1 /* getndelim2 - Read a line from a stream, stopping at one of 2 delimiters,
2 with bounded memory allocation.
4 Copyright (C) 1993, 1996, 1997, 1998, 2000, 2003, 2004 Free Software
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)
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.
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. */
21 /* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu. */
27 #include "getndelim2.h"
33 # include "unlocked-io.h"
38 # include <inttypes.h>
44 # define PTRDIFF_MAX ((ptrdiff_t) (SIZE_MAX / 2))
47 # define SIZE_MAX ((size_t) -1)
50 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
53 /* The maximum value that getndelim2 can return without suffering from
54 overflow problems, either internally (because of pointer
55 subtraction overflow) or due to the API (because of ssize_t). */
56 #define GETNDELIM2_MAXIMUM (PTRDIFF_MAX < SSIZE_MAX ? PTRDIFF_MAX : SSIZE_MAX)
58 /* Try to add at least this many bytes when extending the buffer.
59 MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM. */
63 getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
64 int delim1, int delim2, FILE *stream)
66 size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */
67 char *read_pos; /* Where we're reading into *LINEPTR. */
68 ssize_t bytes_stored = -1;
70 size_t size = *linesize;
74 size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
83 nbytes_avail = size - offset;
84 read_pos = ptr + offset;
86 if (nbytes_avail == 0 && nmax <= size)
91 /* Here always ptr + size == read_pos + nbytes_avail. */
95 /* We always want at least one byte left in the buffer, since we
96 always (unless we get an error while reading the first byte)
97 NUL-terminate the line buffer. */
99 if (nbytes_avail < 2 && size < nmax)
101 size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
104 if (! (size < newsize && newsize <= nmax))
107 if (GETNDELIM2_MAXIMUM < newsize - offset)
109 size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
110 if (size == newsizemax)
112 newsize = newsizemax;
115 nbytes_avail = newsize - (read_pos - ptr);
116 newptr = realloc (ptr, newsize);
121 read_pos = size - nbytes_avail + ptr;
127 /* Return partial line, if any. */
134 if (nbytes_avail >= 2)
140 if (c == delim1 || c == delim2)
141 /* Return the line. */
145 /* Done - NUL terminate and return the number of bytes read.
146 At this point we know that nbytes_avail >= 1. */
149 bytes_stored = read_pos - (ptr + offset);