/*-
 * Copyright (c) 2003-2007 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*-
 * This is a new directory-walking system that addresses a number
 * of problems I've had with fts(3).  In particular, it has no
 * pathname-length limits (other than the size of 'int'), handles
 * deep logical traversals, uses considerably less memory, and has
 * an opaque interface (easier to modify in the future).
 *
 * Internally, it keeps a single list of "tree_entry" items that
 * represent filesystem objects that require further attention.
 * Non-directories are not kept in memory: they are pulled from
 * readdir(), returned to the client, then freed as soon as possible.
 * Any directory entry to be traversed gets pushed onto the stack.
 *
 * There is surprisingly little information that needs to be kept for
 * each item on the stack.  Just the name, depth (represented here as the
 * string length of the parent directory's pathname), and some markers
 * indicating how to get back to the parent (via chdir("..") for a
 * regular dir or via fchdir(2) for a symlink).
 */
#include "bsdtar_platform.h"
__FBSDID("$FreeBSD: src/usr.bin/tar/tree.c,v 1.9 2008/11/27 05:49:52 kientzle Exp $");

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_DIRECT_H
#include <direct.h>
#endif
#ifdef HAVE_DIRENT_H
#include <dirent.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#if defined(HAVE_WINDOWS_H) && !defined(__CYGWIN__)
#include <windows.h>
#endif

#include "tree.h"

/*
 * TODO:
 *    1) Loop checking.
 *    3) Arbitrary logical traversals by closing/reopening intermediate fds.
 */

struct tree_entry {
    int depth;
    struct tree_entry *next;
    struct tree_entry *parent;
    char *name;
    size_t dirname_length;
    dev_t dev;
    ino_t ino;
    int flags;
    /* How to return back to the parent of a symlink. */
#ifdef HAVE_FCHDIR
    int symlink_parent_fd;
#elif defined(_WIN32) && !defined(__CYGWIN__)
    char *symlink_parent_path;
#else
#error fchdir function required.
#endif
};

/* Definitions for tree_entry.flags bitmap. */
#define isDir 1 /* This entry is a regular directory. */
#define isDirLink 2 /* This entry is a symbolic link to a directory. */
#define needsFirstVisit 4 /* This is an initial entry. */
#define needsDescent 8 /* This entry needs to be previsited. */
#define needsOpen 16 /* This is a directory that needs to be opened. */
#define needsAscent 32 /* This entry needs to be postvisited. */

/*
 * On Windows, "first visit" is handled as a pattern to be handed to
 * _findfirst().  This is consistent with Windows conventions that
 * file patterns are handled within the application.  On Posix,
 * "first visit" is just returned to the client.
 */

/*
 * Local data for this package.
 */
struct tree {
    struct tree_entry   *stack;
    struct tree_entry   *current;
#if defined(HAVE_WINDOWS_H) && !defined(__CYGWIN__)
    HANDLE d;
    BY_HANDLE_FILE_INFORMATION fileInfo;
#define INVALID_DIR_HANDLE INVALID_HANDLE_VALUE
    WIN32_FIND_DATA _findData;
    WIN32_FIND_DATA *findData;
#else
    DIR *d;
#define INVALID_DIR_HANDLE NULL
    struct dirent *de;
#endif
    int  flags;
    int  visit_type;
    int  tree_errno; /* Error code from last failed operation. */

    /* Dynamically-sized buffer for holding path */
    char    *buff;
    size_t   buff_length;

    const char *basename; /* Last path element */
    size_t   dirname_length; /* Leading dir length */
    size_t   path_length; /* Total path length */

    int  depth;
    int  openCount;
    int  maxOpenCount;

    struct stat lst;
    struct stat st;
};

/* Definitions for tree.flags bitmap. */
#define hasStat 16  /* The st entry is valid. */
#define hasLstat 32 /* The lst entry is valid. */
#define hasFileInfo 64 /* The Windows fileInfo entry is valid. */

#if defined(_WIN32) && !defined(__CYGWIN__)
static int
tree_dir_next_windows(struct tree *t, const char *pattern);
#else
static int
tree_dir_next_posix(struct tree *t);
#endif

#ifdef HAVE_DIRENT_D_NAMLEN
/* BSD extension; avoids need for a strlen() call. */
#define D_NAMELEN(dp)   (dp)->d_namlen
#else
#define D_NAMELEN(dp)   (strlen((dp)->d_name))
#endif

