Scott Baker | 2d89798 | 2019-09-24 11:50:08 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2013-2016 Dave Collins <dave@davec.name> |
| 3 | * |
| 4 | * Permission to use, copy, modify, and distribute this software for any |
| 5 | * purpose with or without fee is hereby granted, provided that the above |
| 6 | * copyright notice and this permission notice appear in all copies. |
| 7 | * |
| 8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
| 9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| 10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
| 11 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| 12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| 13 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
| 14 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| 15 | */ |
| 16 | |
| 17 | package spew |
| 18 | |
| 19 | import ( |
| 20 | "bytes" |
| 21 | "encoding/hex" |
| 22 | "fmt" |
| 23 | "io" |
| 24 | "os" |
| 25 | "reflect" |
| 26 | "regexp" |
| 27 | "strconv" |
| 28 | "strings" |
| 29 | ) |
| 30 | |
| 31 | var ( |
| 32 | // uint8Type is a reflect.Type representing a uint8. It is used to |
| 33 | // convert cgo types to uint8 slices for hexdumping. |
| 34 | uint8Type = reflect.TypeOf(uint8(0)) |
| 35 | |
| 36 | // cCharRE is a regular expression that matches a cgo char. |
| 37 | // It is used to detect character arrays to hexdump them. |
| 38 | cCharRE = regexp.MustCompile(`^.*\._Ctype_char$`) |
| 39 | |
| 40 | // cUnsignedCharRE is a regular expression that matches a cgo unsigned |
| 41 | // char. It is used to detect unsigned character arrays to hexdump |
| 42 | // them. |
| 43 | cUnsignedCharRE = regexp.MustCompile(`^.*\._Ctype_unsignedchar$`) |
| 44 | |
| 45 | // cUint8tCharRE is a regular expression that matches a cgo uint8_t. |
| 46 | // It is used to detect uint8_t arrays to hexdump them. |
| 47 | cUint8tCharRE = regexp.MustCompile(`^.*\._Ctype_uint8_t$`) |
| 48 | ) |
| 49 | |
| 50 | // dumpState contains information about the state of a dump operation. |
| 51 | type dumpState struct { |
| 52 | w io.Writer |
| 53 | depth int |
| 54 | pointers map[uintptr]int |
| 55 | ignoreNextType bool |
| 56 | ignoreNextIndent bool |
| 57 | cs *ConfigState |
| 58 | } |
| 59 | |
| 60 | // indent performs indentation according to the depth level and cs.Indent |
| 61 | // option. |
| 62 | func (d *dumpState) indent() { |
| 63 | if d.ignoreNextIndent { |
| 64 | d.ignoreNextIndent = false |
| 65 | return |
| 66 | } |
| 67 | d.w.Write(bytes.Repeat([]byte(d.cs.Indent), d.depth)) |
| 68 | } |
| 69 | |
| 70 | // unpackValue returns values inside of non-nil interfaces when possible. |
| 71 | // This is useful for data types like structs, arrays, slices, and maps which |
| 72 | // can contain varying types packed inside an interface. |
| 73 | func (d *dumpState) unpackValue(v reflect.Value) reflect.Value { |
| 74 | if v.Kind() == reflect.Interface && !v.IsNil() { |
| 75 | v = v.Elem() |
| 76 | } |
| 77 | return v |
| 78 | } |
| 79 | |
| 80 | // dumpPtr handles formatting of pointers by indirecting them as necessary. |
| 81 | func (d *dumpState) dumpPtr(v reflect.Value) { |
| 82 | // Remove pointers at or below the current depth from map used to detect |
| 83 | // circular refs. |
| 84 | for k, depth := range d.pointers { |
| 85 | if depth >= d.depth { |
| 86 | delete(d.pointers, k) |
| 87 | } |
| 88 | } |
| 89 | |
| 90 | // Keep list of all dereferenced pointers to show later. |
| 91 | pointerChain := make([]uintptr, 0) |
| 92 | |
| 93 | // Figure out how many levels of indirection there are by dereferencing |
