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, 2008 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 3 of the License, or
10 (at your option) any later version.
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, see <http://www.gnu.org/licenses/>. */
20 /* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu. */
24 #include "getndelim2.h"
32 # include "unlocked-io.h"
36 # define flockfile(x) ((void) 0)
40 # define funlockfile(x) ((void) 0)
47 #include "freadseek.h"
51 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
54 /* The maximum value that getndelim2 can return without suffering from
55 overflow problems, either internally (because of pointer
56 subtraction overflow) or due to the API (because of ssize_t). */
57 #define GETNDELIM2_MAXIMUM (PTRDIFF_MAX < SSIZE_MAX ? PTRDIFF_MAX : SSIZE_MAX)
59 /* Try to add at least this many bytes when extending the buffer.
60 MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM. */
64 getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
65 int delim1, int delim2, FILE *stream)
67 size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */
68 char *read_pos; /* Where we're reading into *LINEPTR. */
69 ssize_t bytes_stored = -1;
71 size_t size = *linesize;
76 size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
85 nbytes_avail = size - offset;
86 read_pos = ptr + offset;
88 if (nbytes_avail == 0 && nmax <= size)
91 /* Normalize delimiters, since memchr2 doesn't handle EOF. */
94 else if (delim2 == EOF)
101 /* Here always ptr + size == read_pos + nbytes_avail. */
107 buffer = freadptr (stream, &buffer_len);
112 const char *end = memchr2 (buffer, delim1, delim2, buffer_len);
115 buffer_len = end - buffer + 1;
125 /* Return partial line, if any. */
131 if (c == delim1 || c == delim2)
136 /* We always want at least one byte left in the buffer, since we
137 always (unless we get an error while reading the first byte)
138 NUL-terminate the line buffer. */
140 if (nbytes_avail < 1 + buffer_len && size < nmax)
142 size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
145 if (newsize < buffer_len)
146 newsize = buffer_len + size;
147 if (! (size < newsize && newsize <= nmax))
150 if (GETNDELIM2_MAXIMUM < newsize - offset)
152 size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
153 if (size == newsizemax)
155 newsize = newsizemax;
158 nbytes_avail = newsize - (read_pos - ptr);
159 newptr = realloc (ptr, newsize);
164 read_pos = size - nbytes_avail + ptr;
167 if (1 < nbytes_avail)
169 size_t copy_len = nbytes_avail - 1;
170 if (buffer_len < copy_len)
171 copy_len = buffer_len;
173 memcpy (read_pos, buffer, copy_len);
176 read_pos += copy_len;
177 nbytes_avail -= copy_len;
179 if (buffer && freadseek (stream, buffer_len))
183 /* Done - NUL terminate and return the number of bytes read.
184 At this point we know that nbytes_avail >= 1. */
187 bytes_stored = read_pos - (ptr + offset);
190 funlockfile (stream);
195 return bytes_stored ? bytes_stored : -1;