Dinesh Belwalkar | e63f7f9 | 2019-11-22 23:11:16 +0000 | [diff] [blame^] | 1 | // Copyright 2018 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 | |
| 5 | // +build ignore |
| 6 | |
| 7 | /* |
| 8 | This program reads a file containing function prototypes |
| 9 | (like syscall_darwin.go) and generates system call bodies. |
| 10 | The prototypes are marked by lines beginning with "//sys" |
| 11 | and read like func declarations if //sys is replaced by func, but: |
| 12 | * The parameter lists must give a name for each argument. |
| 13 | This includes return parameters. |
| 14 | * The parameter lists must give a type for each argument: |
| 15 | the (x, y, z int) shorthand is not allowed. |
| 16 | * If the return parameter is an error number, it must be named errno. |
| 17 | |
| 18 | A line beginning with //sysnb is like //sys, except that the |
| 19 | goroutine will not be suspended during the execution of the system |
| 20 | call. This must only be used for system calls which can never |
| 21 | block, as otherwise the system call could cause all goroutines to |
| 22 | hang. |
| 23 | */ |
| 24 | package main |
| 25 | |
| 26 | import ( |
| 27 | "bufio" |
| 28 | "flag" |
| 29 | "fmt" |
| 30 | "os" |
| 31 | "regexp" |
| 32 | "strings" |
| 33 | ) |
| 34 | |
| 35 | var ( |
| 36 | b32 = flag.Bool("b32", false, "32bit big-endian") |
| 37 | l32 = flag.Bool("l32", false, "32bit little-endian") |
| 38 | plan9 = flag.Bool("plan9", false, "plan9") |
| 39 | openbsd = flag.Bool("openbsd", false, "openbsd") |
| 40 | netbsd = flag.Bool("netbsd", false, "netbsd") |
| 41 | dragonfly = flag.Bool("dragonfly", false, "dragonfly") |
| 42 | arm = flag.Bool("arm", false, "arm") // 64-bit value should use (even, odd)-pair |
| 43 | tags = flag.String("tags", "", "build tags") |
| 44 | filename = flag.String("output", "", "output file name (standard output if omitted)") |
| 45 | ) |
| 46 | |
| 47 | // cmdLine returns this programs's commandline arguments |
| 48 | func cmdLine() string { |
| 49 | return "go run mksyscall.go " + strings.Join(os.Args[1:], " ") |
| 50 | } |
| 51 | |
| 52 | // buildTags returns build tags |
| 53 | func buildTags() string { |
| 54 | return *tags |
| 55 | } |
| 56 | |
| 57 | // Param is function parameter |
| 58 | type Param struct { |
| 59 | Name string |
| 60 | Type string |
| 61 | } |
| 62 | |
| 63 | // usage prints the program usage |
| 64 | func usage() { |
| 65 | fmt.Fprintf(os.Stderr, "usage: go run mksyscall.go [-b32 | -l32] [-tags x,y] [file ...]\n") |
| 66 | os.Exit(1) |
| 67 | } |
| 68 | |
| 69 | // parseParamList parses parameter list and returns a slice of parameters |
| 70 | func parseParamList(list string) []string { |
| 71 | list = strings.TrimSpace(list) |
| 72 | if list == "" { |
| 73 | return []string{} |
| 74 | } |
| 75 | return regexp.MustCompile(`\s*,\s*`).Split(list, -1) |
| 76 | } |
| 77 | |
| 78 | // parseParam splits a parameter into name and type |
| 79 | func parseParam(p string) Param { |
| 80 | ps := regexp.MustCompile(`^(\S*) (\S*)$`).FindStringSubmatch(p) |
| 81 | if ps == nil { |
