aboutsummaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/sys/unix/mksyscall.go
blob: e4af9424e97886239f52a5035fbe64c3402c4792 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ignore

/*
This program reads a file containing function prototypes
(like syscall_darwin.go) and generates system call bodies.
The prototypes are marked by lines beginning with "//sys"
and read like func declarations if //sys is replaced by func, but:
	* The parameter lists must give a name for each argument.
	  This includes return parameters.
	* The parameter lists must give a type for each argument:
	  the (x, y, z int) shorthand is not allowed.
	* If the return parameter is an error number, it must be named errno.

A line beginning with //sysnb is like //sys, except that the
goroutine will not be suspended during the execution of the system
call.  This must only be used for system calls which can never
block, as otherwise the system call could cause all goroutines to
hang.
*/
package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
	"regexp"
	"strings"
)

var (
	b32       = flag.Bool("b32", false, "32bit big-endian")
	l32       = flag.Bool("l32", false, "32bit little-endian")
	plan9     = flag.Bool("plan9", false, "plan9")
	openbsd   = flag.Bool("openbsd", false, "openbsd")
	netbsd    = flag.Bool("netbsd", false, "netbsd")
	dragonfly = flag.Bool("dragonfly", false, "dragonfly")
	arm       = flag.Bool("arm", false, "arm") // 64-bit value should use (even, odd)-pair
	tags      = flag.String("tags", "", "build tags")
	filename  = flag.String("output", "", "output file name (standard output if omitted)")
)

// cmdLine returns this programs's commandline arguments
func cmdLine() string {
	return "go run mksyscall.go " + strings.Join(os.Args[1:], " ")
}

// buildTags returns build tags
func buildTags() string {
	return *tags
}

// Param is function parameter
type Param struct {
	Name string
	Type string
}

// usage prints the program usage
func usage() {
	fmt.Fprintf(os.Stderr, "usage: go run mksyscall.go [-b32 | -l32] [-tags x,y] [file ...]\n")
	os.Exit(1)
}

// parseParamList parses parameter list and returns a slice of parameters
func parseParamList(list string) []string {
	list = strings.TrimSpace(list)
	if list == "" {
		return []string{}
	}
	return regexp.MustCompile(`\s*,\s*`).Split(list, -1)
}

// parseParam splits a parameter into name and type
func parseParam(p string) Param {
	ps := regexp.MustCompile(`^(\S*) (\S*)$`).FindStringSubmatch(p)
	if ps == nil {
		fmt.Fprintf(os.Stderr, "malformed parameter: %s\n", p)
		os.Exit(1)
	}
	return Param{ps[1], ps[2]}
}

func main() {
	// Get the OS and architecture (using GOARCH_TARGET if it exists)
	goos := os.Getenv("GOOS")
	if goos == "" {
		fmt.Fprintln(os.Stderr, "GOOS not defined in environment")
		os.Exit(1)
	}
	goarch := os.Getenv("GOARCH_TARGET")
	if goarch == "" {
		goarch = os.Getenv("GOARCH")
	}

	// Check that we are using the Docker-based build system if we should
	if goos == "linux" {
		if os.Getenv("GOLANG_SYS_BUILD") != "docker" {
			fmt.Fprintf(os.Stderr, "In the Docker-based build system, mksyscall should not be called directly.\n")
			fmt.Fprintf(os.Stderr, "See README.md\n")
			os.Exit(1)
		}
	}

	flag.Usage = usage
	flag.Parse()
	if len(flag.Args()) <= 0 {
		fmt.Fprintf(os.Stderr, "no files to parse provided\n")
		usage()
	}

	endianness := ""
	if *b32 {
		endianness = "big-endian"
	} else if *l32 {
		endianness = "little-endian"
	}

	libc := false
	if goos == "darwin" && strings.Contains(buildTags(), ",go1.12") {
		libc = true
	}
	trampolines := map[string]bool{}

	text := ""
	for _, path := range flag.Args() {
		file, err := os.Open(path)
		if err != nil {
			fmt.Fprintf(os.Stderr, err.Error())
			os.Exit(1)
		}
		s := bufio.NewScanner(file)
		for s.Scan() {
			t := s.Text()
			t = strings.TrimSpace(t)
			t = regexp.MustCompile(`\s+`).ReplaceAllString(t, ` `)
			nonblock := regexp.MustCompile(`^\/\/sysnb `).FindStringSubmatch(t)
			if regexp.MustCompile(`^\/\/sys `).FindStringSubmatch(t) == nil && nonblock == nil {
				continue
			}

