |
| 195 | |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 196 | case formRefAddr, formRef1, formRef2, formRef4, formRef8, formRefUdata, formRefSup4, formRefSup8: |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 197 | return ClassReference |
| 198 | |
| 199 | case formRefSig8: |
| 200 | return ClassReferenceSig |
| 201 | |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 202 | case formString, formStrp, formStrx, formStrpSup, formLineStrp, formStrx1, formStrx2, formStrx3, formStrx4: |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 203 | return ClassString |
| 204 | |
| 205 | case formSecOffset: |
| 206 | // DWARF 4 defines four *ptr classes, but doesn't |
| 207 | // distinguish them in the encoding. Disambiguate |
| 208 | // these classes using the attribute. |
| 209 | if class, ok := attrPtrClass[attr]; ok { |
| 210 | return class |
| 211 | } |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 212 | return ClassUnknown |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 213 | |
| 214 | case formExprloc: |
| 215 | return ClassExprLoc |
| 216 | |
| 217 | case formGnuRefAlt: |
| 218 | return ClassReferenceAlt |
| 219 | |
| 220 | case formGnuStrpAlt: |
| 221 | return ClassStringAlt |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 222 | |
| 223 | case formLoclistx: |
| 224 | return ClassLocList |
| 225 | |
| 226 | case formRnglistx: |
| 227 | return ClassRngList |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 228 | } |
| 229 | } |
| 230 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 231 | // An entry is a sequence of attribute/value pairs. |
| 232 | type Entry struct { |
| 233 | Offset Offset // offset of Entry in DWARF info |
| 234 | Tag Tag // tag (kind of Entry) |
| 235 | Children bool // whether Entry is followed by children |
| 236 | Field []Field |
| 237 | } |
| 238 | |
| 239 | // A Field is a single attribute/value pair in an Entry. |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 240 | // |
| 241 | // A value can be one of several "attribute classes" defined by DWARF. |
| 242 | // The Go types corresponding to each class are: |
| 243 | // |
| 244 | // DWARF class Go type Class |
| 245 | // ----------- ------- ----- |
| 246 | // address uint64 ClassAddress |
| 247 | // block []byte ClassBlock |
| 248 | // constant int64 ClassConstant |
| 249 | // flag bool ClassFlag |
| 250 | // reference |
| 251 | // to info dwarf.Offset ClassReference |
| 252 | // to type unit uint64 ClassReferenceSig |
| 253 | // string string ClassString |
| 254 | // exprloc []byte ClassExprLoc |
| 255 | // lineptr int64 ClassLinePtr |
| 256 | // loclistptr int64 ClassLocListPtr |
| 257 | // macptr int64 ClassMacPtr |
| 258 | // rangelistptr int64 ClassRangeListPtr |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 259 | // |
| 260 | // For unrecognized or vendor-defined attributes, Class may be |
| 261 | // ClassUnknown. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 262 | type Field struct { |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 263 | Attr Attr |
Dan Willemsen | bc60c3c | 2021-12-15 01:09:00 -0800 | [diff] [blame] | 264 | Val any |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 265 | Class Class |
| 266 | } |
| 267 | |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 268 | // A Class is the DWARF 4 class of an attribute value. |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 269 | // |
| 270 | // In general, a given attribute's value may take on one of several |
| 271 | // possible classes defined by DWARF, each of which leads to a |
| 272 | // slightly different interpretation of the attribute. |
| 273 | // |
| 274 | // DWARF version 4 distinguishes attribute value classes more finely |
| 275 | // than previous versions of DWARF. The reader will disambiguate |
| 276 | // coarser classes from earlier versions of DWARF into the appropriate |
| 277 | // DWARF 4 class. For example, DWARF 2 uses "constant" for constants |
| 278 | // as well as all types of section offsets, but the reader will |
| 279 | // canonicalize attributes in DWARF 2 files that refer to section |
| 280 | // offsets to one of the Class*Ptr classes, even though these classes |
| 281 | // were only defined in DWARF 3. |
| 282 | type Class int |
| 283 | |
| 284 | const ( |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 285 | // ClassUnknown represents values of unknown DWARF class. |
| 286 | ClassUnknown Class = iota |
| 287 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 288 | // ClassAddress represents values of type uint64 that are |
| 289 | // addresses on the target machine. |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 290 | ClassAddress |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 291 | |
| 292 | // ClassBlock represents values of type []byte whose |
| 293 | // interpretation depends on the attribute. |
| 294 | ClassBlock |
| 295 | |
| 296 | // ClassConstant represents values of type int64 that are |
| 297 | // constants. The interpretation of this constant depends on |
| 298 | // the attribute. |
| 299 | ClassConstant |
| 300 | |
| 301 | // ClassExprLoc represents values of type []byte that contain |
