405 lines
9.4 KiB
C
405 lines
9.4 KiB
C
/* Copyright (C) 2002-2003, 2005, 2006, 2007, 2009 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 3, or (at your option)
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any later version.
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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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Under Section 7 of GPL version 3, you are granted additional
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permissions described in the GCC Runtime Library Exception, version
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3.1, as published by the Free Software Foundation.
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You should have received a copy of the GNU General Public License and
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a copy of the GCC Runtime Library Exception along with this program;
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see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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<http://www.gnu.org/licenses/>. */
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#include "io.h"
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#include <string.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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static const int 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[READ_CHUNK];
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ssize_t n;
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base = stell (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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if (sseek (u->s, base, SEEK_SET) < 0)
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goto io_error;
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if (sread (u->s, p, n) != n)
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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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while (n > 0)
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{
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n--;
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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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}
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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, SEEK_SET) < 0)
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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, LIBERROR_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, slen;
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GFC_INTEGER_4 m4;
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GFC_INTEGER_8 m8;
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ssize_t length;
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int continued;
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char p[sizeof (GFC_INTEGER_8)];
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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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slen = - (gfc_offset) length;
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if (sseek (u->s, slen, SEEK_CUR) < 0)
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goto io_error;
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if (sread (u->s, p, length) != length)
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goto io_error;
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/* Only GFC_CONVERT_NATIVE and GFC_CONVERT_SWAP are valid here. */
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if (likely (u->flags.convert == GFC_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 (sseek (u->s, -m -2 * length, SEEK_CUR) < 0)
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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, LIBERROR_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, LIBERROR_BAD_UNIT, NULL);
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goto done;
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}
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/* Direct access is prohibited, and so is unformatted stream access. */
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if (u->flags.access == ACCESS_DIRECT)
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{
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generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
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"Cannot BACKSPACE a file opened for DIRECT access");
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goto done;
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}
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if (u->flags.access == ACCESS_STREAM && u->flags.form == FORM_UNFORMATTED)
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{
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generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
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"Cannot BACKSPACE an unformatted stream file");
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goto done;
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}
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/* Make sure format buffer is flushed and reset. */
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if (u->flags.form == FORM_FORMATTED)
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{
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int pos = fbuf_reset (u);
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if (pos != 0)
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sseek (u->s, pos, SEEK_CUR);
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}
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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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sflush (u->s);
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}
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else
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{
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if (stell (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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/* If there are previously written bytes from a write with
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ADVANCE="no", add a record marker before performing the
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BACKSPACE. */
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if (u->previous_nonadvancing_write)
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finish_last_advance_record (u);
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u->previous_nonadvancing_write = 0;
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unit_truncate (u, stell (u->s), &fpp->common);
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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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u->flags.position = POSITION_UNSPECIFIED;
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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->flags.access == ACCESS_DIRECT)
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{
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generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
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"Cannot perform ENDFILE on a file opened"
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" for DIRECT access");
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goto done;
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}
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/* If there are previously written bytes from a write with ADVANCE="no",
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add a record marker before performing the ENDFILE. */
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if (u->previous_nonadvancing_write)
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finish_last_advance_record (u);
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u->previous_nonadvancing_write = 0;
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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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unit_truncate (u, stell (u->s), &fpp->common);
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u->endfile = AFTER_ENDFILE;
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if (0 == stell (u->s))
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u->flags.position = POSITION_REWIND;
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done:
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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, LIBERROR_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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/* If there are previously written bytes from a write with ADVANCE="no",
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add a record marker before performing the ENDFILE. */
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if (u->previous_nonadvancing_write)
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finish_last_advance_record (u);
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u->previous_nonadvancing_write = 0;
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fbuf_reset (u);
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u->last_record = 0;
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if (sseek (u->s, 0, SEEK_SET) < 0)
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generate_error (&fpp->common, LIBERROR_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 && stell (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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/* Make sure format buffer is flushed. */
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if (u->flags.form == FORM_FORMATTED)
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fbuf_flush (u, u->mode);
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sflush (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, LIBERROR_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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