1// Copyright 2014 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package runtime 6 7import ( 8 "internal/bytealg" 9 "unsafe" 10) 11 12// For gccgo, use go:linkname to export compiler-called functions. 13// 14//go:linkname concatstrings 15//go:linkname slicebytetostring 16//go:linkname slicebytetostringtmp 17//go:linkname stringtoslicebyte 18//go:linkname stringtoslicerune 19//go:linkname slicerunetostring 20//go:linkname intstring 21// Temporary for C code to call: 22//go:linkname gostringnocopy 23//go:linkname findnull 24 25// The constant is known to the compiler. 26// There is no fundamental theory behind this number. 27const tmpStringBufSize = 32 28 29type tmpBuf [tmpStringBufSize]byte 30 31// concatstrings implements a Go string concatenation x+y+z+... 32// The operands are passed in the slice a. 33// If buf != nil, the compiler has determined that the result does not 34// escape the calling function, so the string data can be stored in buf 35// if small enough. 36func concatstrings(buf *tmpBuf, p *string, n int) string { 37 var a []string 38 *(*slice)(unsafe.Pointer(&a)) = slice{unsafe.Pointer(p), n, n} 39 // idx := 0 40 l := 0 41 count := 0 42 for _, x := range a { 43 n := len(x) 44 if n == 0 { 45 continue 46 } 47 if l+n < l { 48 throw("string concatenation too long") 49 } 50 l += n 51 count++ 52 // idx = i 53 } 54 if count == 0 { 55 return "" 56 } 57 58 // If there is just one string and either it is not on the stack 59 // or our result does not escape the calling frame (buf != nil), 60 // then we can return that string directly. 61 // Commented out for gccgo--no implementation of stringDataOnStack. 62 // if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) { 63 // return a[idx] 64 // } 65 s, b := rawstringtmp(buf, l) 66 for _, x := range a { 67 copy(b, x) 68 b = b[len(x):] 69 } 70 return s 71} 72 73// Buf is a fixed-size buffer for the result, 74// it is not nil if the result does not escape. 75func slicebytetostring(buf *tmpBuf, b []byte) (str string) { 76 l := len(b) 77 if l == 0 { 78 // Turns out to be a relatively common case. 79 // Consider that you want to parse out data between parens in "foo()bar", 80 // you find the indices and convert the subslice to string. 81 return "" 82 } 83 if raceenabled { 84 racereadrangepc(unsafe.Pointer(&b[0]), 85 uintptr(l), 86 getcallerpc(), 87 funcPC(slicebytetostring)) 88 } 89 if msanenabled { 90 msanread(unsafe.Pointer(&b[0]), uintptr(l)) 91 } 92 if l == 1 { 93 stringStructOf(&str).str = unsafe.Pointer(&staticbytes[b[0]]) 94 stringStructOf(&str).len = 1 95 return 96 } 97 98 var p unsafe.Pointer 99 if buf != nil && len(b) <= len(buf) { 100 p = unsafe.Pointer(buf) 101 } else { 102 p = mallocgc(uintptr(len(b)), nil, false) 103 } 104 stringStructOf(&str).str = p 105 stringStructOf(&str).len = len(b) 106 memmove(p, (*(*slice)(unsafe.Pointer(&b))).array, uintptr(len(b))) 107 return 108} 109 110func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) { 111 if buf != nil && l <= len(buf) { 112 b = buf[:l] 113 s = slicebytetostringtmp(b) 114 } else { 115 s, b = rawstring(l) 116 } 117 return 118} 119 120// slicebytetostringtmp returns a "string" referring to the actual []byte bytes. 121// 122// Callers need to ensure that the returned string will not be used after 123// the calling goroutine modifies the original slice or synchronizes with 124// another goroutine. 125// 126// The function is only called when instrumenting 127// and otherwise intrinsified by the compiler. 128// 129// Some internal compiler optimizations use this function. 130// - Used for m[T1{... Tn{..., string(k), ...} ...}] and m[string(k)] 131// where k is []byte, T1 to Tn is a nesting of struct and array literals. 132// - Used for "<"+string(b)+">" concatenation where b is []byte. 133// - Used for string(b)=="foo" comparison where b is []byte. 134func slicebytetostringtmp(b []byte) string { 135 if raceenabled && len(b) > 0 { 136 racereadrangepc(unsafe.Pointer(&b[0]), 137 uintptr(len(b)), 138 getcallerpc(), 139 funcPC(slicebytetostringtmp)) 140 } 141 if msanenabled && len(b) > 0 { 142 msanread(unsafe.Pointer(&b[0]), uintptr(len(b))) 143 } 144 return *(*string)(unsafe.Pointer(&b)) 145} 146 147func stringtoslicebyte(buf *tmpBuf, s string) []byte { 148 var b []byte 149 if buf != nil && len(s) <= len(buf) { 150 *buf = tmpBuf{} 151 b = buf[:len(s)] 152 } else { 153 b = rawbyteslice(len(s)) 154 } 155 copy(b, s) 156 return b 157} 158 159func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune { 160 // two passes. 