369 lines
8.5 KiB
C
369 lines
8.5 KiB
C
/* Copyright (C) 2002-2003, 2005, 2006, 2007 Free Software Foundation, Inc.
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Contributed by Andy Vaught and Janne Blomqvist
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This file is part of the GNU Fortran runtime library (libgfortran).
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Libgfortran is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file into combinations with other programs,
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and to distribute those combinations without any restriction coming
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from the use of this file. (The General Public License restrictions
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do apply in other respects; for example, they cover modification of
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the file, and distribution when not linked into a combine
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executable.)
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Libgfortran is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Libgfortran; see the file COPYING. If not, write to
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the Free Software Foundation, 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA. */
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#include "config.h"
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#include <string.h>
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#include "libgfortran.h"
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#include "io.h"
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/* file_pos.c-- Implement the file positioning statements, i.e. BACKSPACE,
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ENDFILE, and REWIND as well as the FLUSH statement. */
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/* formatted_backspace(fpp, u)-- Move the file back one line. The
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current position is after the newline that terminates the previous
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record, and we have to sift backwards to find the newline before
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that or the start of the file, whichever comes first. */
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#define READ_CHUNK 4096
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static void
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formatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
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{
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gfc_offset base;
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char *p;
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int n;
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base = file_position (u->s) - 1;
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do
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{
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n = (base < READ_CHUNK) ? base : READ_CHUNK;
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base -= n;
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p = salloc_r_at (u->s, &n, base);
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if (p == NULL)
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goto io_error;
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/* We have moved backwards from the current position, it should
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not be possible to get a short read. Because it is not
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clear what to do about such thing, we ignore the possibility. */
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/* There is no memrchr() in the C library, so we have to do it
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ourselves. */
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n--;
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while (n >= 0)
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{
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if (p[n] == '\n')
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{
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base += n + 1;
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goto done;
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}
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n--;
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}
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}
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while (base != 0);
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/* base is the new pointer. Seek to it exactly. */
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done:
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if (sseek (u->s, base) == FAILURE)
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goto io_error;
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u->last_record--;
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u->endfile = NO_ENDFILE;
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return;
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io_error:
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generate_error (&fpp->common, ERROR_OS, NULL);
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}
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/* unformatted_backspace(fpp) -- Move the file backwards for an unformatted
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sequential file. We are guaranteed to be between records on entry and
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we have to shift to the previous record. Loop over subrecords. */
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static void
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unformatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
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{
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gfc_offset m, new;
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GFC_INTEGER_4 m4;
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GFC_INTEGER_8 m8;
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int length, length_read;
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int continued;
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char *p;
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if (compile_options.record_marker == 0)
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length = sizeof (GFC_INTEGER_4);
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else
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length = compile_options.record_marker;
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do
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{
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length_read = length;
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p = salloc_r_at (u->s, &length_read,
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file_position (u->s) - length);
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if (p == NULL || length_read != length)
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goto io_error;
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/* Only CONVERT_NATIVE and CONVERT_SWAP are valid here. */
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if (u->flags.convert == CONVERT_NATIVE)
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{
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switch (length)
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{
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case sizeof(GFC_INTEGER_4):
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memcpy (&m4, p, sizeof (m4));
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m = m4;
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break;
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case sizeof(GFC_INTEGER_8):
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memcpy (&m8, p, sizeof (m8));
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m = m8;
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break;
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default:
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runtime_error ("Illegal value for record marker");
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break;
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}
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}
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else
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{
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switch (length)
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{
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case sizeof(GFC_INTEGER_4):
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reverse_memcpy (&m4, p, sizeof (m4));
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m = m4;
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break;
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case sizeof(GFC_INTEGER_8):
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reverse_memcpy (&m8, p, sizeof (m8));
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m = m8;
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break;
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default:
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runtime_error ("Illegal value for record marker");
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break;
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}
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}
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continued = m < 0;
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if (continued)
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m = -m;
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if ((new = file_position (u->s) - m - 2*length) < 0)
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new = 0;
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if (sseek (u->s, new) == FAILURE)
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goto io_error;
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} while (continued);
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u->last_record--;
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return;
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io_error:
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generate_error (&fpp->common, ERROR_OS, NULL);
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}
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extern void st_backspace (st_parameter_filepos *);
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export_proto(st_backspace);
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void
