dot_test.go

     1  // Copyright 2022 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 exec_test
     6  
     7  import (
     8  	"errors"
     9  	"internal/testenv"
    10  	"os"
    11  	. "os/exec"
    12  	"path/filepath"
    13  	"runtime"
    14  	"strings"
    15  	"testing"
    16  )
    17  
    18  var pathVar string = func() string {
    19  	if runtime.GOOS == "plan9" {
    20  		return "path"
    21  	}
    22  	return "PATH"
    23  }()
    24  
    25  func TestLookPath(t *testing.T) {
    26  	testenv.MustHaveExec(t)
    27  	// Not parallel: uses Chdir and Setenv.
    28  
    29  	tmpDir := filepath.Join(t.TempDir(), "testdir")
    30  	if err := os.Mkdir(tmpDir, 0777); err != nil {
    31  		t.Fatal(err)
    32  	}
    33  
    34  	executable := "execabs-test"
    35  	if runtime.GOOS == "windows" {
    36  		executable += ".exe"
    37  	}
    38  	if err := os.WriteFile(filepath.Join(tmpDir, executable), []byte{1, 2, 3}, 0777); err != nil {
    39  		t.Fatal(err)
    40  	}
    41  	chdir(t, tmpDir)
    42  	t.Setenv("PWD", tmpDir)
    43  	t.Logf(". is %#q", tmpDir)
    44  
    45  	origPath := os.Getenv(pathVar)
    46  
    47  	// Add "." to PATH so that exec.LookPath looks in the current directory on all systems.
    48  	// And try to trick it with "../testdir" too.
    49  	for _, errdot := range []string{"1", "0"} {
    50  		t.Run("GODEBUG=execerrdot="+errdot, func(t *testing.T) {
    51  			t.Setenv("GODEBUG", "execerrdot="+errdot+",execwait=2")
    52  			for _, dir := range []string{".", "../testdir"} {
    53  				t.Run(pathVar+"="+dir, func(t *testing.T) {
    54  					t.Setenv(pathVar, dir+string(filepath.ListSeparator)+origPath)
    55  					good := dir + "/execabs-test"
    56  					if found, err := LookPath(good); err != nil || !strings.HasPrefix(found, good) {
    57  						t.Fatalf(`LookPath(%#q) = %#q, %v, want "%s...", nil`, good, found, err, good)
    58  					}
    59  					if runtime.GOOS == "windows" {
    60  						good = dir + `\execabs-test`
    61  						if found, err := LookPath(good); err != nil || !strings.HasPrefix(found, good) {
    62  							t.Fatalf(`LookPath(%#q) = %#q, %v, want "%s...", nil`, good, found, err, good)
    63  						}
    64  					}
    65  
    66  					_, err := LookPath("execabs-test")
    67  					if errdot == "1" {
    68  						if err == nil {
    69  							t.Fatalf("LookPath didn't fail when finding a non-relative path")
    70  						} else if !errors.Is(err, ErrDot) {
    71  							t.Fatalf("LookPath returned unexpected error: want Is ErrDot, got %q", err)
    72  						}
    73  					} else {
    74  						if err != nil {
    75  							t.Fatalf("LookPath failed unexpectedly: %v", err)
    76  						}
    77  					}
    78  
    79  					cmd := Command("execabs-test")
    80  					if errdot == "1" {
    81  						if cmd.Err == nil {
    82  							t.Fatalf("Command didn't fail when finding a non-relative path")
    83  						} else if !errors.Is(cmd.Err, ErrDot) {
    84  							t.Fatalf("Command returned unexpected error: want Is ErrDot, got %q", cmd.Err)
    85  						}
    86  						cmd.Err = nil
    87  					} else {
    88  						if cmd.Err != nil {
    89  							t.Fatalf("Command failed unexpectedly: %v", err)
    90  						}
    91  					}
    92  
    93  					// Clearing cmd.Err should let the execution proceed,
    94  					// and it should fail because it's not a valid binary.
    95  					if err := cmd.Run(); err == nil {
    96  						t.Fatalf("Run did not fail: expected exec error")
    97  					} else if errors.Is(err, ErrDot) {
    98  						t.Fatalf("Run returned unexpected error ErrDot: want error like ENOEXEC: %q", err)
    99  					}
   100  				})
   101  			}
   102  		})
   103  	}
   104  
   105  	// Test the behavior when the first entry in PATH is an absolute name for the
   106  	// current directory.