			// Line must be of the form
			//	func Open(path string, mode int, perm int) (fd int, errno error)
			// Split into name, in params, out params.
			f := regexp.MustCompile(`^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)SYS_[A-Z0-9_]+))?$`).FindStringSubmatch(t)
			if f == nil {
				fmt.Fprintf(os.Stderr, "%s:%s\nmalformed //sys declaration\n", path, t)
				os.Exit(1)
			}
			funct, inps, outps, sysname := f[2], f[3], f[4], f[5]

			// ClockGettime doesn't have a syscall number on Darwin, only generate libc wrappers.
			if goos == "darwin" && !libc && funct == "ClockGettime" {
				continue
			}

			// Split argument lists on comma.
			in := parseParamList(inps)
			out := parseParamList(outps)

			// Try in vain to keep people from editing this file.
			// The theory is that they jump into the middle of the file
			// without reading the header.
			text += "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n"

			// Go function header.
			outDecl := ""
			if len(out) > 0 {
				outDecl = fmt.Sprintf(" (%s)", strings.Join(out, ", "))
			}
			text += fmt.Sprintf("func %s(%s)%s {\n", funct, strings.Join(in, ", "), outDecl)

			// Check if err return available
			errvar := ""
			for _, param := range out {
				p := parseParam(param)
				if p.Type == "error" {
					errvar = p.Name
					break
				}
			}

			// Prepare arguments to Syscall.
			var args []string
			n := 0
			for _, param := range in {
				p := parseParam(param)
				if regexp.MustCompile(`^\*`).FindStringSubmatch(p.Type) != nil {
					args = append(args, "uintptr(unsafe.Pointer("+p.Name+"))")
				} else if p.Type == "string" && errvar != "" {
					text += fmt.Sprintf("\tvar _p%d *byte\n", n)
					text += fmt.Sprintf("\t_p%d, %s = BytePtrFromString(%s)\n", n, errvar, p.Name)
					text += fmt.Sprintf("\tif %s != nil {\n\t\treturn\n\t}\n", errvar)
					args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n))
					n++
				} else if p.Type == "string" {
					fmt.Fprintf(os.Stderr, path+":"+funct+" uses string arguments, but has no error return\n")
					text += fmt.Sprintf("\tvar _p%d *byte\n", n)
					text += fmt.Sprintf("\t_p%d, _ = BytePtrFromString(%s)\n", n, p.Name)
					args = append(args, fmt.Sprintf("uintptr(unsafe.Pointer(_p%d))", n))
					n++
				} else if regexp.MustCompile(`^\[\](.*)`).FindStringSubmatch(p.Type) != nil {
					// Convert slice into pointer, length.
					// Have to be careful not to take address of &a[0] if len == 0:
					// pass dummy pointer in that case.
					// Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
					text += fmt.Sprintf("\tvar _p%d unsafe.Pointer\n", n)
					text += fmt.Sprintf("\tif len(%s) > 0 {\n\t\t_p%d = unsafe.Pointer(&%s[0])\n\t}", p.Name, n, p.Name)
					text += fmt.Sprintf(" else {\n\t\t_p%d = unsafe.Pointer(&_zero)\n\t}\n", n)
					args = append(args, fmt.Sprintf("uintptr(_p%d)", n), fmt.Sprintf("uintptr(len(%s))", p.Name))
					n++
				} else if p.Type == "int64" && (*openbsd || *netbsd) {
					args = append(args, "0")
					if endianness == "big-endian" {
						args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
					} else if endianness == "little-endian" {
						args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
					} else {
						args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
					}
				} else if p.Type == "int64" && *dragonfly {
					if regexp.MustCompile(`^(?i)extp(read|write)`).FindStringSubmatch(funct) == nil {
						args = append(args, "0")
					}
					if endianness == "big-endian" {
						args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
					} else if endianness == "little-endian" {
						args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
					} else {
						args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
					}
				} else if (p.Type == "int64" || p.Type == "uint64") && endianness != "" {
					if len(args)%2 == 1 && *arm {
						// arm abi specifies 64-bit argument uses
						// (even, odd) pair
						args = append(args, "0")
					}
					if endianness == "big-endian" {
						args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
					} else {
						args = append(args, fmt.Sprintf("uintptr(%s)", p.Name), fmt.Sprintf("uintptr(%s>>32)", p.Name))
					}
				} else {
					args = append(args, fmt.Sprintf("uintptr(%s)", p.Name))
				}
			}

			// Determine which form to use; pad args with zeros.
			asm := "Syscall"
			if nonblock != nil {
				if errvar == "" && goos == "linux" {
					asm = "RawSyscallNoError"
				} else {
					asm = "RawSyscall"
				}
			} else {
				if errvar == "" && goos == "linux" {
					asm = "SyscallNoError"
				}
			}
			if len(args) <= 3 {
				for len(args) < 3 {
					args = append(args, "0")
				}
			} else if len(args) <= 6 {
				asm += "6"
				for len(args) < 6 {
					args = append(args, "0")
				}
			} else if len(args) <= 9 {
				asm += "9"
				for len(args) < 9 {
					args = append(args, "0")
				}
			} else {
				fmt.Fprintf(os.Stderr, "%s:%s too many arguments to system call\n", path, funct)
			}

