s3/docs: Fix typo.

[Samba/gebeck_regimport.git] / source3 / smbd / vfs.c

/*
   Unix SMB/Netbios implementation.
   Version 1.9.
   VFS initialisation and support functions
   Copyright (C) Tim Potter 1999
   Copyright (C) Alexander Bokovoy 2002
   Copyright (C) James Peach 2006

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   This work was sponsored by Optifacio Software Services, Inc.
*/

#include "includes.h"
#include "smbd/globals.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_VFS

static_decl_vfs;

struct vfs_init_function_entry {
        char *name;
        const vfs_op_tuple *vfs_op_tuples;
        struct vfs_init_function_entry *prev, *next;
};

/****************************************************************************
    maintain the list of available backends
****************************************************************************/

static struct vfs_init_function_entry *vfs_find_backend_entry(const char *name)
{
        struct vfs_init_function_entry *entry = backends;

        DEBUG(10, ("vfs_find_backend_entry called for %s\n", name));
 
        while(entry) {
                if (strcmp(entry->name, name)==0) return entry;
                entry = entry->next;
        }

        return NULL;
}

NTSTATUS smb_register_vfs(int version, const char *name, const vfs_op_tuple *vfs_op_tuples)
{
        struct vfs_init_function_entry *entry = backends;

        if ((version != SMB_VFS_INTERFACE_VERSION)) {
                DEBUG(0, ("Failed to register vfs module.\n"
                          "The module was compiled against SMB_VFS_INTERFACE_VERSION %d,\n"
                          "current SMB_VFS_INTERFACE_VERSION is %d.\n"
                          "Please recompile against the current Samba Version!\n",  
                          version, SMB_VFS_INTERFACE_VERSION));
                return NT_STATUS_OBJECT_TYPE_MISMATCH;
        }

        if (!name || !name[0] || !vfs_op_tuples) {
                DEBUG(0,("smb_register_vfs() called with NULL pointer or empty name!\n"));
                return NT_STATUS_INVALID_PARAMETER;
        }

        if (vfs_find_backend_entry(name)) {
                DEBUG(0,("VFS module %s already loaded!\n", name));
                return NT_STATUS_OBJECT_NAME_COLLISION;
        }

        entry = SMB_XMALLOC_P(struct vfs_init_function_entry);
        entry->name = smb_xstrdup(name);
        entry->vfs_op_tuples = vfs_op_tuples;

        DLIST_ADD(backends, entry);
        DEBUG(5, ("Successfully added vfs backend '%s'\n", name));
        return NT_STATUS_OK;
}

/****************************************************************************
  initialise default vfs hooks
****************************************************************************/

static void vfs_init_default(connection_struct *conn)
{
        DEBUG(3, ("Initialising default vfs hooks\n"));
        vfs_init_custom(conn, DEFAULT_VFS_MODULE_NAME);
}

/****************************************************************************
  initialise custom vfs hooks
 ****************************************************************************/

static inline void vfs_set_operation(struct vfs_ops * vfs, vfs_op_type which,
                                struct vfs_handle_struct * handle, void * op)
{
        ((struct vfs_handle_struct **)&vfs->handles)[which] = handle;
        ((void **)(void *)&vfs->ops)[which] = op;
}

bool vfs_init_custom(connection_struct *conn, const char *vfs_object)
{
        const vfs_op_tuple *ops;
        char *module_path = NULL;
        char *module_name = NULL;
        char *module_param = NULL, *p;
        int i;
        vfs_handle_struct *handle;
        const struct vfs_init_function_entry *entry;
        
        if (!conn||!vfs_object||!vfs_object[0]) {
                DEBUG(0,("vfs_init_custon() called with NULL pointer or emtpy vfs_object!\n"));
                return False;
        }

        if(!backends) {
                static_init_vfs;
        }

        DEBUG(3, ("Initialising custom vfs hooks from [%s]\n", vfs_object));

        module_path = smb_xstrdup(vfs_object);

        p = strchr_m(module_path, ':');

        if (p) {
                *p = 0;
                module_param = p+1;
                trim_char(module_param, ' ', ' ');
        }

        trim_char(module_path, ' ', ' ');

        module_name = smb_xstrdup(module_path);

        if ((module_name[0] == '/') &&
            (strcmp(module_path, DEFAULT_VFS_MODULE_NAME) != 0)) {

