/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */

/*
 * Implement dirent-style opendir(), readdir(), closedir(), rewinddir(),
 * seekdir() and telldir on Windows - Based on mingw-runtime package sources.
 */

/*
 * Original file info follow:
 *
 * dirent.c
 * This file has no copyright assigned and is placed in the Public Domain.
 * This file is a part of the mingw-runtime package.
 * No warranty is given; refer to the file DISCLAIMER within the package.
 *
 * Derived from DIRLIB.C by Matt J. Weinstein
 * This note appears in the DIRLIB.H
 * DIRLIB.H by M. J. Weinstein   Released to public domain 1-Jan-89
 *
 * Updated by Jeremy Bettis <jeremy@hksys.com>
 * Significantly revised and rewinddir, seekdir and telldir added by Colin
 * Peters <colin@fu.is.saga-u.ac.jp>
 *
 */

#include "squid.h"

/* The following code section is part of the native Windows Squid port */
#if _SQUID_WINDOWS_

#include "util.h"
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <io.h>
#include <dirent.h>

#define WIN32_LEAN_AND_MEAN
#include <windows.h>        /* for GetFileAttributes */

#define SUFFIX  ("*")
#define SLASH   ("\\")

/*
 * opendir
 *
 * Returns a pointer to a DIR structure appropriately filled in to begin
 * searching a directory.
 */
DIR *
opendir(const CHAR * szPath)
{
    DIR *nd;
    unsigned int rc;
    CHAR szFullPath[MAX_PATH];

    errno = 0;

    if (!szPath) {
        errno = EFAULT;
        return (DIR *) 0;
    }
    if (szPath[0] == '\0') {
        errno = ENOTDIR;
        return (DIR *) 0;
    }
    /* Attempt to determine if the given path really is a directory. */
    rc = GetFileAttributes(szPath);
    if (rc == (unsigned int) -1) {
        /* call GetLastError for more error info */
        errno = ENOENT;
        return (DIR *) 0;
    }
    if (!(rc & FILE_ATTRIBUTE_DIRECTORY)) {
        /* Error, entry exists but not a directory. */
        errno = ENOTDIR;
        return (DIR *) 0;
    }
    /* Make an absolute pathname.  */
    _fullpath(szFullPath, szPath, MAX_PATH);

    /* Allocate enough space to store DIR structure and the complete
     * directory path given. */
    nd = (DIR *) malloc(sizeof(DIR) + (strlen(szFullPath)
                                       + strlen(SLASH)
                                       + strlen(SUFFIX) + 1)
                        * sizeof(CHAR));

    if (!nd) {
        /* Error, out of memory. */
        errno = ENOMEM;
        return (DIR *) 0;
    }
    /* Create the search expression. */
    strcpy(nd->dd_name, szFullPath);

    /* Add on a slash if the path does not end with one. */
    if (nd->dd_name[0] != '\0'
            && strchr(nd->dd_name, '/') != nd->dd_name
            + strlen(nd->dd_name) - 1
            && strchr(nd->dd_name, '\\') != nd->dd_name
            + strlen(nd->dd_name) - 1) {
        strcat(nd->dd_name, SLASH);
    }
    /* Add on the search pattern */
    strcat(nd->dd_name, SUFFIX);

    /* Initialize handle to -1 so that a premature closedir doesn't try
     * to call _findclose on it. */
    nd->dd_handle = -1;

    /* Initialize the status. */
    nd->dd_stat = 0;

    /* Initialize the dirent structure. ino and reclen are invalid under
     * Win32, and name simply points at the appropriate part of the
     * findfirst_t structure. */
    nd->dd_dir.d_ino = 0;
    nd->dd_dir.d_reclen = 0;
    nd->dd_dir.d_namlen = 0;
    memset(nd->dd_dir.d_name, 0, FILENAME_MAX);

    return nd;
}

/*
 * readdir
 *
 * Return a pointer to a dirent structure filled with the information on the
 * next entry in the directory.
 */
struct dirent *
readdir(DIR * dirp) {
    errno = 0;

