ARM Club 1/ARM_CLUB_CD.iso/contents/apps/clib/progs/utilslib/c/Dirscan

Text File | 1991-04-20 | 4.9 KB | 240 lines

/* C.Dirscan: Get filenames for a wildcarded value */

/* Use as:
 *
 *    for (file = dirscan(wild); file; file = dirscan(0))
 *        ...
 *
 * Specifying an argument other than 0 restarts the scan with the
 * new wildcard value.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "kernel.h"
#include "swis.h"

#include "utils.h"

/* Constants. The function assumes that a directory can hold no more than
 * MAX_DIR entries, and a filename can be no longer than NAME_LEN characters.
 * It also assumes that OS_GBPB 9 will only ever fail to return all possible
 * filenames on the first call if the supplied buffer becomes full. In this
 * case, dirscan() will ignore any omitted entries. This behaviour is not
 * ideal, but gains significantly in efficiency. (The given buffer size
 * should be easily enough for all normal cases).
 */
#define MAX_DIR        255
#define NAME_LEN    10
#define BUFFER_SIZE    (MAX_DIR * (NAME_LEN + 1))

char *dirscan (const char *f)
{
    int len;
    int dot_stripped = 0;
    const char *file;
    _kernel_swi_regs regs;

    static char *ptr = NULL;
    static int num_left = 0;
    static char *buffer = NULL;
    static char *name;
    static char res[255];

    if (f && *f)
    {

#ifdef DEBUG
printf("New call: looking at %s\n", f);
#endif

        /* Delete any old buffer */
        if (buffer)
        {
            free (buffer);
            buffer = NULL;
        }

        /* Try for a directory prefix */
        file = strrchr (f, '.');

        /* If not, try for a filing system prefix */
        if (file == NULL)
        {
            if (*f == '-')
                file = strchr (f + 1, '-');
            else
                file = strchr (f, ':');
        }

        if (file == NULL)
        {
            /* We have a simple file name, with no directory. So
             * we set name to point to the place to store the
             * file name (ie, res), and we temporarily set res
             * to hold the directory name (ie, ""). We also set
             * file to the file name f.
             */
            name = res;
            file = f;
            name[0] = '\0';
        }
        else
        {
            /* More work to do. Set res up with the directory,
             * as above, and point name to the place to put the
             * file name(s). And set file to the file name.
             */

            len = file - f + 1;

            /* Do not allow file names over 255 characters
             * (ie, 245 for the directory, and 10 for the
             * base name).
             */
            if (len > 245)
                return 0;

            /* Build the start of the file name to be returned */
            strncpy (res, f, len);
            name = &res[len];

            /* Temporarily, put the name of the directory to scan
             * into res. At the moment, res holds "dir." or "FS:"
             * without a NULL terminator. If the former, we must
             * temporarily remove the dot and add a NULL, but if
             * the latter, we must add the current directory
             * name "@".
             */
            if (*file == '.')
            {
                dot_stripped = name[-1];
                name[-1] = '\0';
            }
            else
            {
                name[0] = '@';
                name[1] = '\0';
            }

            /* Now, set file to the base file name */
            ++file;
        }

#ifdef DEBUG
printf("Split: dir = %s, file = %s\n", res, file);
#endif

        /* Is the file name wildcarded? */
        if (!strchr (file, '*') && !strchr (file, '#'))
        {
            /* If not, we return the name we were handed,
             * and remember not to return any more later.
             */

            /* First restore the proper prefix */
            if (dot_stripped)
                name[-1] = dot_stripped;

            strcpy (name, file);
            num_left = 0;
            return res;
        }
        else
        {
            /* OK, this is the big one. We set up a buffer, and
             * read all the names from the selected directory
             * which match the pattern into it.
             */

            buffer = malloc (BUFFER_SIZE) ;
            if (buffer == NULL)
                return 0;

            regs.r[0] = 9;
            regs.r[1] = (int) res;
            regs.r[2] = (int) buffer;
            regs.r[3] = BUFFER_SIZE;
            regs.r[4] = 0;
            regs.r[5] = BUFFER_SIZE;
            regs.r[6] = (int) file;

            if (_kernel_swi (OS_GBPB, ®s, ®s))
                return 0;

#ifdef DEBUG
printf("Swi call succeeded: %d entries found\n", regs.r[3]);
#endif

            /* Now restore the proper prefix */
            if (dot_stripped)
                name[-1] = dot_stripped;

            /* If there were no entries to find, say so */
            if (regs.r[3] == 0)
            {
                num_left = 0;
                free (buffer);
                buffer = NULL;
                return 0;
            }

            /* Remember how many more to return and set ptr
             * ready to return the next one.
             */
            num_left = regs.r[3] - 1;
            ptr = buffer + strlen (buffer) + 1;

#ifdef DEBUG
printf("Buffer set up: first = %s, next = %s\n", buffer, ptr);
#endif

            /* Return the first one */
            strcpy (name, buffer);
            return res;
        }
    }

    /* If we've run out of names to return, free the buffer and stop */
    if (num_left == 0)
    {
        if (buffer)
        {
            free (buffer);
            buffer = NULL;
        }
        return 0;
    }


    /* Return the next entry in the buffer, and move on in the buffer */
    strcpy (name, ptr);
    ptr += strlen(ptr) + 1;
    --num_left;

#ifdef DEBUG
printf("Skipped on to %s\n",ptr);
#endif

    return res;
}

#ifdef TEST
#include <stdio.h>

int main (int argc, char *argv[])
{
    char *name;

    while (--argc > 0)
    {
        printf("Scanning %s\n", *++argv);
        for (name = dirscan(*argv); name; name = dirscan(0))
            printf("%s\n", name);
    }

    return 0;
}
#endif