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/* Copyright (C) 2008, 2009 Free Software Foundation, Inc.
Contributed by Janne Blomqvist
This file is part of the GNU Fortran runtime library (libgfortran).
Libgfortran 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 3, or (at your option)
any later version.
Libgfortran is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<>. */
#include "io.h"
#include <string.h>
#include <stdlib.h>
//#define FBUF_DEBUG
fbuf_init (gfc_unit * u, int len)
if (len == 0)
len = 512; /* Default size. */
u->fbuf = get_mem (sizeof (fbuf));
u->fbuf->buf = get_mem (len);
u->fbuf->len = len;
u->fbuf->act = u->fbuf->pos = 0;
fbuf_destroy (gfc_unit * u)
if (u->fbuf == NULL)
if (u->fbuf->buf)
free_mem (u->fbuf->buf);
free_mem (u->fbuf);
u->fbuf = NULL;
static void
fbuf_debug (gfc_unit * u, const char * format, ...)
va_list args;
va_start(args, format);
vfprintf(stderr, format, args);
fprintf (stderr, "fbuf_debug pos: %d, act: %d, buf: ''",
u->fbuf->pos, u->fbuf->act);
for (int ii = 0; ii < u->fbuf->act; ii++)
putc (u->fbuf->buf[ii], stderr);
fprintf (stderr, "''\n");
fbuf_debug (gfc_unit * u __attribute__ ((unused)),
const char * format __attribute__ ((unused)),
...) {}
/* You should probably call this before doing a physical seek on the
underlying device. Returns how much the physical position was
modified. */
fbuf_reset (gfc_unit * u)
int seekval = 0;
if (!u->fbuf)
return 0;
fbuf_debug (u, "fbuf_reset: ");
fbuf_flush (u, u->mode);
/* If we read past the current position, seek the underlying device
back. */
if (u->mode == READING && u->fbuf->act > u->fbuf->pos)
seekval = - (u->fbuf->act - u->fbuf->pos);
fbuf_debug (u, "fbuf_reset seekval %d, ", seekval);
u->fbuf->act = u->fbuf->pos = 0;
return seekval;
/* Return a pointer to the current position in the buffer, and increase
the pointer by len. Makes sure that the buffer is big enough,
reallocating if necessary. */
char *
fbuf_alloc (gfc_unit * u, int len)
int newlen;
char *dest;
fbuf_debug (u, "fbuf_alloc len %d, ", len);
if (u->fbuf->pos + len > u->fbuf->len)
/* Round up to nearest multiple of the current buffer length. */
newlen = ((u->fbuf->pos + len) / u->fbuf->len + 1) * u->fbuf->len;
dest = realloc (u->fbuf->buf, newlen);
if (dest == NULL)
return NULL;
u->fbuf->buf = dest;
u->fbuf->len = newlen;
dest = u->fbuf->buf + u->fbuf->pos;
u->fbuf->pos += len;
if (u->fbuf->pos > u->fbuf->act)
u->fbuf->act = u->fbuf->pos;
return dest;
/* mode argument is WRITING for write mode and READING for read
mode. Return value is 0 for success, -1 on failure. */
fbuf_flush (gfc_unit * u, unit_mode mode)
int nwritten;
if (!u->fbuf)
return 0;
fbuf_debug (u, "fbuf_flush with mode %d: ", mode);
if (mode == WRITING)
if (u->fbuf->pos > 0)
nwritten = swrite (u->s, u->fbuf->buf, u->fbuf->pos);
if (nwritten < 0)
return -1;
/* Salvage remaining bytes for both reading and writing. This
happens with the combination of advance='no' and T edit
descriptors leaving the final position somewhere not at the end
of the record. For reading, this also happens if we sread() past
the record boundary. */
if (u->fbuf->act > u->fbuf->pos && u->fbuf->pos > 0)
memmove (u->fbuf->buf, u->fbuf->buf + u->fbuf->pos,
u->fbuf->act - u->fbuf->pos);
u->fbuf->act -= u->fbuf->pos;
u->fbuf->pos = 0;
return 0;
fbuf_seek (gfc_unit * u, int off, int whence)
if (!u->fbuf)
return -1;
switch (whence)
case SEEK_SET:
case SEEK_CUR:
off += u->fbuf->pos;
case SEEK_END:
off += u->fbuf->act;
return -1;
fbuf_debug (u, "fbuf_seek, off %d ", off);
/* The start of the buffer is always equal to the left tab
limit. Moving to the left past the buffer is illegal in C and
would also imply moving past the left tab limit, which is never
allowed in Fortran. Similarly, seeking past the end of the buffer
is not possible, in that case the user must make sure to allocate
space with fbuf_alloc(). So return error if that is
attempted. */
if (off < 0 || off > u->fbuf->act)
return -1;
u->fbuf->pos = off;
return off;
/* Fill the buffer with bytes for reading. Returns a pointer to start
reading from. If we hit EOF, returns a short read count. If any
other error occurs, return NULL. After reading, the caller is
expected to call fbuf_seek to update the position with the number
of bytes actually processed. */
char *
fbuf_read (gfc_unit * u, int * len)
char *ptr;
int oldact, oldpos;
int readlen = 0;
fbuf_debug (u, "fbuf_read, len %d: ", *len);
oldact = u->fbuf->act;
oldpos = u->fbuf->pos;
ptr = fbuf_alloc (u, *len);
u->fbuf->pos = oldpos;
if (oldpos + *len > oldact)
fbuf_debug (u, "reading %d bytes starting at %d ",
oldpos + *len - oldact, oldact);
readlen = sread (u->s, u->fbuf->buf + oldact, oldpos + *len - oldact);
if (readlen < 0)
return NULL;
*len = oldact - oldpos + readlen;
u->fbuf->act = oldact + readlen;
fbuf_debug (u, "fbuf_read done: ");
return ptr;
/* When the fbuf_getc() inline function runs out of buffer space, it
calls this function to fill the buffer with bytes for
reading. Never call this function directly. */
fbuf_getc_refill (gfc_unit * u)
int nread;
char *p;
fbuf_debug (u, "fbuf_getc_refill ");
/* Read 80 bytes (average line length?). This is a compromise
between not needing to call the read() syscall all the time and
not having to memmove unnecessary stuff when switching to the
next record. */
nread = 80;
p = fbuf_read (u, &nread);
if (p && nread > 0)
return (unsigned char) u->fbuf->buf[u->fbuf->pos++];
return EOF;