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
62ssize_t
63getndelim2 (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