GUAC-847: Implement recursive descent parser for guacd config files.
This commit is contained in:
Michael Jumper
parent
8420ed7b13
commit
6f3fd21232
@ -27,10 +27,21 @@ AM_CFLAGS = -Werror -Wall -pedantic @LIBGUAC_INCLUDE@ @COMMON_INCLUDE@
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sbin_PROGRAMS = guacd
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man_MANS = man/guacd.8
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noinst_HEADERS = client.h client-map.h log.h
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guacd_SOURCES = daemon.c client.c client-map.c log.c
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guacd_LDADD = @LIBGUAC_LTLIB@ @COMMON_LTLIB@
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guacd_LDFLAGS = @PTHREAD_LIBS@ @SSL_LIBS@
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noinst_HEADERS = \
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client.h \
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client-map.h \
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conf-file.h \
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log.h
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guacd_SOURCES = \
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daemon.c \
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client.c \
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client-map.c \
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conf-file.c \
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log.c
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guacd_LDADD = @LIBGUAC_LTLIB@ @COMMON_LTLIB@
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guacd_LDFLAGS = @PTHREAD_LIBS@ @SSL_LIBS@
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EXTRA_DIST = init.d/guacd.in man/guacd.8
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CLEANFILES = $(init_SCRIPTS)
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513
src/guacd/conf-file.c
Normal file
513
src/guacd/conf-file.c
Normal file
@ -0,0 +1,513 @@
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/*
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* Copyright (C) 2014 Glyptodon LLC
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "config.h"
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#include "conf-file.h"
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#include <ctype.h>
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#include <string.h>
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/*
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* Simple recursive descent parser for an INI-like conf file grammar. The
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* grammar is, roughly:
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*
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* <line> ::= <opt-whitespace> <declaration> <line-end>
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* <line-end> ::= <opt-whitespace> <opt-comment> <EOL>
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* <declaration> ::= <section-name> | <parameter-value> | ""
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* <section-name> ::= "[" <name> "]"
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* <parameter-value> ::= <name> <opt-whitespace> "=" <opt-whitespace> <value>
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*
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* Where:
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* <opt-whitespace> is any number of tabs or spaces.
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* <opt-comment> is a # character followed by any length of text without an EOL.
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* <name> is an alpha-numeric string consisting of: [A-Za-z0-9_-].
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* <value> is any length of text without an EOL or # character, or a double-quoted string (backslash escapes legal).
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* <EOL> is a carriage return or line feed character.
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*/
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/**
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* The current section. Note that this means the parser is NOT threadsafe.
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*/
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char __guacd_current_section[GUACD_CONF_MAX_NAME_LENGTH + 1] = "";
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char* guacd_conf_parse_error = NULL;
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char* guacd_conf_parse_error_location = NULL;
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/**
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* Reads through all whitespace at the beginning of the buffer, returning the
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* number of characters read. This is <opt-whitespace> in the grammar above. As
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* the whitespace is zero or more whitespace characters, this function cannot
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* fail, but it may read zero chars overall.
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*/
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static int guacd_parse_whitespace(char* buffer, int length) {
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int chars_read = 0;
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/* Read through all whitespace */
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while (chars_read < length) {
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/* Read character */
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char c = *buffer;
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/* Stop at non-whitespace */
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if (c != ' ' && c != '\t')
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break;
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chars_read++;
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buffer++;
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}
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return chars_read;
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}
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/**
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* Parses the name of a parameter, section, etc. A section/parameter name can
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* consist only of alphanumeric characters and underscores. The resulting name
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* will be stored in the name string, which must have at least 256 bytes
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* available.
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*/
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static int guacd_parse_name(char* buffer, int length, char* name) {
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char* name_start = buffer;
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int chars_read = 0;
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/* Read through all valid name chars */
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while (chars_read < length) {
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/* Read character */
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char c = *buffer;
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/* Stop at non-name characters */
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if (!isalnum(c) && c != '_')
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break;
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chars_read++;
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buffer++;
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/* Ensure name does not exceed maximum length */
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if (chars_read > GUACD_CONF_MAX_NAME_LENGTH) {
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guacd_conf_parse_error = "Names can be no more than 255 characters long";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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}
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/* Names must contain at least one character */
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if (chars_read == 0)
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return 0;
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/* Copy name from buffer */
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memcpy(name, name_start, chars_read);
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name[chars_read] = '\0';
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return chars_read;
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}
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/**
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* Parses the value of a parameter. A value can consist of any character except
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* '#', whitespace, or EOL. The resulting value will be stored in the value
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* string, which must have at least 256 bytes available.