| 82 | fmt.Fprintf(os.Stderr, "malformed parameter: %s\n", p) |
| 83 | os.Exit(1) |
| 84 | } |
| 85 | return Param{ps[1], ps[2]} |
| 86 | } |
| 87 | |
| 88 | func main() { |
| 89 | // Get the OS and architecture (using GOARCH_TARGET if it exists) |
| 90 | goos := os.Getenv("GOOS") |
| 91 | if goos == "" { |
| 92 | fmt.Fprintln(os.Stderr, "GOOS not defined in environment") |
| 93 | os.Exit(1) |
| 94 | } |
| 95 | goarch := os.Getenv("GOARCH_TARGET") |
| 96 | if goarch == "" { |
| 97 | goarch = os.Getenv("GOARCH") |
| 98 | } |
| 99 | |
| 100 | // Check that we are using the Docker-based build system if we should |
| 101 | if goos == "linux" { |
| 102 | if os.Getenv("GOLANG_SYS_BUILD") != "docker" { |
| 103 | fmt.Fprintf(os.Stderr, "In the Docker-based build system, mksyscall should not be called directly.\n") |
| 104 | fmt.Fprintf(os.Stderr, "See README.md\n") |
| 105 | os.Exit(1) |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | flag.Usage = usage |
| 110 | flag.Parse() |
| 111 | if len(flag.Args()) <= 0 { |
| 112 | fmt.Fprintf(os.Stderr, "no files to parse provided\n") |
| 113 | usage() |
| 114 | } |
| 115 | |
| 116 | endianness := "" |
| 117 | if *b32 { |
| 118 | endianness = "big-endian" |
| 119 | } else if *l32 { |
| 120 | endianness = "little-endian" |
| 121 | } |
| 122 | |
| 123 | libc := false |
| 124 | if goos == "darwin" && strings.Contains(buildTags(), ",go1.12") { |
| 125 | libc = true |
| 126 | } |
| 127 | trampolines := map[string]bool{} |
| 128 | |
| 129 | text := "" |
| 130 | for _, path := range flag.Args() { |
| 131 | file, err := os.Open(path) |
| 132 | if err != nil { |
| 133 | fmt.Fprintf(os.Stderr, err.Error()) |
| 134 | os.Exit(1) |
| 135 | } |
| 136 | s := bufio.NewScanner(file) |
| 137 | for s.Scan() { |
| 138 | t := s.Text() |
| 139 | t = strings.TrimSpace(t) |
| 140 | t = regexp.MustCompile(`\s+`).ReplaceAllString(t, ` `) |
| 141 | nonblock := regexp.MustCompile(`^\/\/sysnb `).FindStringSubmatch(t) |
| 142 | if regexp.MustCompile(`^\/\/sys `).FindStringSubmatch(t) == nil && nonblock == nil { |
| 143 | continue |
| 144 | } |
| 145 | |
| 146 | // Line must be of the form |
| 147 | // func Open(path string, mode int, perm int) (fd int, errno error) |
| 148 | // Split into name, in params, out params. |
| 149 | f := regexp.MustCompile(`^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)SYS_[A-Z0-9_]+))?$`).FindStringSubmatch(t) |
| 150 | if f == nil { |
| 151 | fmt.Fprintf(os.Stderr, "%s:%s\nmalformed //sys declaration\n", path, t) |
| 152 | os.Exit(1) |
| 153 | } |
| 154 | funct, inps, outps, sysname := f[2], f[3], f[4], f[5] |
| 155 | |
| 156 | // ClockGettime doesn't have a syscall number on Darwin, only generate libc wrappers. |
| 157 | if goos == "darwin" && !libc && funct == "ClockGettime" { |
| 158 | continue |
| 159 | } |
| 160 | |
| 161 | // Split argument lists on comma. |
| 162 | in := parseParamList(inps) |
| 163 | out := parseParamList(outps) |
| 164 | |
| 165 | // Try in vain to keep people from editing this file. |
| 166 | // The theory is that they jump into the middle of the file |