#include <stdio.h>
void
tree_dump(struct tree *t, FILE *out)
{
    char buff[300];
    struct tree_entry *te;

    fprintf(out, "\tdepth: %d\n", t->depth);
    fprintf(out, "\tbuff: %s\n", t->buff);
    fprintf(out, "\tpwd: %s\n", getcwd(buff, sizeof(buff)));
    fprintf(out, "\tbasename: %s\n", t->basename);
    fprintf(out, "\tstack:\n");
    for (te = t->stack; te != NULL; te = te->next) {
        fprintf(out, "\t\t%s%d:\"%s\" %s%s%s%s%s\n",
            t->current == te ? "*" : " ",
            te->depth,
            te->name,
            te->flags & needsFirstVisit ? "V" : "",
            te->flags & needsDescent ? "D" : "",
            te->flags & needsOpen ? "O" : "",
            te->flags & needsAscent ? "A" : "",
            (t->current == te && t->d) ? "+" : ""
        );
    }
}

/*
 * Add a directory path to the current stack.
 */
static void
tree_push(struct tree *t, const char *path)
{
    struct tree_entry *te;

    te = malloc(sizeof(*te));
    memset(te, 0, sizeof(*te));
    te->next = t->stack;
    te->parent = t->current;
    if (te->parent)
        te->depth = te->parent->depth + 1;
    t->stack = te;
#ifdef HAVE_FCHDIR
    te->symlink_parent_fd = -1;
    te->name = strdup(path);
#elif defined(_WIN32) && !defined(__CYGWIN__)
    te->symlink_parent_path = NULL;
    te->name = _strdup(path);
#endif
    te->flags = needsDescent | needsOpen | needsAscent;
    te->dirname_length = t->dirname_length;
}

/*
 * Append a name to the current dir path.
 */
static void
tree_append(struct tree *t, const char *name, size_t name_length)
{
    char *p;

    if (t->buff != NULL)
        t->buff[t->dirname_length] = '\0';
    /* Strip trailing '/' from name, unless entire name is "/". */
    while (name_length > 1 &&
        (name[name_length - 1] == '/' || name[name_length - 1] == '/'))
        name_length--;

    /* Resize pathname buffer as needed. */
    while (name_length + 1 + t->dirname_length >= t->buff_length) {
        t->buff_length *= 2;
        if (t->buff_length < 1024)
            t->buff_length = 1024;
        t->buff = realloc(t->buff, t->buff_length);
        if (t->buff == NULL)
            abort();
    }
    p = t->buff + t->dirname_length;
    t->path_length = t->dirname_length + name_length;
    /* Add a separating '/' if it's needed. */
    if (t->dirname_length > 0 && p[-1] != '/') {
        *p++ = '/';
        t->path_length ++;
    }
#if HAVE_STRNCPY_S
    strncpy_s(p, t->buff_length - (p - t->buff), name, name_length);
#else
    strncpy(p, name, name_length);
#endif
    p[name_length] = '\0';
    t->basename = p;
}

/*
 * Open a directory tree for traversal.
 */
struct tree *
tree_open(const char *path)
{
    struct tree *t;

    t = malloc(sizeof(*t));
    memset(t, 0, sizeof(*t));
//  tree_append(t, path, strlen(path));
    /* First item is set up a lot like a symlink traversal. */
    tree_push(t, path);
    t->stack->flags = needsFirstVisit | isDirLink;
#ifdef HAVE_FCHDIR
    t->stack->symlink_parent_fd = open(".", O_RDONLY);
    t->openCount++;
#elif defined(_WIN32) && !defined(__CYGWIN__)
    t->stack->symlink_parent_path = _getcwd(NULL, 0);
#endif
    t->d = INVALID_DIR_HANDLE;
    return (t);
}

/*
 * We've finished a directory; ascend back to the parent.
 */
static int
tree_ascend(struct tree *t)
{
    struct tree_entry *te;
    int r = 0;

    te = t->stack;
    t->depth--;
    if (te->flags & isDirLink) {
#ifdef HAVE_FCHDIR
        if (fchdir(te->symlink_parent_fd) != 0) {
            t->tree_errno = errno;
            r = TREE_ERROR_FATAL;
        }
        close(te->symlink_parent_fd);
#elif defined(_WIN32) && !defined(__CYGWIN__)
        if (SetCurrentDirectory(te->symlink_parent_path) == 0) {
            t->tree_errno = errno;
            r = TREE_ERROR_FATAL;
        }
        free(te->symlink_parent_path);
        te->symlink_parent_path = NULL;
#endif
        t->openCount--;
    } else {
#if defined(_WIN32) && !defined(__CYGWIN__)
        if (SetCurrentDirectory("..") == 0) {
#else
        if (chdir("..") != 0) {
#endif
            t->tree_errno = errno;
            r = TREE_ERROR_FATAL;
        }
    }
    return (r);
}