| 302 | // an encoded DWARF expression or location description. |
| 303 | ClassExprLoc |
| 304 | |
| 305 | // ClassFlag represents values of type bool. |
| 306 | ClassFlag |
| 307 | |
| 308 | // ClassLinePtr represents values that are an int64 offset |
| 309 | // into the "line" section. |
| 310 | ClassLinePtr |
| 311 | |
| 312 | // ClassLocListPtr represents values that are an int64 offset |
| 313 | // into the "loclist" section. |
| 314 | ClassLocListPtr |
| 315 | |
| 316 | // ClassMacPtr represents values that are an int64 offset into |
| 317 | // the "mac" section. |
| 318 | ClassMacPtr |
| 319 | |
Dan Willemsen | cc753b7 | 2021-08-31 13:25:42 -0700 | [diff] [blame] | 320 | // ClassRangeListPtr represents values that are an int64 offset into |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 321 | // the "rangelist" section. |
| 322 | ClassRangeListPtr |
| 323 | |
| 324 | // ClassReference represents values that are an Offset offset |
| 325 | // of an Entry in the info section (for use with Reader.Seek). |
| 326 | // The DWARF specification combines ClassReference and |
| 327 | // ClassReferenceSig into class "reference". |
| 328 | ClassReference |
| 329 | |
| 330 | // ClassReferenceSig represents values that are a uint64 type |
| 331 | // signature referencing a type Entry. |
| 332 | ClassReferenceSig |
| 333 | |
| 334 | // ClassString represents values that are strings. If the |
| 335 | // compilation unit specifies the AttrUseUTF8 flag (strongly |
| 336 | // recommended), the string value will be encoded in UTF-8. |
| 337 | // Otherwise, the encoding is unspecified. |
| 338 | ClassString |
| 339 | |
| 340 | // ClassReferenceAlt represents values of type int64 that are |
| 341 | // an offset into the DWARF "info" section of an alternate |
| 342 | // object file. |
| 343 | ClassReferenceAlt |
| 344 | |
| 345 | // ClassStringAlt represents values of type int64 that are an |
| 346 | // offset into the DWARF string section of an alternate object |
| 347 | // file. |
| 348 | ClassStringAlt |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 349 | |
| 350 | // ClassAddrPtr represents values that are an int64 offset |
| 351 | // into the "addr" section. |
| 352 | ClassAddrPtr |
| 353 | |
| 354 | // ClassLocList represents values that are an int64 offset |
| 355 | // into the "loclists" section. |
| 356 | ClassLocList |
| 357 | |
Dan Willemsen | cc753b7 | 2021-08-31 13:25:42 -0700 | [diff] [blame] | 358 | // ClassRngList represents values that are a uint64 offset |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 359 | // from the base of the "rnglists" section. |
| 360 | ClassRngList |
| 361 | |
| 362 | // ClassRngListsPtr represents values that are an int64 offset |
| 363 | // into the "rnglists" section. These are used as the base for |
| 364 | // ClassRngList values. |
| 365 | ClassRngListsPtr |
| 366 | |
| 367 | // ClassStrOffsetsPtr represents values that are an int64 |
| 368 | // offset into the "str_offsets" section. |
| 369 | ClassStrOffsetsPtr |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 370 | ) |
| 371 | |
| 372 | //go:generate stringer -type=Class |
| 373 | |
| 374 | func (i Class) GoString() string { |
| 375 | return "dwarf." + i.String() |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 376 | } |
| 377 | |
| 378 | // Val returns the value associated with attribute Attr in Entry, |
| 379 | // or nil if there is no such attribute. |
| 380 | // |
| 381 | // A common idiom is to merge the check for nil return with |
| 382 | // the check that the value has the expected dynamic type, as in: |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 383 | // v, ok := e.Val(AttrSibling).(int64) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 384 | // |
Dan Willemsen | bc60c3c | 2021-12-15 01:09:00 -0800 | [diff] [blame] | 385 | func (e *Entry) Val(a Attr) any { |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 386 | if f := e.AttrField(a); f != nil { |
| 387 | return f.Val |
| 388 | } |
| 389 | return nil |
| 390 | } |
| 391 | |
| 392 | // AttrField returns the Field associated with attribute Attr in |
| 393 | // Entry, or nil if there is no such attribute. |
| 394 | func (e *Entry) AttrField(a Attr) *Field { |
| 395 | for i, f := range e.Field { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 396 | if f.Attr == a { |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 397 | return &e.Field[i] |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 398 | } |
| 399 | } |
| 400 | return nil |
| 401 | } |
| 402 | |
| 403 | // An Offset represents the location of an Entry within the DWARF info. |
| 404 | // (See Reader.Seek.) |
| 405 | type Offset uint32 |
| 406 | |
| 407 | // Entry reads a single entry from buf, decoding |
| 408 | // according to the given abbreviation table. |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 409 | func (b *buf) entry(cu *Entry, atab abbrevTable, ubase Offset, vers int) *Entry { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 410 | off := b.off |
| 411 | id := uint32(b.uint()) |
| 412 | if id == 0 { |
| 413 | return &Entry{} |
| 414 | } |
| 415 | a, ok := atab[id] |