| 167 | // without reading the header. |
| 168 | text += "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n" |
| 169 | |
| 170 | // Go function header. |
| 171 | outDecl := "" |
| 172 | if len(out) > 0 { |
| 173 | outDecl = fmt.Sprintf(" (%s)", strings.Join(out, ", ")) |
| 174 | } |
| 175 | text += fmt.Sprintf("func %s(%s)%s {\n", funct, strings.Join(in, ", "), outDecl) |
| 176 | |
| 177 | // Check if err return available |
| 178 | errvar := "" |
| 179 | for _, param := range out { |
| 180 | p := parseParam(param) |
| 181 | if p.Type == "error" { |
| 182 | errvar = p.Name |
| 183 | break |
| 184 | } |
| 185 | } |
| 186 | |
| 187 | // Prepare arguments to Syscall. |
| 188 | var args []string |
| 189 | n := 0 |
| 190 | for _, param := range in { |
| 191 | p := parseParam(param) |
| 192 | if regexp.MustCompile(`^\*`).FindStringSubmatch(p.Type) != nil { |
| 193 | args = append(args, "uintptr(unsafe.Pointer("+p.Name+"))") |
| 194 | } else if p.Type == "string" && errvar != "" { |
| 195 | text += fmt.Sprintf("\tvar _p%d *byte\n", n) |
| 196 | text += fmt.Sprintf("\t_p%d, %s = BytePtrFromString(%s)\n", n, errvar, p.Name) |
| 197 | text += fmt.Sprintf("\tif %s != nil {\n\t\treturn\n\t}\n", errvar) |
| 198 | args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n)) |
| 199 | n++ |
| 200 | } else if p.Type == "string" { |
| 201 | fmt.Fprintf(os.Stderr, path+":"+funct+" uses string arguments, but has no error return\n") |
| 202 | text += fmt.Sprintf("\tvar _p%d *byte\n", n) |
| 203 | text += fmt.Sprintf("\t_p%d, _ = BytePtrFromString(%s)\n", n, p.Name) |
| 204 | args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n)) |
| 205 | n++ |
| 206 | } else if regexp.MustCompile(`^\[\](.*)`).FindStringSubmatch(p.Type) != nil { |
| 207 | // Convert slice into pointer, length. |
| 208 | // Have to be careful not to take address of &a[0] if len == 0: |
| 209 | // pass dummy pointer in that case. |
| 210 | // Used to pass nil, but some OSes or simulators reject write(fd, nil, 0). |
| 211 | text += fmt.Sprintf("\tvar _p%d unsafe.Pointer\n", n) |
| 212 | text += fmt.Sprintf("\tif len(%s) > 0 {\n\t\t_p%d = unsafe.Pointer(&%s[0])\n\t}", p.Name, n, p.Name) |
| 213 | text += fmt.Sprintf(" else {\n\t\t_p%d = unsafe.Pointer(&_zero)\n\t}\n", n) |
| 214 | args = append(args, fmt.Sprintf("uintptr(_p%d)", n), fmt.Sprintf("uintptr(len(%s))", p.Name)) |
| 215 | n++ |
| 216 | } else if p.Type == "int64" && (*openbsd || *netbsd) { |
| 217 | args = append(args, "0") |
| 218 | if endianness == "big-endian" { |
| 219 | args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name)) |
| 220 | } else if endianness == "little-endian" { |
| 221 | args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name)) |
| 222 | } else { |
| 223 | args = append(args, fmt.Sprintf("uintptr(%s)", p.Name)) |
| 224 | } |
| 225 | } else if p.Type == "int64" && *dragonfly { |
| 226 | if regexp.MustCompile(`^(?i)extp(read|write)`).FindStringSubmatch(funct) == nil { |
| 227 | args = append(args, "0") |
| 228 | } |
| 229 | if endianness == "big-endian" { |
