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0cdde1e7ae
On NetBSD, for backwards compatibility, various libc symbols are
renamed to a symbol with a version suffix. For example, this is the
(abbreviated) definition of sigaction:
int sigaction(...) __asm__ ("__sigaction14")
This poses a challenge for libgo, which attempts to link sigaction by
way of an "//extern" comment:
//extern sigaction
func sigaction(...)
This results in a reference to the deprecated compatibility symbol
"sigaction", rather than the desired "__sigaction14" symbol.
This patch introduces a new "//extern-sysinfo" comment to handle this
situation. The new mklinknames.awk script scans a package for these
comments and outputs a "//go:linkname" directive that links the wrapper
to the correct versioned symbol, as determined by parsing the __asm__
annotation on the function's declaration in gen-sysinfo.go.
For now, only the following packages are scanned by mklinknames.awk:
os
os/user
runtime
syscall
gotools/:
* Makefile.am (check-runtime): Add runtime_linknames.go to
--extrafiles.
* Makefile.in: Regenerate.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/265125
47 lines
1.6 KiB
Awk
47 lines
1.6 KiB
Awk
# Copyright 2020 The Go Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style
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# license that can be found in the LICENSE file.
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# This AWK script reads a Go file with special //extern-sysinfo
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# comments annotating functions which should be linked to libc
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# functions. It generates a Go file containing the appropriate
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# //go:linkname directives.
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#
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# For each annotated function, the script searches gen-sysinfo.go
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# to see if a different assembly name is known for the function.
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# For example, on NetBSD, the timegm symbol is renamed to
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# __timegm50 by an __asm__ annotation on its declaration in time.h.
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BEGIN {
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print "// Code generated by mklinknames.awk. DO NOT EDIT."
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print ""
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print "package", package
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print ""
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print "import _ \"unsafe\""
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print ""
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}
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/^\/\/extern-sysinfo/ {
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cfnname = $2
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getline
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if ($1 != "func") {
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printf("mklinknames.awk: error: %s:%d: unattached extern-sysinfo directive\n", FILENAME, FNR) | "cat 1>&2"
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exit 1
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}
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split($2, a, "(")
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gofnname = a[1]
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def = sprintf("grep '^func _%s[ (]' gen-sysinfo.go", cfnname)
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# def looks like one of the following:
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# func _timegm (*_tm) int64 __asm__("__timegm50")
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# func _timegm (*_tm) int64 __asm__("*__timegm50")
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# The goal is to extract "__timegm50".
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if ((def | getline fndef) > 0 && match(fndef, "__asm__\\(\"\\*?")) {
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asmname = substr(fndef, RSTART + RLENGTH)
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asmname = substr(asmname, 0, length(asmname) - 2)
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printf("//go:linkname %s %s\n", gofnname, asmname)
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} else {
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# Assume the asm name is the same as the declared C name.
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printf("//go:linkname %s %s\n", gofnname, cfnname)
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}
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}
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