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scandir dir and subdir c

Ill Ibis answered on June 20, 2022 Popularity 1/10 Helpfulness 1/10

answer scandir dir and subdir c

scandir dir and subdir c

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// SPDX-License-Identifier: CC0-1.0
#define  _POSIX_C_SOURCE  200809L
#define  _GNU_SOURCE
#include <stdlib.h>
#include <locale.h>
#include <ftw.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>

struct entry {
    /* Insert additional properties like 'off_t size' here. */
    char           *name;       /* Always points to name part of pathname */
    char            pathname[]; /* Full path and name */
};

struct listing {
    size_t          max;        /* Number of entries allocated for */
    size_t          num;        /* Number of entries in the array */
    struct entry  **ent;        /* Array of pointers, one per entry */
};
#define  STRUCT_LISTING_INITIALIZER  { 0, 0, NULL }

/* Locale-aware sort for arrays of struct entry pointers.
*/
static int  entrysort(const void *ptr1, const void *ptr2)
{
    const struct entry  *ent1 = *(const struct entry **)ptr1;
    const struct entry  *ent2 = *(const struct entry **)ptr2;
    return strcoll(ent1->pathname, ent2->pathname);
}

/* Global variable used by nftw_add() to add to the listing */
static struct listing  *nftw_listing = NULL;

static int nftw_add(const char *pathname, const struct stat *info, int typeflag, struct FTW *ftwbuf)
{
    const char *name = pathname + ftwbuf->base;

    /* These generate no code, just silences the warnings about unused parameters. */
    (void)info;
    (void)typeflag;

    /* Ignore "." and "..". */
    if (name[0] == '.' && !name[1])
        return 0;
    if (name[0] == '.' && name[1] == '.' && !name[2])
        return 0;

    /* Make sure there is room for at least one more entry in the listing. */
    if (nftw_listing->num >= nftw_listing->max) {
        const size_t   new_max = nftw_listing->num + 1000;
        struct entry **new_ent;

        new_ent = realloc(nftw_listing->ent, new_max * sizeof (struct entry *));
        if (!new_ent)
            return -ENOMEM;

        nftw_listing->max = new_max;
        nftw_listing->ent = new_ent;
    }

    const size_t  pathnamelen = strlen(pathname);
    struct entry *ent;

    /* Allocate memory for this entry.
       Remember to account for the name, and the end-of-string terminator, '\0', at end of name. */
    ent = malloc(sizeof (struct entry) + pathnamelen + 1);
    if (!ent)
        return -ENOMEM;

    /* Copy other filesystem entry properties to ent here; say 'ent->size = info->st_size;'. */

    /* Copy pathname, including the end-of-string terminator, '\0'. */
    memcpy(ent->pathname, pathname, pathnamelen + 1);

    /* The name pointer is always to within the pathname. */
    ent->name = ent->pathname + ftwbuf->base;

    /* Append. */
    nftw_listing->ent[nftw_listing->num++] = ent;

    return 0;
}

/* Scan directory tree starting at path, adding the entries to struct listing.
   Note: the listing must already have been properly initialized!
   Returns 0 if success, nonzero if error; -1 if errno is set to indicate error.
*/
int scan_tree_sorted(struct listing *list, const char *path)
{
    if (!list) {
        errno = EINVAL;
        return -1;
    }
    if (!path || !*path) {
        errno = ENOENT;
        return -1;
    }

    nftw_listing = list;

    int  result = nftw(path, nftw_add, 64, FTW_DEPTH);

    nftw_listing = NULL;

    if (result < 0) {
        errno = -result;
        return -1;
    } else
    if (result > 0) {
        errno = 0;
        return result;
    }

    if (list->num > 2)
        qsort(list->ent, list->num,  sizeof list->ent[0], entrysort);

    return 0;
}

int main(int argc, char *argv[])
{
    struct listing  list = STRUCT_LISTING_INITIALIZER;

    setlocale(LC_ALL, "");

    if (argc < 2 || !strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
        const char *arg0 = (argc > 0 && argv && argv[0] && argv[0][0]) ? argv[0] : "(this)";
        fprintf(stderr, "\n");
        fprintf(stderr, "Usage: %s [ -h | --help ]\n", arg0);
        fprintf(stderr, "       %s .\n", arg0);
        fprintf(stderr, "       %s TREE [ TREE ... ]\n", arg0);
        fprintf(stderr, "\n");
        fprintf(stderr, "This program lists all files and directories starting at TREE,\n");
        fprintf(stderr, "in sorted order.\n");
        fprintf(stderr, "\n");
        return EXIT_SUCCESS;
    }

    for (int arg = 1; arg < argc; arg++) {
        if (scan_tree_sorted(&list, argv[arg])) {
            fprintf(stderr, "%s: Error scanning directory tree: %s.\n", argv[arg], strerror(errno));
            return EXIT_FAILURE;
        }
    }

    printf("Found %zu entries:\n", list.num);
    for (size_t i = 0; i < list.num; i++)
        printf("\t%s\t(%s)\n", list.ent[i]->pathname, list.ent[i]->name);

    return EXIT_SUCCESS;
}

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Source: stackoverflow.com

Tags: c dir scandir whatever

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Contributed on Jun 20 2022

Ill Ibis

0 Answers Avg Quality 2/10

scandir dir and subdir c

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