1 /* getndelim2 - Read a line from a stream, stopping at one of 2 delimiters, 2 with bounded memory allocation. 3 4 Copyright (C) 1993, 1996, 1997, 1998, 2000, 2003, 2004 Free Software 5 Foundation, Inc. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 2, or (at your option) 10 any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program; if not, write to the Free Software Foundation, 19 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 20 #include <sys/cdefs.h> 21 __RCSID("$NetBSD: getndelim2.c,v 1.2 2016/05/17 14:00:09 christos Exp $"); 22 23 24 /* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu. */ 25 26 #ifdef HAVE_CONFIG_H 27 # include <config.h> 28 #endif 29 30 #include "getndelim2.h" 31 32 #include <stdlib.h> 33 #include <stddef.h> 34 35 #if USE_UNLOCKED_IO 36 # include "unlocked-io.h" 37 #endif 38 39 #include <limits.h> 40 #if HAVE_INTTYPES_H 41 # include <inttypes.h> 42 #endif 43 #if HAVE_STDINT_H 44 # include <stdint.h> 45 #endif 46 #ifndef PTRDIFF_MAX 47 # define PTRDIFF_MAX ((ptrdiff_t) (SIZE_MAX / 2)) 48 #endif 49 #ifndef SIZE_MAX 50 # define SIZE_MAX ((size_t) -1) 51 #endif 52 #ifndef SSIZE_MAX 53 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) 54 #endif 55 56 /* The maximum value that getndelim2 can return without suffering from 57 overflow problems, either internally (because of pointer 58 subtraction overflow) or due to the API (because of ssize_t). */ 59 #define GETNDELIM2_MAXIMUM (PTRDIFF_MAX < SSIZE_MAX ? PTRDIFF_MAX : SSIZE_MAX) 60 61 /* Try to add at least this many bytes when extending the buffer. 62 MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM. */ 63 #define MIN_CHUNK 64 64 65 ssize_t 66 getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax, 67 int delim1, int delim2, FILE *stream) 68 { 69 size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */ 70 char *read_pos; /* Where we're reading into *LINEPTR. */ 71 ssize_t bytes_stored = -1; 72 char *ptr = *lineptr; 73 size_t size = *linesize; 74 75 if (!ptr) 76 { 77 size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK; 78 ptr = malloc (size); 79 if (!ptr) 80 return -1; 81 } 82 83 if (size < offset) 84 goto done; 85 86 nbytes_avail = size - offset; 87 read_pos = ptr + offset; 88 89 if (nbytes_avail == 0 && nmax <= size) 90 goto done; 91 92 for (;;) 93 { 94 /* Here always ptr + size == read_pos + nbytes_avail. */ 95 96 int c; 97 98 /* We always want at least one byte left in the buffer, since we 99 always (unless we get an error while reading the first byte) 100 NUL-terminate the line buffer. */ 101 102 if (nbytes_avail < 2 && size < nmax) 103 { 104 size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size; 105 char *newptr; 106 107 if (! (size < newsize && newsize <= nmax)) 108 newsize = nmax; 109 110 if (GETNDELIM2_MAXIMUM < newsize - offset) 111 { 112 size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1; 113 if (size == newsizemax) 114 goto done; 115 newsize = newsizemax; 116 } 117 118 nbytes_avail = newsize - (read_pos - ptr); 119 newptr = realloc (ptr, newsize); 120 if (!newptr) 121 goto done; 122 ptr = newptr; 123 size = newsize; 124 read_pos = size - nbytes_avail + ptr; 125 } 126 127 c = getc (stream); 128 if (c == EOF) 129 { 130 /* Return partial line, if any. */ 131 if (read_pos == ptr) 132 goto done; 133 else 134 break; 135 } 136 137 if (nbytes_avail >= 2) 138 { 139 *read_pos++ = c; 140 nbytes_avail--; 141 } 142 143 if (c == delim1 || c == delim2) 144 /* Return the line. */ 145 break; 146 } 147 148 /* Done - NUL terminate and return the number of bytes read. 149 At this point we know that nbytes_avail >= 1. */ 150 *read_pos = '\0'; 151 152 bytes_stored = read_pos - (ptr + offset); 153 154 done: 155 *lineptr = ptr; 156 *linesize = size; 157 return bytes_stored; 158 } 159