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/* Buffered read-only streams.
Copyright (C) 2008 Bruno Haible <bruno@clisp.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#include <errno.h> /* errno, EINTR */
#include <fcntl.h> /* O_RDONLY */
#include <stddef.h> /* size_t */
#include <unistd.h> /* read, close */
/* Buffered read-only streams.
We cannot use <stdio.h> here, because fopen() calls malloc(), and a malloc()
call may have been interrupted. */
struct rofile
{
int fd;
size_t position;
size_t filled;
int eof_seen;
char buffer[4096];
};
/* Open a read-only file stream. */
static int
rof_open (struct rofile *rof, const char *filename)
{
int fd = open (filename, O_RDONLY);
if (fd < 0)
return -1;
rof->fd = fd;
rof->position = 0;
rof->filled = 0;
rof->eof_seen = 0;
return 0;
}
/* Return the next byte from a read-only file stream without consuming it,
or -1 at EOF. */
static int
rof_peekchar (struct rofile *rof)
{
if (rof->position == rof->filled)
{
if (rof->eof_seen)
return -1;
else
for (;;)
{
int n = read (rof->fd, rof->buffer, sizeof (rof->buffer));
#ifdef EINTR
if (n < 0 && errno == EINTR)
continue;
#endif
if (n <= 0)
{
rof->eof_seen = 1;
return -1;
}
rof->filled = n;
rof->position = 0;
break;
}
}
return (unsigned char) rof->buffer[rof->position];
}
/* Return the next byte from a read-only file stream, or -1 at EOF. */
static int
rof_getchar (struct rofile *rof)
{
int c = rof_peekchar (rof);
if (c >= 0)
rof->position++;
return c;
}
/* Parse an unsigned hexadecimal number from a read-only file stream. */
static int
rof_scanf_lx (struct rofile *rof, unsigned long *valuep)
{
unsigned long value = 0;
unsigned int numdigits = 0;
for (;;)
{
int c = rof_peekchar (rof);
if (c >= '0' && c <= '9')
value = (value << 4) + (c - '0');
else if (c >= 'A' && c <= 'F')
value = (value << 4) + (c - 'A' + 10);
else if (c >= 'a' && c <= 'f')
value = (value << 4) + (c - 'a' + 10);
else
break;
rof_getchar (rof);
numdigits++;
}
if (numdigits == 0)
return -1;
*valuep = value;
return 0;
}
/* Close a read-only file stream. */
static void
rof_close (struct rofile *rof)
{
close (rof->fd);
}
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