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# Copyright 2011 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.
# This AWK script reads a Go file with comments describing syscall
# functions and the C routines they map to. It generates the Go code
# which calls the C routines.
# The syscall functins 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, it must be named err.
# A line beginning with //sysnb is like //sys, except that the
# goroutine will not be suspended during the execution of the library
# call. This must only be used for library calls which can never
# block, as otherwise the library call could cause all goroutines to
# hang.
# After the //sys or //sysnb line comes a second line which describes
# the C function. The name must be the name of the function in the C
# library, and may be the same as the Go function. The limitations on
# the argument list are the same as for the //sys line, but there must
# be at most one result parameter, and it must be given as just a
# type, without a name.
BEGIN {
print "// This file was automatically generated by mksyscall.awk"
print ""
print "package syscall"
print ""
print "import \"unsafe\""
print ""
status = 0
}
/^\/\/sys/ {
if ($1 == "//sysnb") {
blocking = 0
} else {
blocking = 1
}
line = $0
if (match(line, "//sys(nb)?[ ]*[a-zA-Z0-9_]+\\([^()]*\\) *(\\(([^()]+)\\))?") == 0) {
print "unmatched line:", $0 | "cat 1>&2"
status = 1
next
}
# Sets a[1] = //sysnb, a[2] == function name.
split(line, a, "[ (]+")
gofnname = a[2]
off = match(line, "\\([^()]*\\)")
end = index(substr(line, off, length(line) - off + 1), ")")
gofnparams = substr(line, off + 1, end - 2)
line = substr(line, off + end, length(line) - (off + end) + 1)
off = match(line, "\\([^()]*\\)")
if (off == 0) {
gofnresults = ""
} else {
end = index(substr(line, off, length(line) - off + 1), ")")
gofnresults = substr(line, off + 1, end - 2)
}
getline
line = $0
if (match(line, "//[a-zA-Z0-9_]+\\([^()]*\\)") == 0) {
print "unmatched C line", $0, "after", gofnname | "cat 1>&2"
status = 1
next
}
split(line, a, "[ (]+")
cfnname = substr(a[1], 3, length(a[1]) - 2)
off = match(line, "\\([^()]*\\)")
end = index(substr(line, off, length(line) - off + 1), ")")
cfnparams = substr(line, off + 1, end - 2)
line = substr(line, off + end + 1, length(line) - (off + end) + 1)
while (substr(line, 1, 1) == " ") {
line = substr(line, 2, length(line) - 1)
}
end = index(line, " ")
if (end != 0) {
line = substr(line, 1, end)
}
cfnresult = line
printf("// Automatically generated wrapper for %s/%s\n", gofnname, cfnname)
if (!(cfnname in cfns)) {
cfns[cfnname] = 1
printf("//go:noescape\n")
printf("//extern %s\n", cfnname)
printf("func c_%s(%s) %s\n", cfnname, cfnparams, cfnresult)
}
printf("func %s(%s) %s%s%s%s{\n",
gofnname, gofnparams, gofnresults == "" ? "" : "(", gofnresults,
gofnresults == "" ? "" : ")", gofnresults == "" ? "" : " ")
loc = gofnname "/" cfnname ":"
haserr = 0
if (gofnresults != "") {
fields = split(gofnresults, goresults, ", *")
for (goresult = 1; goresults[goresult] != ""; goresult++) {
if (split(goresults[goresult], goparam) == 2) {
if (goparam[1] == "err") {
haserr = 1
break
}
}
}
}
split(gofnparams, goargs, ", *")
split(cfnparams, cargs, ", *")
args = ""
carg = 1
for (goarg = 1; goargs[goarg] != ""; goarg++) {
if (cargs[carg] == "") {
print loc, "not enough C parameters"
}
if (args != "") {
args = args ", "
}
if (split(goargs[goarg], a) != 2) {
print loc, "bad parameter:", goargs[goarg] | "cat 1>&2"
status = 1
next
}
goname = a[1]
gotype = a[2]
if (split(cargs[carg], a) != 2) {
print loc, "bad C parameter:", cargs[carg] | "cat 1>&2"
status = 1
next
}
ctype = a[2]
if (gotype ~ /^\*/) {
if (gotype != ctype) {
print loc, "Go/C pointer type mismatch:", gotype, ctype | "cat 1>&2"
status = 1
next
}
args = args goname
} else if (gotype == "string") {
if (ctype != "*byte") {
print loc, "Go string not matched to C *byte:", gotype, ctype | "cat 1>&2"
status = 1
next
}
printf("\tvar _p%d *byte\n", goarg)
if (haserr) {
printf("\t_p%d, err = BytePtrFromString(%s)\n", goarg, goname)
printf("\tif err != nil {\n\t\treturn\n\t}\n")
} else {
print loc, "uses string arguments but has no error return" | "cat 1>&2"
printf("\t_p%d, _ = BytePtrFromString(%s)\n", goarg, goname)
}
args = sprintf("%s_p%d", args, goarg)
} else if (gotype ~ /^\[\](.*)/) {
if (ctype !~ /^\*/ || cargs[carg + 1] == "") {
print loc, "bad C type for slice:", gotype, ctype | "cat 1>&2"
