1236099Sdes/*- 2236099Sdes * Copyright (c) 2012 Dag-Erling Sm��rgrav 3236099Sdes * All rights reserved. 4236099Sdes * 5236099Sdes * Redistribution and use in source and binary forms, with or without 6236099Sdes * modification, are permitted provided that the following conditions 7236099Sdes * are met: 8236099Sdes * 1. Redistributions of source code must retain the above copyright 9255376Sdes * notice, this list of conditions and the following disclaimer. 10236099Sdes * 2. Redistributions in binary form must reproduce the above copyright 11236099Sdes * notice, this list of conditions and the following disclaimer in the 12236099Sdes * documentation and/or other materials provided with the distribution. 13236099Sdes * 3. The name of the author may not be used to endorse or promote 14236099Sdes * products derived from this software without specific prior written 15236099Sdes * permission. 16236099Sdes * 17236099Sdes * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18236099Sdes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19236099Sdes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20236099Sdes * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21236099Sdes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22236099Sdes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23236099Sdes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24236099Sdes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25236099Sdes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26236099Sdes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27236099Sdes * SUCH DAMAGE. 28236099Sdes * 29255376Sdes * $Id: openpam_readword.c 648 2013-03-05 17:54:27Z des $ 30236099Sdes */ 31236099Sdes 32236099Sdes#ifdef HAVE_CONFIG_H 33236099Sdes# include "config.h" 34236099Sdes#endif 35236099Sdes 36236099Sdes#include <errno.h> 37236099Sdes#include <stdio.h> 38236099Sdes#include <stdlib.h> 39236099Sdes 40236099Sdes#include <security/pam_appl.h> 41236099Sdes 42236099Sdes#include "openpam_impl.h" 43236099Sdes#include "openpam_ctype.h" 44236099Sdes 45236099Sdes#define MIN_WORD_SIZE 32 46236099Sdes 47236099Sdes/* 48236099Sdes * OpenPAM extension 49236099Sdes * 50236099Sdes * Read a word from a file, respecting shell quoting rules. 51236099Sdes */ 52236099Sdes 53236099Sdeschar * 54236099Sdesopenpam_readword(FILE *f, int *lineno, size_t *lenp) 55236099Sdes{ 56236099Sdes char *word; 57236099Sdes size_t size, len; 58273326Sdes int ch, escape, quote; 59236099Sdes int serrno; 60236099Sdes 61236099Sdes errno = 0; 62236099Sdes 63236099Sdes /* skip initial whitespace */ 64273326Sdes escape = quote = 0; 65273326Sdes while ((ch = getc(f)) != EOF) { 66273326Sdes if (ch == '\n') { 67273326Sdes /* either EOL or line continuation */ 68273326Sdes if (!escape) 69273326Sdes break; 70273326Sdes if (lineno != NULL) 71273326Sdes ++*lineno; 72273326Sdes escape = 0; 73273326Sdes } else if (escape) { 74273326Sdes /* escaped something else */ 75236099Sdes break; 76273326Sdes } else if (ch == '#') { 77273326Sdes /* comment: until EOL, no continuation */ 78273326Sdes while ((ch = getc(f)) != EOF) 79273326Sdes if (ch == '\n') 80273326Sdes break; 81273326Sdes break; 82273326Sdes } else if (ch == '\\') { 83273326Sdes escape = 1; 84273326Sdes } else if (!is_ws(ch)) { 85273326Sdes break; 86273326Sdes } 87236099Sdes } 88236099Sdes if (ch == EOF) 89236099Sdes return (NULL); 90236099Sdes ungetc(ch, f); 91236099Sdes if (ch == '\n') 92236099Sdes return (NULL); 93236099Sdes 94236099Sdes word = NULL; 95236099Sdes size = len = 0; 96236099Sdes while ((ch = fgetc(f)) != EOF && (!is_ws(ch) || quote || escape)) { 97236099Sdes if (ch == '\\' && !escape && quote != '\'') { 98236099Sdes /* escape next character */ 99236099Sdes escape = ch; 100236099Sdes } else if ((ch == '\'' || ch == '"') && !quote && !escape) { 101236099Sdes /* begin quote */ 102236099Sdes quote = ch; 103236099Sdes /* edge case: empty quoted string */ 104247809Sdes if (openpam_straddch(&word, &size, &len, 0) != 0) 105236099Sdes return (NULL); 106236099Sdes } else if (ch == quote && !escape) { 107236099Sdes /* end quote */ 108236099Sdes quote = 0; 109273326Sdes } else if (ch == '\n' && escape) { 110236099Sdes /* line continuation */ 111236099Sdes escape = 0; 112236099Sdes } else { 113236099Sdes if (escape && quote && ch != '\\' && ch != quote && 114236099Sdes openpam_straddch(&word, &size, &len, '\\') != 0) { 115236099Sdes free(word); 116236099Sdes errno = ENOMEM; 117236099Sdes return (NULL); 118236099Sdes } 119236099Sdes if (openpam_straddch(&word, &size, &len, ch) != 0) { 120236099Sdes free(word); 121236099Sdes errno = ENOMEM; 122236099Sdes return (NULL); 123236099Sdes } 124236099Sdes escape = 0; 125236099Sdes } 126236099Sdes if (lineno != NULL && ch == '\n') 127236099Sdes ++*lineno; 128236099Sdes } 129236099Sdes if (ch == EOF && ferror(f)) { 130236099Sdes serrno = errno; 131236099Sdes free(word); 132236099Sdes errno = serrno; 133236099Sdes return (NULL); 134236099Sdes } 135236099Sdes if (ch == EOF && (escape || quote)) { 136236099Sdes /* Missing escaped character or closing quote. */ 137236099Sdes openpam_log(PAM_LOG_ERROR, "unexpected end of file"); 138236099Sdes free(word); 139236099Sdes errno = EINVAL; 140236099Sdes return (NULL); 141236099Sdes } 142236099Sdes ungetc(ch, f); 143236099Sdes if (lenp != NULL) 144236099Sdes *lenp = len; 145236099Sdes return (word); 146236099Sdes} 147236099Sdes 148236099Sdes/** 149236099Sdes * The =openpam_readword function reads the next word from a file, and 150236099Sdes * returns it in a NUL-terminated buffer allocated with =!malloc. 151236099Sdes * 152236099Sdes * A word is a sequence of non-whitespace characters. 153236099Sdes * However, whitespace characters can be included in a word if quoted or 154236099Sdes * escaped according to the following rules: 155236099Sdes * 156236099Sdes * - An unescaped single or double quote introduces a quoted string, 157236099Sdes * which ends when the same quote character is encountered a second 158236099Sdes * time. 159236099Sdes * The quotes themselves are stripped. 160236099Sdes * 161236099Sdes * - Within a single- or double-quoted string, all whitespace characters, 162236099Sdes * including the newline character, are preserved as-is. 163236099Sdes * 164236099Sdes * - Outside a quoted string, a backslash escapes the next character, 165236099Sdes * which is preserved as-is, unless that character is a newline, in 166236099Sdes * which case it is discarded and reading continues at the beginning of 167236099Sdes * the next line as if the backslash and newline had not been there. 168236099Sdes * In all cases, the backslash itself is discarded. 169236099Sdes * 170236099Sdes * - Within a single-quoted string, double quotes and backslashes are 171236099Sdes * preserved as-is. 172236099Sdes * 173236099Sdes * - Within a double-quoted string, a single quote is preserved as-is, 174236099Sdes * and a backslash is preserved as-is unless used to escape a double 175236099Sdes * quote. 176236099Sdes * 177236099Sdes * In addition, if the first non-whitespace character on the line is a 178236099Sdes * hash character (#), the rest of the line is discarded. 179236099Sdes * If a hash character occurs within a word, however, it is preserved 180236099Sdes * as-is. 181236099Sdes * A backslash at the end of a comment does cause line continuation. 182236099Sdes * 183236099Sdes * If =lineno is not =NULL, the integer variable it points to is 184236099Sdes * incremented every time a quoted or escaped newline character is read. 185236099Sdes * 186236099Sdes * If =lenp is not =NULL, the length of the word (after quotes and 187236099Sdes * backslashes have been removed) is stored in the variable it points to. 188236099Sdes * 189236099Sdes * RETURN VALUES 190236099Sdes * 191236099Sdes * If successful, the =openpam_readword function returns a pointer to a 192236099Sdes * dynamically allocated NUL-terminated string containing the first word 193236099Sdes * encountered on the line. 194236099Sdes * 195236099Sdes * The caller is responsible for releasing the returned buffer by passing 196236099Sdes * it to =!free. 197236099Sdes * 198236099Sdes * If =openpam_readword reaches the end of the line or file before any 199236099Sdes * characters are copied to the word, it returns =NULL. In the former 200236099Sdes * case, the newline is pushed back to the file. 201236099Sdes * 202236099Sdes * If =openpam_readword reaches the end of the file while a quote or 203236099Sdes * backslash escape is in effect, it sets :errno to =EINVAL and returns 204236099Sdes * =NULL. 205236099Sdes * 206236099Sdes * IMPLEMENTATION NOTES 207236099Sdes * 208236099Sdes * The parsing rules are intended to be equivalent to the normal POSIX 209236099Sdes * shell quoting rules. 210236099Sdes * Any discrepancy is a bug and should be reported to the author along 211236099Sdes * with sample input that can be used to reproduce the error. 212236099Sdes * 213236099Sdes * >openpam_readline 214236099Sdes * >openpam_readlinev 215236099Sdes * 216236099Sdes * AUTHOR DES 217236099Sdes */ 218