github.heygears.com/openimsdk/tools@v0.0.49/field/file.go (about)

     1  // Copyright © 2024 OpenIM open source community. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package field
    16  
    17  import (
    18  	"os"
    19  
    20  	"github.com/openimsdk/tools/errs"
    21  )
    22  
    23  // LinkTreatment is the base type for constants used by Exists that indicate
    24  // how symlinks are treated for existence checks.
    25  type LinkTreatment int
    26  
    27  const (
    28  	// CheckFollowSymlink follows the symlink and verifies that the target of
    29  	// the symlink exists.
    30  	CheckFollowSymlink LinkTreatment = iota
    31  
    32  	// CheckSymlinkOnly does not follow the symlink and verifies only that they
    33  	// symlink itself exists.
    34  	CheckSymlinkOnly
    35  )
    36  
    37  // ErrInvalidLinkTreatment indicates that the link treatment behavior requested
    38  // is not a valid behavior.
    39  var ErrInvalidLinkTreatment = errs.New("unknown link behavior")
    40  
    41  // Exists checks if specified file, directory, or symlink exists. The behavior
    42  // of the test depends on the linkBehaviour argument. See LinkTreatment for
    43  // more details.
    44  func Exists(linkBehavior LinkTreatment, filename string) (bool, error) {
    45  	var err error
    46  
    47  	if linkBehavior == CheckFollowSymlink {
    48  		_, err = os.Stat(filename)
    49  	} else if linkBehavior == CheckSymlinkOnly {
    50  		_, err = os.Lstat(filename)
    51  	} else {
    52  		return false, errs.Wrap(ErrInvalidLinkTreatment)
    53  	}
    54  
    55  	if os.IsNotExist(err) {
    56  		return false, nil
    57  	} else if err != nil {
    58  		return false, errs.WrapMsg(err, "failed to check if file exists", "file", filename)
    59  	}
    60  	return true, nil
    61  }
    62  
    63  // ReadDirNoStat returns a string of files/directories contained
    64  // in dirname without calling lstat on them.
    65  func ReadDirNoStat(dirname string) ([]string, error) {
    66  	if dirname == "" {
    67  		dirname = "."
    68  	}
    69  
    70  	f, err := os.Open(dirname)
    71  	if err != nil {
    72  		return nil, errs.WrapMsg(err, "failed to open directory", "dir", dirname)
    73  	}
    74  	defer f.Close()
    75  
    76  	return f.Readdirnames(-1)
    77  }