summaryrefslogtreecommitdiff
path: root/libgfortran/io/file_pos.c
diff options
context:
space:
mode:
Diffstat (limited to 'libgfortran/io/file_pos.c')
-rw-r--r--libgfortran/io/file_pos.c463
1 files changed, 463 insertions, 0 deletions
diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
new file mode 100644
index 000000000..da83aa594
--- /dev/null
+++ b/libgfortran/io/file_pos.c
@@ -0,0 +1,463 @@
+/* Copyright (C) 2002-2003, 2005, 2006, 2007, 2009, 2010
+ Free Software Foundation, Inc.
+ Contributed by Andy Vaught and 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
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+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
+<http://www.gnu.org/licenses/>. */
+
+#include "io.h"
+#include "fbuf.h"
+#include "unix.h"
+#include <string.h>
+
+/* file_pos.c-- Implement the file positioning statements, i.e. BACKSPACE,
+ ENDFILE, and REWIND as well as the FLUSH statement. */
+
+
+/* formatted_backspace(fpp, u)-- Move the file back one line. The
+ current position is after the newline that terminates the previous
+ record, and we have to sift backwards to find the newline before
+ that or the start of the file, whichever comes first. */
+
+static const int READ_CHUNK = 4096;
+
+static void
+formatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
+{
+ gfc_offset base;
+ char p[READ_CHUNK];
+ ssize_t n;
+
+ base = stell (u->s) - 1;
+
+ do
+ {
+ n = (base < READ_CHUNK) ? base : READ_CHUNK;
+ base -= n;
+ if (sseek (u->s, base, SEEK_SET) < 0)
+ goto io_error;
+ if (sread (u->s, p, n) != n)
+ goto io_error;
+
+ /* We have moved backwards from the current position, it should
+ not be possible to get a short read. Because it is not
+ clear what to do about such thing, we ignore the possibility. */
+
+ /* There is no memrchr() in the C library, so we have to do it
+ ourselves. */
+
+ while (n > 0)
+ {
+ n--;
+ if (p[n] == '\n')
+ {
+ base += n + 1;
+ goto done;
+ }
+ }
+
+ }
+ while (base != 0);
+
+ /* base is the new pointer. Seek to it exactly. */
+ done:
+ if (sseek (u->s, base, SEEK_SET) < 0)
+ goto io_error;
+ u->last_record--;
+ u->endfile = NO_ENDFILE;
+
+ return;
+
+ io_error:
+ generate_error (&fpp->common, LIBERROR_OS, NULL);
+}
+
+
+/* unformatted_backspace(fpp) -- Move the file backwards for an unformatted
+ sequential file. We are guaranteed to be between records on entry and
+ we have to shift to the previous record. Loop over subrecords. */
+
+static void
+unformatted_backspace (st_parameter_filepos *fpp, gfc_unit *u)
+{
+ gfc_offset m, slen;
+ GFC_INTEGER_4 m4;
+ GFC_INTEGER_8 m8;
+ ssize_t length;
+ int continued;
+ char p[sizeof (GFC_INTEGER_8)];
+
+ if (compile_options.record_marker == 0)
+ length = sizeof (GFC_INTEGER_4);
+ else
+ length = compile_options.record_marker;
+
+ do
+ {
+ slen = - (gfc_offset) length;
+ if (sseek (u->s, slen, SEEK_CUR) < 0)
+ goto io_error;
+ if (sread (u->s, p, length) != length)
+ goto io_error;
+
+ /* Only GFC_CONVERT_NATIVE and GFC_CONVERT_SWAP are valid here. */
+ if (likely (u->flags.convert == GFC_CONVERT_NATIVE))
+ {
+ switch (length)
+ {
+ case sizeof(GFC_INTEGER_4):
+ memcpy (&m4, p, sizeof (m4));
+ m = m4;
+ break;
+
+ case sizeof(GFC_INTEGER_8):
+ memcpy (&m8, p, sizeof (m8));
+ m = m8;
+ break;
+
+ default:
+ runtime_error ("Illegal value for record marker");
+ break;
+ }
+ }
+ else
+ {
+ switch (length)
+ {
+ case sizeof(GFC_INTEGER_4):
+ reverse_memcpy (&m4, p, sizeof (m4));
