mc/src/treestore.c

/*
 * Tree Store
 *
 * Contains a storage of the file system tree representation
 *
 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2009
 Free Software Foundation, Inc.

 Written: 1994, 1996 Janne Kukonlehto
 1997 Norbert Warmuth
 1996, 1999 Miguel de Icaza

 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.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 This module has been converted to be a widget.

 The program load and saves the tree each time the tree widget is
 created and destroyed.  This is required for the future vfs layer,
 it will be possible to have tree views over virtual file systems.
 */

/** \file treestore.c
 *  \brief Source: tree store
 *
 *  Contains a storage of the file system tree representation.
 */

#include <config.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#include "lib/global.h"
#include "lib/mcconfig.h"
#include "lib/vfs/mc-vfs/vfs.h"
#include "lib/fileloc.h"

#include "treestore.h"
#include "setup.h"

#define TREE_SIGNATURE "Midnight Commander TreeStore v 2.0"

static struct TreeStore ts;

static tree_entry *tree_store_add_entry (const char *name);

static void
tree_store_dirty (int state)
{
    ts.dirty = state;
}

/* Returns the number of common bytes in the strings. */
static size_t
str_common (const char *s1, const char *s2)
{
    size_t result = 0;

    while (*s1 != '\0' && *s2 != '\0' && *s1++ == *s2++)
        result++;
    return result;
}

/* The directory names are arranged in a single linked list in the same
   order as they are displayed. When the tree is displayed the expected
   order is like this:
   /
   /bin
   /etc
   /etc/X11
   /etc/rc.d
   /etc.old/X11
   /etc.old/rc.d
   /usr

   i.e. the required collating sequence when comparing two directory names is 
   '\0' < PATH_SEP < all-other-characters-in-encoding-order

   Since strcmp doesn't fulfil this requirement we use pathcmp when
   inserting directory names into the list. The meaning of the return value 
   of pathcmp and strcmp are the same (an integer less than, equal to, or 
   greater than zero if p1 is found to be less than, to match, or be greater 
   than p2.
 */
static int
pathcmp (const char *p1, const char *p2)
{
    for (; *p1 == *p2; p1++, p2++)
        if (*p1 == '\0')
            return 0;

    if (*p1 == '\0')
        return -1;
    if (*p2 == '\0')
        return 1;
    if (*p1 == PATH_SEP)
        return -1;
    if (*p2 == PATH_SEP)
        return 1;
    return (*p1 - *p2);
}

/* Searches for specified directory */
tree_entry *
tree_store_whereis (const char *name)
{
    tree_entry *current = ts.tree_first;
    int flag = -1;

    while (current && (flag = pathcmp (current->name, name)) < 0)
        current = current->next;

    if (flag == 0)
        return current;
    else
        return NULL;
}

struct TreeStore *
tree_store_get (void)
{
    return &ts;
}

static char *
decode (char *buffer)
{
    char *res = g_strdup (buffer);
    char *p, *q;

    for (p = q = res; *p; p++, q++)
    {
        if (*p == '\n')
        {
            *q = 0;
            return res;
        }

        if (*p != '\\')
        {
            *q = *p;
            continue;
        }

        p++;

        switch (*p)
        {
        case 'n':
            *q = '\n';
            break;
        case '\\':
            *q = '\\';
            break;
        }
    }
    *q = *p;

    return res;
}

/* Loads the tree store from the specified filename */
static int
tree_store_load_from (char *name)
{
    FILE *file;
    char buffer[MC_MAXPATHLEN + 20], oldname[MC_MAXPATHLEN];
    char *different;
    int len, common;
    int do_load;

    g_return_val_if_fail (name != NULL, FALSE);

    if (ts.loaded)
        return TRUE;

    file = fopen (name, "r");

    if (file)
    {
        if (fgets (buffer, sizeof (buffer), file) != NULL)
        {
            if (strncmp (buffer, TREE_SIGNATURE, strlen (TREE_SIGNATURE)) != 0)
            {
                fclose (file);
                do_load = FALSE;
            }
            else
                do_load = TRUE;
        }
        else
            do_load = FALSE;
    }
    else
        do_load = FALSE;

    if (do_load)
    {
        ts.loaded = TRUE;

        /* File open -> read contents */
        oldname[0] = 0;
        while (fgets (buffer, MC_MAXPATHLEN, file))
        {
            tree_entry *e;
            int scanned;
            char *lc_name;