    /* Check for valid DIR struct. */
    if (!dirp) {
        errno = EFAULT;
        return (struct dirent *) 0;
    }
    if (dirp->dd_stat < 0) {
        /* We have already returned all files in the directory
         * (or the structure has an invalid dd_stat). */
        return (struct dirent *) 0;
    } else if (dirp->dd_stat == 0) {
        /* We haven't started the search yet. */
        /* Start the search */
        dirp->dd_handle = _findfirst(dirp->dd_name, &(dirp->dd_dta));

        if (dirp->dd_handle == -1) {
            /* Whoops! Seems there are no files in that
             * directory. */
            dirp->dd_stat = -1;
        } else {
            dirp->dd_stat = 1;
        }
    } else {
        /* Get the next search entry. */
        if (_findnext(dirp->dd_handle, &(dirp->dd_dta))) {
            /* We are off the end or otherwise error.
             * _findnext sets errno to ENOENT if no more file
             * Undo this. */
            DWORD winerr = GetLastError();
            if (winerr == ERROR_NO_MORE_FILES)
                errno = 0;
            _findclose(dirp->dd_handle);
            dirp->dd_handle = -1;
            dirp->dd_stat = -1;
        } else {
            /* Update the status to indicate the correct
             * number. */
            dirp->dd_stat++;
        }
    }

    if (dirp->dd_stat > 0) {
        /* Successfully got an entry. Everything about the file is
         * already appropriately filled in except the length of the
         * file name. */
        dirp->dd_dir.d_namlen = strlen(dirp->dd_dta.name);
        strcpy(dirp->dd_dir.d_name, dirp->dd_dta.name);
        return &dirp->dd_dir;
    }
    return (struct dirent *) 0;
}

/*
 * closedir
 *
 * Frees up resources allocated by opendir.
 */
int
closedir(DIR * dirp)
{
    int rc;

    errno = 0;
    rc = 0;

    if (!dirp) {
        errno = EFAULT;
        return -1;
    }
    if (dirp->dd_handle != -1) {
        rc = _findclose(dirp->dd_handle);
    }
    /* Delete the dir structure. */
    free(dirp);

    return rc;
}

/*
 * rewinddir
 *
 * Return to the beginning of the directory "stream". We simply call findclose
 * and then reset things like an opendir.
 */
void
rewinddir(DIR * dirp)
{
    errno = 0;

    if (!dirp) {
        errno = EFAULT;
        return;
    }
    if (dirp->dd_handle != -1) {
        _findclose(dirp->dd_handle);
    }
    dirp->dd_handle = -1;
    dirp->dd_stat = 0;
}

/*
 * telldir
 *
 * Returns the "position" in the "directory stream" which can be used with
 * seekdir to go back to an old entry. We simply return the value in stat.
 */
long
telldir(DIR * dirp)
{
    errno = 0;

    if (!dirp) {
        errno = EFAULT;
        return -1;
    }
    return dirp->dd_stat;
}

/*
 * seekdir
 *
 * Seek to an entry previously returned by telldir. We rewind the directory
 * and call readdir repeatedly until either dd_stat is the position number
 * or -1 (off the end). This is not perfect, in that the directory may
 * have changed while we weren't looking. But that is probably the case with
 * any such system.
 */
void
seekdir(DIR * dirp, long lPos)
{
    errno = 0;

    if (!dirp) {
        errno = EFAULT;
        return;
    }
    if (lPos < -1) {
        /* Seeking to an invalid position. */
        errno = EINVAL;
        return;
    } else if (lPos == -1) {
        /* Seek past end. */
        if (dirp->dd_handle != -1) {
            _findclose(dirp->dd_handle);
        }
        dirp->dd_handle = -1;
        dirp->dd_stat = -1;
    } else {
        /* Rewind and read forward to the appropriate index. */
        rewinddir(dirp);

        while ((dirp->dd_stat < lPos) && readdir(dirp));
    }
}
#endif /* _SQUID_WINDOWS_ */