| 416 | if !ok { |
| 417 | b.error("unknown abbreviation table index") |
| 418 | return nil |
| 419 | } |
| 420 | e := &Entry{ |
| 421 | Offset: off, |
| 422 | Tag: a.tag, |
| 423 | Children: a.children, |
| 424 | Field: make([]Field, len(a.field)), |
| 425 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 426 | |
| 427 | // If we are currently parsing the compilation unit, |
| 428 | // we can't evaluate Addrx or Strx until we've seen the |
| 429 | // relevant base entry. |
| 430 | type delayed struct { |
| 431 | idx int |
| 432 | off uint64 |
| 433 | fmt format |
| 434 | } |
| 435 | var delay []delayed |
| 436 | |
| 437 | resolveStrx := func(strBase, off uint64) string { |
| 438 | off += strBase |
| 439 | if uint64(int(off)) != off { |
| 440 | b.error("DW_FORM_strx offset out of range") |
| 441 | } |
| 442 | |
| 443 | b1 := makeBuf(b.dwarf, b.format, "str_offsets", 0, b.dwarf.strOffsets) |
| 444 | b1.skip(int(off)) |
| 445 | is64, _ := b.format.dwarf64() |
| 446 | if is64 { |
| 447 | off = b1.uint64() |
| 448 | } else { |
| 449 | off = uint64(b1.uint32()) |
| 450 | } |
| 451 | if b1.err != nil { |
| 452 | b.err = b1.err |
| 453 | return "" |
| 454 | } |
| 455 | if uint64(int(off)) != off { |
| 456 | b.error("DW_FORM_strx indirect offset out of range") |
| 457 | } |
| 458 | b1 = makeBuf(b.dwarf, b.format, "str", 0, b.dwarf.str) |
| 459 | b1.skip(int(off)) |
| 460 | val := b1.string() |
| 461 | if b1.err != nil { |
| 462 | b.err = b1.err |
| 463 | } |
| 464 | return val |
| 465 | } |
| 466 | |
Dan Willemsen | cc753b7 | 2021-08-31 13:25:42 -0700 | [diff] [blame] | 467 | resolveRnglistx := func(rnglistsBase, off uint64) uint64 { |
| 468 | is64, _ := b.format.dwarf64() |
| 469 | if is64 { |
| 470 | off *= 8 |
| 471 | } else { |
| 472 | off *= 4 |
| 473 | } |
| 474 | off += rnglistsBase |
| 475 | if uint64(int(off)) != off { |
| 476 | b.error("DW_FORM_rnglistx offset out of range") |
| 477 | } |
| 478 | |
| 479 | b1 := makeBuf(b.dwarf, b.format, "rnglists", 0, b.dwarf.rngLists) |
| 480 | b1.skip(int(off)) |
| 481 | if is64 { |
| 482 | off = b1.uint64() |
| 483 | } else { |
| 484 | off = uint64(b1.uint32()) |
| 485 | } |
| 486 | if b1.err != nil { |
| 487 | b.err = b1.err |
| 488 | return 0 |
| 489 | } |
| 490 | if uint64(int(off)) != off { |
| 491 | b.error("DW_FORM_rnglistx indirect offset out of range") |
| 492 | } |
| 493 | return rnglistsBase + off |
| 494 | } |
| 495 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 496 | for i := range e.Field { |
| 497 | e.Field[i].Attr = a.field[i].attr |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 498 | e.Field[i].Class = a.field[i].class |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 499 | fmt := a.field[i].fmt |
| 500 | if fmt == formIndirect { |
| 501 | fmt = format(b.uint()) |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 502 | e.Field[i].Class = formToClass(fmt, a.field[i].attr, vers, b) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 503 | } |
Dan Willemsen | bc60c3c | 2021-12-15 01:09:00 -0800 | [diff] [blame] | 504 | var val any |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 505 | switch fmt { |
| 506 | default: |
| 507 | b.error("unknown entry attr format 0x" + strconv.FormatInt(int64(fmt), 16)) |
| 508 | |
| 509 | // address |
| 510 | case formAddr: |
| 511 | val = b.addr() |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 512 | case formAddrx, formAddrx1, formAddrx2, formAddrx3, formAddrx4: |
| 513 | var off uint64 |
| 514 | switch fmt { |
| 515 | case formAddrx: |
| 516 | off = b.uint() |
| 517 | case formAddrx1: |
| 518 | off = uint64(b.uint8()) |
| 519 | case formAddrx2: |
| 520 | off = uint64(b.uint16()) |
| 521 | case formAddrx3: |
| 522 | off = uint64(b.uint24()) |
| 523 | case formAddrx4: |
| 524 | off = uint64(b.uint32()) |
| 525 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 526 | if b.dwarf.addr == nil { |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 527 | b.error("DW_FORM_addrx with no .debug_addr section") |
| 528 | } |
| 529 | if b.err != nil { |
| 530 | return nil |
| 531 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 532 | |
| 533 | // We have to adjust by the offset of the |
| 534 | // compilation unit. This won't work if the |
| 535 | // program uses Reader.Seek to skip over the |
| 536 | // unit. Not much we can do about that. |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 537 | var addrBase int64 |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 538 | if cu != nil { |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 539 | addrBase, _ = cu.Val(AttrAddrBase).(int64) |
| 540 | } else if a.tag == TagCompileUnit { |
| 541 | delay = append(delay, delayed{i, off, formAddrx}) |
| 542 | break |
| 543 | } |
| 544 | |
| 545 | var err error |
| 546 | val, err = b.dwarf.debugAddr(b.format, uint64(addrBase), off) |
| 547 | if err != nil { |
| 548 | if b.err == nil { |
| 549 | b.err = err |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 550 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 551 | return nil |
| 552 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 553 | |
| 554 | // block |
