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138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
/* sexp-parse.h - S-expression helper functions
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* Copyright (C) 2002, 2003, 2007 Free Software Foundation, Inc.
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of either
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*
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* - the GNU Lesser General Public License as published by the Free
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* Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* or
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*
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* - the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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*
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* or both in parallel, as here.
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*
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* This file 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 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, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef SEXP_PARSE_H
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#define SEXP_PARSE_H
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#include <gpg-error.h>
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/* Return the length of the next S-Exp part and update the pointer to
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the first data byte. 0 is returned on error */
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static inline size_t
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snext (unsigned char const **buf)
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{
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const unsigned char *s;
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int n;
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s = *buf;
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for (n=0; *s && *s != ':' && (*s >= '0' && *s <= '9'); s++)
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n = n*10 + (*s - '0');
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if (!n || *s != ':')
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return 0; /* we don't allow empty lengths */
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*buf = s+1;
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return n;
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}
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/* Skip over the S-Expression BUF points to and update BUF to point to
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the character right behind. DEPTH gives the initial number of open
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lists and may be passed as a positive number to skip over the
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remainder of an S-Expression if the current position is somewhere
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in an S-Expression. The function may return an error code if it
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encounters an impossible condition. */
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static inline gpg_error_t
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sskip (unsigned char const **buf, int *depth)
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{
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const unsigned char *s = *buf;
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size_t n;
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int d = *depth;
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while (d > 0)
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{
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if (*s == '(')
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{
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d++;
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s++;
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}
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else if (*s == ')')
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{
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d--;
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s++;
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}
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else
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{
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if (!d)
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return gpg_error (GPG_ERR_INV_SEXP);
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n = snext (&s);
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if (!n)
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return gpg_error (GPG_ERR_INV_SEXP);
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s += n;
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}
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}
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*buf = s;
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*depth = d;
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return 0;
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}
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/* Check whether the the string at the address BUF points to matches
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the token. Return true on match and update BUF to point behind the
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token. Return false and do not update the buffer if it does not
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match. */
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static inline int
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smatch (unsigned char const **buf, size_t buflen, const char *token)
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{
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size_t toklen = strlen (token);
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if (buflen != toklen || memcmp (*buf, token, toklen))
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return 0;
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*buf += toklen;
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return 1;
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}
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/* Format VALUE for use as the length indicatior of an S-expression.
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The caller needs to provide a buffer HELP_BUFFER wth a length of
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HELP_BUFLEN. The return value is a pointer into HELP_BUFFER with
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the formatted length string. The colon and a trailing nul are
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appended. HELP_BUFLEN must be at least 3 - a more useful value is
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15. If LENGTH is not NULL, the LENGTH of the resulting string
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(excluding the terminating nul) is stored at that address. */
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static inline char *
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smklen (char *help_buffer, size_t help_buflen, size_t value, size_t *length)
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{
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char *p = help_buffer + help_buflen;
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if (help_buflen >= 3)
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{
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*--p = 0;
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*--p = ':';
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do
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{
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*--p = '0' + (value % 10);
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value /= 10;
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}
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while (value && p > help_buffer);
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}
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if (length)
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*length = (help_buffer + help_buflen) - p;
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return p;
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}
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#endif /*SEXP_PARSE_H*/
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