open_misc.c

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/****************************************************************************
 *
 * MODULE:       gis library
 * AUTHOR(S):    Glynn Clements <glynn@gclements.plus.com>
 * COPYRIGHT:    (C) 2007 Glynn Clements and the GRASS Development Team
 *
 * NOTE:         Based upon open.c
 *
 *  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 of the License, 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.
 *
 *****************************************************************************/
 
#include <grass/config.h>
#include <errno.h>
#include <string.h>
 
#include <unistd.h>
#include <fcntl.h>
 
#include <grass/gis.h>
#include <grass/glocale.h>
 
#include "gis_local_proto.h"
 
static int G__open_misc(const char *dir, const char *element, const char *name,
                        const char *mapset, int mode)
{
    int fd;
    char path[GPATH_MAX];
    char xname[GNAME_MAX], xmapset[GMAPSET_MAX];
 
    G__check_gisinit();
 
    /* READ */
    if (mode == 0) {
        if (G_name_is_fully_qualified(name, xname, xmapset)) {
            if (*mapset && strcmp(xmapset, mapset) != 0) {
                G_warning(_("G__open_misc(read): mapset <%s> doesn't match "
                            "xmapset <%s>"),
                          mapset, xmapset);
                return -1;
            }
            name = xname;
            mapset = xmapset;
        }
 
        mapset = G_find_file2_misc(dir, element, name, mapset);
 
        if (!mapset)
            return -1;
 
        G_file_name_misc(path, dir, element, name, mapset);
 
        if ((fd = open(path, 0)) < 0)
            G_warning("G__open_misc(read): Unable to open '%s': %s", path,
                      strerror(errno));
        return fd;
    }
    /* WRITE */
    if (mode == 1 || mode == 2) {
        mapset = G_mapset();
        if (G_name_is_fully_qualified(name, xname, xmapset)) {
            if (strcmp(xmapset, mapset) != 0) {
                G_warning(
                    _("G__open_misc(write): xmapset <%s> != G_mapset() <%s>"),
                    xmapset, mapset);
                return -1;
            }
            name = xname;
        }
 
        if (G_legal_filename(name) == -1)
            return -1;
 
        G_file_name_misc(path, dir, element, name, mapset);
        if (mode == 1 || access(path, 0) != 0) {
            G__make_mapset_element_misc(dir, name);
            close(creat(path, 0666));
        }
 
        if ((fd = open(path, mode)) < 0)
            G_warning("G__open_misc(write): Unable to open '%s': %s", path,
                      strerror(errno));
        return fd;
    }
    return -1;
}
 
/*!
 * \brief open a new database misc file
 *
 * The database file <b>element</b> under <b>dir/name</b> in the
 * current mapset is created and opened for writing (but not reading).
 * The UNIX open( ) routine is used to open the file. If the file does not
 * exist, -1 is returned. Otherwise the file is positioned at the end of the
 * file and the file descriptor from the open( ) is returned.
 *
 *  \param dir
 *  \param element
 *  \param name
 *  \return int
 */
int G_open_new_misc(const char *dir, const char *element, const char *name)
{
    return G__open_misc(dir, element, name, G_mapset(), 1);
}
 
/*!
 * \brief open a database misc file for reading
 *
 * The database file <b>element</b> under
 * <b>dir/name</b> in the specified <b>mapset</b> is opened for reading (but
 * not for writing).
 * The UNIX open( ) routine is used to open the file. If the file does not
 * exist, -1 is returned. Otherwise the file descriptor from the open( ) is
 * returned.
 *
 *  \param dir
 *  \param element
 *  \param name
 *  \param mapset
 *  \return int
 */
int G_open_old_misc(const char *dir, const char *element, const char *name,
                    const char *mapset)
{
    return G__open_misc(dir, element, name, mapset, 0);
}
 
/*!
 * \brief open a database misc file for update
 *
 * The database file <b>element</b> under <b>dir/name</b> in the
 * current mapset is opened for reading and writing.
 * The UNIX open( ) routine is used to open the file. If the file does not
 * exist, -1 is returned. Otherwise the file is positioned at the end of the
 * file and the file descriptor from the open( ) is returned.
 *
 *  \param dir
 *  \param element
 *  \param name
 *  \return int
 */
int G_open_update_misc(const char *dir, const char *element, const char *name)
{
    int fd;
 
    fd = G__open_misc(dir, element, name, G_mapset(), 2);
    if (fd >= 0)
        if (lseek(fd, 0L, SEEK_END) == -1) {
            int err = errno;
            G_warning(_("File read/write operation failed: %s (%d)"),
                      strerror(err), err);
            return -1;
        }
 
    return fd;
}
 
/*!
 * \brief open a new database misc file
 *
 * The database file <b>element</b> under <b>dir/name</b> in the
 * current mapset is created and opened for writing (but not reading).
 * The UNIX fopen( ) routine, with "w" write mode, is used to open the file.  If
 * the file does not exist, the NULL pointer is returned. Otherwise the file is
 * positioned at the end of the file and the file descriptor from the fopen( )
 * is returned.
 *
 *  \param dir
 *  \param element
 *  \param name
 *  \return FILE *
 */
FILE *G_fopen_new_misc(const char *dir, const char *element, const char *name)
{
    int fd;
 
    fd = G__open_misc(dir, element, name, G_mapset(), 1);
    if (fd < 0)
        return (FILE *)0;
 
    return fdopen(fd, "w");
}
 
/*!
 * \brief open a database misc file for reading
 *
 * The database file <b>element</b> under
 * <b>dir/name</b> in the specified <b>mapset</b> is opened for reading (but
 * not for writing).
 * The UNIX fopen( ) routine, with "r" read mode, is used to open the file.  If
 * the file does not exist, the NULL pointer is returned. Otherwise the file
 * descriptor from the fopen( ) is returned.
 *
 *  \param dir
 *  \param element
 *  \param name
 *  \param mapset
 *  \return FILE *
 */
FILE *G_fopen_old_misc(const char *dir, const char *element, const char *name,
                       const char *mapset)
{
    int fd;
 
    fd = G__open_misc(dir, element, name, mapset, 0);
    if (fd < 0)
        return (FILE *)0;
 
    return fdopen(fd, "r");
}
 
FILE *G_fopen_append_misc(const char *dir, const char *element,
                          const char *name)
{
    int fd;
 
    fd = G__open_misc(dir, element, name, G_mapset(), 2);
    if (fd < 0)
        return (FILE *)0;
    if (lseek(fd, 0L, SEEK_END) == -1) {
        int err = errno;
        G_warning(_("File read/write operation failed: %s (%d)"), strerror(err),
                  err);
        return (FILE *)-1;
    }
 
    return fdopen(fd, "a");
}
 
FILE *G_fopen_modify_misc(const char *dir, const char *element,
                          const char *name)
{
    int fd;
 
    fd = G__open_misc(dir, element, name, G_mapset(), 2);
    if (fd < 0)
        return (FILE *)0;
    if (lseek(fd, 0L, SEEK_END) == -1) {
        int err = errno;
        G_warning(_("File read/write operation failed: %s (%d)"), strerror(err),
                  err);
        return (FILE *)-1;
    }
 
    return fdopen(fd, "r+");
}