/*
 * Pop the working stack.
 */
static void
tree_pop(struct tree *t)
{
    struct tree_entry *te;

    if (t->buff)
        t->buff[t->dirname_length] = '\0';
    if (t->stack == t->current && t->current != NULL)
        t->current = t->current->parent;
    te = t->stack;
    t->stack = te->next;
    t->dirname_length = te->dirname_length;
    if (t->buff) {
        t->basename = t->buff + t->dirname_length;
        while (t->basename[0] == '/')
            t->basename++;
    }
    free(te->name);
    free(te);
}

/*
 * Get the next item in the tree traversal.
 */
int
tree_next(struct tree *t)
{
    int r;

    /* If we're called again after a fatal error, that's an API
     * violation.  Just crash now. */
    if (t->visit_type == TREE_ERROR_FATAL) {
        fprintf(stderr, "Unable to continue traversing"
            " directory heirarchy after a fatal error.");
        abort();
    }

    while (t->stack != NULL) {
        /* If there's an open dir, get the next entry from there. */
        if (t->d != INVALID_DIR_HANDLE) {
#if defined(_WIN32) && !defined(__CYGWIN__)
            r = tree_dir_next_windows(t, NULL);
#else
            r = tree_dir_next_posix(t);
#endif
            if (r == 0)
                continue;
            return (r);
        }

        if (t->stack->flags & needsFirstVisit) {
#if defined(_WIN32) && !defined(__CYGWIN__)
            char *d = strdup(t->stack->name);
            char *p, *pattern;
            //tree_pop(t);
            t->stack->flags &= ~needsFirstVisit;
            if (strchr(d, '*') || strchr(d, '?')) {
                // It has a wildcard in it...
                if ((p = strrchr(d, '\\')) != NULL) {
                    pattern = strdup(p + 1);
                    p[1] = '\0';
                    chdir(d);
                    tree_append(t, d, strlen(d));
                    free(d);
                } else {
                    pattern = d;
                }
                r = tree_dir_next_windows(t, pattern);
                free(pattern);
                if (r == 0)
                    continue;
                return (r);
            }
            // Not a pattern, handle it as-is...
#endif
            /* Top stack item needs a regular visit. */
            t->current = t->stack;
            tree_append(t, t->stack->name, strlen(t->stack->name));
            //t->dirname_length = t->path_length;
            //tree_pop(t);
            t->stack->flags &= ~needsFirstVisit;
            return (t->visit_type = TREE_REGULAR);
        } else if (t->stack->flags & needsDescent) {
            /* Top stack item is dir to descend into. */
            t->current = t->stack;
            tree_append(t, t->stack->name, strlen(t->stack->name));
            t->stack->flags &= ~needsDescent;
            /* If it is a link, set up fd for the ascent. */
            if (t->stack->flags & isDirLink) {
#ifdef HAVE_FCHDIR
                t->stack->symlink_parent_fd = open(".", O_RDONLY);
                t->openCount++;
                if (t->openCount > t->maxOpenCount)
                    t->maxOpenCount = t->openCount;
#elif defined(_WIN32) && !defined(__CYGWIN__)
                t->stack->symlink_parent_path = _getcwd(NULL, 0);
#endif
            }
            t->dirname_length = t->path_length;
#if defined(_WIN32) && !defined(__CYGWIN__)
            if (t->path_length == 259 || !SetCurrentDirectory(t->stack->name) != 0)
#else
            if (chdir(t->stack->name) != 0)
#endif
            {
                /* chdir() failed; return error */
                tree_pop(t);
                t->tree_errno = errno;
                return (t->visit_type = TREE_ERROR_DIR);
            }
            t->depth++;
            return (t->visit_type = TREE_POSTDESCENT);
        } else if (t->stack->flags & needsOpen) {
            t->stack->flags &= ~needsOpen;
#if defined(_WIN32) && !defined(__CYGWIN__)
            r = tree_dir_next_windows(t, "*");
#else
            r = tree_dir_next_posix(t);
#endif
            if (r == 0)
                continue;
            return (r);
        } else if (t->stack->flags & needsAscent) {
                /* Top stack item is dir and we're done with it. */
            r = tree_ascend(t);
            tree_pop(t);
            t->visit_type = r != 0 ? r : TREE_POSTASCENT;
            return (t->visit_type);
        } else {
            /* Top item on stack is dead. */
            tree_pop(t);
            t->flags &= ~hasLstat;
            t->flags &= ~hasStat;
        }
    }
    return (t->visit_type = 0);
}

