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
21 /* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu. */
22
23 #ifdef HAVE_CONFIG_H
24 # include <config.h>
25 #endif
26
27 #include "getndelim2.h"
28
29 #include <stdlib.h>
30 #include <stddef.h>
31
32 #if USE_UNLOCKED_IO
33 # include "unlocked-io.h"
34 #endif
35
36 #include <limits.h>
37 #if HAVE_INTTYPES_H
38 # include <inttypes.h>
39 #endif
40 #if HAVE_STDINT_H
41 # include <stdint.h>
42 #endif
43 #ifndef PTRDIFF_MAX
44 # define PTRDIFF_MAX ((ptrdiff_t) (SIZE_MAX / 2))
45 #endif
46 #ifndef SIZE_MAX
47 # define SIZE_MAX ((size_t) -1)
48 #endif
49 #ifndef SSIZE_MAX
50 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
51 #endif
52
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)
57
58 /* Try to add at least this many bytes when extending the buffer.
59 MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM. */
60 #define MIN_CHUNK 64
61
62 ssize_t
getndelim2(char ** lineptr,size_t * linesize,size_t offset,size_t nmax,int delim1,int delim2,FILE * stream)63 getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
64 int delim1, int delim2, FILE *stream)
65 {
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;
69 char *ptr = *lineptr;
70 size_t size = *linesize;
71
72 if (!ptr)
73 {
74 size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
75 ptr = malloc (size);
76 if (!ptr)
77 return -1;
78 }
79
80 if (size < offset)
81 goto done;
82
83 nbytes_avail = size - offset;
84 read_pos = ptr + offset;
85
86 if (nbytes_avail == 0 && nmax <= size)
87 goto done;
88
89 for (;;)
90 {
91 /* Here always ptr + size == read_pos + nbytes_avail. */
92
93 int c;
94
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. */
98
99 if (nbytes_avail < 2 && size < nmax)
100 {
101 size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
102 char *newptr;
103
104 if (! (size < newsize && newsize <= nmax))
105 newsize = nmax;
106
107 if (GETNDELIM2_MAXIMUM < newsize - offset)
108 {
109 size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
110 if (size == newsizemax)
111 goto done;
112 newsize = newsizemax;
113 }
114
115 nbytes_avail = newsize - (read_pos - ptr);
116 newptr = realloc (ptr, newsize);
117 if (!newptr)
118 goto done;
119 ptr = newptr;
120 size = newsize;
121 read_pos = size - nbytes_avail + ptr;
122 }
123
124 c = getc (stream);
125 if (c == EOF)
126 {
127 /* Return partial line, if any. */
128 if (read_pos == ptr)
129 goto done;
130 else
131 break;
132 }
133
134 if (nbytes_avail >= 2)
135 {
136 *read_pos++ = c;
137 nbytes_avail--;
138 }
139
140 if (c == delim1 || c == delim2)
141 /* Return the line. */
142 break;
143 }
144
145 /* Done - NUL terminate and return the number of bytes read.
146 At this point we know that nbytes_avail >= 1. */
147 *read_pos = '\0';
148
149 bytes_stored = read_pos - (ptr + offset);
150
151 done:
152 *lineptr = ptr;
153 *linesize = size;
154 return bytes_stored;
155 }
156