| 555 | case formDwarfBlock1: |
| 556 | val = b.bytes(int(b.uint8())) |
| 557 | case formDwarfBlock2: |
| 558 | val = b.bytes(int(b.uint16())) |
| 559 | case formDwarfBlock4: |
| 560 | val = b.bytes(int(b.uint32())) |
| 561 | case formDwarfBlock: |
| 562 | val = b.bytes(int(b.uint())) |
| 563 | |
| 564 | // constant |
| 565 | case formData1: |
| 566 | val = int64(b.uint8()) |
| 567 | case formData2: |
| 568 | val = int64(b.uint16()) |
| 569 | case formData4: |
| 570 | val = int64(b.uint32()) |
| 571 | case formData8: |
| 572 | val = int64(b.uint64()) |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 573 | case formData16: |
| 574 | val = b.bytes(16) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 575 | case formSdata: |
| 576 | val = int64(b.int()) |
| 577 | case formUdata: |
| 578 | val = int64(b.uint()) |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 579 | case formImplicitConst: |
| 580 | val = a.field[i].val |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 581 | |
| 582 | // flag |
| 583 | case formFlag: |
| 584 | val = b.uint8() == 1 |
| 585 | // New in DWARF 4. |
| 586 | case formFlagPresent: |
| 587 | // The attribute is implicitly indicated as present, and no value is |
| 588 | // encoded in the debugging information entry itself. |
| 589 | val = true |
| 590 | |
| 591 | // reference to other entry |
| 592 | case formRefAddr: |
| 593 | vers := b.format.version() |
| 594 | if vers == 0 { |
| 595 | b.error("unknown version for DW_FORM_ref_addr") |
| 596 | } else if vers == 2 { |
| 597 | val = Offset(b.addr()) |
| 598 | } else { |
| 599 | is64, known := b.format.dwarf64() |
| 600 | if !known { |
| 601 | b.error("unknown size for DW_FORM_ref_addr") |
| 602 | } else if is64 { |
| 603 | val = Offset(b.uint64()) |
| 604 | } else { |
| 605 | val = Offset(b.uint32()) |
| 606 | } |
| 607 | } |
| 608 | case formRef1: |
| 609 | val = Offset(b.uint8()) + ubase |
| 610 | case formRef2: |
| 611 | val = Offset(b.uint16()) + ubase |
| 612 | case formRef4: |
| 613 | val = Offset(b.uint32()) + ubase |
| 614 | case formRef8: |
| 615 | val = Offset(b.uint64()) + ubase |
| 616 | case formRefUdata: |
| 617 | val = Offset(b.uint()) + ubase |
| 618 | |
| 619 | // string |
| 620 | case formString: |
| 621 | val = b.string() |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 622 | case formStrp, formLineStrp: |
Dan Willemsen | c741332 | 2018-08-27 23:21:26 -0700 | [diff] [blame] | 623 | var off uint64 // offset into .debug_str |
| 624 | is64, known := b.format.dwarf64() |
| 625 | if !known { |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 626 | b.error("unknown size for DW_FORM_strp/line_strp") |
Dan Willemsen | c741332 | 2018-08-27 23:21:26 -0700 | [diff] [blame] | 627 | } else if is64 { |
| 628 | off = b.uint64() |
| 629 | } else { |
| 630 | off = uint64(b.uint32()) |
| 631 | } |
| 632 | if uint64(int(off)) != off { |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 633 | b.error("DW_FORM_strp/line_strp offset out of range") |
Dan Willemsen | c741332 | 2018-08-27 23:21:26 -0700 | [diff] [blame] | 634 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 635 | if b.err != nil { |
| 636 | return nil |
| 637 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 638 | var b1 buf |
| 639 | if fmt == formStrp { |
| 640 | b1 = makeBuf(b.dwarf, b.format, "str", 0, b.dwarf.str) |
| 641 | } else { |
| 642 | if len(b.dwarf.lineStr) == 0 { |
| 643 | b.error("DW_FORM_line_strp with no .debug_line_str section") |
Dan Willemsen | bc60c3c | 2021-12-15 01:09:00 -0800 | [diff] [blame] | 644 | return nil |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 645 | } |
| 646 | b1 = makeBuf(b.dwarf, b.format, "line_str", 0, b.dwarf.lineStr) |
| 647 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 648 | b1.skip(int(off)) |
| 649 | val = b1.string() |
| 650 | if b1.err != nil { |
| 651 | b.err = b1.err |
| 652 | return nil |
| 653 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 654 | case formStrx, formStrx1, formStrx2, formStrx3, formStrx4: |
| 655 | var off uint64 |
| 656 | switch fmt { |
| 657 | case formStrx: |
| 658 | off = b.uint() |
| 659 | case formStrx1: |
| 660 | off = uint64(b.uint8()) |
| 661 | case formStrx2: |
| 662 | off = uint64(b.uint16()) |
| 663 | case formStrx3: |
| 664 | off = uint64(b.uint24()) |
| 665 | case formStrx4: |
| 666 | off = uint64(b.uint32()) |
| 667 | } |
| 668 | if len(b.dwarf.strOffsets) == 0 { |
| 669 | b.error("DW_FORM_strx with no .debug_str_offsets section") |
| 670 | } |
| 671 | is64, known := b.format.dwarf64() |
| 672 | if !known { |
| 673 | b.error("unknown offset size for DW_FORM_strx") |
| 674 | } |
| 675 | if b.err != nil { |
| 676 | return nil |
| 677 | } |
| 678 | if is64 { |
| 679 | off *= 8 |
| 680 | } else { |
| 681 | off *= 4 |
| 682 | } |
| 683 | |
| 684 | // We have to adjust by the offset of the |
| 685 | // compilation unit. This won't work if the |
| 686 | // program uses Reader.Seek to skip over the |
| 687 | // unit. Not much we can do about that. |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 688 | var strBase int64 |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 689 | if cu != nil { |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 690 | strBase, _ = cu.Val(AttrStrOffsetsBase).(int64) |