status = 1
next
}
# Convert a slice into a pair of pointer, length.
# Don't try to take the address of the zeroth element of a
# nil slice.
printf("\tvar _p%d %s\n", goarg, ctype)
printf("\tif len(%s) > 0 {\n", goname)
printf("\t\t_p%d = (%s)(unsafe.Pointer(&%s[0]))\n", goarg, ctype, goname)
printf("\t} else {\n")
printf("\t\t_p%d = (%s)(unsafe.Pointer(&_zero))\n", goarg, ctype)
printf("\t}\n")
++carg
if (split(cargs[carg], cparam) != 2) {
print loc, "bad C parameter:", cargs[carg] | "cat 1>&2"
status = 1
next
}
args = sprintf("%s_p%d, %s(len(%s))", args, goarg, cparam[2], goname)
} else if (gotype == "uintptr" && ctype ~ /^\*/) {
args = sprintf("%s(%s)(unsafe.Pointer(%s))", args, ctype, goname)
} else if (gotype == "unsafe.Pointer" && ctype ~ /^\*/) {
args = sprintf("%s(%s)(%s)", args, ctype, goname)
} else {
args = sprintf("%s%s(%s)", args, ctype, goname)
}
carg++
}
if (cargs[carg] != "") {
print loc, "too many C parameters" | "cat 1>&2"
status = 1
next
}
if (blocking) {
print "\tEntersyscall()"
}
printf("\t")
if (gofnresults != "") {
printf("_r := ")
}
printf("c_%s(%s)\n", cfnname, args)
seterr = 0
if (gofnresults != "") {
fields = split(gofnresults, goresults, ", *")
if (fields > 2) {
print loc, "too many Go results" | "cat 1>&2"
status = 1
next
}
usedr = 0
for (goresult = 1; goresults[goresult] != ""; goresult++) {
if (split(goresults[goresult], goparam) != 2) {
print loc, "bad result:", goresults[goresult] | "cat 1>&2"
status = 1
next
}
goname = goparam[1]
gotype = goparam[2]
if (goname == "err") {
print "\tvar errno Errno"
print "\tsetErrno := false"
if (cfnresult ~ /^\*/) {
print "\tif _r == nil {"
} else {
print "\tif _r < 0 {"
}
print "\t\terrno = GetErrno()"
print "\t\tsetErrno = true"
print "\t}"
seterr = 1
} else if (gotype == "uintptr" && cfnresult ~ /^\*/) {
printf("\t%s = (%s)(unsafe.Pointer(_r))\n", goname, gotype)
} else {
if (usedr) {
print loc, "two parameters but no errno parameter" | "cat 1>&2"
status = 1
next
}
printf("\t%s = (%s)(_r)\n", goname, gotype)
usedr = 1
}
}
}
if (blocking) {
print "\tExitsyscall()"
}
if (seterr) {
print "\tif setErrno {"
print "\t\terr = errno"
print "\t}"
}
if (gofnresults != "") {
print "\treturn"
}
print "}"
print ""
next
}
{ next }
END {
if (status != 0) {
print "*** mksyscall.awk failed" | "cat 1>&2"
exit status
}
}