			// System call number.
			if sysname == "" {
				sysname = "SYS_" + funct
				sysname = regexp.MustCompile(`([a-z])([A-Z])`).ReplaceAllString(sysname, `${1}_$2`)
				sysname = strings.ToUpper(sysname)
			}

			var libcFn string
			if libc {
				asm = "syscall_" + strings.ToLower(asm[:1]) + asm[1:] // internal syscall call
				sysname = strings.TrimPrefix(sysname, "SYS_")         // remove SYS_
				sysname = strings.ToLower(sysname)                    // lowercase
				if sysname == "getdirentries64" {
					// Special case - libSystem name and
					// raw syscall name don't match.
					sysname = "__getdirentries64"
				}
				libcFn = sysname
				sysname = "funcPC(libc_" + sysname + "_trampoline)"
			}

			// Actual call.
			arglist := strings.Join(args, ", ")
			call := fmt.Sprintf("%s(%s, %s)", asm, sysname, arglist)

			// Assign return values.
			body := ""
			ret := []string{"_", "_", "_"}
			doErrno := false
			for i := 0; i < len(out); i++ {
				p := parseParam(out[i])
				reg := ""
				if p.Name == "err" && !*plan9 {
					reg = "e1"
					ret[2] = reg
					doErrno = true
				} else if p.Name == "err" && *plan9 {
					ret[0] = "r0"
					ret[2] = "e1"
					break
				} else {
					reg = fmt.Sprintf("r%d", i)
					ret[i] = reg
				}
				if p.Type == "bool" {
					reg = fmt.Sprintf("%s != 0", reg)
				}
				if p.Type == "int64" && endianness != "" {
					// 64-bit number in r1:r0 or r0:r1.
					if i+2 > len(out) {
						fmt.Fprintf(os.Stderr, "%s:%s not enough registers for int64 return\n", path, funct)
					}
					if endianness == "big-endian" {
						reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i, i+1)
					} else {
						reg = fmt.Sprintf("int64(r%d)<<32 | int64(r%d)", i+1, i)
					}
					ret[i] = fmt.Sprintf("r%d", i)
					ret[i+1] = fmt.Sprintf("r%d", i+1)
				}
				if reg != "e1" || *plan9 {
					body += fmt.Sprintf("\t%s = %s(%s)\n", p.Name, p.Type, reg)
				}
			}
			if ret[0] == "_" && ret[1] == "_" && ret[2] == "_" {
				text += fmt.Sprintf("\t%s\n", call)
			} else {
				if errvar == "" && goos == "linux" {
					// raw syscall without error on Linux, see golang.org/issue/22924
					text += fmt.Sprintf("\t%s, %s := %s\n", ret[0], ret[1], call)
				} else {
					text += fmt.Sprintf("\t%s, %s, %s := %s\n", ret[0], ret[1], ret[2], call)
				}
			}
			text += body

			if *plan9 && ret[2] == "e1" {
				text += "\tif int32(r0) == -1 {\n"
				text += "\t\terr = e1\n"
				text += "\t}\n"
			} else if doErrno {
				text += "\tif e1 != 0 {\n"
				text += "\t\terr = errnoErr(e1)\n"
				text += "\t}\n"
			}
			text += "\treturn\n"
			text += "}\n\n"

			if libc && !trampolines[libcFn] {
				// some system calls share a trampoline, like read and readlen.
				trampolines[libcFn] = true
				// Declare assembly trampoline.
				text += fmt.Sprintf("func libc_%s_trampoline()\n", libcFn)
				// Assembly trampoline calls the libc_* function, which this magic
				// redirects to use the function from libSystem.
				text += fmt.Sprintf("//go:linkname libc_%s libc_%s\n", libcFn, libcFn)
				text += fmt.Sprintf("//go:cgo_import_dynamic libc_%s %s \"/usr/lib/libSystem.B.dylib\"\n", libcFn, libcFn)
				text += "\n"
			}
		}
		if err := s.Err(); err != nil {
			fmt.Fprintf(os.Stderr, err.Error())
			os.Exit(1)
		}
		file.Close()
	}
	fmt.Printf(srcTemplate, cmdLine(), buildTags(), text)
}

const srcTemplate = `// %s
// Code generated by the command above; see README.md. DO NOT EDIT.

// +build %s

package unix

import (
	"syscall"
	"unsafe"
)

var _ syscall.Errno

%s
`