| 691 | } else if a.tag == TagCompileUnit { |
| 692 | delay = append(delay, delayed{i, off, formStrx}) |
| 693 | break |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 694 | } |
| 695 | |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 696 | val = resolveStrx(uint64(strBase), off) |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 697 | |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 698 | case formStrpSup: |
| 699 | is64, known := b.format.dwarf64() |
| 700 | if !known { |
| 701 | b.error("unknown size for DW_FORM_strp_sup") |
| 702 | } else if is64 { |
| 703 | val = b.uint64() |
| 704 | } else { |
| 705 | val = b.uint32() |
| 706 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 707 | |
| 708 | // lineptr, loclistptr, macptr, rangelistptr |
| 709 | // New in DWARF 4, but clang can generate them with -gdwarf-2. |
| 710 | // Section reference, replacing use of formData4 and formData8. |
| 711 | case formSecOffset, formGnuRefAlt, formGnuStrpAlt: |
| 712 | is64, known := b.format.dwarf64() |
| 713 | if !known { |
| 714 | b.error("unknown size for form 0x" + strconv.FormatInt(int64(fmt), 16)) |
| 715 | } else if is64 { |
| 716 | val = int64(b.uint64()) |
| 717 | } else { |
| 718 | val = int64(b.uint32()) |
| 719 | } |
| 720 | |
| 721 | // exprloc |
| 722 | // New in DWARF 4. |
| 723 | case formExprloc: |
| 724 | val = b.bytes(int(b.uint())) |
| 725 | |
| 726 | // reference |
| 727 | // New in DWARF 4. |
| 728 | case formRefSig8: |
| 729 | // 64-bit type signature. |
| 730 | val = b.uint64() |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 731 | case formRefSup4: |
| 732 | val = b.uint32() |
| 733 | case formRefSup8: |
| 734 | val = b.uint64() |
| 735 | |
| 736 | // loclist |
| 737 | case formLoclistx: |
| 738 | val = b.uint() |
| 739 | |
| 740 | // rnglist |
| 741 | case formRnglistx: |
Dan Willemsen | cc753b7 | 2021-08-31 13:25:42 -0700 | [diff] [blame] | 742 | off := b.uint() |
| 743 | |
| 744 | // We have to adjust by the rnglists_base of |
| 745 | // the compilation unit. This won't work if |
| 746 | // the program uses Reader.Seek to skip over |
| 747 | // the unit. Not much we can do about that. |
| 748 | var rnglistsBase int64 |
| 749 | if cu != nil { |
| 750 | rnglistsBase, _ = cu.Val(AttrRnglistsBase).(int64) |
| 751 | } else if a.tag == TagCompileUnit { |
| 752 | delay = append(delay, delayed{i, off, formRnglistx}) |
| 753 | break |
| 754 | } |
| 755 | |
| 756 | val = resolveRnglistx(uint64(rnglistsBase), off) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 757 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 758 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 759 | e.Field[i].Val = val |
| 760 | } |
| 761 | if b.err != nil { |
| 762 | return nil |
| 763 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 764 | |
| 765 | for _, del := range delay { |
| 766 | switch del.fmt { |
| 767 | case formAddrx: |
| 768 | addrBase, _ := e.Val(AttrAddrBase).(int64) |
| 769 | val, err := b.dwarf.debugAddr(b.format, uint64(addrBase), del.off) |
| 770 | if err != nil { |
| 771 | b.err = err |
| 772 | return nil |
| 773 | } |
| 774 | e.Field[del.idx].Val = val |
| 775 | case formStrx: |
| 776 | strBase, _ := e.Val(AttrStrOffsetsBase).(int64) |
| 777 | e.Field[del.idx].Val = resolveStrx(uint64(strBase), del.off) |
| 778 | if b.err != nil { |
| 779 | return nil |
| 780 | } |
Dan Willemsen | cc753b7 | 2021-08-31 13:25:42 -0700 | [diff] [blame] | 781 | case formRnglistx: |
| 782 | rnglistsBase, _ := e.Val(AttrRnglistsBase).(int64) |
| 783 | e.Field[del.idx].Val = resolveRnglistx(uint64(rnglistsBase), del.off) |
| 784 | if b.err != nil { |
| 785 | return nil |
| 786 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 787 | } |
| 788 | } |
| 789 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 790 | return e |
| 791 | } |
| 792 | |
| 793 | // A Reader allows reading Entry structures from a DWARF ``info'' section. |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 794 | // The Entry structures are arranged in a tree. The Reader's Next function |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 795 | // return successive entries from a pre-order traversal of the tree. |
| 796 | // If an entry has children, its Children field will be true, and the children |
| 797 | // follow, terminated by an Entry with Tag 0. |
| 798 | type Reader struct { |
| 799 | b buf |
| 800 | d *Data |
| 801 | err error |
| 802 | unit int |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 803 | lastUnit bool // set if last entry returned by Next is TagCompileUnit/TagPartialUnit |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 804 | lastChildren bool // .Children of last entry returned by Next |
| 805 | lastSibling Offset // .Val(AttrSibling) of last entry returned by Next |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 806 | cu *Entry // current compilation unit |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 807 | } |
| 808 | |
| 809 | // Reader returns a new Reader for Data. |
