github.com/rogpeppe/go-internal@v1.12.1-0.20240509064211-c8567cf8e95f/internal/os/execpath/lp_plan9.go (about)

     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 execpath
     6  
     7  import (
     8  	"os"
     9  	"path/filepath"
    10  	"strings"
    11  )
    12  
    13  func findExecutable(file string) error {
    14  	d, err := os.Stat(file)
    15  	if err != nil {
    16  		return err
    17  	}
    18  	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
    19  		return nil
    20  	}
    21  	return os.ErrPermission
    22  }
    23  
    24  // Look searches for an executable named file, using getenv to look up
    25  // environment variables. If getenv is nil, os.Getenv will be used. If file
    26  // contains a slash, it is tried directly and getenv will not be called.  The
    27  // result may be an absolute path or a path relative to the current directory.
    28  func Look(file string, getenv func(string) string) (string, error) {
    29  	if getenv == nil {
    30  		getenv = os.Getenv
    31  	}
    32  
    33  	// skip the path lookup for these prefixes
    34  	skip := []string{"/", "#", "./", "../"}
    35  
    36  	for _, p := range skip {
    37  		if strings.HasPrefix(file, p) {
    38  			err := findExecutable(file)
    39  			if err == nil {
    40  				return file, nil
    41  			}
    42  			return "", &Error{file, err}
    43  		}
    44  	}
    45  
    46  	path := getenv("path")
    47  	for _, dir := range filepath.SplitList(path) {
    48  		path := filepath.Join(dir, file)
    49  		if err := findExecutable(path); err == nil {
    50  			return path, nil
    51  		}
    52  	}
    53  	return "", &Error{file, ErrNotFound}
    54  }