            /* Skip invalid records */
            if ((buffer[0] != '0' && buffer[0] != '1'))
                continue;

            if (buffer[1] != ':')
                continue;

            scanned = buffer[0] == '1';

            lc_name = decode (buffer + 2);

            len = strlen (lc_name);
            if (lc_name[0] != PATH_SEP)
            {
                /* Clear-text decompression */
                char *s = strtok (lc_name, " ");

                if (s)
                {
                    common = atoi (s);
                    different = strtok (NULL, "");
                    if (different)
                    {
                        strcpy (oldname + common, different);
                        if (vfs_file_is_local (oldname))
                        {
                            e = tree_store_add_entry (oldname);
                            e->scanned = scanned;
                        }
                    }
                }
            }
            else
            {
                if (vfs_file_is_local (lc_name))
                {
                    e = tree_store_add_entry (lc_name);
                    e->scanned = scanned;
                }
                strcpy (oldname, lc_name);
            }
            g_free (lc_name);
        }
        fclose (file);
    }

    /* Nothing loaded, we add some standard directories */
    if (!ts.tree_first)
    {
        tree_store_add_entry (PATH_SEP_STR);
        tree_store_rescan (PATH_SEP_STR);
        ts.loaded = TRUE;
    }

    return TRUE;
}

/**
 * \fn int tree_store_load(void)
 * \brief Loads the tree from the default location
 * \return 1 if success (true), 0 otherwise (false)
 */
int
tree_store_load (void)
{
    char *name;
    int retval;

    name = g_build_filename (home_dir, MC_USERCONF_DIR, MC_TREESTORE_FILE, NULL);
    retval = tree_store_load_from (name);
    g_free (name);

    return retval;
}

static char *
encode (const char *string)
{
    int special_chars;
    const char *p;
    char *q;
    char *res;

    for (special_chars = 0, p = string; *p; p++)
    {
        if (*p == '\n' || *p == '\\')
            special_chars++;
    }

    res = g_malloc (p - string + special_chars + 1);
    for (p = string, q = res; *p; p++, q++)
    {
        if (*p != '\n' && *p != '\\')
        {
            *q = *p;
            continue;
        }

        *q++ = '\\';

        switch (*p)
        {
        case '\n':
            *q = 'n';
            break;

        case '\\':
            *q = '\\';
            break;
        }
    }
    *q = 0;
    return res;
}

/* Saves the tree to the specified filename */
static int
tree_store_save_to (char *name)
{
    tree_entry *current;
    FILE *file;

    file = fopen (name, "w");
    if (!file)
        return errno;

    fprintf (file, "%s\n", TREE_SIGNATURE);

    current = ts.tree_first;
    while (current)
    {
        int i, common;

        if (vfs_file_is_local (current->name))
        {
            /* Clear-text compression */
            if (current->prev && (common = str_common (current->prev->name, current->name)) > 2)
            {
                char *encoded = encode (current->name + common);

                i = fprintf (file, "%d:%d %s\n", current->scanned, common, encoded);
                g_free (encoded);
            }
            else
            {
                char *encoded = encode (current->name);

                i = fprintf (file, "%d:%s\n", current->scanned, encoded);
                g_free (encoded);
            }

            if (i == EOF)
            {
                fprintf (stderr, _("Cannot write to the %s file:\n%s\n"),
                         name, unix_error_string (errno));
                break;
            }
        }
        current = current->next;
    }
    tree_store_dirty (FALSE);
    fclose (file);

    return 0;
}

/**
 * \fn int tree_store_save(void)
 * \brief Saves the tree to the default file in an atomic fashion
 * \return 0 if success, errno on error
 */
int
tree_store_save (void)
{
    char *name;
    int retval;

    name = g_build_filename (home_dir, MC_USERCONF_DIR, MC_TREESTORE_FILE, NULL);
    mc_util_make_backup_if_possible (name, ".tmp");

    retval = tree_store_save_to (name);
    if (retval != 0)
    {
        mc_util_restore_from_backup_if_possible (name, ".tmp");
        g_free (name);
        return retval;
    }

    mc_util_unlink_backup_if_possible (name, ".tmp");
    g_free (name);
    return 0;
}

static tree_entry *
tree_store_add_entry (const char *name)
{
    int flag = -1;
    tree_entry *current = ts.tree_first;
    tree_entry *old = NULL;
    tree_entry *new;
    int i, len;
    int submask = 0;

    if (ts.tree_last && ts.tree_last->next)
        abort ();

    /* Search for the correct place */
    while (current && (flag = pathcmp (current->name, name)) < 0)
    {
        old = current;
        current = current->next;
    }

    if (flag == 0)
        return current;         /* Already in the list */

    /* Not in the list -> add it */
    new = g_new0 (tree_entry, 1);
    if (!current)
    {
        /* Append to the end of the list */
        if (!ts.tree_first)
        {
            /* Empty list */
            ts.tree_first = new;
            new->prev = NULL;
        }
        else
        {
            old->next = new;
            new->prev = old;
        }
        new->next = NULL;
        ts.tree_last = new;
    }
    else
    {
        /* Insert in to the middle of the list */
        new->prev = old;
        if (old)
        {
            /* Yes, in the middle */
            new->next = old->next;
            old->next = new;
        }
        else
        {
            /* Nope, in the beginning of the list */
            new->next = ts.tree_first;
            ts.tree_first = new;
        }
        new->next->prev = new;
    }