| 230 | args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name)) |
| 231 | } else if endianness == "little-endian" { |
| 232 | args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name)) |
| 233 | } else { |
| 234 | args = append(args, fmt.Sprintf("uintptr(%s)", p.Name)) |
| 235 | } |
| 236 | } else if (p.Type == "int64" || p.Type == "uint64") && endianness != "" { |
| 237 | if len(args)%2 == 1 && *arm { |
| 238 | // arm abi specifies 64-bit argument uses |
| 239 | // (even, odd) pair |
| 240 | args = append(args, "0") |
| 241 | } |
| 242 | if endianness == "big-endian" { |
| 243 | args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name)) |
| 244 | } else { |
| 245 | args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name)) |
| 246 | } |
| 247 | } else { |
| 248 | args = append(args, fmt.Sprintf("uintptr(%s)", p.Name)) |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | // Determine which form to use; pad args with zeros. |
| 253 | asm := "Syscall" |
| 254 | if nonblock != nil { |
| 255 | if errvar == "" && goos == "linux" { |
| 256 | asm = "RawSyscallNoError" |
| 257 | } else { |
| 258 | asm = "RawSyscall" |
| 259 | } |
| 260 | } else { |
| 261 | if errvar == "" && goos == "linux" { |
| 262 | asm = "SyscallNoError" |
| 263 | } |
| 264 | } |
| 265 | if len(args) <= 3 { |
| 266 | for len(args) < 3 { |
| 267 | args = append(args, "0") |
| 268 | } |
| 269 | } else if len(args) <= 6 { |
| 270 | asm += "6" |
| 271 | for len(args) < 6 { |
| 272 | args = append(args, "0") |
| 273 | } |
| 274 | } else if len(args) <= 9 { |
| 275 | asm += "9" |
| 276 | for len(args) < 9 { |
| 277 | args = append(args, "0") |
| 278 | } |
| 279 | } else { |
| 280 | fmt.Fprintf(os.Stderr, "%s:%s too many arguments to system call\n", path, funct) |
| 281 | } |
| 282 | |
| 283 | // System call number. |
| 284 | if sysname == "" { |
| 285 | sysname = "SYS_" + funct |
| 286 | sysname = regexp.MustCompile(`([a-z])([A-Z])`).ReplaceAllString(sysname, `${1}_$2`) |
| 287 | sysname = strings.ToUpper(sysname) |
| 288 | } |
| 289 | |
| 290 | var libcFn string |
| 291 | if libc { |
| 292 | asm = "syscall_" + strings.ToLower(asm[:1]) + asm[1:] // internal syscall call |
| 293 | sysname = strings.TrimPrefix(sysname, "SYS_") // remove SYS_ |
| 294 | sysname = strings.ToLower(sysname) // lowercase |
| 295 | if sysname == "getdirentries64" { |
| 296 | // Special case - libSystem name and |
| 297 | // raw syscall name don't match. |
| 298 | sysname = "__getdirentries64" |
| 299 | } |
| 300 | libcFn = sysname |
| 301 | sysname = "funcPC(libc_" + sysname + "_trampoline)" |
| 302 | } |
| 303 | |
| 304 | // Actual call. |
| 305 | arglist := strings.Join(args, ", ") |
| 306 | call := fmt.Sprintf("%s(%s, %s)", asm, sysname, arglist) |
| 307 | |
| 308 | // Assign return values. |
| 309 | body := "" |
| 310 | ret := []string{"_", "_", "_"} |
| 311 | doErrno := false |
| 312 | for i := 0; i < len(out); i++ { |
| 313 | p := parseParam(out[i]) |
| 314 | reg := "" |
| 315 | if p.Name == "err" && !*plan9 { |
| 316 | reg = "e1" |
| 317 | ret[2] = reg |