                /*
                 * Extract the module name from the path. Just use the base
                 * name of the last path component.
                 */

                SAFE_FREE(module_name);
                module_name = smb_xstrdup(strrchr_m(module_path, '/')+1);

                p = strchr_m(module_name, '.');

                if (p != NULL) {
                        *p = '\0';
                }
        }

        /* First, try to load the module with the new module system */
        entry = vfs_find_backend_entry(module_name);
        if (!entry) {
                NTSTATUS status;

                DEBUG(5, ("vfs module [%s] not loaded - trying to load...\n",
                          vfs_object));

                status = smb_probe_module("vfs", module_path);
                if (!NT_STATUS_IS_OK(status)) {
                        DEBUG(0, ("error probing vfs module '%s': %s\n",
                                  module_path, nt_errstr(status)));
                        goto fail;
                }

                entry = vfs_find_backend_entry(module_name);
                if (!entry) {
                        DEBUG(0,("Can't find a vfs module [%s]\n",vfs_object));
                        goto fail;
                }
        }

        DEBUGADD(5,("Successfully loaded vfs module [%s] with the new modules system\n", vfs_object));
        if ((ops = entry->vfs_op_tuples) == NULL) {
                DEBUG(0, ("entry->vfs_op_tuples==NULL for [%s] failed\n", vfs_object));
                goto fail;
        }

        handle = TALLOC_ZERO_P(conn, vfs_handle_struct);
        if (!handle) {
                DEBUG(0,("TALLOC_ZERO() failed!\n"));
                goto fail;
        }
        memcpy(&handle->vfs_next, &conn->vfs, sizeof(struct vfs_ops));
        handle->conn = conn;
        if (module_param) {
                handle->param = talloc_strdup(conn, module_param);
        }
        DLIST_ADD(conn->vfs_handles, handle);

        for(i=0; ops[i].op != NULL; i++) {
                DEBUG(5, ("Checking operation #%d (type %d, layer %d)\n", i, ops[i].type, ops[i].layer));
                if(ops[i].layer == SMB_VFS_LAYER_OPAQUE) {
                        /* If this operation was already made opaque by different module, it
                         * will be overridden here.
                         */
                        DEBUGADD(5, ("Making operation type %d opaque [module %s]\n", ops[i].type, vfs_object));
                        vfs_set_operation(&conn->vfs_opaque, ops[i].type, handle, ops[i].op);
                }
                /* Change current VFS disposition*/
                DEBUGADD(5, ("Accepting operation type %d from module %s\n", ops[i].type, vfs_object));
                vfs_set_operation(&conn->vfs, ops[i].type, handle, ops[i].op);
        }

        SAFE_FREE(module_path);
        SAFE_FREE(module_name);
        return True;

 fail:
        SAFE_FREE(module_path);
        SAFE_FREE(module_name);
        return False;
}

/*****************************************************************
 Allow VFS modules to extend files_struct with VFS-specific state.
 This will be ok for small numbers of extensions, but might need to
 be refactored if it becomes more widely used.
******************************************************************/

#define EXT_DATA_AREA(e) ((uint8 *)(e) + sizeof(struct vfs_fsp_data))

void *vfs_add_fsp_extension_notype(vfs_handle_struct *handle,
                                   files_struct *fsp, size_t ext_size,
                                   void (*destroy_fn)(void *p_data))
{
        struct vfs_fsp_data *ext;
        void * ext_data;

