github.com/code-reading/golang@v0.0.0-20220303082512-ba5bc0e589a3/go/src/mime/type_unix.go (about)

     1  // Copyright 2010 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  //go:build aix || darwin || dragonfly || freebsd || (js && wasm) || linux || netbsd || openbsd || solaris
     6  // +build aix darwin dragonfly freebsd js,wasm linux netbsd openbsd solaris
     7  
     8  package mime
     9  
    10  import (
    11  	"bufio"
    12  	"os"
    13  	"strings"
    14  )
    15  
    16  func init() {
    17  	osInitMime = initMimeUnix
    18  }
    19  
    20  // See https://specifications.freedesktop.org/shared-mime-info-spec/shared-mime-info-spec-0.21.html
    21  // for the FreeDesktop Shared MIME-info Database specification.
    22  var mimeGlobs = []string{
    23  	"/usr/local/share/mime/globs2",
    24  	"/usr/share/mime/globs2",
    25  }
    26  
    27  // Common locations for mime.types files on unix.
    28  var typeFiles = []string{
    29  	"/etc/mime.types",
    30  	"/etc/apache2/mime.types",
    31  	"/etc/apache/mime.types",
    32  	"/etc/httpd/conf/mime.types",
    33  }
    34  
    35  func loadMimeGlobsFile(filename string) error {
    36  	f, err := os.Open(filename)
    37  	if err != nil {
    38  		return err
    39  	}
    40  	defer f.Close()
    41  
    42  	scanner := bufio.NewScanner(f)
    43  	for scanner.Scan() {
    44  		// Each line should be of format: weight:mimetype:*.ext
    45  		fields := strings.Split(scanner.Text(), ":")
    46  		if len(fields) < 3 || len(fields[0]) < 1 || len(fields[2]) < 2 {
    47  			continue
    48  		} else if fields[0][0] == '#' || fields[2][0] != '*' {
    49  			continue
    50  		}
    51  
    52  		extension := fields[2][1:]
    53  		if _, ok := mimeTypes.Load(extension); ok {
    54  			// We've already seen this extension.
    55  			// The file is in weight order, so we keep
    56  			// the first entry that we see.
    57  			continue
    58  		}
    59  
    60  		setExtensionType(extension, fields[1])
    61  	}
    62  	if err := scanner.Err(); err != nil {
    63  		panic(err)
    64  	}
    65  	return nil
    66  }
    67  
    68  func loadMimeFile(filename string) {
    69  	f, err := os.Open(filename)
    70  	if err != nil {
    71  		return
    72  	}
    73  	defer f.Close()
    74  
    75  	scanner := bufio.NewScanner(f)
    76  	for scanner.Scan() {
    77  		fields := strings.Fields(scanner.Text())
    78  		if len(fields) <= 1 || fields[0][0] == '#' {
    79  			continue
    80  		}
    81  		mimeType := fields[0]
    82  		for _, ext := range fields[1:] {
    83  			if ext[0] == '#' {
    84  				break
    85  			}
    86  			setExtensionType("."+ext, mimeType)
    87  		}
    88  	}
    89  	if err := scanner.Err(); err != nil {
    90  		panic(err)
    91  	}
    92  }
    93  
    94  func initMimeUnix() {
    95  	for _, filename := range mimeGlobs {
    96  		if err := loadMimeGlobsFile(filename); err == nil {
    97  			return // Stop checking more files if mimetype database is found.
    98  		}
    99  	}
   100  
   101  	// Fallback if no system-generated mimetype database exists.
   102  	for _, filename := range typeFiles {
   103  		loadMimeFile(filename)
   104  	}
   105  }
   106  
   107  func initMimeForTests() map[string]string {
   108  	mimeGlobs = []string{""}
   109  	typeFiles = []string{"testdata/test.types"}
   110  	return map[string]string{
   111  		".T1":  "application/test",
   112  		".t2":  "text/test; charset=utf-8",
   113  		".png": "image/png",
   114  	}
   115  }