s3 cache client-side support

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

vendor/github.com/aws/smithy-go/encoding/httpbinding/path_replace.go

@@ -0,0 +1,108 @@
+package httpbinding
+
+import (
+	"bytes"
+	"fmt"
+)
+
+const (
+	uriTokenStart = '{'
+	uriTokenStop  = '}'
+	uriTokenSkip  = '+'
+)
+
+func bufCap(b []byte, n int) []byte {
+	if cap(b) < n {
+		return make([]byte, 0, n)
+	}
+
+	return b[0:0]
+}
+
+// replacePathElement replaces a single element in the path []byte.
+// Escape is used to control whether the value will be escaped using Amazon path escape style.
+func replacePathElement(path, fieldBuf []byte, key, val string, escape bool) ([]byte, []byte, error) {
+	fieldBuf = bufCap(fieldBuf, len(key)+3) // { <key> [+] }
+	fieldBuf = append(fieldBuf, uriTokenStart)
+	fieldBuf = append(fieldBuf, key...)
+
+	start := bytes.Index(path, fieldBuf)
+	end := start + len(fieldBuf)
+	if start < 0 || len(path[end:]) == 0 {
+		// TODO what to do about error?
+		return path, fieldBuf, fmt.Errorf("invalid path index, start=%d,end=%d. %s", start, end, path)
+	}
+
+	encodeSep := true
+	if path[end] == uriTokenSkip {
+		// '+' token means do not escape slashes
+		encodeSep = false
+		end++
+	}
+
+	if escape {
+		val = EscapePath(val, encodeSep)
+	}
+
+	if path[end] != uriTokenStop {
+		return path, fieldBuf, fmt.Errorf("invalid path element, does not contain token stop, %s", path)
+	}
+	end++
+
+	fieldBuf = bufCap(fieldBuf, len(val))
+	fieldBuf = append(fieldBuf, val...)
+
+	keyLen := end - start
+	valLen := len(fieldBuf)
+
+	if keyLen == valLen {
+		copy(path[start:], fieldBuf)
+		return path, fieldBuf, nil
+	}
+
+	newLen := len(path) + (valLen - keyLen)
+	if len(path) < newLen {
+		path = path[:cap(path)]
+	}
+	if cap(path) < newLen {
+		newURI := make([]byte, newLen)
+		copy(newURI, path)
+		path = newURI
+	}
+
+	// shift
+	copy(path[start+valLen:], path[end:])
+	path = path[:newLen]
+	copy(path[start:], fieldBuf)
+
+	return path, fieldBuf, nil
+}
+
+// EscapePath escapes part of a URL path in Amazon style.
+func EscapePath(path string, encodeSep bool) string {
+	var buf bytes.Buffer
+	for i := 0; i < len(path); i++ {
+		c := path[i]
+		if noEscape[c] || (c == '/' && !encodeSep) {
+			buf.WriteByte(c)
+		} else {
+			fmt.Fprintf(&buf, "%%%02X", c)
+		}
+	}
+	return buf.String()
+}
+
+var noEscape [256]bool
+
+func init() {
+	for i := 0; i < len(noEscape); i++ {
+		// AWS expects every character except these to be escaped
+		noEscape[i] = (i >= 'A' && i <= 'Z') ||
+			(i >= 'a' && i <= 'z') ||
+			(i >= '0' && i <= '9') ||
+			i == '-' ||
+			i == '.' ||
+			i == '_' ||
+			i == '~'
+	}
+}