        /* Prevent VFS modules adding multiple extensions. */
        if ((ext_data = vfs_fetch_fsp_extension(handle, fsp))) {
                return ext_data;
        }

        ext = (struct vfs_fsp_data *)TALLOC_ZERO(
                handle->conn, sizeof(struct vfs_fsp_data) + ext_size);
        if (ext == NULL) {
                return NULL;
        }

        ext->owner = handle;
        ext->next = fsp->vfs_extension;
        ext->destroy = destroy_fn;
        fsp->vfs_extension = ext;
        return EXT_DATA_AREA(ext);
}

void vfs_remove_fsp_extension(vfs_handle_struct *handle, files_struct *fsp)
{
        struct vfs_fsp_data *curr;
        struct vfs_fsp_data *prev;

        for (curr = fsp->vfs_extension, prev = NULL;
             curr;
             prev = curr, curr = curr->next) {
                if (curr->owner == handle) {
                    if (prev) {
                            prev->next = curr->next;
                    } else {
                            fsp->vfs_extension = curr->next;
                    }
                    if (curr->destroy) {
                            curr->destroy(EXT_DATA_AREA(curr));
                    }
                    TALLOC_FREE(curr);
                    return;
                }
        }
}

void *vfs_memctx_fsp_extension(vfs_handle_struct *handle, files_struct *fsp)
{
        struct vfs_fsp_data *head;

        for (head = fsp->vfs_extension; head; head = head->next) {
                if (head->owner == handle) {
                        return head;
                }
        }

        return NULL;
}

void *vfs_fetch_fsp_extension(vfs_handle_struct *handle, files_struct *fsp)
{
        struct vfs_fsp_data *head;

        head = (struct vfs_fsp_data *)vfs_memctx_fsp_extension(handle, fsp);
        if (head != NULL) {
                return EXT_DATA_AREA(head);
        }

        return NULL;
}

#undef EXT_DATA_AREA

/*****************************************************************
 Generic VFS init.
******************************************************************/

bool smbd_vfs_init(connection_struct *conn)
{
        const char **vfs_objects;
        unsigned int i = 0;
        int j = 0;
        
        /* Normal share - initialise with disk access functions */
        vfs_init_default(conn);
        vfs_objects = lp_vfs_objects(SNUM(conn));

        /* Override VFS functions if 'vfs object' was not specified*/
        if (!vfs_objects || !vfs_objects[0])
                return True;
        
        for (i=0; vfs_objects[i] ;) {
                i++;
        }

        for (j=i-1; j >= 0; j--) {
                if (!vfs_init_custom(conn, vfs_objects[j])) {
                        DEBUG(0, ("smbd_vfs_init: vfs_init_custom failed for %s\n", vfs_objects[j]));
                        return False;
                }
        }
        return True;
}

/*******************************************************************
 Check if directory exists.
********************************************************************/

bool vfs_directory_exist(connection_struct *conn, const char *dname, SMB_STRUCT_STAT *st)
{
        SMB_STRUCT_STAT st2;
        bool ret;

        if (!st)
                st = &st2;

        if (SMB_VFS_STAT(conn,dname,st) != 0)
                return(False);

        ret = S_ISDIR(st->st_ex_mode);
        if(!ret)
                errno = ENOTDIR;

        return ret;
}

/*******************************************************************
 Check if an object exists in the vfs.
********************************************************************/

bool vfs_object_exist(connection_struct *conn,const char *fname,SMB_STRUCT_STAT *sbuf)
{
        SMB_STRUCT_STAT st;

        if (!sbuf)
                sbuf = &st;

        ZERO_STRUCTP(sbuf);

        if (SMB_VFS_STAT(conn,fname,sbuf) == -1)
                return(False);
        return True;
}

/*******************************************************************
 Check if a file exists in the vfs.
********************************************************************/

NTSTATUS vfs_file_exist(connection_struct *conn, struct smb_filename *smb_fname)
{
        char *fname = NULL;
        NTSTATUS status;

        status = get_full_smb_filename(talloc_tos(), smb_fname, &fname);
        if (!NT_STATUS_IS_OK(status)) {
                goto out;
        }

        status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
        if (SMB_VFS_STAT(conn, fname, &smb_fname->st) == -1) {
                goto out;
        }

        /* Only return OK if stat was successful and S_ISREG */
        if (S_ISREG(smb_fname->st.st_ex_mode)) {
                status = NT_STATUS_OK;
        }
 out:
        TALLOC_FREE(fname);
        return status;
}