| 810 | // The reader is positioned at byte offset 0 in the DWARF ``info'' section. |
| 811 | func (d *Data) Reader() *Reader { |
| 812 | r := &Reader{d: d} |
| 813 | r.Seek(0) |
| 814 | return r |
| 815 | } |
| 816 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 817 | // AddressSize returns the size in bytes of addresses in the current compilation |
| 818 | // unit. |
| 819 | func (r *Reader) AddressSize() int { |
| 820 | return r.d.unit[r.unit].asize |
| 821 | } |
| 822 | |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 823 | // ByteOrder returns the byte order in the current compilation unit. |
| 824 | func (r *Reader) ByteOrder() binary.ByteOrder { |
| 825 | return r.b.order |
| 826 | } |
| 827 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 828 | // Seek positions the Reader at offset off in the encoded entry stream. |
| 829 | // Offset 0 can be used to denote the first entry. |
| 830 | func (r *Reader) Seek(off Offset) { |
| 831 | d := r.d |
| 832 | r.err = nil |
| 833 | r.lastChildren = false |
| 834 | if off == 0 { |
| 835 | if len(d.unit) == 0 { |
| 836 | return |
| 837 | } |
| 838 | u := &d.unit[0] |
| 839 | r.unit = 0 |
| 840 | r.b = makeBuf(r.d, u, "info", u.off, u.data) |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 841 | r.cu = nil |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 842 | return |
| 843 | } |
| 844 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 845 | i := d.offsetToUnit(off) |
| 846 | if i == -1 { |
| 847 | r.err = errors.New("offset out of range") |
| 848 | return |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 849 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 850 | if i != r.unit { |
| 851 | r.cu = nil |
| 852 | } |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 853 | u := &d.unit[i] |
| 854 | r.unit = i |
| 855 | r.b = makeBuf(r.d, u, "info", off, u.data[off-u.off:]) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 856 | } |
| 857 | |
| 858 | // maybeNextUnit advances to the next unit if this one is finished. |
| 859 | func (r *Reader) maybeNextUnit() { |
| 860 | for len(r.b.data) == 0 && r.unit+1 < len(r.d.unit) { |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 861 | r.nextUnit() |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 862 | } |
| 863 | } |
| 864 | |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 865 | // nextUnit advances to the next unit. |
| 866 | func (r *Reader) nextUnit() { |
| 867 | r.unit++ |
| 868 | u := &r.d.unit[r.unit] |
| 869 | r.b = makeBuf(r.d, u, "info", u.off, u.data) |
| 870 | r.cu = nil |
| 871 | } |
| 872 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 873 | // Next reads the next entry from the encoded entry stream. |
| 874 | // It returns nil, nil when it reaches the end of the section. |
| 875 | // It returns an error if the current offset is invalid or the data at the |
| 876 | // offset cannot be decoded as a valid Entry. |
| 877 | func (r *Reader) Next() (*Entry, error) { |
| 878 | if r.err != nil { |
| 879 | return nil, r.err |
| 880 | } |
| 881 | r.maybeNextUnit() |
| 882 | if len(r.b.data) == 0 { |
| 883 | return nil, nil |
| 884 | } |
| 885 | u := &r.d.unit[r.unit] |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 886 | e := r.b.entry(r.cu, u.atable, u.base, u.vers) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 887 | if r.b.err != nil { |
| 888 | r.err = r.b.err |
| 889 | return nil, r.err |
| 890 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 891 | r.lastUnit = false |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 892 | if e != nil { |
| 893 | r.lastChildren = e.Children |
| 894 | if r.lastChildren { |
| 895 | r.lastSibling, _ = e.Val(AttrSibling).(Offset) |
| 896 | } |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 897 | if e.Tag == TagCompileUnit || e.Tag == TagPartialUnit { |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 898 | r.lastUnit = true |
Patrice Arruda | 748609c | 2020-06-25 12:12:21 -0700 | [diff] [blame] | 899 | r.cu = e |
| 900 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 901 | } else { |
| 902 | r.lastChildren = false |
| 903 | } |
| 904 | return e, nil |
| 905 | } |
| 906 | |
| 907 | // SkipChildren skips over the child entries associated with |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 908 | // the last Entry returned by Next. If that Entry did not have |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 909 | // children or Next has not been called, SkipChildren is a no-op. |
| 910 | func (r *Reader) SkipChildren() { |
| 911 | if r.err != nil || !r.lastChildren { |
| 912 | return |
| 913 | } |
| 914 | |
| 915 | // If the last entry had a sibling attribute, |
| 916 | // that attribute gives the offset of the next |
| 917 | // sibling, so we can avoid decoding the |
| 918 | // child subtrees. |
| 919 | if r.lastSibling >= r.b.off { |
| 920 | r.Seek(r.lastSibling) |
| 921 | return |
| 922 | } |
| 923 | |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 924 | if r.lastUnit && r.unit+1 < len(r.d.unit) { |
| 925 | r.nextUnit() |
| 926 | return |
| 927 | } |
| 928 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 929 | for { |