    /* Calculate attributes */
    new->name = g_strdup (name);
    len = strlen (new->name);
    new->sublevel = 0;
    for (i = 0; i < len; i++)
        if (new->name[i] == PATH_SEP)
        {
            new->sublevel++;
            new->subname = new->name + i + 1;
        }
    if (new->next)
        submask = new->next->submask;
    else
        submask = 0;
    submask |= 1 << new->sublevel;
    submask &= (2 << new->sublevel) - 1;
    new->submask = submask;
    new->mark = 0;

    /* Correct the submasks of the previous entries */
    current = new->prev;
    while (current && current->sublevel > new->sublevel)
    {
        current->submask |= 1 << new->sublevel;
        current = current->prev;
    }

    /* The entry has now been added */

    if (new->sublevel > 1)
    {
        /* Let's check if the parent directory is in the tree */
        char *parent = g_strdup (new->name);

        for (i = strlen (parent) - 1; i > 1; i--)
        {
            if (parent[i] == PATH_SEP)
            {
                parent[i] = 0;
                tree_store_add_entry (parent);
                break;
            }
        }
        g_free (parent);
    }

    tree_store_dirty (TRUE);
    return new;
}

static Hook *remove_entry_hooks;

void
tree_store_add_entry_remove_hook (tree_store_remove_fn callback, void *data)
{
    add_hook (&remove_entry_hooks, (void (*)(void *)) callback, data);
}

void
tree_store_remove_entry_remove_hook (tree_store_remove_fn callback)
{
    delete_hook (&remove_entry_hooks, (void (*)(void *)) callback);
}

static void
tree_store_notify_remove (tree_entry * entry)
{
    Hook *p = remove_entry_hooks;
    tree_store_remove_fn r;

    while (p)
    {
        r = (tree_store_remove_fn) p->hook_fn;
        r (entry, p->hook_data);
        p = p->next;
    }
}

static tree_entry *
remove_entry (tree_entry * entry)
{
    tree_entry *current = entry->prev;
    long submask = 0;
    tree_entry *ret = NULL;

    tree_store_notify_remove (entry);

    /* Correct the submasks of the previous entries */
    if (entry->next)
        submask = entry->next->submask;
    while (current && current->sublevel > entry->sublevel)
    {
        submask |= 1 << current->sublevel;
        submask &= (2 << current->sublevel) - 1;
        current->submask = submask;
        current = current->prev;
    }

    /* Unlink the entry from the list */
    if (entry->prev)
        entry->prev->next = entry->next;
    else
        ts.tree_first = entry->next;

    if (entry->next)
        entry->next->prev = entry->prev;
    else
        ts.tree_last = entry->prev;

    /* Free the memory used by the entry */
    g_free (entry->name);
    g_free (entry);

    return ret;
}

void
tree_store_remove_entry (const char *name)
{
    tree_entry *current, *base, *old;
    int len;

    g_return_if_fail (name != NULL);

    /* Miguel Ugly hack */
    if (name[0] == PATH_SEP && name[1] == 0)
        return;
    /* Miguel Ugly hack end */

    base = tree_store_whereis (name);
    if (!base)
        return;                 /* Doesn't exist */

    len = strlen (base->name);
    current = base->next;
    while (current
           && strncmp (current->name, base->name, len) == 0
           && (current->name[len] == '\0' || current->name[len] == PATH_SEP))
    {
        old = current;
        current = current->next;
        remove_entry (old);
    }
    remove_entry (base);
    tree_store_dirty (TRUE);

    return;
}

/* This subdirectory exists -> clear deletion mark */
void
tree_store_mark_checked (const char *subname)
{
    char *name;
    tree_entry *current, *base;
    int flag = 1, len;
    if (!ts.loaded)
        return;

    if (ts.check_name == NULL)
        return;

    /* Calculate the full name of the subdirectory */
    if (subname[0] == '.' && (subname[1] == 0 || (subname[1] == '.' && subname[2] == 0)))
        return;
    if (ts.check_name[0] == PATH_SEP && ts.check_name[1] == 0)
        name = g_strconcat (PATH_SEP_STR, subname, (char *) NULL);
    else
        name = concat_dir_and_file (ts.check_name, subname);

    /* Search for the subdirectory */
    current = ts.check_start;
    while (current && (flag = pathcmp (current->name, name)) < 0)
        current = current->next;

    if (flag != 0)
    {
        /* Doesn't exist -> add it */
        current = tree_store_add_entry (name);
        ts.add_queue = g_list_prepend (ts.add_queue, g_strdup (name));
    }
    g_free (name);