/****************************************************************************
 Read data from fsp on the vfs. (note: EINTR re-read differs from vfs_write_data)
****************************************************************************/

ssize_t vfs_read_data(files_struct *fsp, char *buf, size_t byte_count)
{
        size_t total=0;

        while (total < byte_count)
        {
                ssize_t ret = SMB_VFS_READ(fsp, buf + total,
                                           byte_count - total);

                if (ret == 0) return total;
                if (ret == -1) {
                        if (errno == EINTR)
                                continue;
                        else
                                return -1;
                }
                total += ret;
        }
        return (ssize_t)total;
}

ssize_t vfs_pread_data(files_struct *fsp, char *buf,
                size_t byte_count, SMB_OFF_T offset)
{
        size_t total=0;

        while (total < byte_count)
        {
                ssize_t ret = SMB_VFS_PREAD(fsp, buf + total,
                                        byte_count - total, offset + total);

                if (ret == 0) return total;
                if (ret == -1) {
                        if (errno == EINTR)
                                continue;
                        else
                                return -1;
                }
                total += ret;
        }
        return (ssize_t)total;
}

/****************************************************************************
 Write data to a fd on the vfs.
****************************************************************************/

ssize_t vfs_write_data(struct smb_request *req,
                        files_struct *fsp,
                        const char *buffer,
                        size_t N)
{
        size_t total=0;
        ssize_t ret;

        if (req && req->unread_bytes) {
                SMB_ASSERT(req->unread_bytes == N);
                /* VFS_RECVFILE must drain the socket
                 * before returning. */
                req->unread_bytes = 0;
                return SMB_VFS_RECVFILE(smbd_server_fd(),
                                        fsp,
                                        (SMB_OFF_T)-1,
                                        N);
        }

        while (total < N) {
                ret = SMB_VFS_WRITE(fsp, buffer + total, N - total);

                if (ret == -1)
                        return -1;
                if (ret == 0)
                        return total;

                total += ret;
        }
        return (ssize_t)total;
}

ssize_t vfs_pwrite_data(struct smb_request *req,
                        files_struct *fsp,
                        const char *buffer,
                        size_t N,
                        SMB_OFF_T offset)
{
        size_t total=0;
        ssize_t ret;

        if (req && req->unread_bytes) {
                SMB_ASSERT(req->unread_bytes == N);
                /* VFS_RECVFILE must drain the socket
                 * before returning. */
                req->unread_bytes = 0;
                return SMB_VFS_RECVFILE(smbd_server_fd(),
                                        fsp,
                                        offset,
                                        N);
        }

        while (total < N) {
                ret = SMB_VFS_PWRITE(fsp, buffer + total, N - total,
                                     offset + total);

                if (ret == -1)
                        return -1;
                if (ret == 0)
                        return total;

                total += ret;
        }
        return (ssize_t)total;
}
/****************************************************************************
 An allocate file space call using the vfs interface.
 Allocates space for a file from a filedescriptor.
 Returns 0 on success, -1 on failure.
****************************************************************************/

int vfs_allocate_file_space(files_struct *fsp, uint64_t len)
{
        int ret;
        SMB_STRUCT_STAT st;
        connection_struct *conn = fsp->conn;
        uint64_t space_avail;
        uint64_t bsize,dfree,dsize;

        /*
         * Actually try and commit the space on disk....
         */

        DEBUG(10,("vfs_allocate_file_space: file %s, len %.0f\n", fsp->fsp_name, (double)len ));

        if (((SMB_OFF_T)len) < 0) {
                DEBUG(0,("vfs_allocate_file_space: %s negative len requested.\n", fsp->fsp_name ));
                errno = EINVAL;
                return -1;
        }

        ret = SMB_VFS_FSTAT(fsp, &st);
        if (ret == -1)
                return ret;

        if (len == (uint64_t)st.st_ex_size)
                return 0;

        if (len < (uint64_t)st.st_ex_size) {
                /* Shrink - use ftruncate. */