| 930 | e, err := r.Next() |
| 931 | if err != nil || e == nil || e.Tag == 0 { |
| 932 | break |
| 933 | } |
| 934 | if e.Children { |
| 935 | r.SkipChildren() |
| 936 | } |
| 937 | } |
| 938 | } |
| 939 | |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 940 | // clone returns a copy of the reader. This is used by the typeReader |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 941 | // interface. |
| 942 | func (r *Reader) clone() typeReader { |
| 943 | return r.d.Reader() |
| 944 | } |
| 945 | |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 946 | // offset returns the current buffer offset. This is used by the |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 947 | // typeReader interface. |
| 948 | func (r *Reader) offset() Offset { |
| 949 | return r.b.off |
| 950 | } |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 951 | |
| 952 | // SeekPC returns the Entry for the compilation unit that includes pc, |
| 953 | // and positions the reader to read the children of that unit. If pc |
| 954 | // is not covered by any unit, SeekPC returns ErrUnknownPC and the |
| 955 | // position of the reader is undefined. |
| 956 | // |
| 957 | // Because compilation units can describe multiple regions of the |
| 958 | // executable, in the worst case SeekPC must search through all the |
| 959 | // ranges in all the compilation units. Each call to SeekPC starts the |
| 960 | // search at the compilation unit of the last call, so in general |
| 961 | // looking up a series of PCs will be faster if they are sorted. If |
| 962 | // the caller wishes to do repeated fast PC lookups, it should build |
| 963 | // an appropriate index using the Ranges method. |
| 964 | func (r *Reader) SeekPC(pc uint64) (*Entry, error) { |
| 965 | unit := r.unit |
| 966 | for i := 0; i < len(r.d.unit); i++ { |
| 967 | if unit >= len(r.d.unit) { |
| 968 | unit = 0 |
| 969 | } |
| 970 | r.err = nil |
| 971 | r.lastChildren = false |
| 972 | r.unit = unit |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 973 | r.cu = nil |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 974 | u := &r.d.unit[unit] |
| 975 | r.b = makeBuf(r.d, u, "info", u.off, u.data) |
| 976 | e, err := r.Next() |
| 977 | if err != nil { |
| 978 | return nil, err |
| 979 | } |
| 980 | ranges, err := r.d.Ranges(e) |
| 981 | if err != nil { |
| 982 | return nil, err |
| 983 | } |
| 984 | for _, pcs := range ranges { |
| 985 | if pcs[0] <= pc && pc < pcs[1] { |
| 986 | return e, nil |
| 987 | } |
| 988 | } |
| 989 | unit++ |
| 990 | } |
| 991 | return nil, ErrUnknownPC |
| 992 | } |
| 993 | |
| 994 | // Ranges returns the PC ranges covered by e, a slice of [low,high) pairs. |
| 995 | // Only some entry types, such as TagCompileUnit or TagSubprogram, have PC |
| 996 | // ranges; for others, this will return nil with no error. |
| 997 | func (d *Data) Ranges(e *Entry) ([][2]uint64, error) { |
| 998 | var ret [][2]uint64 |
| 999 | |
| 1000 | low, lowOK := e.Val(AttrLowpc).(uint64) |
| 1001 | |
| 1002 | var high uint64 |
| 1003 | var highOK bool |
| 1004 | highField := e.AttrField(AttrHighpc) |
| 1005 | if highField != nil { |
| 1006 | switch highField.Class { |
| 1007 | case ClassAddress: |
| 1008 | high, highOK = highField.Val.(uint64) |
| 1009 | case ClassConstant: |
| 1010 | off, ok := highField.Val.(int64) |
| 1011 | if ok { |
| 1012 | high = low + uint64(off) |
| 1013 | highOK = true |
| 1014 | } |
| 1015 | } |
| 1016 | } |
| 1017 | |
| 1018 | if lowOK && highOK { |
| 1019 | ret = append(ret, [2]uint64{low, high}) |
| 1020 | } |
| 1021 | |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 1022 | var u *unit |
| 1023 | if uidx := d.offsetToUnit(e.Offset); uidx >= 0 && uidx < len(d.unit) { |
| 1024 | u = &d.unit[uidx] |
| 1025 | } |
| 1026 | |
| 1027 | if u != nil && u.vers >= 5 && d.rngLists != nil { |
| 1028 | // DWARF version 5 and later |
| 1029 | field := e.AttrField(AttrRanges) |
| 1030 | if field == nil { |
| 1031 | return ret, nil |
| 1032 | } |
| 1033 | switch field.Class { |
| 1034 | case ClassRangeListPtr: |
| 1035 | ranges, rangesOK := field.Val.(int64) |
| 1036 | if !rangesOK { |
| 1037 | return ret, nil |
| 1038 | } |
| 1039 | cu, base, err := d.baseAddressForEntry(e) |
| 1040 | if err != nil { |
| 1041 | return nil, err |
| 1042 | } |
| 1043 | return d.dwarf5Ranges(u, cu, base, ranges, ret) |
| 1044 | |
| 1045 | case ClassRngList: |
Dan Willemsen | cc753b7 | 2021-08-31 13:25:42 -0700 | [diff] [blame] | 1046 | rnglist, ok := field.Val.(uint64) |
| 1047 | if !ok { |
| 1048 | return ret, nil |
| 1049 | } |
| 1050 | cu, base, err := d.baseAddressForEntry(e) |
| 1051 | if err != nil { |
| 1052 | return nil, err |
| 1053 | } |
| 1054 | return d.dwarf5Ranges(u, cu, base, int64(rnglist), ret) |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 1055 | |
| 1056 | default: |
| 1057 | return ret, nil |
| 1058 | } |
| 1059 | } |
| 1060 | |
| 1061 | // DWARF version 2 through 4 |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 1062 | ranges, rangesOK := e.Val(AttrRanges).(int64) |
| 1063 | if rangesOK && d.ranges != nil { |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 1064 | _, base, err := d.baseAddressForEntry(e) |
