os: do not use procfs for os.Executable in dragonfly

  procfs(5) is not always mounted in DragonFly BSD, for example during
  the binary package build with synth. os.Executable() consumers
  will then fail, we've spotted this when trying to build tinygo:

    [...]

    copying source files
    ./build/tinygo build-builtins -target=armv6m-none-eabi [...]
    panic: could not get executable path: readlink /proc/curproc/file:
    no such file or directory

    [...]

  Use KERN_PROC_PATHNAME as FreeBSD does.

Change-Id: Ic65bea02cd0309fb24dec8ba8d2b151d1acde67b
GitHub-Last-Rev: 083120a43b3158bb45d7e1a66fa32e3335a2d407
GitHub-Pull-Request: golang/go#36826
Reviewed-on: https://go-review.googlesource.com/c/go/+/216622
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Trust: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/os/executable_dragonfly.go b/src/os/executable_dragonfly.go
new file mode 100644 (file)
index 0000000..b0deb7b
--- /dev/null
+++ b/src/os/executable_dragonfly.go
@@ -0,0 +1,12 @@
+// Copyright 2020 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.
+
+package os
+
+// From DragonFly's <sys/sysctl.h>
+const (
+        _CTL_KERN           = 1
+        _KERN_PROC          = 14
+        _KERN_PROC_PATHNAME = 9
+)

diff --git a/src/os/executable_freebsd.go b/src/os/executable_freebsd.go
index ccaf8e6dd4408c6113747de17a24ed25b4632edd..57930b1b16178df3c68af321bf3636034a46a5a3 100644 (file)
--- a/src/os/executable_freebsd.go
+++ b/src/os/executable_freebsd.go
@@ -1,33 +1,12 @@
-// Copyright 2016 The Go Authors. All rights reserved.
+// Copyright 2020 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.
 
 package os
 
-import (
-       "syscall"
-       "unsafe"
+// From FreeBSD's <sys/sysctl.h>
+const (
+        _CTL_KERN           = 1
+        _KERN_PROC          = 14
+        _KERN_PROC_PATHNAME = 12
 )
-
-func executable() (string, error) {
-       mib := [4]int32{1 /* CTL_KERN */, 14 /* KERN_PROC */, 12 /* KERN_PROC_PATHNAME */, -1}
-
-       n := uintptr(0)
-       // get length
-       _, _, err := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
-       if err != 0 {
-               return "", err
-       }
-       if n == 0 { // shouldn't happen
-               return "", nil
-       }
-       buf := make([]byte, n)
-       _, _, err = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
-       if err != 0 {
-               return "", err
-       }
-       if n == 0 { // shouldn't happen
-               return "", nil
-       }
-       return string(buf[:n-1]), nil
-}

diff --git a/src/os/executable_procfs.go b/src/os/executable_procfs.go
index 2628223b8db8434221be8b33835ca867a5a4050b..5ee41a4b2e28f6dc4579e09ad7a4558257bbdca8 100644 (file)
--- a/src/os/executable_procfs.go
+++ b/src/os/executable_procfs.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build linux netbsd dragonfly js,wasm
+// +build linux netbsd js,wasm
 
 package os
 
@@ -23,8 +23,6 @@ var executablePath, executablePathErr = func() (string, error) {
                procfn = "/proc/self/exe"
        case "netbsd":
                procfn = "/proc/curproc/exe"
-       case "dragonfly":
-               procfn = "/proc/curproc/file"
        }
        return Readlink(procfn)
 }()

diff --git a/src/os/executable_sysctl.go b/src/os/executable_sysctl.go
new file mode 100644 (file)
index 0000000..f9a4b18
--- /dev/null
+++ b/src/os/executable_sysctl.go
@@ -0,0 +1,35 @@
+// Copyright 2016 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 freebsd dragonfly
+
+package os
+
+import (
+       "syscall"
+       "unsafe"
+)
+
+func executable() (string, error) {
+       mib := [4]int32{_CTL_KERN, _KERN_PROC, _KERN_PROC_PATHNAME, -1}
+
+       n := uintptr(0)
+       // get length
+       _, _, err := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, 0, uintptr(unsafe.Pointer(&n)), 0, 0)
+       if err != 0 {
+               return "", err
+       }
+       if n == 0 { // shouldn't happen
+               return "", nil
+       }
+       buf := make([]byte, n)
+       _, _, err = syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(unsafe.Pointer(&mib[0])), 4, uintptr(unsafe.Pointer(&buf[0])), uintptr(unsafe.Pointer(&n)), 0, 0)
+       if err != 0 {
+               return "", err
+       }
+       if n == 0 { // shouldn't happen
+               return "", nil
+       }
+       return string(buf[:n-1]), nil
+}