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// Copyright 2015 Light Code Labs, LLC
//
// 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 caddy
import (
"errors"
"runtime"
"unicode"
"github.com/flynn/go-shlex"
)
var runtimeGoos = runtime.GOOS
// SplitCommandAndArgs takes a command string and parses it shell-style into the
// command and its separate arguments.
func SplitCommandAndArgs(command string) (cmd string, args []string, err error) {
var parts []string
if runtimeGoos == "windows" {
parts = parseWindowsCommand(command) // parse it Windows-style
} else {
parts, err = parseUnixCommand(command) // parse it Unix-style
if err != nil {
err = errors.New("error parsing command: " + err.Error())
return
}
}
if len(parts) == 0 {
err = errors.New("no command contained in '" + command + "'")
return
}
cmd = parts[0]
if len(parts) > 1 {
args = parts[1:]
}
return
}
// parseUnixCommand parses a unix style command line and returns the
// command and its arguments or an error
func parseUnixCommand(cmd string) ([]string, error) {
return shlex.Split(cmd)
}
// parseWindowsCommand parses windows command lines and
// returns the command and the arguments as an array. It
// should be able to parse commonly used command lines.
// Only basic syntax is supported:
// - spaces in double quotes are not token delimiters
// - double quotes are escaped by either backspace or another double quote
// - except for the above case backspaces are path separators (not special)
//
// Many sources point out that escaping quotes using backslash can be unsafe.
// Use two double quotes when possible. (Source: http://stackoverflow.com/a/31413730/2616179 )
//
// This function has to be used on Windows instead
// of the shlex package because this function treats backslash
// characters properly.
func parseWindowsCommand(cmd string) []string {
const backslash = '\\'
const quote = '"'
var parts []string
var part string
var inQuotes bool
var lastRune rune
for i, ch := range cmd {
if i != 0 {
lastRune = rune(cmd[i-1])
}
if ch == backslash {
// put it in the part - for now we don't know if it's an
// escaping char or path separator
part += string(ch)
continue
}
if ch == quote {
if lastRune == backslash {
// remove the backslash from the part and add the escaped quote instead
part = part[:len(part)-1]
part += string(ch)
continue
}
if lastRune == quote {
// revert the last change of the inQuotes state
// it was an escaping quote
inQuotes = !inQuotes
part += string(ch)
continue
}
// normal escaping quotes
inQuotes = !inQuotes
continue
}
if unicode.IsSpace(ch) && !inQuotes && len(part) > 0 {
parts = append(parts, part)
part = ""
continue
}
part += string(ch)
}
if len(part) > 0 {
parts = append(parts, part)
}
return parts
}
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