Support multi-dir wildcards in .dockerignore

Closes #13113

Signed-off-by: Doug Davis <dug@us.ibm.com>

fileutils/fileutils.go

@@ -6,7 +6,9 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
+	"text/scanner"
 
 	"github.com/Sirupsen/logrus"
 )
@@ -92,15 +94,15 @@ func OptimizedMatches(file string, patterns []string, patDirs [][]string) (bool,
 			pattern = pattern[1:]
 		}
 
-		match, err := filepath.Match(pattern, file)
+		match, err := regexpMatch(pattern, file)
 		if err != nil {
-			return false, err
+			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, _ = filepath.Match(strings.Join(patDirs[i], "/"),
+				match, _ = regexpMatch(strings.Join(patDirs[i], "/"),
 					strings.Join(parentPathDirs[:len(patDirs[i])], "/"))
 			}
 		}
@@ -117,6 +119,99 @@ func OptimizedMatches(file string, patterns []string, patDirs [][]string) (bool,
 	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.