nvidia-container-toolkit/internal/lookup/file.go
Evan Lezar 390e5747ea Add lookup abstraction for locating executable files
Signed-off-by: Evan Lezar <elezar@nvidia.com>
2022-04-04 14:16:25 +02:00

86 lines
2.3 KiB
Go

/*
# Copyright (c) 2021, NVIDIA CORPORATION. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
*/
package lookup
import (
"fmt"
"os"
"path/filepath"
log "github.com/sirupsen/logrus"
)
// file can be used to locate file (or file-like elements) at a specified set of
// prefixes. The validity of a file is determined by a filter function.
type file struct {
logger *log.Logger
prefixes []string
filter func(string) error
}
// NewFileLocator creates a Locator that can be used to find files at the specified root. A logger
// can also be specified.
func NewFileLocator(logger *log.Logger, root string) Locator {
l := newFileLocator(logger, root)
return &l
}
func newFileLocator(logger *log.Logger, root string) file {
return file{
logger: logger,
prefixes: []string{root},
filter: assertFile,
}
}
var _ Locator = (*file)(nil)
// Locate attempts to find the specified file. All prefixes are searched and any matching
// candidates are returned. If no matches are found, an error is returned.
func (p file) Locate(filename string) ([]string, error) {
var filenames []string
for _, prefix := range p.prefixes {
candidate := filepath.Join(prefix, filename)
p.logger.Debugf("Checking candidate '%v'", candidate)
err := p.filter(candidate)
if err != nil {
p.logger.Debugf("Candidate '%v' does not meet requirements: %v", candidate, err)
continue
}
filenames = append(filenames, candidate)
}
if len(filename) == 0 {
return nil, fmt.Errorf("file %v not found", filename)
}
return filenames, nil
}
// assertFile checks whether the specified path is a regular file
func assertFile(filename string) error {
info, err := os.Stat(filename)
if err != nil {
return fmt.Errorf("error getting info for %v: %v", filename, err)
}
if info.IsDir() {
return fmt.Errorf("specified path '%v' is a directory", filename)
}
return nil
}