| 94 | // pointers and unpacking interfaces down the chain while detecting circular |
| 95 | // references. |
| 96 | nilFound := false |
| 97 | cycleFound := false |
| 98 | indirects := 0 |
| 99 | ve := v |
| 100 | for ve.Kind() == reflect.Ptr { |
| 101 | if ve.IsNil() { |
| 102 | nilFound = true |
| 103 | break |
| 104 | } |
| 105 | indirects++ |
| 106 | addr := ve.Pointer() |
| 107 | pointerChain = append(pointerChain, addr) |
| 108 | if pd, ok := d.pointers[addr]; ok && pd < d.depth { |
| 109 | cycleFound = true |
| 110 | indirects-- |
| 111 | break |
| 112 | } |
| 113 | d.pointers[addr] = d.depth |
| 114 | |
| 115 | ve = ve.Elem() |
| 116 | if ve.Kind() == reflect.Interface { |
| 117 | if ve.IsNil() { |
| 118 | nilFound = true |
| 119 | break |
| 120 | } |
| 121 | ve = ve.Elem() |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | // Display type information. |
| 126 | d.w.Write(openParenBytes) |
| 127 | d.w.Write(bytes.Repeat(asteriskBytes, indirects)) |
| 128 | d.w.Write([]byte(ve.Type().String())) |
| 129 | d.w.Write(closeParenBytes) |
| 130 | |
| 131 | // Display pointer information. |
| 132 | if !d.cs.DisablePointerAddresses && len(pointerChain) > 0 { |
| 133 | d.w.Write(openParenBytes) |
| 134 | for i, addr := range pointerChain { |
| 135 | if i > 0 { |
| 136 | d.w.Write(pointerChainBytes) |
| 137 | } |
| 138 | printHexPtr(d.w, addr) |
| 139 | } |
| 140 | d.w.Write(closeParenBytes) |
| 141 | } |
| 142 | |
| 143 | // Display dereferenced value. |
| 144 | d.w.Write(openParenBytes) |
| 145 | switch { |
| 146 | case nilFound: |
| 147 | d.w.Write(nilAngleBytes) |
| 148 | |
| 149 | case cycleFound: |
| 150 | d.w.Write(circularBytes) |
| 151 | |
| 152 | default: |
| 153 | d.ignoreNextType = true |
| 154 | d.dump(ve) |
| 155 | } |
| 156 | d.w.Write(closeParenBytes) |
| 157 | } |
| 158 | |
| 159 | // dumpSlice handles formatting of arrays and slices. Byte (uint8 under |
| 160 | // reflection) arrays and slices are dumped in hexdump -C fashion. |
| 161 | func (d *dumpState) dumpSlice(v reflect.Value) { |
| 162 | // Determine whether this type should be hex dumped or not. Also, |
| 163 | // for types which should be hexdumped, try to use the underlying data |
| 164 | // first, then fall back to trying to convert them to a uint8 slice. |
| 165 | var buf []uint8 |
| 166 | doConvert := false |
| 167 | doHexDump := false |
| 168 | numEntries := v.Len() |
| 169 | if numEntries > 0 { |
| 170 | vt := v.Index(0).Type() |
| 171 | vts := vt.String() |
| 172 | switch { |
| 173 | // C types that need to be converted. |
| 174 | case cCharRE.MatchString(vts): |
| 175 | fallthrough |
| 176 | case cUnsignedCharRE.MatchString(vts): |
| 177 | fallthrough |
| 178 | case cUint8tCharRE.MatchString(vts): |
| 179 | doConvert = true |
| 180 | |
| 181 | // Try to use existing uint8 slices and fall back to converting |
| 182 | // and copying if that fails. |
| 183 | case vt.Kind() == reflect.Uint8: |
| 184 | // We need an addressable interface to convert the type |
| 185 | // to a byte slice. However, the reflect package won't |
| 186 | // give us an interface on certain things like |
| 187 | // unexported struct fields in order to enforce |
| 188 | // visibility rules. We use unsafe, when available, to |
| 189 | // bypass these restrictions since this package does not |
| 190 | // mutate the values. |
| 191 | vs := v |
| 192 | if !vs.CanInterface() || !vs.CanAddr() { |
| 193 | vs = unsafeReflectValue(vs) |
| 194 | } |
| 195 | if !UnsafeDisabled { |
| 196 | vs = vs.Slice(0, numEntries) |