    /* Clear the deletion mark from the subdirectory and its children */
    base = current;
    if (base)
    {
        len = strlen (base->name);
        base->mark = 0;
        current = base->next;
        while (current
               && strncmp (current->name, base->name, len) == 0
               && (current->name[len] == '\0' || current->name[len] == PATH_SEP || len == 1))
        {
            current->mark = 0;
            current = current->next;
        }
    }
}

/* Mark the subdirectories of the current directory for delete */
tree_entry *
tree_store_start_check (const char *path)
{
    tree_entry *current, *retval;
    int len;

    if (!ts.loaded)
        return NULL;

    g_return_val_if_fail (ts.check_name == NULL, NULL);
    ts.check_start = NULL;

    /* Search for the start of subdirectories */
    current = tree_store_whereis (path);
    if (!current)
    {
        struct stat s;

        if (mc_stat (path, &s) == -1)
            return NULL;

        if (!S_ISDIR (s.st_mode))
            return NULL;

        current = tree_store_add_entry (path);
        ts.check_name = g_strdup (path);

        return current;
    }

    ts.check_name = g_strdup (path);

    retval = current;

    /* Mark old subdirectories for delete */
    ts.check_start = current->next;
    len = strlen (ts.check_name);

    current = ts.check_start;
    while (current
           && strncmp (current->name, ts.check_name, len) == 0
           && (current->name[len] == '\0' || current->name[len] == PATH_SEP || len == 1))
    {
        current->mark = 1;
        current = current->next;
    }

    return retval;
}

/* Delete subdirectories which still have the deletion mark */
void
tree_store_end_check (void)
{
    tree_entry *current, *old;
    size_t len;
    GList *the_queue;

    if (!ts.loaded)
        return;

    g_return_if_fail (ts.check_name != NULL);

    /* Check delete marks and delete if found */
    len = strlen (ts.check_name);

    current = ts.check_start;
    while (current
           && strncmp (current->name, ts.check_name, len) == 0
           && (current->name[len] == '\0' || current->name[len] == PATH_SEP || len == 1))
    {
        old = current;
        current = current->next;
        if (old->mark)
            remove_entry (old);
    }

    /* get the stuff in the scan order */
    ts.add_queue = g_list_reverse (ts.add_queue);
    the_queue = ts.add_queue;
    ts.add_queue = NULL;
    g_free (ts.check_name);
    ts.check_name = NULL;

    g_list_foreach (the_queue, (GFunc) g_free, NULL);
    g_list_free (the_queue);
}

static void
process_special_dirs (GList ** special_dirs, char *file)
{
    gchar **buffers, **start_buff;
    mc_config_t *cfg;
    gsize buffers_len;

    cfg = mc_config_init (file);
    if (cfg == NULL)
        return;

    start_buff = buffers = mc_config_get_string_list (cfg, "Special dirs", "list", &buffers_len);
    if (buffers != NULL)
    {
        while (*buffers != NULL)
        {
            *special_dirs = g_list_prepend (*special_dirs, *buffers);
            *buffers = NULL;
            buffers++;
        }
        g_strfreev (start_buff);
    }
    mc_config_deinit (cfg);
}

static gboolean
should_skip_directory (const char *dir)
{
    static GList *special_dirs = NULL;
    GList *l;
    static gboolean loaded = FALSE;

    if (!loaded)
    {
        loaded = TRUE;
        setup_init ();
        process_special_dirs (&special_dirs, profile_name);
        process_special_dirs (&special_dirs, global_profile_name);
    }

    for (l = special_dirs; l != NULL; l = g_list_next (l))
        if (strncmp (dir, l->data, strlen (l->data)) == 0)
            return TRUE;

    return FALSE;
}

tree_entry *
tree_store_rescan (const char *dir)
{
    DIR *dirp;
    struct dirent *dp;
    struct stat buf;
    tree_entry *entry;

    if (should_skip_directory (dir))
    {
        entry = tree_store_add_entry (dir);
        entry->scanned = 1;

        return entry;
    }

    entry = tree_store_start_check (dir);

    if (!entry)
        return NULL;

    dirp = mc_opendir (dir);
    if (dirp)
    {
        for (dp = mc_readdir (dirp); dp; dp = mc_readdir (dirp))
        {
            char *full_name;

            if (dp->d_name[0] == '.')
            {
                if (dp->d_name[1] == 0 || (dp->d_name[1] == '.' && dp->d_name[2] == 0))
                    continue;
            }

            full_name = concat_dir_and_file (dir, dp->d_name);
            if (mc_lstat (full_name, &buf) != -1)
            {
                if (S_ISDIR (buf.st_mode))
                    tree_store_mark_checked (dp->d_name);
            }
            g_free (full_name);
        }
        mc_closedir (dirp);
    }
    tree_store_end_check ();
    entry->scanned = 1;

    return entry;
}