#if defined(_WIN32) && !defined(__CYGWIN__)
static int
tree_dir_next_windows(struct tree *t, const char *pattern)
{
    const char *name;
    size_t namelen;
    int r;

    for (;;) {
        if (pattern != NULL) {
            t->d = FindFirstFile(pattern, &t->_findData);
            if (t->d == INVALID_DIR_HANDLE) {
                r = tree_ascend(t); /* Undo "chdir" */
                tree_pop(t);
                t->tree_errno = errno;
                t->visit_type = r != 0 ? r : TREE_ERROR_DIR;
                return (t->visit_type);
            }
            t->findData = &t->_findData;
            pattern = NULL;
        } else if (!FindNextFile(t->d, &t->_findData)) {
            FindClose(t->d);
            t->d = INVALID_DIR_HANDLE;
            t->findData = NULL;
            return (0);
        }
        name = t->findData->cFileName;
        namelen = strlen(name);
        t->flags &= ~hasLstat;
        t->flags &= ~hasStat;
        if (name[0] == '.' && name[1] == '\0')
            continue;
        if (name[0] == '.' && name[1] == '.' && name[2] == '\0')
            continue;
        tree_append(t, name, namelen);
        return (t->visit_type = TREE_REGULAR);
    }
}
#else
static int
tree_dir_next_posix(struct tree *t)
{
    int r;
    const char *name;
    size_t namelen;

    if (t->d == NULL) {
        if ((t->d = opendir(".")) == NULL) {
            r = tree_ascend(t); /* Undo "chdir" */
            tree_pop(t);
            t->tree_errno = errno;
            t->visit_type = r != 0 ? r : TREE_ERROR_DIR;
            return (t->visit_type);
        }
    }
    for (;;) {
        t->de = readdir(t->d);
        if (t->de == NULL) {
            closedir(t->d);
            t->d = INVALID_DIR_HANDLE;
            return (0);
        }
        name = t->de->d_name;
        namelen = D_NAMELEN(t->de);
        t->flags &= ~hasLstat;
        t->flags &= ~hasStat;
        if (name[0] == '.' && name[1] == '\0')
            continue;
        if (name[0] == '.' && name[1] == '.' && name[2] == '\0')
            continue;
        tree_append(t, name, namelen);
        return (t->visit_type = TREE_REGULAR);
    }
}
#endif

/*
 * Return error code.
 */
int
tree_errno(struct tree *t)
{
    return (t->tree_errno);
}

/*
 * Called by the client to mark the directory just returned from
 * tree_next() as needing to be visited.
 */
void
tree_descend(struct tree *t)
{
    if (t->visit_type != TREE_REGULAR)
        return;

    if (tree_current_is_physical_dir(t)) {
        tree_push(t, t->basename);
        t->stack->flags |= isDir;
    } else if (tree_current_is_dir(t)) {
        tree_push(t, t->basename);
        t->stack->flags |= isDirLink;
    }
}

/*
 * Get the stat() data for the entry just returned from tree_next().
 */
const struct stat *
tree_current_stat(struct tree *t)
{
    if (!(t->flags & hasStat)) {
        if (stat(tree_current_access_path(t), &t->st) != 0)
            return NULL;
        t->flags |= hasStat;
    }
    return (&t->st);
}

#if defined(HAVE_WINDOWS_H) && !defined(__CYGWIN__)
const BY_HANDLE_FILE_INFORMATION *
tree_current_file_information(struct tree *t)
{
    if (!(t->flags & hasFileInfo)) {
        HANDLE h = CreateFile(tree_current_access_path(t),
            0, 0, NULL,
            OPEN_EXISTING,
            FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT,
            NULL);
        if (h == INVALID_HANDLE_VALUE)
            return NULL;
        if (!GetFileInformationByHandle(h, &t->fileInfo)) {
            CloseHandle(h);
            return NULL;
        }
        CloseHandle(h);
        t->flags |= hasFileInfo;
    }
    return (&t->fileInfo);
}
#endif
/*
 * Get the lstat() data for the entry just returned from tree_next().
 */
const struct stat *
tree_current_lstat(struct tree *t)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
    return (tree_current_stat(t));
#else
    if (!(t->flags & hasLstat)) {
        if (lstat(tree_current_access_path(t), &t->lst) != 0)
            return NULL;
        t->flags |= hasLstat;
    }
    return (&t->lst);
#endif
}