| 197 | |
| 198 | // Use the existing uint8 slice if it can be |
| 199 | // type asserted. |
| 200 | iface := vs.Interface() |
| 201 | if slice, ok := iface.([]uint8); ok { |
| 202 | buf = slice |
| 203 | doHexDump = true |
| 204 | break |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | // The underlying data needs to be converted if it can't |
| 209 | // be type asserted to a uint8 slice. |
| 210 | doConvert = true |
| 211 | } |
| 212 | |
| 213 | // Copy and convert the underlying type if needed. |
| 214 | if doConvert && vt.ConvertibleTo(uint8Type) { |
| 215 | // Convert and copy each element into a uint8 byte |
| 216 | // slice. |
| 217 | buf = make([]uint8, numEntries) |
| 218 | for i := 0; i < numEntries; i++ { |
| 219 | vv := v.Index(i) |
| 220 | buf[i] = uint8(vv.Convert(uint8Type).Uint()) |
| 221 | } |
| 222 | doHexDump = true |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | // Hexdump the entire slice as needed. |
| 227 | if doHexDump { |
| 228 | indent := strings.Repeat(d.cs.Indent, d.depth) |
| 229 | str := indent + hex.Dump(buf) |
| 230 | str = strings.Replace(str, "\n", "\n"+indent, -1) |
| 231 | str = strings.TrimRight(str, d.cs.Indent) |
| 232 | d.w.Write([]byte(str)) |
| 233 | return |
| 234 | } |
| 235 | |
| 236 | // Recursively call dump for each item. |
| 237 | for i := 0; i < numEntries; i++ { |
| 238 | d.dump(d.unpackValue(v.Index(i))) |
| 239 | if i < (numEntries - 1) { |
| 240 | d.w.Write(commaNewlineBytes) |
| 241 | } else { |
| 242 | d.w.Write(newlineBytes) |
| 243 | } |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | // dump is the main workhorse for dumping a value. It uses the passed reflect |
| 248 | // value to figure out what kind of object we are dealing with and formats it |
| 249 | // appropriately. It is a recursive function, however circular data structures |
| 250 | // are detected and handled properly. |
| 251 | func (d *dumpState) dump(v reflect.Value) { |
| 252 | // Handle invalid reflect values immediately. |
| 253 | kind := v.Kind() |
| 254 | if kind == reflect.Invalid { |
| 255 | d.w.Write(invalidAngleBytes) |
| 256 | return |
| 257 | } |
| 258 | |
| 259 | // Handle pointers specially. |
| 260 | if kind == reflect.Ptr { |
| 261 | d.indent() |
| 262 | d.dumpPtr(v) |
| 263 | return |
| 264 | } |
| 265 | |
| 266 | // Print type information unless already handled elsewhere. |
| 267 | if !d.ignoreNextType { |
| 268 | d.indent() |
| 269 | d.w.Write(openParenBytes) |
| 270 | d.w.Write([]byte(v.Type().String())) |
| 271 | d.w.Write(closeParenBytes) |
| 272 | d.w.Write(spaceBytes) |
| 273 | } |
| 274 | d.ignoreNextType = false |
| 275 | |
| 276 | // Display length and capacity if the built-in len and cap functions |
| 277 | // work with the value's kind and the len/cap itself is non-zero. |
| 278 | valueLen, valueCap := 0, 0 |
| 279 | switch v.Kind() { |
| 280 | case reflect.Array, reflect.Slice, reflect.Chan: |
| 281 | valueLen, valueCap = v.Len(), v.Cap() |
| 282 | case reflect.Map, reflect.String: |
| 283 | valueLen = v.Len() |
| 284 | } |
| 285 | if valueLen != 0 || !d.cs.DisableCapacities && valueCap != 0 { |
| 286 | d.w.Write(openParenBytes) |
| 287 | if valueLen != 0 { |
| 288 | d.w.Write(lenEqualsBytes) |
| 289 | printInt(d.w, int64(valueLen), 10) |
| 290 | } |
| 291 | if !d.cs.DisableCapacities && valueCap != 0 { |
| 292 | if valueLen != 0 { |
| 293 | d.w.Write(spaceBytes) |
| 294 | } |
| 295 | d.w.Write(capEqualsBytes) |
| 296 | printInt(d.w, int64(valueCap), 10) |
| 297 | } |
| 298 | d.w.Write(closeParenBytes) |
