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moby--moby/pkg/fileutils/fileutils.go
Tonis Tiigi adeb3e3684 Fix inefficient file paths filter
Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
2017-03-08 18:59:25 -08:00

298 lines
7.2 KiB
Go

package fileutils
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strings"
"text/scanner"
"github.com/Sirupsen/logrus"
)
// PatternMatcher allows checking paths agaist a list of patterns
type PatternMatcher struct {
patterns []*Pattern
exclusions bool
}
// NewPatternMatcher creates a new matcher object for specific patterns that can
// be used later to match against patterns against paths
func NewPatternMatcher(patterns []string) (*PatternMatcher, error) {
pm := &PatternMatcher{
patterns: make([]*Pattern, 0, len(patterns)),
}
for _, p := range patterns {
// Eliminate leading and trailing whitespace.
p = strings.TrimSpace(p)
if p == "" {
continue
}
p = filepath.Clean(p)
newp := &Pattern{}
if p[0] == '!' {
if len(p) == 1 {
return nil, errors.New("illegal exclusion pattern: \"!\"")
}
newp.exclusion = true
p = p[1:]
pm.exclusions = true
}
// Do some syntax checking on the pattern.
// filepath's Match() has some really weird rules that are inconsistent
// so instead of trying to dup their logic, just call Match() for its
// error state and if there is an error in the pattern return it.
// If this becomes an issue we can remove this since its really only
// needed in the error (syntax) case - which isn't really critical.
if _, err := filepath.Match(p, "."); err != nil {
return nil, err
}
newp.cleanedPattern = p
newp.dirs = strings.Split(p, string(os.PathSeparator))
pm.patterns = append(pm.patterns, newp)
}
return pm, nil
}
// Matches matches path against all the patterns. Matches is not safe to be
// called concurrently
func (pm *PatternMatcher) Matches(file string) (bool, error) {
matched := false
file = filepath.FromSlash(file)
parentPath := filepath.Dir(file)
parentPathDirs := strings.Split(parentPath, string(os.PathSeparator))
for _, pattern := range pm.patterns {
negative := false
if pattern.exclusion {
negative = true
}
match, err := pattern.match(file)
if err != nil {
return false, err
}
if !match && parentPath != "." {
// Check to see if the pattern matches one of our parent dirs.
if len(pattern.dirs) <= len(parentPathDirs) {
match, _ = pattern.match(strings.Join(parentPathDirs[:len(pattern.dirs)], string(os.PathSeparator)))
}
}
if match {
matched = !negative
}
}
if matched {
logrus.Debugf("Skipping excluded path: %s", file)
}
return matched, nil
}
// Exclusions returns true if any of the patterns define exclusions
func (pm *PatternMatcher) Exclusions() bool {
return pm.exclusions
}
// Patterns returns array of active patterns
func (pm *PatternMatcher) Patterns() []*Pattern {
return pm.patterns
}
// Pattern defines a single regexp used used to filter file paths.
type Pattern struct {
cleanedPattern string
dirs []string
regexp *regexp.Regexp
exclusion bool
}
func (p *Pattern) String() string {
return p.cleanedPattern
}
// Exclusion returns true if this pattern defines exclusion
func (p *Pattern) Exclusion() bool {
return p.exclusion
}
func (p *Pattern) match(path string) (bool, error) {
if p.regexp == nil {
if err := p.compile(); err != nil {
return false, filepath.ErrBadPattern
}
}
b := p.regexp.MatchString(path)
return b, nil
}
func (p *Pattern) compile() error {
regStr := "^"
pattern := p.cleanedPattern
// Go through the pattern and convert it to a regexp.
