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, 2006 Free
5 Software Foundation, Inc.
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. */
25 #include "getndelim2.h"
31 # include "unlocked-io.h"
37 /* Mingw doesn't have SSIZE_MAX. */
39 # define SSIZE_MAX ((((ssize_t)1 << (sizeof (ssize_t) * CHAR_BIT - 2)) - 1) * 2 + 1)
42 /* The maximum value that getndelim2 can return without suffering from
43 overflow problems, either internally (because of pointer
44 subtraction overflow) or due to the API (because of ssize_t). */
45 #define GETNDELIM2_MAXIMUM (PTRDIFF_MAX < SSIZE_MAX ? PTRDIFF_MAX : SSIZE_MAX)
47 /* Try to add at least this many bytes when extending the buffer.
48 MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM. */
52 getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
53 int delim1, int delim2, FILE *stream)
55 size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */
56 char *read_pos; /* Where we're reading into *LINEPTR. */
57 ssize_t bytes_stored = -1;
59 size_t size = *linesize;
63 size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
72 nbytes_avail = size - offset;
73 read_pos = ptr + offset;
75 if (nbytes_avail == 0 && nmax <= size)
80 /* Here always ptr + size == read_pos + nbytes_avail. */
84 /* We always want at least one byte left in the buffer, since we
85 always (unless we get an error while reading the first byte)
86 NUL-terminate the line buffer. */
88 if (nbytes_avail < 2 && size < nmax)
90 size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
93 if (! (size < newsize && newsize <= nmax))
96 if (GETNDELIM2_MAXIMUM < newsize - offset)
98 size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
99 if (size == newsizemax)
101 newsize = newsizemax;
104 nbytes_avail = newsize - (read_pos - ptr);
105 newptr = realloc (ptr, newsize);
110 read_pos = size - nbytes_avail + ptr;
116 /* Return partial line, if any. */
123 if (nbytes_avail >= 2)
129 if (c == delim1 || c == delim2)
130 /* Return the line. */
134 /* Done - NUL terminate and return the number of bytes read.
135 At this point we know that nbytes_avail >= 1. */
138 bytes_stored = read_pos - (ptr + offset);