| 299 | d.w.Write(spaceBytes) |
| 300 | } |
| 301 | |
| 302 | // Call Stringer/error interfaces if they exist and the handle methods flag |
| 303 | // is enabled |
| 304 | if !d.cs.DisableMethods { |
| 305 | if (kind != reflect.Invalid) && (kind != reflect.Interface) { |
| 306 | if handled := handleMethods(d.cs, d.w, v); handled { |
| 307 | return |
| 308 | } |
| 309 | } |
| 310 | } |
| 311 | |
| 312 | switch kind { |
| 313 | case reflect.Invalid: |
| 314 | // Do nothing. We should never get here since invalid has already |
| 315 | // been handled above. |
| 316 | |
| 317 | case reflect.Bool: |
| 318 | printBool(d.w, v.Bool()) |
| 319 | |
| 320 | case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int: |
| 321 | printInt(d.w, v.Int(), 10) |
| 322 | |
| 323 | case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint: |
| 324 | printUint(d.w, v.Uint(), 10) |
| 325 | |
| 326 | case reflect.Float32: |
| 327 | printFloat(d.w, v.Float(), 32) |
| 328 | |
| 329 | case reflect.Float64: |
| 330 | printFloat(d.w, v.Float(), 64) |
| 331 | |
| 332 | case reflect.Complex64: |
| 333 | printComplex(d.w, v.Complex(), 32) |
| 334 | |
| 335 | case reflect.Complex128: |
| 336 | printComplex(d.w, v.Complex(), 64) |
| 337 | |
| 338 | case reflect.Slice: |
| 339 | if v.IsNil() { |
| 340 | d.w.Write(nilAngleBytes) |
| 341 | break |
| 342 | } |
| 343 | fallthrough |
| 344 | |
| 345 | case reflect.Array: |
| 346 | d.w.Write(openBraceNewlineBytes) |
| 347 | d.depth++ |
| 348 | if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) { |
| 349 | d.indent() |
| 350 | d.w.Write(maxNewlineBytes) |
| 351 | } else { |
| 352 | d.dumpSlice(v) |
| 353 | } |
| 354 | d.depth-- |
| 355 | d.indent() |
| 356 | d.w.Write(closeBraceBytes) |
| 357 | |
| 358 | case reflect.String: |
| 359 | d.w.Write([]byte(strconv.Quote(v.String()))) |
| 360 | |
| 361 | case reflect.Interface: |
| 362 | // The only time we should get here is for nil interfaces due to |
| 363 | // unpackValue calls. |
| 364 | if v.IsNil() { |
| 365 | d.w.Write(nilAngleBytes) |
| 366 | } |
| 367 | |
| 368 | case reflect.Ptr: |
| 369 | // Do nothing. We should never get here since pointers have already |
| 370 | // been handled above. |
| 371 | |
| 372 | case reflect.Map: |
| 373 | // nil maps should be indicated as different than empty maps |
| 374 | if v.IsNil() { |
| 375 | d.w.Write(nilAngleBytes) |
| 376 | break |
| 377 | } |
| 378 | |
| 379 | d.w.Write(openBraceNewlineBytes) |
| 380 | d.depth++ |
| 381 | if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) { |
| 382 | d.indent() |
| 383 | d.w.Write(maxNewlineBytes) |
| 384 | } else { |
| 385 | numEntries := v.Len() |
| 386 | keys := v.MapKeys() |
| 387 | if d.cs.SortKeys { |
| 388 | sortValues(keys, d.cs) |
| 389 | } |
| 390 | for i, key := range keys { |
| 391 | d.dump(d.unpackValue(key)) |
| 392 | d.w.Write(colonSpaceBytes) |
| 393 | d.ignoreNextIndent = true |
| 394 | d.dump(d.unpackValue(v.MapIndex(key))) |
| 395 | if i < (numEntries - 1) { |
| 396 | d.w.Write(commaNewlineBytes) |
| 397 | } else { |
| 398 | d.w.Write(newlineBytes) |
| 399 | } |
| 400 | } |
| 401 | } |
| 402 | d.depth-- |
| 403 | d.indent() |
| 404 | d.w.Write(closeBraceBytes) |
| 405 | |
| 406 | case reflect.Struct: |
| 407 | d.w.Write(openBraceNewlineBytes) |
| 408 | d.depth++ |
| 409 | if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) { |
| 410 | d.indent() |
| 411 | d.w.Write(maxNewlineBytes) |
| 412 | } else { |
| 413 | vt := v.Type() |
| 414 | numFields := v.NumField() |
| 415 | for i := 0; i < numFields; i++ { |
| 416 | d.indent() |
