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fileutils.go
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fileutils.go
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package fileutils
import (
"errors"
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strings"
"text/scanner"
"github.com/Sirupsen/logrus"
)
// exclusion return true if the specified pattern is an exclusion
func exclusion(pattern string) bool {
return pattern[0] == '!'
}
// empty return true if the specified pattern is empty
func empty(pattern string) bool {
return pattern == ""
}
// CleanPatterns takes a slice of patterns returns a new
// slice of patterns cleaned with filepath.Clean, stripped
// of any empty patterns and lets the caller know whether the
// slice contains any exception patterns (prefixed with !).
func CleanPatterns(patterns []string) ([]string, [][]string, bool, error) {
// Loop over exclusion patterns and:
// 1. Clean them up.
// 2. Indicate whether we are dealing with any exception rules.
// 3. Error if we see a single exclusion marker on it's own (!).
cleanedPatterns := []string{}
patternDirs := [][]string{}
exceptions := false
for _, pattern := range patterns {
// Eliminate leading and trailing whitespace.
pattern = strings.TrimSpace(pattern)
if empty(pattern) {
continue
}
if exclusion(pattern) {
if len(pattern) == 1 {
return nil, nil, false, errors.New("Illegal exclusion pattern: !")
}
exceptions = true
}
pattern = filepath.Clean(pattern)
cleanedPatterns = append(cleanedPatterns, pattern)
if exclusion(pattern) {
pattern = pattern[1:]
}
patternDirs = append(patternDirs, strings.Split(pattern, "/"))
}
return cleanedPatterns, patternDirs, exceptions, 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) {
file = filepath.Clean(file)
if file == "." {
// Don't let them exclude everything, kind of silly.
return false, nil
}
patterns, patDirs, _, err := CleanPatterns(patterns)
if err != nil {
return false, err
}
return OptimizedMatches(file, patterns, patDirs)
}
// OptimizedMatches is basically the same as fileutils.Matches() but optimized for archive.go.
// It will assume that the inputs have been preprocessed and therefore the function
// doesn't need to do as much error checking and clean-up. This was done to avoid
// repeating these steps on each file being checked during the archive process.
// The more generic fileutils.Matches() can't make these assumptions.
func OptimizedMatches(file string, patterns []string, patDirs [][]string) (bool, error) {
matched := false
parentPath := filepath.Dir(file)
parentPathDirs := strings.Split(parentPath, "/")
for i, pattern := range patterns {
negative := false
if exclusion(pattern) {
negative = true
pattern = pattern[1:]
}
match, err := regexpMatch(pattern, file)
if err != nil {
return false, fmt.Errorf("Error in pattern (%s): %s", pattern, err)
}
if !match && parentPath != "." {
// Check to see if the pattern matches one of our parent dirs.
if len(patDirs[i]) <= len(parentPathDirs) {
match, _ = regexpMatch(strings.Join(patDirs[i], "/"),
strings.Join(parentPathDirs[:len(patDirs[i])], "/"))
}
}
if match {
matched = !negative
}
}
if matched {
logrus.Debugf("Skipping excluded path: %s", file)
}
return matched, nil
}
// regexpMatch tries to match the logic of filepath.Match but
// does so using regexp logic. We do this so that we can expand the
// wildcard set to include other things, like "**" to mean any number
// of directories. This means that we should be backwards compatible
// with filepath.Match(). We'll end up supporting more stuff, due to
// the fact that we're using regexp, but that's ok - it does no harm.
func regexpMatch(pattern, path string) (bool, error) {
regStr := "^"
// 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(pattern, path); err != nil {
return false, err
}
// 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()
if scan.Peek() == scanner.EOF {
// is "**EOF" - to align with .gitignore just accept all
regStr += ".*"
} else {
// is "**"
regStr += "((.*" + escSL + ")|([^" + escSL + "]*))"
}
// Treat **/ as ** so eat the "/"
if string(scan.Peek()) == sl {
scan.Next()
}
} else {
// is "*" so map it to anything but "/"
regStr += "[^" + escSL + "]*"
}
} else if ch == '?' {
// "?" is any char except "/"
regStr += "[^" + escSL + "]"
} else if strings.Index(".$", string(ch)) != -1 {
// Escape some regexp special chars that have no meaning
// in golang's filepath.Match
regStr += `\` + string(ch)
} else if ch == '\\' {
// escape next char. Note that a trailing \ in the pattern
// will be left alone (but need to escape it)
if sl == `\` {
// On windows map "\" to "\\", meaning an escaped backslash,
// and then just continue because filepath.Match on
// Windows doesn't allow escaping at all
regStr += escSL
continue
}
if scan.Peek() != scanner.EOF {
regStr += `\` + string(scan.Next())
} else {
regStr += `\`
}
} else {
regStr += string(ch)
}
}
regStr += "$"
res, err := regexp.MatchString(regStr, path)
// Map regexp's error to filepath's so no one knows we're not using filepath
if err != nil {
err = filepath.ErrBadPattern
}
return res, err
}
// CopyFile copies from src to dst until either EOF is reached
// on src or an error occurs. It verifies src exists and remove
// 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
}