   107  	//
   108  	// On Windows, "." may or may not be implicitly included before the explicit
   109  	// %PATH%, depending on the process environment;
   110  	// see https://go.dev/issue/4394.
   111  	//
   112  	// If the relative entry from "." resolves to the same executable as what
   113  	// would be resolved from an absolute entry in %PATH% alone, LookPath should
   114  	// return the absolute version of the path instead of ErrDot.
   115  	// (See https://go.dev/issue/53536.)
   116  	//
   117  	// If PATH does not implicitly include "." (such as on Unix platforms, or on
   118  	// Windows configured with NoDefaultCurrentDirectoryInExePath), then this
   119  	// lookup should succeed regardless of the behavior for ".", so it may be
   120  	// useful to run as a control case even on those platforms.
   121  	t.Run(pathVar+"=$PWD", func(t *testing.T) {
   122  		t.Setenv(pathVar, tmpDir+string(filepath.ListSeparator)+origPath)
   123  		good := filepath.Join(tmpDir, "execabs-test")
   124  		if found, err := LookPath(good); err != nil || !strings.HasPrefix(found, good) {
   125  			t.Fatalf(`LookPath(%#q) = %#q, %v, want \"%s...\", nil`, good, found, err, good)
   126  		}
   127  
   128  		if found, err := LookPath("execabs-test"); err != nil || !strings.HasPrefix(found, good) {
   129  			t.Fatalf(`LookPath(%#q) = %#q, %v, want \"%s...\", nil`, "execabs-test", found, err, good)
   130  		}
   131  
   132  		cmd := Command("execabs-test")
   133  		if cmd.Err != nil {
   134  			t.Fatalf("Command(%#q).Err = %v; want nil", "execabs-test", cmd.Err)
   135  		}
   136  	})
   137  
   138  	t.Run(pathVar+"=$OTHER", func(t *testing.T) {
   139  		// Control case: if the lookup returns ErrDot when PATH is empty, then we
   140  		// know that PATH implicitly includes ".". If it does not, then we don't
   141  		// expect to see ErrDot at all in this test (because the path will be
   142  		// unambiguously absolute).
   143  		wantErrDot := false
   144  		t.Setenv(pathVar, "")
   145  		if found, err := LookPath("execabs-test"); errors.Is(err, ErrDot) {
   146  			wantErrDot = true
   147  		} else if err == nil {
   148  			t.Fatalf(`with PATH='', LookPath(%#q) = %#q; want non-nil error`, "execabs-test", found)
   149  		}
   150  
   151  		// Set PATH to include an explicit directory that contains a completely
   152  		// independent executable that happens to have the same name as an
   153  		// executable in ".". If "." is included implicitly, looking up the
   154  		// (unqualified) executable name will return ErrDot; otherwise, the
   155  		// executable in "." should have no effect and the lookup should
   156  		// unambiguously resolve to the directory in PATH.
   157  
   158  		dir := t.TempDir()
   159  		executable := "execabs-test"
   160  		if runtime.GOOS == "windows" {
   161  			executable += ".exe"
   162  		}
   163  		if err := os.WriteFile(filepath.Join(dir, executable), []byte{1, 2, 3}, 0777); err != nil {
   164  			t.Fatal(err)
   165  		}
   166  		t.Setenv(pathVar, dir+string(filepath.ListSeparator)+origPath)
   167  
   168  		found, err := LookPath("execabs-test")
   169  		if wantErrDot {
   170  			wantFound := filepath.Join(".", executable)
   171  			if found != wantFound || !errors.Is(err, ErrDot) {
   172  				t.Fatalf(`LookPath(%#q) = %#q, %v, want %#q, Is ErrDot`, "execabs-test", found, err, wantFound)
   173  			}
   174  		} else {
   175  			wantFound := filepath.Join(dir, executable)
   176  			if found != wantFound || err != nil {
   177  				t.Fatalf(`LookPath(%#q) = %#q, %v, want %#q, nil`, "execabs-test", found, err, wantFound)
   178  			}
   179  		}
   180  	})
   181  }
   182
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