| 417 | vtf := vt.Field(i) |
| 418 | d.w.Write([]byte(vtf.Name)) |
| 419 | d.w.Write(colonSpaceBytes) |
| 420 | d.ignoreNextIndent = true |
| 421 | d.dump(d.unpackValue(v.Field(i))) |
| 422 | if i < (numFields - 1) { |
| 423 | d.w.Write(commaNewlineBytes) |
| 424 | } else { |
| 425 | d.w.Write(newlineBytes) |
| 426 | } |
| 427 | } |
| 428 | } |
| 429 | d.depth-- |
| 430 | d.indent() |
| 431 | d.w.Write(closeBraceBytes) |
| 432 | |
| 433 | case reflect.Uintptr: |
| 434 | printHexPtr(d.w, uintptr(v.Uint())) |
| 435 | |
| 436 | case reflect.UnsafePointer, reflect.Chan, reflect.Func: |
| 437 | printHexPtr(d.w, v.Pointer()) |
| 438 | |
| 439 | // There were not any other types at the time this code was written, but |
| 440 | // fall back to letting the default fmt package handle it in case any new |
| 441 | // types are added. |
| 442 | default: |
| 443 | if v.CanInterface() { |
| 444 | fmt.Fprintf(d.w, "%v", v.Interface()) |
| 445 | } else { |
| 446 | fmt.Fprintf(d.w, "%v", v.String()) |
| 447 | } |
| 448 | } |
| 449 | } |
| 450 | |
| 451 | // fdump is a helper function to consolidate the logic from the various public |
| 452 | // methods which take varying writers and config states. |
| 453 | func fdump(cs *ConfigState, w io.Writer, a ...interface{}) { |
| 454 | for _, arg := range a { |
| 455 | if arg == nil { |
| 456 | w.Write(interfaceBytes) |
| 457 | w.Write(spaceBytes) |
| 458 | w.Write(nilAngleBytes) |
| 459 | w.Write(newlineBytes) |
| 460 | continue |
| 461 | } |
| 462 | |
| 463 | d := dumpState{w: w, cs: cs} |
| 464 | d.pointers = make(map[uintptr]int) |
| 465 | d.dump(reflect.ValueOf(arg)) |
| 466 | d.w.Write(newlineBytes) |
| 467 | } |
| 468 | } |
| 469 | |
| 470 | // Fdump formats and displays the passed arguments to io.Writer w. It formats |
| 471 | // exactly the same as Dump. |
| 472 | func Fdump(w io.Writer, a ...interface{}) { |
| 473 | fdump(&Config, w, a...) |
| 474 | } |
| 475 | |
| 476 | // Sdump returns a string with the passed arguments formatted exactly the same |
| 477 | // as Dump. |
| 478 | func Sdump(a ...interface{}) string { |
| 479 | var buf bytes.Buffer |
| 480 | fdump(&Config, &buf, a...) |
| 481 | return buf.String() |
| 482 | } |
| 483 | |
| 484 | /* |
| 485 | Dump displays the passed parameters to standard out with newlines, customizable |
| 486 | indentation, and additional debug information such as complete types and all |
| 487 | pointer addresses used to indirect to the final value. It provides the |
| 488 | following features over the built-in printing facilities provided by the fmt |
| 489 | package: |
| 490 | |
| 491 | * Pointers are dereferenced and followed |
| 492 | * Circular data structures are detected and handled properly |
| 493 | * Custom Stringer/error interfaces are optionally invoked, including |
| 494 | on unexported types |
| 495 | * Custom types which only implement the Stringer/error interfaces via |
| 496 | a pointer receiver are optionally invoked when passing non-pointer |
| 497 | variables |
| 498 | * Byte arrays and slices are dumped like the hexdump -C command which |
| 499 | includes offsets, byte values in hex, and ASCII output |
| 500 | |
| 501 | The configuration options are controlled by an exported package global, |
| 502 | spew.Config. See ConfigState for options documentation. |
| 503 | |
| 504 | See Fdump if you would prefer dumping to an arbitrary io.Writer or Sdump to |
| 505 | get the formatted result as a string. |
| 506 | */ |
| 507 | func Dump(a ...interface{}) { |
| 508 | fdump(&Config, os.Stdout, a...) |
| 509 | } |