1 # Copyright 2011 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.
5 # This AWK script reads a Go file with comments describing syscall
6 # functions and the C routines they map to. It generates the Go code
7 # which calls the C routines.
9 # The syscall functins are marked by lines beginning with "//sys" and
10 # read like func declarations if //sys is replaced by func, but:
11 # * The parameter lists must give a name for each argument.
12 # This includes return parameters.
13 # * The parameter lists must give a type for each argument:
14 # the (x, y, z int) shorthand is not allowed.
15 # * If the return parameter is an error, it must be named err.
17 # A line beginning with //sysnb is like //sys, except that the
18 # goroutine will not be suspended during the execution of the library
19 # call. This must only be used for library calls which can never
20 # block, as otherwise the library call could cause all goroutines to
23 # After the //sys or //sysnb line comes a second line which describes
24 # the C function. The name must be the name of the function in the C
25 # library, and may be the same as the Go function. The limitations on
26 # the argument list are the same as for the //sys line, but there must
27 # be at most one result parameter, and it must be given as just a
28 # type, without a name.
31 print "// This file was automatically generated by mksyscall.awk"
33 print "package syscall"
35 print "import \"unsafe\""
41 if ($1 == "//sysnb") {
49 if (match(line, "//sys(nb)?[ ]*[a-zA-Z0-9_]+\\([^()]*\\) *(\\(([^()]+)\\))?") == 0) {
50 print "unmatched line:", $0 | "cat 1>&2"
55 # Sets a[1] = //sysnb, a[2] == function name.
56 split(line, a, "[ (]*")
59 off = match(line, "\\([^()]*\\)")
60 end = index(substr(line, off, length(line) - off + 1), ")")
61 gofnparams = substr(line, off + 1, end - 2)
63 line = substr(line, off + end, length(line) - (off + end) + 1)
64 off = match(line, "\\([^()]*\\)")
68 end = index(substr(line, off, length(line) - off + 1), ")")
69 gofnresults = substr(line, off + 1, end - 2)
75 if (match(line, "//[a-zA-Z0-9_]+\\([^()]*\\)") == 0) {
76 print "unmatched C line", $0, "after", gofnname | "cat 1>&2"
81 split(line, a, "[ (]*")
82 cfnname = substr(a[1], 3, length(a[1]) - 2)
84 off = match(line, "\\([^()]*\\)")
85 end = index(substr(line, off, length(line) - off + 1), ")")
86 cfnparams = substr(line, off + 1, end - 2)
88 line = substr(line, off + end + 1, length(line) - (off + end) + 1)
89 while (substr(line, 1, 1) == " ") {
90 line = substr(line, 2, length(line) - 1)
92 end = index(line, " ")
94 line = substr(line, 1, end)
98 printf("// Automatically generated wrapper for %s/%s\n", gofnname, cfnname)
99 printf("//extern %s\n", cfnname)
100 printf("func c_%s(%s) %s\n", cfnname, cfnparams, cfnresult)
101 printf("func %s(%s) %s%s%s%s{\n",
102 gofnname, gofnparams, gofnresults == "" ? "" : "(", gofnresults,
103 gofnresults == "" ? "" : ")", gofnresults == "" ? "" : " ")
105 loc = gofnname "/" cfnname ":"
107 split(gofnparams, goargs, ", *")
108 split(cfnparams, cargs, ", *")
111 for (goarg = 1; goargs[goarg] != ""; goarg++) {
112 if (cargs[carg] == "") {
113 print loc, "not enough C parameters"
120 if (split(goargs[goarg], a) != 2) {
121 print loc, "bad parameter:", goargs[goarg] | "cat 1>&2"
129 if (split(cargs[carg], a) != 2) {
130 print loc, "bad C parameter:", cargs[carg] | "cat 1>&2"
137 if (gotype ~ /^\*/) {
138 if (gotype != ctype) {
139 print loc, "Go/C pointer type mismatch:", gotype, ctype | "cat 1>&2"
144 } else if (gotype == "string") {
145 if (ctype != "*byte") {
146 print loc, "Go string not matched to C *byte:", gotype, ctype | "cat 1>&2"
150 printf("\t_p%d := StringBytePtr(%s)\n", goarg, goname)
151 args = sprintf("%s_p%d", args, goarg)
152 } else if (gotype ~ /^\[\](.*)/) {
153 if (ctype !~ /^\*/ || cargs[carg + 1] == "") {
154 print loc, "bad C type for slice:", gotype, ctype | "cat 1>&2"
159 # Convert a slice into a pair of pointer, length.
160 # Don't try to take the address of the zeroth element of a
162 printf("\tvar _p%d %s\n", goarg, ctype)
163 printf("\tif len(%s) > 0 {\n", goname)
164 printf("\t\t_p%d = (%s)(unsafe.Pointer(&%s[0]))\n", goarg, ctype, goname)
165 printf("\t} else {\n")
166 printf("\t\t_p%d = (%s)(unsafe.Pointer(&_zero))\n", goarg, ctype)
170 if (split(cargs[carg], cparam) != 2) {
171 print loc, "bad C parameter:", cargs[carg] | "cat 1>&2"
176 args = sprintf("%s_p%d, %s(len(%s))", args, goarg, cparam[2], goname)
177 } else if (gotype == "uintptr" && ctype ~ /^\*/) {
178 args = sprintf("%s(%s)(unsafe.Pointer(%s))", args, ctype, goname)
180 args = sprintf("%s%s(%s)", args, ctype, goname)
186 if (cargs[carg] != "") {
187 print loc, "too many C parameters" | "cat 1>&2"
193 print "\tentersyscall()"
197 if (gofnresults != "") {
200 printf("c_%s(%s)\n", cfnname, args)
202 if (gofnresults != "") {
203 fields = split(gofnresults, goresults, ", *")
205 print loc, "too many Go results" | "cat 1>&2"
210 for (goresult = 1; goresults[goresult] != ""; goresult++) {
211 if (split(goresults[goresult], goparam) != 2) {
212 print loc, "bad result:", goresults[goresult] | "cat 1>&2"
220 if (goname == "err") {
221 if (cfnresult ~ /^\*/) {
222 print "\tif _r == nil {"
224 print "\tif _r < 0 {"
226 print "\t\terr = GetErrno()"
228 } else if (gotype == "uintptr" && cfnresult ~ /^\*/) {
229 printf("\t%s = (%s)(unsafe.Pointer(_r))\n", goname, gotype)
232 print loc, "two parameters but no errno parameter" | "cat 1>&2"
236 printf("\t%s = (%s)(_r)\n", goname, gotype)
243 print "\texitsyscall()"
246 if (gofnresults != "") {
261 print "*** mksyscall.awk failed" | "cat 1>&2"