+ m = m4;
+ break;
+
+ case sizeof(GFC_INTEGER_8):
+ reverse_memcpy (&m8, p, sizeof (m8));
+ m = m8;
+ break;
+
+ default:
+ runtime_error ("Illegal value for record marker");
+ break;
+ }
+
+ }
+
+ continued = m < 0;
+ if (continued)
+ m = -m;
+
+ if (sseek (u->s, -m -2 * length, SEEK_CUR) < 0)
+ goto io_error;
+ } while (continued);
+
+ u->last_record--;
+ return;
+
+ io_error:
+ generate_error (&fpp->common, LIBERROR_OS, NULL);
+}
+
+
+extern void st_backspace (st_parameter_filepos *);
+export_proto(st_backspace);
+
+void
+st_backspace (st_parameter_filepos *fpp)
+{
+ gfc_unit *u;
+
+ library_start (&fpp->common);
+
+ u = find_unit (fpp->common.unit);
+ if (u == NULL)
+ {
+ generate_error (&fpp->common, LIBERROR_BAD_UNIT, NULL);
+ goto done;
+ }
+
+ /* Direct access is prohibited, and so is unformatted stream access. */
+
+
+ if (u->flags.access == ACCESS_DIRECT)
+ {
+ generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
+ "Cannot BACKSPACE a file opened for DIRECT access");
+ goto done;
+ }
+
+ if (u->flags.access == ACCESS_STREAM && u->flags.form == FORM_UNFORMATTED)
+ {
+ generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
+ "Cannot BACKSPACE an unformatted stream file");
+ goto done;
+ }
+
+ /* Make sure format buffer is flushed and reset. */
+ if (u->flags.form == FORM_FORMATTED)
+ {
+ int pos = fbuf_reset (u);
+ if (pos != 0)
+ sseek (u->s, pos, SEEK_CUR);
+ }
+
+
+ /* Check for special cases involving the ENDFILE record first. */
+
+ if (u->endfile == AFTER_ENDFILE)
+ {
+ u->endfile = AT_ENDFILE;
+ u->flags.position = POSITION_APPEND;
+ sflush (u->s);
+ }
+ else
+ {
+ if (stell (u->s) == 0)
+ {
+ u->flags.position = POSITION_REWIND;
+ goto done; /* Common special case */
+ }
+
+ if (u->mode == WRITING)
+ {
+ /* If there are previously written bytes from a write with
+ ADVANCE="no", add a record marker before performing the
+ BACKSPACE. */
+
+ if (u->previous_nonadvancing_write)
+ finish_last_advance_record (u);
+
+ u->previous_nonadvancing_write = 0;
+
+ unit_truncate (u, stell (u->s), &fpp->common);
+ u->mode = READING;
+ }
+
+ if (u->flags.form == FORM_FORMATTED)
+ formatted_backspace (fpp, u);
+ else
+ unformatted_backspace (fpp, u);
+
+ u->flags.position = POSITION_UNSPECIFIED;
+ u->endfile = NO_ENDFILE;
+ u->current_record = 0;
+ u->bytes_left = 0;
+ }
+
+ done:
+ if (u != NULL)
+ unlock_unit (u);
+
+ library_end ();
+}
+
+
+extern void st_endfile (st_parameter_filepos *);
+export_proto(st_endfile);
+
+void
+st_endfile (st_parameter_filepos *fpp)
+{
+ gfc_unit *u;
+
+ library_start (&fpp->common);
+
+ u = find_unit (fpp->common.unit);
+ if (u != NULL)
+ {
+ if (u->flags.access == ACCESS_DIRECT)
+ {
+ generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
+ "Cannot perform ENDFILE on a file opened "
+ "for DIRECT access");
+ goto done;
+ }
+
+ if (u->flags.access == ACCESS_SEQUENTIAL
+ && u->endfile == AFTER_ENDFILE)
+ {
+ generate_error (&fpp->common, LIBERROR_OPTION_CONFLICT,
+ "Cannot perform ENDFILE on a file already "
+ "positioned after the EOF marker");
+ goto done;
+ }
+
+ /* If there are previously written bytes from a write with ADVANCE="no",
+ add a record marker before performing the ENDFILE. */
+
+ if (u->previous_nonadvancing_write)
+ finish_last_advance_record (u);
+
+ u->previous_nonadvancing_write = 0;
+
+ if (u->current_record)
+ {
+ st_parameter_dt dtp;
+ dtp.common = fpp->common;
+ memset (&dtp.u.p, 0, sizeof (dtp.u.p));
