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/* getndelim2 - Read a line from a stream, stopping at one of 2 delimiters,
with bounded memory allocation.
Copyright (C) 1993, 1996-1998, 2000, 2003-2004, 2006, 2008-2023 Free
Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Originally written by Jan Brittenson, bson@gnu.ai.mit.edu. */
#include <config.h>
#include "getndelim2.h"
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#if USE_UNLOCKED_IO
# include "unlocked-io.h"
#endif
#if !HAVE_FLOCKFILE
# undef flockfile
# define flockfile(x) ((void) 0)
#endif
#if !HAVE_FUNLOCKFILE
# undef funlockfile
# define funlockfile(x) ((void) 0)
#endif
#include <limits.h>
#include <stdint.h>
#include "freadptr.h"
#include "freadseek.h"
#include "memchr2.h"
/* Avoid false GCC warning "'c' may be used uninitialized". */
#if __GNUC__ + (__GNUC_MINOR__ >= 7) > 4
# pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
#endif
/* The maximum value that getndelim2 can return without suffering from
overflow problems, either internally (because of pointer
subtraction overflow) or due to the API (because of ssize_t). */
#define GETNDELIM2_MAXIMUM (PTRDIFF_MAX < SSIZE_MAX ? PTRDIFF_MAX : SSIZE_MAX)
/* Try to add at least this many bytes when extending the buffer.
MIN_CHUNK must be no greater than GETNDELIM2_MAXIMUM. */
#define MIN_CHUNK 64
ssize_t
getndelim2 (char **lineptr, size_t *linesize, size_t offset, size_t nmax,
int delim1, int delim2, FILE *stream)
{
size_t nbytes_avail; /* Allocated but unused bytes in *LINEPTR. */
char *read_pos; /* Where we're reading into *LINEPTR. */
ssize_t bytes_stored = -1;
char *ptr = *lineptr;
size_t size = *linesize;
bool found_delimiter;
if (!ptr)
{
size = nmax < MIN_CHUNK ? nmax : MIN_CHUNK;
ptr = malloc (size);
if (!ptr)
return -1;
}
if (size < offset)
goto done;
nbytes_avail = size - offset;
read_pos = ptr + offset;
if (nbytes_avail == 0 && nmax <= size)
goto done;
/* Normalize delimiters, since memchr2 doesn't handle EOF. */
if (delim1 == EOF)
delim1 = delim2;
else if (delim2 == EOF)
delim2 = delim1;
flockfile (stream);
found_delimiter = false;
do
{
/* Here always ptr + size == read_pos + nbytes_avail.
Also nbytes_avail > 0 || size < nmax. */
int c;
const char *buffer;
size_t buffer_len;
buffer = freadptr (stream, &buffer_len);
if (buffer)
{
if (delim1 != EOF)
{
const char *end = memchr2 (buffer, delim1, delim2, buffer_len);
if (end)
{
buffer_len = end - buffer + 1;
found_delimiter = true;
}
}
}
else
{
c = getc (stream);
if (c == EOF)
{
/* Return partial line, if any. */
if (read_pos == ptr)
goto unlock_done;
else
break;
}
if (c == delim1 || c == delim2)
found_delimiter = true;
buffer_len = 1;
}
/* We always want at least one byte left in the buffer, since we
always (unless we get an error while reading the first byte)
NUL-terminate the line buffer. */
if (nbytes_avail < buffer_len + 1 && size < nmax)
{
/* Grow size proportionally, not linearly, to avoid O(n^2)
running time. */
size_t newsize = size < MIN_CHUNK ? size + MIN_CHUNK : 2 * size;
char *newptr;
/* Increase newsize so that it becomes
>= (read_pos - ptr) + buffer_len. */
if (newsize - (read_pos - ptr) < buffer_len + 1)
newsize = (read_pos - ptr) + buffer_len + 1;
/* Respect nmax. This handles possible integer overflow. */
if (! (size < newsize && newsize <= nmax))
newsize = nmax;
if (GETNDELIM2_MAXIMUM < newsize - offset)
{
size_t newsizemax = offset + GETNDELIM2_MAXIMUM + 1;
if (size == newsizemax)
goto unlock_done;
newsize = newsizemax;
}
nbytes_avail = newsize - (read_pos - ptr);
newptr = realloc (ptr, newsize);
if (!newptr)
goto unlock_done;
ptr = newptr;
size = newsize;
read_pos = size - nbytes_avail + ptr;
}
/* Here, if size < nmax, nbytes_avail >= buffer_len + 1.
If size == nmax, nbytes_avail > 0. */
if (1 < nbytes_avail)
{
size_t copy_len = nbytes_avail - 1;
if (buffer_len < copy_len)
copy_len = buffer_len;
if (buffer)
memcpy (read_pos, buffer, copy_len);
else
*read_pos = c;
read_pos += copy_len;
nbytes_avail -= copy_len;
}
/* Here still nbytes_avail > 0. */
if (buffer && freadseek (stream, buffer_len))
goto unlock_done;
}
while (!found_delimiter);
/* Done - NUL terminate and return the number of bytes read.
At this point we know that nbytes_avail >= 1. */
*read_pos = '\0';
bytes_stored = read_pos - (ptr + offset);
unlock_done:
funlockfile (stream);
done:
*lineptr = ptr;
*linesize = size;
return bytes_stored ? bytes_stored : -1;
}
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