feat(portforwarding): allow running script upon port forwarding success (#2399)

2024-11-10 03:49:02 -05:00
parent e69966381d
commit a035a151bd
15 changed files with 480 additions and 4 deletions
--- a/internal/command/split.go
+++ b/internal/command/split.go
@@ -0,0 +1,150 @@
+package command
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"strings"
+	"unicode/utf8"
+)
+
+var (
+	ErrCommandEmpty            = errors.New("command is empty")
+	ErrSingleQuoteUnterminated = errors.New("unterminated single-quoted string")
+	ErrDoubleQuoteUnterminated = errors.New("unterminated double-quoted string")
+	ErrEscapeUnterminated      = errors.New("unterminated backslash-escape")
+)
+
+// Split splits a command string into a slice of arguments.
+// This is especially important for commands such as:
+// /bin/sh -c "echo hello"
+// which should be split into: ["/bin/sh", "-c", "echo hello"]
+// It supports backslash-escapes, single-quotes and double-quotes.
+// It does not support:
+// - the $" quoting style.
+// - expansion (brace, shell or pathname).
+func Split(command string) (words []string, err error) {
+	if command == "" {
+		return nil, fmt.Errorf("%w", ErrCommandEmpty)
+	}
+
+	const bufferSize = 1024
+	buffer := bytes.NewBuffer(make([]byte, bufferSize))
+
+	startIndex := 0
+
+	for startIndex < len(command) {
+		// skip any split characters at the start
+		character, runeSize := utf8.DecodeRuneInString(command[startIndex:])
+		switch {
+		case strings.ContainsRune(" \n\t", character):
+			startIndex += runeSize
+		case character == '\\':
+			// Look ahead to eventually skip an escaped newline
+			if command[startIndex+runeSize:] == "" {
+				return nil, fmt.Errorf("%w: %q", ErrEscapeUnterminated, command)
+			}
+			character, runeSize := utf8.DecodeRuneInString(command[startIndex+runeSize:])
+			if character == '\n' {
+				startIndex += runeSize + runeSize // backslash and newline
+			}
+		default:
+			var word string
+			buffer.Reset()
+			word, startIndex, err = splitWord(command, startIndex, buffer)
+			if err != nil {
+				return nil, fmt.Errorf("splitting word in %q: %w", command, err)
+			}
+			words = append(words, word)
+		}
+	}
+	return words, nil
+}
+
+// WARNING: buffer must be cleared before calling this function.
+func splitWord(input string, startIndex int, buffer *bytes.Buffer) (
+	word string, newStartIndex int, err error,
+) {
+	cursor := startIndex
+	for cursor < len(input) {
+		character, runeLength := utf8.DecodeRuneInString(input[cursor:])
+		cursor += runeLength
+		if character == '"' ||
+			character == '\'' ||
+			character == '\\' ||
+			character == ' ' ||
+			character == '\n' ||
+			character == '\t' {
+			buffer.WriteString(input[startIndex : cursor-runeLength])
+		}
+
+		switch {
+		case strings.ContainsRune(" \n\t", character): // spacing character
+			return buffer.String(), cursor, nil
+		case character == '"':
+			return handleDoubleQuoted(input, cursor, buffer)
+		case character == '\'':
+			return handleSingleQuoted(input, cursor, buffer)
+		case character == '\\':
+			return handleEscaped(input, cursor, buffer)
+		}
+	}
+
+	buffer.WriteString(input[startIndex:])
+	return buffer.String(), len(input), nil
+}
+
+func handleDoubleQuoted(input string, startIndex int, buffer *bytes.Buffer) (
+	word string, newStartIndex int, err error,
+) {
+	cursor := startIndex
+	for cursor < len(input) {
+		nextCharacter, nextRuneLength := utf8.DecodeRuneInString(input[cursor:])
+		cursor += nextRuneLength
+		switch nextCharacter {
+		case '"': // end of the double quoted string
+			buffer.WriteString(input[startIndex : cursor-nextRuneLength])
+			return splitWord(input, cursor, buffer)
+		case '\\': // escaped character
+			escapedCharacter, escapedRuneLength := utf8.DecodeRuneInString(input[cursor:])
+			cursor += escapedRuneLength
+			if !strings.ContainsRune("$`\"\n\\", escapedCharacter) {
+				break
+			}
+			buffer.WriteString(input[startIndex : cursor-nextRuneLength-escapedRuneLength])
+			if escapedCharacter != '\n' {
+				// skip backslash entirely for the newline character
+				buffer.WriteRune(escapedCharacter)
+			}
+			startIndex = cursor
+		}
+	}
+	return "", 0, fmt.Errorf("%w", ErrDoubleQuoteUnterminated)
+}
+
+func handleSingleQuoted(input string, startIndex int, buffer *bytes.Buffer) (
+	word string, newStartIndex int, err error,
+) {
+	closingQuoteIndex := strings.IndexRune(input[startIndex:], '\'')
+	if closingQuoteIndex == -1 {
+		return "", 0, fmt.Errorf("%w", ErrSingleQuoteUnterminated)
+	}
+	buffer.WriteString(input[startIndex : startIndex+closingQuoteIndex])
+	const singleQuoteRuneLength = 1
+	startIndex += closingQuoteIndex + singleQuoteRuneLength
+	return splitWord(input, startIndex, buffer)
+}
+
+func handleEscaped(input string, startIndex int, buffer *bytes.Buffer) (
+	word string, newStartIndex int, err error,
+) {
+	if input[startIndex:] == "" {
+		return "", 0, fmt.Errorf("%w", ErrEscapeUnterminated)
+	}
+	character, runeLength := utf8.DecodeRuneInString(input[startIndex:])
+	if character != '\n' { // backslash-escaped newline is ignored
+		buffer.WriteString(input[startIndex : startIndex+runeLength])
+	}
+	startIndex += runeLength
+	return splitWord(input, startIndex, buffer)
+}