                DEBUG(10,("vfs_allocate_file_space: file %s, shrink. Current size %.0f\n",
                                fsp->fsp_name, (double)st.st_ex_size ));

                contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_ALLOC_SHRINK);

                flush_write_cache(fsp, SIZECHANGE_FLUSH);
                if ((ret = SMB_VFS_FTRUNCATE(fsp, (SMB_OFF_T)len)) != -1) {
                        set_filelen_write_cache(fsp, len);
                }

                contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_ALLOC_SHRINK);

                return ret;
        }

        /* Grow - we need to test if we have enough space. */

        contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_ALLOC_GROW);
        contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_ALLOC_GROW);

        if (!lp_strict_allocate(SNUM(fsp->conn)))
                return 0;

        len -= st.st_ex_size;
        len /= 1024; /* Len is now number of 1k blocks needed. */
        space_avail = get_dfree_info(conn,fsp->fsp_name,False,&bsize,&dfree,&dsize);
        if (space_avail == (uint64_t)-1) {
                return -1;
        }

        DEBUG(10,("vfs_allocate_file_space: file %s, grow. Current size %.0f, needed blocks = %.0f, space avail = %.0f\n",
                        fsp->fsp_name, (double)st.st_ex_size, (double)len, (double)space_avail ));

        if (len > space_avail) {
                errno = ENOSPC;
                return -1;
        }

        return 0;
}

/****************************************************************************
 A vfs set_filelen call.
 set the length of a file from a filedescriptor.
 Returns 0 on success, -1 on failure.
****************************************************************************/

int vfs_set_filelen(files_struct *fsp, SMB_OFF_T len)
{
        int ret;

        contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_SET_FILE_LEN);

        DEBUG(10,("vfs_set_filelen: ftruncate %s to len %.0f\n", fsp->fsp_name, (double)len));
        flush_write_cache(fsp, SIZECHANGE_FLUSH);
        if ((ret = SMB_VFS_FTRUNCATE(fsp, len)) != -1) {
                set_filelen_write_cache(fsp, len);
                notify_fname(fsp->conn, NOTIFY_ACTION_MODIFIED,
                             FILE_NOTIFY_CHANGE_SIZE
                             | FILE_NOTIFY_CHANGE_ATTRIBUTES,
                             fsp->fsp_name);
        }

        contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_SET_FILE_LEN);

        return ret;
}

/****************************************************************************
 A vfs fill sparse call.
 Writes zeros from the end of file to len, if len is greater than EOF.
 Used only by strict_sync.
 Returns 0 on success, -1 on failure.
****************************************************************************/

#define SPARSE_BUF_WRITE_SIZE (32*1024)

int vfs_fill_sparse(files_struct *fsp, SMB_OFF_T len)
{
        int ret;
        SMB_STRUCT_STAT st;
        SMB_OFF_T offset;
        size_t total;
        size_t num_to_write;
        ssize_t pwrite_ret;

        ret = SMB_VFS_FSTAT(fsp, &st);
        if (ret == -1) {
                return ret;
        }

        if (len <= st.st_ex_size) {
                return 0;
        }

        DEBUG(10,("vfs_fill_sparse: write zeros in file %s from len %.0f to len %.0f (%.0f bytes)\n",
                fsp->fsp_name, (double)st.st_ex_size, (double)len, (double)(len - st.st_ex_size)));

        contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_FILL_SPARSE);

        flush_write_cache(fsp, SIZECHANGE_FLUSH);

        if (!sparse_buf) {
                sparse_buf = SMB_CALLOC_ARRAY(char, SPARSE_BUF_WRITE_SIZE);
                if (!sparse_buf) {
                        errno = ENOMEM;
                        ret = -1;
                        goto out;
                }
        }

        offset = st.st_ex_size;
        num_to_write = len - st.st_ex_size;
        total = 0;

        while (total < num_to_write) {
                size_t curr_write_size = MIN(SPARSE_BUF_WRITE_SIZE, (num_to_write - total));

                pwrite_ret = SMB_VFS_PWRITE(fsp, sparse_buf, curr_write_size, offset + total);
                if (pwrite_ret == -1) {
                        DEBUG(10,("vfs_fill_sparse: SMB_VFS_PWRITE for file %s failed with error %s\n",
                                fsp->fsp_name, strerror(errno) ));
                        ret = -1;
                        goto out;
                }
                if (pwrite_ret == 0) {
                        ret = 0;
                        goto out;
                }

                total += pwrite_ret;
        }

        set_filelen_write_cache(fsp, len);

        ret = 0;
 out:
        contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_FILL_SPARSE);
        return ret;
}

