218 lines
6.5 KiB
C
218 lines
6.5 KiB
C
/*-
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* Copyright (c) 2012-2017 Dag-Erling Smørgrav
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $OpenPAM$
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <security/pam_appl.h>
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#include "openpam_impl.h"
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#include "openpam_ctype.h"
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#define MIN_WORD_SIZE 32
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/*
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* OpenPAM extension
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*
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* Read a word from a file, respecting shell quoting rules.
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*/
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char *
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openpam_readword(FILE *f, int *lineno, size_t *lenp)
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{
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char *word;
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size_t size, len;
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int ch, escape, quote;
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int serrno;
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errno = 0;
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/* skip initial whitespace */
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escape = quote = 0;
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while ((ch = getc(f)) != EOF) {
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if (ch == '\n') {
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/* either EOL or line continuation */
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if (!escape)
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break;
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if (lineno != NULL)
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++*lineno;
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escape = 0;
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} else if (escape) {
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/* escaped something else */
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break;
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} else if (ch == '#') {
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/* comment: until EOL, no continuation */
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while ((ch = getc(f)) != EOF)
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if (ch == '\n')
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break;
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break;
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} else if (ch == '\\') {
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escape = 1;
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} else if (!is_ws(ch)) {
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break;
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}
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}
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if (ch == EOF)
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return (NULL);
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ungetc(ch, f);
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if (ch == '\n')
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return (NULL);
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word = NULL;
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size = len = 0;
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while ((ch = fgetc(f)) != EOF && (!is_ws(ch) || quote || escape)) {
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if (ch == '\\' && !escape && quote != '\'') {
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/* escape next character */
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escape = ch;
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} else if ((ch == '\'' || ch == '"') && !quote && !escape) {
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/* begin quote */
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quote = ch;
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/* edge case: empty quoted string */
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if (openpam_straddch(&word, &size, &len, 0) != 0)
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return (NULL);
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} else if (ch == quote && !escape) {
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/* end quote */
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quote = 0;
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} else if (ch == '\n' && escape) {
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/* line continuation */
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escape = 0;
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} else {
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if (escape && quote && ch != '\\' && ch != quote &&
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openpam_straddch(&word, &size, &len, '\\') != 0) {
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free(word);
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errno = ENOMEM;
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return (NULL);
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}
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if (openpam_straddch(&word, &size, &len, ch) != 0) {
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free(word);
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errno = ENOMEM;
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return (NULL);
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}
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escape = 0;
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}
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if (lineno != NULL && ch == '\n')
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++*lineno;
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}
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if (ch == EOF && ferror(f)) {
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serrno = errno;
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free(word);
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errno = serrno;
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return (NULL);
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}
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if (ch == EOF && (escape || quote)) {
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/* Missing escaped character or closing quote. */
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openpam_log(PAM_LOG_DEBUG, "unexpected end of file");
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free(word);
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errno = EINVAL;
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return (NULL);
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}
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ungetc(ch, f);
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if (lenp != NULL)
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*lenp = len;
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return (word);
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}
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/**
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* The =openpam_readword function reads the next word from a file, and
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* returns it in a NUL-terminated buffer allocated with =!malloc.
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*
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* A word is a sequence of non-whitespace characters.
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* However, whitespace characters can be included in a word if quoted or
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* escaped according to the following rules:
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*
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* - An unescaped single or double quote introduces a quoted string,
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* which ends when the same quote character is encountered a second
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* time.
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* The quotes themselves are stripped.
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*
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* - Within a single- or double-quoted string, all whitespace characters,
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* including the newline character, are preserved as-is.
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*
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* - Outside a quoted string, a backslash escapes the next character,
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* which is preserved as-is, unless that character is a newline, in
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* which case it is discarded and reading continues at the beginning of
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* the next line as if the backslash and newline had not been there.
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* In all cases, the backslash itself is discarded.
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*
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* - Within a single-quoted string, double quotes and backslashes are
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* preserved as-is.
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*
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* - Within a double-quoted string, a single quote is preserved as-is,
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* and a backslash is preserved as-is unless used to escape a double
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* quote.
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*
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* In addition, if the first non-whitespace character on the line is a
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* hash character (#), the rest of the line is discarded.
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* If a hash character occurs within a word, however, it is preserved
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* as-is.
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* A backslash at the end of a comment does cause line continuation.
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*
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* If =lineno is not =NULL, the integer variable it points to is
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* incremented every time a quoted or escaped newline character is read.
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*
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* If =lenp is not =NULL, the length of the word (after quotes and
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* backslashes have been removed) is stored in the variable it points to.
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*
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* RETURN VALUES
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*
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* If successful, the =openpam_readword function returns a pointer to a
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* dynamically allocated NUL-terminated string containing the first word
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* encountered on the line.
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*
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* The caller is responsible for releasing the returned buffer by passing
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* it to =!free.
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*
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* If =openpam_readword reaches the end of the line or file before any
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* characters are copied to the word, it returns =NULL. In the former
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* case, the newline is pushed back to the file.
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*
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* If =openpam_readword reaches the end of the file while a quote or
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* backslash escape is in effect, it sets :errno to =EINVAL and returns
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* =NULL.
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*
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* IMPLEMENTATION NOTES
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*
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* The parsing rules are intended to be equivalent to the normal POSIX
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* shell quoting rules.
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* Any discrepancy is a bug and should be reported to the author along
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* with sample input that can be used to reproduce the error.
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*
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* >openpam_readline
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* >openpam_readlinev
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*
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* AUTHOR DES
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*/
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