mirror of
https://github.com/go-vikunja/vikunja.git
synced 2026-11-09 00:22:38 -06:00
49 lines
1.6 KiB
Go
49 lines
1.6 KiB
Go
// Vikunja is a to-do list application to facilitate your life.
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// Copyright 2018-present Vikunja and contributors. All rights reserved.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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package utils
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import (
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"bytes"
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"errors"
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)
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// ErrJSONContainsNUL is returned for JSON that decodes to a string containing NUL.
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var ErrJSONContainsNUL = errors.New("text must not contain NUL characters (\\u0000)")
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var jsonNULEscape = []byte(`u0000`)
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// CheckJSONForNUL rejects JSON containing a \u0000 escape. Raw NUL bytes are
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// already invalid JSON, so the escape is the only way to smuggle one in.
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func CheckJSONForNUL(data []byte) error {
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for i := 0; ; {
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j := bytes.Index(data[i:], jsonNULEscape)
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if j < 0 {
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return nil
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}
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j += i
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backslashes := 0
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for k := j - 1; k >= 0 && data[k] == '\\'; k-- {
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backslashes++
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}
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// An even run means the backslashes escape each other: literal "\u0000" text.
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if backslashes%2 == 1 {
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return ErrJSONContainsNUL
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}
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i = j + len(jsonNULEscape)
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}
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}
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