| 318 | doErrno = true |
| 319 | } else if p.Name == "err" && *plan9 { |
| 320 | ret[0] = "r0" |
| 321 | ret[2] = "e1" |
| 322 | break |
| 323 | } else { |
| 324 | reg = fmt.Sprintf("r%d", i) |
| 325 | ret[i] = reg |
| 326 | } |
| 327 | if p.Type == "bool" { |
| 328 | reg = fmt.Sprintf("%s != 0", reg) |
| 329 | } |
| 330 | if p.Type == "int64" && endianness != "" { |
| 331 | // 64-bit number in r1:r0 or r0:r1. |
| 332 | if i+2 > len(out) { |
| 333 | fmt.Fprintf(os.Stderr, "%s:%s not enough registers for int64 return\n", path, funct) |
| 334 | } |
| 335 | if endianness == "big-endian" { |
| 336 | reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i, i+1) |
| 337 | } else { |
| 338 | reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i+1, i) |
| 339 | } |
| 340 | ret[i] = fmt.Sprintf("r%d", i) |
| 341 | ret[i+1] = fmt.Sprintf("r%d", i+1) |
| 342 | } |
| 343 | if reg != "e1" || *plan9 { |
| 344 | body += fmt.Sprintf("\t%s = %s(%s)\n", p.Name, p.Type, reg) |
| 345 | } |
| 346 | } |
| 347 | if ret[0] == "_" && ret[1] == "_" && ret[2] == "_" { |
| 348 | text += fmt.Sprintf("\t%s\n", call) |
| 349 | } else { |
| 350 | if errvar == "" && goos == "linux" { |
| 351 | // raw syscall without error on Linux, see golang.org/issue/22924 |
| 352 | text += fmt.Sprintf("\t%s, %s := %s\n", ret[0], ret[1], call) |
| 353 | } else { |
| 354 | text += fmt.Sprintf("\t%s, %s, %s := %s\n", ret[0], ret[1], ret[2], call) |
| 355 | } |
| 356 | } |
| 357 | text += body |
| 358 | |
| 359 | if *plan9 && ret[2] == "e1" { |
| 360 | text += "\tif int32(r0) == -1 {\n" |
| 361 | text += "\t\terr = e1\n" |
| 362 | text += "\t}\n" |
| 363 | } else if doErrno { |
| 364 | text += "\tif e1 != 0 {\n" |
| 365 | text += "\t\terr = errnoErr(e1)\n" |
| 366 | text += "\t}\n" |
| 367 | } |
| 368 | text += "\treturn\n" |
| 369 | text += "}\n\n" |
| 370 | |
| 371 | if libc && !trampolines[libcFn] { |
| 372 | // some system calls share a trampoline, like read and readlen. |
| 373 | trampolines[libcFn] = true |
| 374 | // Declare assembly trampoline. |
| 375 | text += fmt.Sprintf("func libc_%s_trampoline()\n", libcFn) |
| 376 | // Assembly trampoline calls the libc_* function, which this magic |
| 377 | // redirects to use the function from libSystem. |
| 378 | text += fmt.Sprintf("//go:linkname libc_%s libc_%s\n", libcFn, libcFn) |
| 379 | text += fmt.Sprintf("//go:cgo_import_dynamic libc_%s %s \"/usr/lib/libSystem.B.dylib\"\n", libcFn, libcFn) |
| 380 | text += "\n" |
| 381 | } |
| 382 | } |
| 383 | if err := s.Err(); err != nil { |
| 384 | fmt.Fprintf(os.Stderr, err.Error()) |
| 385 | os.Exit(1) |
| 386 | } |
| 387 | file.Close() |
| 388 | } |
| 389 | fmt.Printf(srcTemplate, cmdLine(), buildTags(), text) |
| 390 | } |
| 391 | |
| 392 | const srcTemplate = `// %s |
| 393 | // Code generated by the command above; see README.md. DO NOT EDIT. |
| 394 | |
| 395 | // +build %s |
| 396 | |
| 397 | package unix |
| 398 | |
| 399 | import ( |
| 400 | "syscall" |
| 401 | "unsafe" |
| 402 | ) |
| 403 | |
| 404 | var _ syscall.Errno |
| 405 | |
| 406 | %s |
| 407 | ` |