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*/
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static int guacd_parse_value(char* buffer, int length, char* value) {
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char* value_start = buffer;
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int chars_read = 0;
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/* Read through all valid value chars */
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while (chars_read < length) {
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/* Read character */
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char c = *buffer;
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/* Stop at invalid character */
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if (c == '#' || c == '"' || c == '\r' || c == '\n' || c == ' ' || c == '\t')
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break;
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chars_read++;
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buffer++;
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/* Ensure value does not exceed maximum length */
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if (chars_read > GUACD_CONF_MAX_VALUE_LENGTH) {
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guacd_conf_parse_error = "Values can be no more than 8191 characters long";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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}
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/* Values must contain at least one character */
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if (chars_read == 0) {
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guacd_conf_parse_error = "Unquoted values must contain at least one character";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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/* Copy value from buffer */
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memcpy(value, value_start, chars_read);
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value[chars_read] = '\0';
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return chars_read;
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}
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/**
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* Parses the quoted value of a parameter. Quoted values may contain any
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* character except double quotes or backslashes, which must be
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* backslash-escaped.
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*/
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static int guacd_parse_quoted_value(char* buffer, int length, char* value) {
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int escaped = 0;
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/* Assert first character is '"' */
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if (length == 0 || *buffer != '"')
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return 0;
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int chars_read = 1;
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buffer++;
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length--;
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/* Read until end of quoted value */
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while (chars_read < length) {
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/* Read character */
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char c = *buffer;
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/* Handle special characters if not escaped */
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if (!escaped) {
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/* Stop at quote or invalid character */
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if (c == '"' || c == '\r' || c == '\n')
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break;
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/* Backslash escaping */
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else if (c == '\\')
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escaped = 1;
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else
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*(value++) = c;
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}
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/* Reset escape flag */
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else {
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escaped = 0;
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*(value++) = c;
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}
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chars_read++;
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buffer++;
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/* Ensure value does not exceed maximum length */
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if (chars_read > GUACD_CONF_MAX_VALUE_LENGTH) {
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guacd_conf_parse_error = "Values can be no more than 8191 characters long";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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}
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/* Assert value ends with '"' */
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if (length == 0 || *buffer != '"') {
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guacd_conf_parse_error = "'\"' expected";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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chars_read++;
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/* Terminate read value */
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*value = '\0';
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return chars_read;
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}
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/**
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* Reads a parameter/value pair, separated by an '=' character. If the
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* parameter/value pair is invalid for any reason, a negative value is
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* returned.
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*/
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static int guacd_parse_parameter(guacd_param_callback* callback, char* buffer, int length) {
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char param_name[GUACD_CONF_MAX_NAME_LENGTH + 1];
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char param_value[GUACD_CONF_MAX_VALUE_LENGTH + 1];
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int retval;
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int chars_read = 0;
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retval = guacd_parse_name(buffer, length, param_name);
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if (retval < 0)
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return -1;
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/* If no name found, no parameter/value pair */
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if (retval == 0)
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return 0;
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/* Validate presence of section header */
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if (__guacd_current_section[0] == '\0') {
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guacd_conf_parse_error = "Parameters must have a corresponding section";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Optional whitespace before '=' */
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retval = guacd_parse_whitespace(buffer, length);
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Required '=' */
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if (length == 0 || *buffer != '=') {
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guacd_conf_parse_error = "'=' expected";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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chars_read++;
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buffer++;
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length--;
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/* Optional whitespace before value */
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retval = guacd_parse_whitespace(buffer, length);
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Quoted parameter value */
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retval = guacd_parse_quoted_value(buffer, length, param_value);
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if (retval < 0)
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return -1;
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/* Non-quoted parameter value (required if no quoted value given) */
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if (retval == 0) retval = guacd_parse_value(buffer, length, param_value);
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if (retval < 0)
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return -1;
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chars_read += retval;
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/* Call callback, handling error code */
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if (callback(__guacd_current_section, param_name, param_value))
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return -1;
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return chars_read;
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}
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/**
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* Reads a section name from the beginning of the given buffer. This section
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* name must conform to the grammar definition. If the section name does not
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* match, a negative value is returned.
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*/
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static int guacd_parse_section(char* buffer, int length) {
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int retval;
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/* Assert first character is '[' */
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if (length == 0 || *buffer != '[')
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return 0;
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int chars_read = 1;
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buffer++;
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length--;
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retval = guacd_parse_name(buffer, length, __guacd_current_section);
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if (retval < 0)
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return -1;
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/* If no name found, invalid section */
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if (retval == 0) {
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guacd_conf_parse_error = "Section names must contain at least one character";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Name must end with ']' */
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if (length == 0 || *buffer != ']') {
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guacd_conf_parse_error = "']' expected";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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chars_read++;
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return chars_read;
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}
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/**
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* Parses a declaration, which may be either a section name or a
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* parameter/value pair. The empty string is acceptable, as well, as a
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* "null declaration".
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*/
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static int guacd_parse_declaration(guacd_param_callback* callback, char* buffer, int length) {
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int retval;
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/* Look for section name */
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retval = guacd_parse_section(buffer, length);
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if (retval != 0)
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return retval;
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/* Lacking a section name, read parameter/value pair */
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retval = guacd_parse_parameter(callback, buffer, length);
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if (retval != 0)
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return retval;
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/* Null declaration (default) */
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return 0;
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}
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/**
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* Parses a comment, which must start with a '#' character, and terminate with
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* an end-of-line character. If no EOL is found, or the first character is not
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* a '#', a negative value is returned. Otherwise, the number of characters
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* parsed is returned. If no comment is present, zero is returned.
