65 lines
3.4 KiB
C
65 lines
3.4 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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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 General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/escape/escape.h"
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#include "libc/macros.h"
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#include "libc/str/str.h"
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// TODO(jart): implement me
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/**
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* Decodes backslash escape sequences in-place.
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*
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* We support the C standard definitions, and the gotchas that entails:
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*
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* \newline ← noop for multi-line str
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* \' \" \? \\ ← we try hard to avoid \?
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* \a \b \f \n \r \t \v \e ← \e is A++ GNU extension
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* \ octal-digit ← base-8 literal encoding
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* \ octal-digit octal-digit ← octal: super dependable
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* \ octal-digit octal-digit octal-digit ← longstanding DEC legacy
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* \x[0-9A-Fa-f]+ ← base16 literal encoding
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* \u[0-9A-Fa-f]{4} ← UNICODEs
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* \U[0-9A-Fa-f]{8} (astral planes) ← UNICODEs: Astral Planes
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*
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* @param n is # bytes in p
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* @param p is byte array of string literal content
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* @return new byte size of s, or -i to indicate first error at s[i]
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* @note we do not check for NUL terminator on input
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* @note array is zero-filled if shortened
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* @see cescapec(), strlen()
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*/
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int cunescape(size_t n, char p[n]) {
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unsigned char t[32];
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unsigned i, j, m, tc, tn, mask;
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for (m = n, i = 0; i < n; i += j) {
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tc = sizeof(t);
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tn = MIN(m - i, tc);
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memset(t, 0, tc);
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memcpy(t, p + i, tn);
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for (mask = j = 0; j < tc; ++j) {
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if (p[j] == '\\') mask |= 1u << j;
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}
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if (j < ARRAYLEN(t)) {
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memcpy(p + i, t, tn);
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}
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}
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return m;
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}
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