lp_plan9.go

     1  // Copyright 2011 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
     6  
     7  import (
     8  	"errors"
     9  	"io/fs"
    10  	"os"
    11  	"path/filepath"
    12  	"strings"
    13  )
    14  
    15  // ErrNotFound is the error resulting if a path search failed to find an executable file.
    16  var ErrNotFound = errors.New("executable file not found in $path")
    17  
    18  func findExecutable(file string) error {
    19  	d, err := os.Stat(file)
    20  	if err != nil {
    21  		return err
    22  	}
    23  	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
    24  		return nil
    25  	}
    26  	return fs.ErrPermission
    27  }
    28  
    29  func lookPath(file string) (string, error) {
    30  	if err := validateLookPath(filepath.Clean(file)); err != nil {
    31  		return "", &Error{file, err}
    32  	}
    33  
    34  	// skip the path lookup for these prefixes
    35  	skip := []string{"/", "#", "./", "../"}
    36  
    37  	for _, p := range skip {
    38  		if strings.HasPrefix(file, p) {
    39  			err := findExecutable(file)
    40  			if err == nil {
    41  				return file, nil
    42  			}
    43  			return "", &Error{file, err}
    44  		}
    45  	}
    46  
    47  	path := os.Getenv("path")
    48  	for _, dir := range filepath.SplitList(path) {
    49  		path := filepath.Join(dir, file)
    50  		if err := findExecutable(path); err == nil {
    51  			if !filepath.IsAbs(path) {
    52  				if execerrdot.Value() != "0" {
    53  					return path, &Error{file, ErrDot}
    54  				}
    55  				execerrdot.IncNonDefault()
    56  			}
    57  			return path, nil
    58  		}
    59  	}
    60  	return "", &Error{file, ErrNotFound}
    61  }
    62  
    63  // lookExtensions is a no-op on non-Windows platforms, since
    64  // they do not restrict executables to specific extensions.
    65  func lookExtensions(path, dir string) (string, error) {
    66  	return path, nil
    67  }
    68
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