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st_backspace (st_parameter_filepos *fpp)
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{
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gfc_unit *u;
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library_start (&fpp->common);
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u = find_unit (fpp->common.unit);
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if (u == NULL)
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{
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generate_error (&fpp->common, ERROR_BAD_UNIT, NULL);
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goto done;
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}
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/* Ignore direct access. Non-advancing I/O is only allowed for formatted
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sequential I/O and the next direct access transfer repositions the file
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anyway. */
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if (u->flags.access == ACCESS_DIRECT || u->flags.access == ACCESS_STREAM)
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goto done;
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/* Check for special cases involving the ENDFILE record first. */
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if (u->endfile == AFTER_ENDFILE)
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{
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u->endfile = AT_ENDFILE;
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u->flags.position = POSITION_APPEND;
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flush (u->s);
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struncate (u->s);
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}
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else
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{
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if (file_position (u->s) == 0)
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{
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u->flags.position = POSITION_REWIND;
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goto done; /* Common special case */
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}
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if (u->mode == WRITING)
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{
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flush (u->s);
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struncate (u->s);
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u->mode = READING;
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}
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if (u->flags.form == FORM_FORMATTED)
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formatted_backspace (fpp, u);
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else
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unformatted_backspace (fpp, u);
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update_position (u);
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u->endfile = NO_ENDFILE;
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u->current_record = 0;
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u->bytes_left = 0;
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}
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done:
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if (u != NULL)
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unlock_unit (u);
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library_end ();
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}
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extern void st_endfile (st_parameter_filepos *);
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export_proto(st_endfile);
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void
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st_endfile (st_parameter_filepos *fpp)
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{
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gfc_unit *u;
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library_start (&fpp->common);
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u = find_unit (fpp->common.unit);
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if (u != NULL)
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{
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if (u->current_record)
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{
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st_parameter_dt dtp;
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dtp.common = fpp->common;
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memset (&dtp.u.p, 0, sizeof (dtp.u.p));
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dtp.u.p.current_unit = u;
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next_record (&dtp, 1);
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}
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flush (u->s);
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struncate (u->s);
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u->endfile = AFTER_ENDFILE;
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update_position (u);
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unlock_unit (u);
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}
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library_end ();
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}
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extern void st_rewind (st_parameter_filepos *);
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export_proto(st_rewind);
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void
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st_rewind (st_parameter_filepos *fpp)
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{
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gfc_unit *u;
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library_start (&fpp->common);
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u = find_unit (fpp->common.unit);
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if (u != NULL)
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{
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if (u->flags.access == ACCESS_DIRECT)
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generate_error (&fpp->common, ERROR_BAD_OPTION,
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"Cannot REWIND a file opened for DIRECT access");
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else
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{
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/* Flush the buffers. If we have been writing to the file, the last
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written record is the last record in the file, so truncate the
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file now. Reset to read mode so two consecutive rewind
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statements do not delete the file contents. */
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flush (u->s);
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if (u->mode == WRITING && u->flags.access != ACCESS_STREAM)
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struncate (u->s);
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u->mode = READING;
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u->last_record = 0;
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if (file_position (u->s) != 0 && sseek (u->s, 0) == FAILURE)
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generate_error (&fpp->common, ERROR_OS, NULL);
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/* Handle special files like /dev/null differently. */
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if (!is_special (u->s))
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{
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/* We are rewinding so we are not at the end. */
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u->endfile = NO_ENDFILE;
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}
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else
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{
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/* Set this for compatibilty with g77 for /dev/null. */
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if (file_length (u->s) == 0 && file_position (u->s) == 0)
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u->endfile = AT_ENDFILE;
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/* Future refinements on special files can go here. */
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}
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u->current_record = 0;
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u->strm_pos = 1;
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u->read_bad = 0;
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}
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/* Update position for INQUIRE. */
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u->flags.position = POSITION_REWIND;
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unlock_unit (u);
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}
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library_end ();
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}
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extern void st_flush (st_parameter_filepos *);
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export_proto(st_flush);
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void
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st_flush (st_parameter_filepos *fpp)
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{
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gfc_unit *u;
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library_start (&fpp->common);
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u = find_unit (fpp->common.unit);
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if (u != NULL)
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{
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flush (u->s);
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unlock_unit (u);
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}
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else
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/* FLUSH on unconnected unit is illegal: F95 std., 9.3.5. */
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generate_error (&fpp->common, ERROR_BAD_OPTION,
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"Specified UNIT in FLUSH is not connected");
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library_end ();
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}
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