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Source file src/os/executable_test.go

Documentation: os

     1  // Copyright 2016 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.
     4  
     5  package os_test
     6  
     7  import (
     8  	"fmt"
     9  	"internal/testenv"
    10  	"os"
    11  	osexec "os/exec"
    12  	"path/filepath"
    13  	"runtime"
    14  	"testing"
    15  )
    16  
    17  const executable_EnvVar = "OSTEST_OUTPUT_EXECPATH"
    18  
    19  func TestExecutable(t *testing.T) {
    20  	testenv.MustHaveExec(t) // will also exclude nacl, which doesn't support Executable anyway
    21  	ep, err := os.Executable()
    22  	if err != nil {
    23  		t.Fatalf("Executable failed: %v", err)
    24  	}
    25  	// we want fn to be of the form "dir/prog"
    26  	dir := filepath.Dir(filepath.Dir(ep))
    27  	fn, err := filepath.Rel(dir, ep)
    28  	if err != nil {
    29  		t.Fatalf("filepath.Rel: %v", err)
    30  	}
    31  
    32  	cmd := &osexec.Cmd{}
    33  	// make child start with a relative program path
    34  	cmd.Dir = dir
    35  	cmd.Path = fn
    36  	// forge argv[0] for child, so that we can verify we could correctly
    37  	// get real path of the executable without influenced by argv[0].
    38  	cmd.Args = []string{"-", "-test.run=XXXX"}
    39  	if runtime.GOOS == "openbsd" {
    40  		// OpenBSD relies on argv[0]
    41  		cmd.Args[0] = fn
    42  	}
    43  	cmd.Env = append(os.Environ(), fmt.Sprintf("%s=1", executable_EnvVar))
    44  	out, err := cmd.CombinedOutput()
    45  	if err != nil {
    46  		t.Fatalf("exec(self) failed: %v", err)
    47  	}
    48  	outs := string(out)
    49  	if !filepath.IsAbs(outs) {
    50  		t.Fatalf("Child returned %q, want an absolute path", out)
    51  	}
    52  	if !sameFile(outs, ep) {
    53  		t.Fatalf("Child returned %q, not the same file as %q", out, ep)
    54  	}
    55  }
    56  
    57  func sameFile(fn1, fn2 string) bool {
    58  	fi1, err := os.Stat(fn1)
    59  	if err != nil {
    60  		return false
    61  	}
    62  	fi2, err := os.Stat(fn2)
    63  	if err != nil {
    64  		return false
    65  	}
    66  	return os.SameFile(fi1, fi2)
    67  }
    68  
    69  func init() {
    70  	if e := os.Getenv(executable_EnvVar); e != "" {
    71  		// first chdir to another path
    72  		dir := "/"
    73  		if runtime.GOOS == "windows" {
    74  			cwd, err := os.Getwd()
    75  			if err != nil {
    76  				panic(err)
    77  			}
    78  			dir = filepath.VolumeName(cwd)
    79  		}
    80  		os.Chdir(dir)
    81  		if ep, err := os.Executable(); err != nil {
    82  			fmt.Fprint(os.Stderr, "ERROR: ", err)
    83  		} else {
    84  			fmt.Fprint(os.Stderr, ep)
    85  		}
    86  		os.Exit(0)
    87  	}
    88  }
    89  

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