| 1065 | if err != nil { |
| 1066 | return nil, err |
| 1067 | } |
| 1068 | return d.dwarf2Ranges(u, base, ranges, ret) |
| 1069 | } |
| 1070 | |
| 1071 | return ret, nil |
| 1072 | } |
| 1073 | |
| 1074 | // baseAddressForEntry returns the initial base address to be used when |
| 1075 | // looking up the range list of entry e. |
| 1076 | // DWARF specifies that this should be the lowpc attribute of the enclosing |
| 1077 | // compilation unit, however comments in gdb/dwarf2read.c say that some |
| 1078 | // versions of GCC use the entrypc attribute, so we check that too. |
| 1079 | func (d *Data) baseAddressForEntry(e *Entry) (*Entry, uint64, error) { |
| 1080 | var cu *Entry |
| 1081 | if e.Tag == TagCompileUnit { |
| 1082 | cu = e |
| 1083 | } else { |
| 1084 | i := d.offsetToUnit(e.Offset) |
| 1085 | if i == -1 { |
| 1086 | return nil, 0, errors.New("no unit for entry") |
| 1087 | } |
| 1088 | u := &d.unit[i] |
| 1089 | b := makeBuf(d, u, "info", u.off, u.data) |
| 1090 | cu = b.entry(nil, u.atable, u.base, u.vers) |
| 1091 | if b.err != nil { |
| 1092 | return nil, 0, b.err |
| 1093 | } |
| 1094 | } |
| 1095 | |
| 1096 | if cuEntry, cuEntryOK := cu.Val(AttrEntrypc).(uint64); cuEntryOK { |
| 1097 | return cu, cuEntry, nil |
| 1098 | } else if cuLow, cuLowOK := cu.Val(AttrLowpc).(uint64); cuLowOK { |
| 1099 | return cu, cuLow, nil |
| 1100 | } |
| 1101 | |
| 1102 | return cu, 0, nil |
| 1103 | } |
| 1104 | |
| 1105 | func (d *Data) dwarf2Ranges(u *unit, base uint64, ranges int64, ret [][2]uint64) ([][2]uint64, error) { |
| 1106 | buf := makeBuf(d, u, "ranges", Offset(ranges), d.ranges[ranges:]) |
| 1107 | for len(buf.data) > 0 { |
| 1108 | low := buf.addr() |
| 1109 | high := buf.addr() |
| 1110 | |
| 1111 | if low == 0 && high == 0 { |
| 1112 | break |
| 1113 | } |
| 1114 | |
| 1115 | if low == ^uint64(0)>>uint((8-u.addrsize())*8) { |
| 1116 | base = high |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 1117 | } else { |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 1118 | ret = append(ret, [2]uint64{base + low, base + high}) |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 1119 | } |
| 1120 | } |
| 1121 | |
| 1122 | return ret, nil |
| 1123 | } |
Colin Cross | 1f80552 | 2021-05-14 11:10:59 -0700 | [diff] [blame] | 1124 | |
| 1125 | // dwarf5Ranges interpets a debug_rnglists sequence, see DWARFv5 section |
| 1126 | // 2.17.3 (page 53). |
| 1127 | func (d *Data) dwarf5Ranges(u *unit, cu *Entry, base uint64, ranges int64, ret [][2]uint64) ([][2]uint64, error) { |
| 1128 | var addrBase int64 |
| 1129 | if cu != nil { |
| 1130 | addrBase, _ = cu.Val(AttrAddrBase).(int64) |
| 1131 | } |
| 1132 | |
| 1133 | buf := makeBuf(d, u, "rnglists", 0, d.rngLists) |
| 1134 | buf.skip(int(ranges)) |
| 1135 | for { |
| 1136 | opcode := buf.uint8() |
| 1137 | switch opcode { |
| 1138 | case rleEndOfList: |
| 1139 | if buf.err != nil { |
| 1140 | return nil, buf.err |
| 1141 | } |
| 1142 | return ret, nil |
| 1143 | |
| 1144 | case rleBaseAddressx: |
| 1145 | baseIdx := buf.uint() |
| 1146 | var err error |
| 1147 | base, err = d.debugAddr(u, uint64(addrBase), baseIdx) |
| 1148 | if err != nil { |
| 1149 | return nil, err |
| 1150 | } |
| 1151 | |
| 1152 | case rleStartxEndx: |
| 1153 | startIdx := buf.uint() |
| 1154 | endIdx := buf.uint() |
| 1155 | |
| 1156 | start, err := d.debugAddr(u, uint64(addrBase), startIdx) |
| 1157 | if err != nil { |
| 1158 | return nil, err |
| 1159 | } |
| 1160 | end, err := d.debugAddr(u, uint64(addrBase), endIdx) |
| 1161 | if err != nil { |
| 1162 | return nil, err |
| 1163 | } |
| 1164 | ret = append(ret, [2]uint64{start, end}) |
| 1165 | |
| 1166 | case rleStartxLength: |
| 1167 | startIdx := buf.uint() |
| 1168 | len := buf.uint() |
| 1169 | start, err := d.debugAddr(u, uint64(addrBase), startIdx) |
| 1170 | if err != nil { |
| 1171 | return nil, err |
| 1172 | } |
| 1173 | ret = append(ret, [2]uint64{start, start + len}) |
| 1174 | |
| 1175 | case rleOffsetPair: |
| 1176 | off1 := buf.uint() |
| 1177 | off2 := buf.uint() |
| 1178 | ret = append(ret, [2]uint64{base + off1, base + off2}) |
| 1179 | |
| 1180 | case rleBaseAddress: |
| 1181 | base = buf.addr() |
| 1182 | |
| 1183 | case rleStartEnd: |
| 1184 | start := buf.addr() |
| 1185 | end := buf.addr() |
| 1186 | ret = append(ret, [2]uint64{start, end}) |
| 1187 | |
| 1188 | case rleStartLength: |
| 1189 | start := buf.addr() |
| 1190 | len := buf.uint() |
| 1191 | ret = append(ret, [2]uint64{start, start + len}) |
| 1192 | } |
| 1193 | } |
| 1194 | } |
| 1195 | |
| 1196 | // debugAddr returns the address at idx in debug_addr |
| 1197 | func (d *Data) debugAddr(format dataFormat, addrBase, idx uint64) (uint64, error) { |
| 1198 | off := idx*uint64(format.addrsize()) + addrBase |
| 1199 | |
| 1200 | if uint64(int(off)) != off { |
| 1201 | return 0, errors.New("offset out of range") |
| 1202 | } |
| 1203 | |
| 1204 | b := makeBuf(d, format, "addr", 0, d.addr) |
| 1205 | b.skip(int(off)) |
| 1206 | val := b.addr() |
| 1207 | if b.err != nil { |
| 1208 | return 0, b.err |
| 1209 | } |
| 1210 | return val, nil |
| 1211 | } |