+ dtp.u.p.current_unit = u;
+ next_record (&dtp, 1);
+ }
+
+ unit_truncate (u, stell (u->s), &fpp->common);
+ u->endfile = AFTER_ENDFILE;
+ if (0 == stell (u->s))
+ u->flags.position = POSITION_REWIND;
+ }
+ else
+ {
+ if (fpp->common.unit < 0)
+ {
+ generate_error (&fpp->common, LIBERROR_BAD_OPTION,
+ "Bad unit number in statement");
+ return;
+ }
+
+ u = find_or_create_unit (fpp->common.unit);
+ if (u->s == NULL)
+ {
+ /* Open the unit with some default flags. */
+ st_parameter_open opp;
+ unit_flags u_flags;
+
+ memset (&u_flags, '\0', sizeof (u_flags));
+ u_flags.access = ACCESS_SEQUENTIAL;
+ u_flags.action = ACTION_READWRITE;
+
+ /* Is it unformatted? */
+ if (!(fpp->common.flags & (IOPARM_DT_HAS_FORMAT | IOPARM_DT_LIST_FORMAT
+ | IOPARM_DT_IONML_SET)))
+ u_flags.form = FORM_UNFORMATTED;
+ else
+ u_flags.form = FORM_UNSPECIFIED;
+
+ u_flags.delim = DELIM_UNSPECIFIED;
+ u_flags.blank = BLANK_UNSPECIFIED;
+ u_flags.pad = PAD_UNSPECIFIED;
+ u_flags.decimal = DECIMAL_UNSPECIFIED;
+ u_flags.encoding = ENCODING_UNSPECIFIED;
+ u_flags.async = ASYNC_UNSPECIFIED;
+ u_flags.round = ROUND_UNSPECIFIED;
+ u_flags.sign = SIGN_UNSPECIFIED;
+ u_flags.status = STATUS_UNKNOWN;
+ u_flags.convert = GFC_CONVERT_NATIVE;
+
+ opp.common = fpp->common;
+ opp.common.flags &= IOPARM_COMMON_MASK;
+ u = new_unit (&opp, u, &u_flags);
+ if (u == NULL)
+ return;
+ u->endfile = AFTER_ENDFILE;
+ }
+ }
+
+ done:
+ unlock_unit (u);
+
+ library_end ();
+}
+
+
+extern void st_rewind (st_parameter_filepos *);
+export_proto(st_rewind);
+
+void
+st_rewind (st_parameter_filepos *fpp)
+{
+ gfc_unit *u;
+
+ library_start (&fpp->common);
+
+ u = find_unit (fpp->common.unit);
+ if (u != NULL)
+ {
+ if (u->flags.access == ACCESS_DIRECT)
+ generate_error (&fpp->common, LIBERROR_BAD_OPTION,
+ "Cannot REWIND a file opened for DIRECT access");
+ else
+ {
+ /* If there are previously written bytes from a write with ADVANCE="no",
+ add a record marker before performing the ENDFILE. */
+
+ if (u->previous_nonadvancing_write)
+ finish_last_advance_record (u);
+
+ u->previous_nonadvancing_write = 0;
+
+ fbuf_reset (u);
+
+ u->last_record = 0;
+
+ if (sseek (u->s, 0, SEEK_SET) < 0)
+ generate_error (&fpp->common, LIBERROR_OS, NULL);
+
+ /* Handle special files like /dev/null differently. */
+ if (!is_special (u->s))
+ {
+ /* We are rewinding so we are not at the end. */
+ u->endfile = NO_ENDFILE;
+ }
+ else
+ {
+ /* Set this for compatibilty with g77 for /dev/null. */
+ if (file_length (u->s) == 0 && stell (u->s) == 0)
+ u->endfile = AT_ENDFILE;
+ /* Future refinements on special files can go here. */
+ }
+
+ u->current_record = 0;
+ u->strm_pos = 1;
+ u->read_bad = 0;
+ }
+ /* Update position for INQUIRE. */
+ u->flags.position = POSITION_REWIND;
+ unlock_unit (u);
+ }
+
+ library_end ();
+}
+
+
+extern void st_flush (st_parameter_filepos *);
+export_proto(st_flush);
+
+void
+st_flush (st_parameter_filepos *fpp)
+{
+ gfc_unit *u;
+
+ library_start (&fpp->common);
+
+ u = find_unit (fpp->common.unit);
+ if (u != NULL)
+ {
+ /* Make sure format buffer is flushed. */
+ if (u->flags.form == FORM_FORMATTED)
+ fbuf_flush (u, u->mode);
+
+ flush_sync (u->s);
+ unlock_unit (u);
+ }
+ else
+ /* FLUSH on unconnected unit is illegal: F95 std., 9.3.5. */
+ generate_error (&fpp->common, LIBERROR_BAD_OPTION,
+ "Specified UNIT in FLUSH is not connected");
+
+ library_end ();
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-17 05:30:18 +0000