161 // unlike slicerunetostring, no race because strings are immutable. 162 n := 0 163 for range s { 164 n++ 165 } 166 167 var a []rune 168 if buf != nil && n <= len(buf) { 169 *buf = [tmpStringBufSize]rune{} 170 a = buf[:n] 171 } else { 172 a = rawruneslice(n) 173 } 174 175 n = 0 176 for _, r := range s { 177 a[n] = r 178 n++ 179 } 180 return a 181} 182 183func slicerunetostring(buf *tmpBuf, a []rune) string { 184 if raceenabled && len(a) > 0 { 185 racereadrangepc(unsafe.Pointer(&a[0]), 186 uintptr(len(a))*unsafe.Sizeof(a[0]), 187 getcallerpc(), 188 funcPC(slicerunetostring)) 189 } 190 if msanenabled && len(a) > 0 { 191 msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0])) 192 } 193 var dum [4]byte 194 size1 := 0 195 for _, r := range a { 196 size1 += encoderune(dum[:], r) 197 } 198 s, b := rawstringtmp(buf, size1+3) 199 size2 := 0 200 for _, r := range a { 201 // check for race 202 if size2 >= size1 { 203 break 204 } 205 size2 += encoderune(b[size2:], r) 206 } 207 return s[:size2] 208} 209 210type stringStruct struct { 211 str unsafe.Pointer 212 len int 213} 214 215// Variant with *byte pointer type for DWARF debugging. 216type stringStructDWARF struct { 217 str *byte 218 len int 219} 220 221func stringStructOf(sp *string) *stringStruct { 222 return (*stringStruct)(unsafe.Pointer(sp)) 223} 224 225func intstring(buf *[4]byte, v int64) (s string) { 226 if v >= 0 && v < runeSelf { 227 stringStructOf(&s).str = unsafe.Pointer(&staticbytes[v]) 228 stringStructOf(&s).len = 1 229 return 230 } 231 232 var b []byte 233 if buf != nil { 234 b = buf[:] 235 s = slicebytetostringtmp(b) 236 } else { 237 s, b = rawstring(4) 238 } 239 if int64(rune(v)) != v { 240 v = runeError 241 } 242 n := encoderune(b, rune(v)) 243 return s[:n] 244} 245 246// rawstring allocates storage for a new string. The returned 247// string and byte slice both refer to the same storage. 248// The storage is not zeroed. Callers should use 249// b to set the string contents and then drop b. 250func rawstring(size int) (s string, b []byte) { 251 p := mallocgc(uintptr(size), nil, false) 252 253 stringStructOf(&s).str = p 254 stringStructOf(&s).len = size 255 256 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, size} 257 258 return 259} 260 261// rawbyteslice allocates a new byte slice. The byte slice is not zeroed. 262func rawbyteslice(size int) (b []byte) { 263 cap := roundupsize(uintptr(size)) 264 p := mallocgc(cap, nil, false) 265 if cap != uintptr(size) { 266 memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size)) 267 } 268 269 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)} 270 return 271} 272 273// rawruneslice allocates a new rune slice. The rune slice is not zeroed. 274func rawruneslice(size int) (b []rune) { 275 if uintptr(size) > maxAlloc/4 { 276 throw("out of memory") 277 } 278 mem := roundupsize(uintptr(size) * 4) 279 p := mallocgc(mem, nil, false) 280 if mem != uintptr(size)*4 { 281 memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4) 282 } 283 284 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)} 285 return 286} 287 288// used by cmd/cgo 289func gobytes(p *byte, n int) (b []byte) { 290 if n == 0 { 291 return make([]byte, 0) 292 } 293 294 if n < 0 || uintptr(n) > maxAlloc { 295 panic(errorString("gobytes: length out of range")) 296 } 297 298 bp := mallocgc(uintptr(n), nil, false) 299 memmove(bp, unsafe.Pointer(p), uintptr(n)) 300 301 *(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n} 302 return 303} 304 305// This is exported via linkname to assembly in syscall (for Plan9). 306//go:linkname gostring 307func gostring(p *byte) string { 308 l := findnull(p) 309 if l == 0 { 310 return "" 311 } 312 s, b := rawstring(l) 313 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l)) 314 return s 315} 316 317func gostringn(p *byte, l int) string { 318 if l == 0 { 319 return "" 320 } 321 s, b := rawstring(l) 322 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l)) 323 return s 324} 325 326func index(s, t string) int { 327 if len(t) == 0 { 328 return 0 329 } 330 for i := 0; i < len(s); i++ { 331 if s[i] == t[0] && hasPrefix(s[i:], t) { 332 return i 333 } 334 } 335 return -1 336} 337 338func contains(s, t string) bool { 339 return index(s, t) >= 0 340} 341 342func hasPrefix(s, prefix string) bool { 343 return len(s) >= len(prefix) && s[:len(prefix)] == prefix 344} 345 346func hasSuffix(s, suffix string) bool { 347 return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix 348} 349 350const ( 351 maxUint = ^uint(0) 352 maxInt = int(maxUint >> 1) 353) 354 355// atoi parses an int from a string s. 356// The bool result reports whether s is a number 357// representable by a value of type int. 358func atoi(s string) (int, bool) { 359 if s == "" { 360 return 0, false 361 } 362 363 neg := false 364 if s[0] == '-' { 365 neg = true 366 s = s[1:] 367 } 368 369 un := uint(0) 370 for i := 0; i < len(s); i++ { 371 c := s[i] 372 if c < '0' || c > '9' { 373 return 0, false 374 } 375 if un > maxUint/10 { 376 // overflow 377 return 0, false 378 } 379 un *= 10 380 un1 := un + uint(c) - '0' 381 if un1 < un { 382 // overflow 383 return 0, false 384 } 385 un = un1 386 } 387 388 if !neg && un > uint(maxInt) { 389 return 0, false 390 } 391 if neg && un > uint(maxInt)+1 { 392 return 0, false 393 } 394 395 n := int(un) 396 if neg { 397 n = -n 398 } 399 400 return n, true 401} 402 403// atoi32 is like atoi but for integers 404// that fit into an int32. 405func atoi32(s string) (int32, bool) { 406 if n, ok := atoi(s); n == int(int32(n)) { 407 return int32(n), ok 408 } 409 return 0, false 410} 411 412//go:nosplit 413func findnull(s *byte) int { 414 if s == nil { 415 return 0 416 } 417 418 // Avoid IndexByteString on Plan 9 because it uses SSE instructions 419 // on x86 machines, and those are classified as floating point instructions, 420 // which are illegal in a note handler. 421 if GOOS == "plan9" { 422 p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s)) 423 l := 0 424 for p[l] != 0 { 425 l++ 426 } 427 return l 428 } 429 430 // pageSize is the unit we scan at a time looking for NULL. 431 // It must be the minimum page size for any architecture Go 432 // runs on. It's okay (just a minor performance loss) if the 433 // actual system page size is larger than this value. 434 const pageSize = 4096 435 436 offset := 0 437 ptr := unsafe.Pointer(s) 438 // IndexByteString uses wide reads, so we need to be careful 439 // with page boundaries. Call IndexByteString on 440 // [ptr, endOfPage) interval. 441 safeLen := int(pageSize - uintptr(ptr)%pageSize) 442 443 for { 444 t := *(*string)(unsafe.Pointer(&stringStruct{ptr, safeLen})) 445 // Check one page at a time. 446 if i := bytealg.IndexByteString(t, 0); i != -1 { 447 return offset + i 448 } 449 // Move to next page 450 ptr = unsafe.Pointer(uintptr(ptr) + uintptr(safeLen)) 451 offset += safeLen 452 safeLen = pageSize 453 } 454} 455 456func findnullw(s *uint16) int { 457 if s == nil { 458 return 0 459 } 460 p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s)) 461 l := 0 462 for p[l] != 0 { 463 l++ 464 } 465 return l 466} 467 468//go:nosplit 469func gostringnocopy(str *byte) string { 470 ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)} 471 s := *(*string)(unsafe.Pointer(&ss)) 472 return s 473} 474 475func gostringw(strw *uint16) string { 476 var buf [8]byte 477 str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw)) 478 n1 := 0 479 for i := 0; str[i] != 0; i++ { 480 n1 += encoderune(buf[:], rune(str[i])) 481 } 482 s, b := rawstring(n1 + 4) 483 n2 := 0 484 for i := 0; str[i] != 0; i++ { 485 // check for race 486 if n2 >= n1 { 487 break 488 } 489 n2 += encoderune(b[n2:], rune(str[i])) 490 } 491 b[n2] = 0 // for luck 492 return s[:n2] 493} 494 495// These two functions are called by code generated by cgo -gccgo. 496 497//go:linkname __go_byte_array_to_string __go_byte_array_to_string 498func __go_byte_array_to_string(p unsafe.Pointer, l int) string { 499 if l == 0 { 500 return "" 501 } 502 s, c := rawstringtmp(nil, l) 503 memmove(unsafe.Pointer(&c[0]), p, uintptr(l)) 504 return s 505} 506 507//go:linkname __go_string_to_byte_array __go_string_to_byte_array 508func __go_string_to_byte_array(s string) []byte { 509 return stringtoslicebyte(nil, s) 510} 511 512// parseRelease parses a dot-separated version number. It follows the 513// semver syntax, but allows the minor and patch versions to be 514// elided. 515func parseRelease(rel string) (major, minor, patch int, ok bool) { 516 // Strip anything after a dash or plus. 517 for i := 0; i < len(rel); i++ { 518 if rel[i] == '-' || rel[i] == '+' { 519 rel = rel[:i] 520 break 521 } 522 } 523 524 next := func() (int, bool) { 525 for i := 0; i < len(rel); i++ { 526 if rel[i] == '.' { 527 ver, ok := atoi(rel[:i]) 528 rel = rel[i+1:] 529 return ver, ok 530 } 531 } 532 ver, ok := atoi(rel) 533 rel = "" 534 return ver, ok 535 } 536 if major, ok = next(); !ok || rel == "" { 537 return 538 } 539 if minor, ok = next(); !ok || rel == "" { 540 return 541 } 542 patch, ok = next() 543 return 544} 545