// We use a scanner so we can support utf-8 chars.
var scan scanner.Scanner
scan.Init(strings.NewReader(pattern))
sl := string(os.PathSeparator)
escSL := sl
if sl == `\` {
escSL += `\`
}
for scan.Peek() != scanner.EOF {
ch := scan.Next()
if ch == '*' {
if scan.Peek() == '*' {
// is some flavor of "**"
scan.Next()
// Treat **/ as ** so eat the "/"
if string(scan.Peek()) == sl {
scan.Next()
}
if scan.Peek() == scanner.EOF {
// is "**EOF" - to align with .gitignore just accept all
regStr += ".*"
} else {
// is "**"
// Note that this allows for any # of /'s (even 0) because
// the .* will eat everything, even /'s
regStr += "(.*" + escSL + ")?"
}
} else {
// is "*" so map it to anything but "/"
regStr += "[^" + escSL + "]*"
}
} else if ch == '?' {
// "?" is any char except "/"
regStr += "[^" + escSL + "]"
} else if ch == '.' || ch == '$' {
// Escape some regexp special chars that have no meaning
// in golang's filepath.Match
regStr += `\` + string(ch)
} else if ch == '\\' {
// escape next char. Note that a trailing \ in the pattern
// will be left alone (but need to escape it)
if sl == `\` {
// On windows map "\" to "\\", meaning an escaped backslash,
// and then just continue because filepath.Match on
// Windows doesn't allow escaping at all
regStr += escSL
continue
}
if scan.Peek() != scanner.EOF {
regStr += `\` + string(scan.Next())
} else {
regStr += `\`
}
} else {
regStr += string(ch)
}
}
regStr += "$"
re, err := regexp.Compile(regStr)
if err != nil {
return err
}
p.regexp = re
return nil
}
// Matches returns true if file matches any of the patterns
// and isn't excluded by any of the subsequent patterns.
func Matches(file string, patterns []string) (bool, error) {
pm, err := NewPatternMatcher(patterns)
if err != nil {
return false, err
}
file = filepath.Clean(file)
if file == "." {
// Don't let them exclude everything, kind of silly.
return false, nil
}
return pm.Matches(file)
}
// CopyFile copies from src to dst until either EOF is reached
// on src or an error occurs. It verifies src exists and removes
// the dst if it exists.
func CopyFile(src, dst string) (int64, error) {
cleanSrc := filepath.Clean(src)
cleanDst := filepath.Clean(dst)
if cleanSrc == cleanDst {
return 0, nil
}
sf, err := os.Open(cleanSrc)
if err != nil {
return 0, err
}
defer sf.Close()
if err := os.Remove(cleanDst); err != nil && !os.IsNotExist(err) {
return 0, err
}
df, err := os.Create(cleanDst)
if err != nil {
return 0, err
}
defer df.Close()
return io.Copy(df, sf)
}
// ReadSymlinkedDirectory returns the target directory of a symlink.
// The target of the symbolic link may not be a file.
func ReadSymlinkedDirectory(path string) (string, error) {
var realPath string
var err error
if realPath, err = filepath.Abs(path); err != nil {
return "", fmt.Errorf("unable to get absolute path for %s: %s", path, err)
}
if realPath, err = filepath.EvalSymlinks(realPath); err != nil {
return "", fmt.Errorf("failed to canonicalise path for %s: %s", path, err)
}
realPathInfo, err := os.Stat(realPath)
if err != nil {
return "", fmt.Errorf("failed to stat target '%s' of '%s': %s", realPath, path, err)
}
if !realPathInfo.Mode().IsDir() {
return "", fmt.Errorf("canonical path points to a file '%s'", realPath)
}
return realPath, nil
}
// CreateIfNotExists creates a file or a directory only if it does not already exist.
func CreateIfNotExists(path string, isDir bool) error {
if _, err := os.Stat(path); err != nil {
if os.IsNotExist(err) {
if isDir {
return os.MkdirAll(path, 0755)
}
if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
return err
}
f, err := os.OpenFile(path, os.O_CREATE, 0755)
if err != nil {
return err
}
f.Close()
}
}
return nil
}