/*
 * Test whether current entry is a dir or link to a dir.
 */
int
tree_current_is_dir(struct tree *t)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
    if (t->findData)
        return (t->findData->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY);
    if (tree_current_file_information(t))
        return (t->fileInfo.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY);
    return (0);
#else
    const struct stat *st;
    /*
     * If we already have lstat() info, then try some
     * cheap tests to determine if this is a dir.
     */
    if (t->flags & hasLstat) {
        /* If lstat() says it's a dir, it must be a dir. */
        if (S_ISDIR(tree_current_lstat(t)->st_mode))
            return 1;
        /* Not a dir; might be a link to a dir. */
        /* If it's not a link, then it's not a link to a dir. */
        if (!S_ISLNK(tree_current_lstat(t)->st_mode))
            return 0;
        /*
         * It's a link, but we don't know what it's a link to,
         * so we'll have to use stat().
         */
    }

    st = tree_current_stat(t);
    /* If we can't stat it, it's not a dir. */
    if (st == NULL)
        return 0;
    /* Use the definitive test.  Hopefully this is cached. */
    return (S_ISDIR(st->st_mode));
#endif
}

/*
 * Test whether current entry is a physical directory.  Usually, we
 * already have at least one of stat() or lstat() in memory, so we
 * use tricks to try to avoid an extra trip to the disk.
 */
int
tree_current_is_physical_dir(struct tree *t)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
    if (tree_current_is_physical_link(t))
        return (0);
    return (tree_current_is_dir(t));
#else
    const struct stat *st;

    /*
     * If stat() says it isn't a dir, then it's not a dir.
     * If stat() data is cached, this check is free, so do it first.
     */
    if ((t->flags & hasStat)
        && (!S_ISDIR(tree_current_stat(t)->st_mode)))
        return 0;

    /*
     * Either stat() said it was a dir (in which case, we have
     * to determine whether it's really a link to a dir) or
     * stat() info wasn't available.  So we use lstat(), which
     * hopefully is already cached.
     */

    st = tree_current_lstat(t);
    /* If we can't stat it, it's not a dir. */
    if (st == NULL)
        return 0;
    /* Use the definitive test.  Hopefully this is cached. */
    return (S_ISDIR(st->st_mode));
#endif
}

/*
 * Test whether current entry is a symbolic link.
 */
int
tree_current_is_physical_link(struct tree *t)
{
#if defined(_WIN32) && !defined(__CYGWIN__)
    if (t->findData)
        return ((t->findData->dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)
                && (t->findData->dwReserved0 == IO_REPARSE_TAG_SYMLINK));
    return (0);
#else
    const struct stat *st = tree_current_lstat(t);
    if (st == NULL)
        return 0;
    return (S_ISLNK(st->st_mode));
#endif
}

/*
 * Return the access path for the entry just returned from tree_next().
 */
const char *
tree_current_access_path(struct tree *t)
{
    return (t->basename);
}

/*
 * Return the full path for the entry just returned from tree_next().
 */
const char *
tree_current_path(struct tree *t)
{
    return (t->buff);
}

/*
 * Return the length of the path for the entry just returned from tree_next().
 */
size_t
tree_current_pathlen(struct tree *t)
{
    return (t->path_length);
}

/*
 * Return the nesting depth of the entry just returned from tree_next().
 */
int
tree_current_depth(struct tree *t)
{
    return (t->depth);
}

/*
 * Terminate the traversal and release any resources.
 */
void
tree_close(struct tree *t)
{
    /* Release anything remaining in the stack. */
    while (t->stack != NULL)
        tree_pop(t);
    if (t->buff)
        free(t->buff);
    /* TODO: Ensure that premature close() resets cwd */
#if 0
#ifdef HAVE_FCHDIR
    if (t->initialDirFd >= 0) {
        int s = fchdir(t->initialDirFd);
        (void)s; /* UNUSED */
        close(t->initialDirFd);
        t->initialDirFd = -1;
    }
#elif defined(_WIN32) && !defined(__CYGWIN__)
    if (t->initialDir != NULL) {
        SetCurrentDir(t->initialDir);
        free(t->initialDir);
        t->initialDir = NULL;
    }
#endif
#endif
    free(t);
}