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*/
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static int guacd_parse_comment(char* buffer, int length) {
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/* Need at least one character */
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if (length == 0)
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return 0;
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/* Assert first character is '#' */
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if (*(buffer++) != '#')
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return 0;
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int chars_read = 1;
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/* Advance to first non-space character */
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while (chars_read < length) {
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/* Read character */
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char c = *buffer;
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/* End of comment found at end of line */
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if (c == '\n' || c == '\r')
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return chars_read;
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chars_read++;
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buffer++;
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}
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/* No end of line in comment */
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guacd_conf_parse_error = "expected end-of-line";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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/**
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* Parses the end of a line, which may contain a comment. If a parse error
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* occurs, a negative value is returned. Otherwise, the number of characters
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* parsed is returned.
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*/
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static int guacd_parse_line_end(char* buffer, int length) {
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int chars_read = 0;
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int retval;
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/* Initial optional whitespace */
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retval = guacd_parse_whitespace(buffer, length);
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Optional comment */
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retval = guacd_parse_comment(buffer, length);
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if (retval < 0)
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return -1;
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Assert EOL */
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if (length == 0 || (*buffer != '\r' && *buffer != '\n')) {
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guacd_conf_parse_error = "expected end-of-line";
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guacd_conf_parse_error_location = buffer;
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return -1;
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}
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chars_read++;
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/* Line is valid */
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return chars_read;
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}
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/**
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* Parses an entire line - declaration, comment, and all. If a parse error
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* occurs, a negative value is returned. Otherwise, the number of characters
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* parsed is returned.
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*/
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static int guacd_parse_line(guacd_param_callback* callback, char* buffer, int length) {
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int chars_read = 0;
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int retval;
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/* Initial optional whitespace */
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retval = guacd_parse_whitespace(buffer, length);
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* Declaration (which may be the empty string) */
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retval = guacd_parse_declaration(callback, buffer, length);
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if (retval < 0)
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return retval;
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chars_read += retval;
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buffer += retval;
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length -= retval;
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/* End of line */
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retval = guacd_parse_line_end(buffer, length);
|
||||
if (retval < 0)
|
||||
return retval;
|
||||
|
||||
chars_read += retval;
|
||||
|
||||
return chars_read;
|
||||
|
||||
}
|
||||
|
||||
int guacd_parse_conf(guacd_param_callback* callback, char* buffer, int length) {
|
||||
return guacd_parse_line(callback, buffer, length);
|
||||
}
|
||||
|
||||
64
src/guacd/conf-file.h
Normal file
64
src/guacd/conf-file.h
Normal file
@ -0,0 +1,64 @@
|
||||
/*
|
||||
* Copyright (C) 2014 Glyptodon LLC
|
||||
*
|
||||
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
||||
* of this software and associated documentation files (the "Software"), to deal
|
||||
* in the Software without restriction, including without limitation the rights
|
||||
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
||||
* copies of the Software, and to permit persons to whom the Software is
|
||||
* furnished to do so, subject to the following conditions:
|
||||
*
|
||||
* The above copyright notice and this permission notice shall be included in
|
||||
* all copies or substantial portions of the Software.
|
||||
*
|
||||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
||||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
||||
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
||||
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
||||
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
||||
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
||||
* THE SOFTWARE.
|
||||
*/
|
||||
|
||||
#ifndef _GUACD_CONF_FILE_H
|
||||
#define _GUACD_CONF_FILE_H
|
||||
|
||||
/**
|
||||
* The maximum length of a name, in characters.
|
||||
*/
|
||||
#define GUACD_CONF_MAX_NAME_LENGTH 255
|
||||
|
||||
/**
|
||||
* The maximum length of a value, in characters.
|
||||
*/
|
||||
#define GUACD_CONF_MAX_VALUE_LENGTH 8191
|
||||
|
||||
/**
|
||||
* A callback function which is provided to guacd_parse_conf() and is called
|
||||
* for each parameter/value pair set. The current section is always given. This
|
||||
* function will not be called for parameters outside of sections, which are
|
||||
* illegal.
|
||||
*/
|
||||
typedef int guacd_param_callback(const char* section, const char* param, const char* value);
|
||||
|
||||
/**
|
||||
* Parses an arbitrary buffer of configuration file data, calling the given
|
||||
* callback for each valid parameter/value pair. Upon success, the number of
|
||||
* characters parsed is returned. On failure, a negative value is returned, and
|
||||
* guacd_conf_parse_error and guacd_conf_parse_error_location are set.
|
||||
*/
|
||||
int guacd_parse_conf(guacd_param_callback* callback, char* buffer, int length);
|
||||
|
||||
/**
|
||||
* Human-readable description of the current error, if any.
|
||||
*/
|
||||
extern char* guacd_conf_parse_error;
|
||||
|
||||
/**
|
||||
* The location of the most recent parse error. This will be a pointer to the
|
||||
* location of the error within the buffer passed to guacd_parse_conf().
|
||||
*/
|
||||
extern char* guacd_conf_parse_error_location;
|
||||
|
||||
#endif
|
||||
|
||||
Loading…
Reference in New Issue
Block a user