ls.c

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/**
   \file lib/gis/ls.c
 
   \brief Functions to list the files in a directory.
 
   \author Paul Kelly
 
   SPDX-FileCopyrightText: 2007, 2008 GRASS Development Team
   SPDX-License-Identifier: GPL-2.0-or-later
*/
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <dirent.h>
#include <unistd.h>
 
#include <grass/gis.h>
#include <grass/config.h>
#include <grass/glocale.h>
 
#ifdef HAVE_TERMIOS_H
#include <termios.h>
#endif
 
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
 
typedef int ls_filter_func(const char * /*filename */, void * /*closure */);
 
static struct state {
    ls_filter_func *ls_filter;
    void *ls_closure;
    ls_filter_func *ls_ex_filter;
    void *ls_ex_closure;
} state;
 
static struct state *st = &state;
 
static int cmp_names(const void *aa, const void *bb)
{
    char *const *a = (char *const *)aa;
    char *const *b = (char *const *)bb;
 
    return strcmp(*a, *b);
}
 
/**
 * \brief Sets a function and its complementary data for G_ls2 filtering.
 *
 * Defines a filter function and its rule data that allow G_ls2 to filter out
 * unwanted file names.  Call this function before G_ls2.
 *
 * \param func      Filter callback function to compare a file name and closure
 *                     pattern (if NULL, no filter will be used).
 *                     func(filename, closure) should return 1 on success, 0 on
 *                     failure.
 * \param closure   Data used to determine if a file name matches the rule.
 **/
 
void G_set_ls_filter(ls_filter_func *func, void *closure)
{
    st->ls_filter = func;
    st->ls_closure = closure;
}
 
void G_set_ls_exclude_filter(ls_filter_func *func, void *closure)
{
    st->ls_ex_filter = func;
    st->ls_ex_closure = closure;
}
 
/**
 * \brief Stores a sorted directory listing in an array
 *
 * The filenames in the specified directory are stored in an array of
 * strings, then sorted alphabetically. Each filename has space allocated
 * using G_store(), which can be freed using G_free() if necessary. The
 * same goes for the array itself.
 *
 *
 * \param dir       Directory to list
 * \param num_files Pointer to an integer in which the total number of
 *                  files listed will be stored
 *
 * \return          Pointer to array of strings containing the listing
 **/
 
char **G_ls2(const char *dir, int *num_files)
{
    struct dirent *dp;
    DIR *dfd;
    char **dir_listing = NULL;
    int n = 0;
 
    if ((dfd = opendir(dir)) == NULL)
        G_fatal_error(_("Unable to open directory %s"), dir);
 
    while ((dp = readdir(dfd)) != NULL) {
        if (dp->d_name[0] == '.') /* Don't list hidden files */
            continue;
        if (st->ls_filter && !(*st->ls_filter)(dp->d_name, st->ls_closure))
            continue;
        if (st->ls_ex_filter &&
            (*st->ls_ex_filter)(dp->d_name, st->ls_ex_closure))
            continue;
        dir_listing = (char **)G_realloc(dir_listing, (1 + n) * sizeof(char *));
        dir_listing[n] = G_store(dp->d_name);
        n++;
    }
    closedir(dfd);
 
    /* Sort list of filenames alphabetically */
    qsort(dir_listing, n, sizeof(char *), cmp_names);
 
    *num_files = n;
    return dir_listing;
}
 
/**
 * \brief Prints a directory listing to a stream, in prettified column format
 *
 * A replacement for system("ls -C"). Lists the contents of the directory
 * specified to the given stream, e.g. stderr. Tries to determine an
 * appropriate column width to keep the number of lines used to a minimum
 * and look pretty on the screen.
 *
 * \param dir    Directory to list
 * \param stream Stream to print listing to
 **/
 
void G_ls(const char *dir, FILE *stream)
{
    int i, n;
    char **dir_listing = G_ls2(dir, &n);
 
    G_ls_format(dir_listing, n, 0, stream);
 
    for (i = 0; i < n; i++)
        G_free(dir_listing[i]);
 
    G_free(dir_listing);
}
 
/**
 * \brief Prints a listing of items to a stream, in prettified column format
 *
 * Lists the contents of the array passed to the given stream, e.g. stderr.
 * Prints the number of items specified by "perline" to each line, unless
 * perline is given as 0 in which case the function tries to determine an
 * appropriate column width to keep the number of lines used to a minimum
 * and look pretty on the screen.
 *
 * \param list      Array of strings containing items to be printed
 * \param num_items Number of items in the array
 * \param perline   Number of items to print per line, 0 for autodetect
 * \param stream    Stream to print listing to
 **/
 
void G_ls_format(char **list, int num_items, int perline, FILE *stream)
{
    int i;
 
    int field_width, column_height;
    int screen_width = 80; /* Default width of 80 columns */
 
    if (num_items < 1)
        return; /* Nothing to print */
 
#ifdef TIOCGWINSZ
    /* Determine screen_width if possible */
    {
        struct winsize size;
 
        if (ioctl(fileno(stream), TIOCGWINSZ, (char *)&size) == 0)
            screen_width = size.ws_col;
    }
#endif
 
    if (perline == 0) {
        unsigned int max_len = 0;
 
        for (i = 0; i < num_items; i++) {
            /* Find maximum filename length */
            if (strlen(list[i]) > max_len)
                max_len = strlen(list[i]);
        }
        /* Auto-fit the number of items that will
         * fit per line (+1 because of space after item) */
        perline = screen_width / (max_len + 1);
        if (perline < 1)
            perline = 1;
    }
 
    /* Field width to accommodate longest filename */
    field_width = screen_width / perline;
    /* Longest column height (i.e. num_items <= perline * column_height) */
    column_height = (num_items / perline) + ((num_items % perline) > 0);
 
    {
        const int max = num_items + column_height - (num_items % column_height);
        char **next;
 
        for (i = 1, next = list; i <= num_items; i++) {
            char **cur = next;
 
            next += column_height;
            if (next >= list + num_items) {
                /* the next item has to be on the other line */
                next -= (max - 1 - (next < list + max ? column_height : 0));
                fprintf(stream, "%s\n", *cur);
            }
            else {
                fprintf(stream, "%-*s", field_width, *cur);
            }
        }
    }
}