restic/internal/backend/shell_split.go

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package backend
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import (
"unicode"
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"github.com/restic/restic/internal/errors"
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)
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// shellSplitter splits a command string into separated arguments. It supports
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// single and double quoted strings.
type shellSplitter struct {
quote rune
lastChar rune
}
func (s *shellSplitter) isSplitChar(c rune) bool {
// only test for quotes if the last char was not a backslash
if s.lastChar != '\\' {
// quote ended
if s.quote != 0 && c == s.quote {
s.quote = 0
return true
}
// quote starts
if s.quote == 0 && (c == '"' || c == '\'') {
s.quote = c
return true
}
}
s.lastChar = c
// within quote
if s.quote != 0 {
return false
}
// outside quote
return c == '\\' || unicode.IsSpace(c)
}
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// SplitShellStrings returns the list of shell strings from a shell command string.
func SplitShellStrings(data string) (strs []string, err error) {
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s := &shellSplitter{}
// derived from strings.SplitFunc
fieldStart := -1 // Set to -1 when looking for start of field.
for i, rune := range data {
if s.isSplitChar(rune) {
if fieldStart >= 0 {
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strs = append(strs, data[fieldStart:i])
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fieldStart = -1
}
} else if fieldStart == -1 {
fieldStart = i
}
}
if fieldStart >= 0 { // Last field might end at EOF.
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strs = append(strs, data[fieldStart:])
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}
switch s.quote {
case '\'':
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return nil, errors.New("single-quoted string not terminated")
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case '"':
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return nil, errors.New("double-quoted string not terminated")
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}
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if len(strs) == 0 {
return nil, errors.New("command string is empty")
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}
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return strs, nil
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}