/****************************************************************************
 Transfer some data (n bytes) between two file_struct's.
****************************************************************************/

static ssize_t vfs_read_fn(void *file, void *buf, size_t len)
{
        struct files_struct *fsp = (struct files_struct *)file;

        return SMB_VFS_READ(fsp, buf, len);
}

static ssize_t vfs_write_fn(void *file, const void *buf, size_t len)
{
        struct files_struct *fsp = (struct files_struct *)file;

        return SMB_VFS_WRITE(fsp, buf, len);
}

SMB_OFF_T vfs_transfer_file(files_struct *in, files_struct *out, SMB_OFF_T n)
{
        return transfer_file_internal((void *)in, (void *)out, n,
                                      vfs_read_fn, vfs_write_fn);
}

/*******************************************************************
 A vfs_readdir wrapper which just returns the file name.
********************************************************************/

char *vfs_readdirname(connection_struct *conn, void *p, SMB_STRUCT_STAT *sbuf)
{
        SMB_STRUCT_DIRENT *ptr= NULL;
        char *dname;

        if (!p)
                return(NULL);

        ptr = SMB_VFS_READDIR(conn, (DIR *)p, sbuf);
        if (!ptr)
                return(NULL);

        dname = ptr->d_name;

#ifdef NEXT2
        if (telldir(p) < 0)
                return(NULL);
#endif

#ifdef HAVE_BROKEN_READDIR_NAME
        /* using /usr/ucb/cc is BAD */
        dname = dname - 2;
#endif

        return(dname);
}

/*******************************************************************
 A wrapper for vfs_chdir().
********************************************************************/

int vfs_ChDir(connection_struct *conn, const char *path)
{
        int res;

        if (!LastDir) {
                LastDir = SMB_STRDUP("");
        }

        if (strcsequal(path,"."))
                return(0);

        if (*path == '/' && strcsequal(LastDir,path))
                return(0);

        DEBUG(4,("vfs_ChDir to %s\n",path));

        res = SMB_VFS_CHDIR(conn,path);
        if (!res) {
                SAFE_FREE(LastDir);
                LastDir = SMB_STRDUP(path);
        }
        return(res);
}

/*******************************************************************
 Return the absolute current directory path - given a UNIX pathname.
 Note that this path is returned in DOS format, not UNIX
 format. Note this can be called with conn == NULL.
********************************************************************/

char *vfs_GetWd(TALLOC_CTX *ctx, connection_struct *conn)
{
        char s[PATH_MAX+1];
        SMB_STRUCT_STAT st, st2;
        char *result;
        DATA_BLOB cache_value;
        struct file_id key;

        *s = 0;

        if (!lp_getwd_cache()) {
                goto nocache;
        }

        SET_STAT_INVALID(st);

        if (SMB_VFS_STAT(conn, ".",&st) == -1) {
                /*
                 * Known to fail for root: the directory may be NFS-mounted
                 * and exported with root_squash (so has no root access).
                 */
                DEBUG(1,("vfs_GetWd: couldn't stat \".\" error %s "
                         "(NFS problem ?)\n", strerror(errno) ));
                goto nocache;
        }

        key = vfs_file_id_from_sbuf(conn, &st);

        if (!memcache_lookup(smbd_memcache(), GETWD_CACHE,
                             data_blob_const(&key, sizeof(key)),
                             &cache_value)) {
                goto nocache;
        }

        SMB_ASSERT((cache_value.length > 0)
                   && (cache_value.data[cache_value.length-1] == '\0'));

        if ((SMB_VFS_STAT(conn, (char *)cache_value.data, &st2) == 0)
            && (st.st_ex_dev == st2.st_ex_dev) && (st.st_ex_ino == st2.st_ex_ino)
            && (S_ISDIR(st.st_ex_mode))) {
                /*
                 * Ok, we're done
                 */
                result = talloc_strdup(ctx, (char *)cache_value.data);
                if (result == NULL) {
                        errno = ENOMEM;
                }
                return result;
        }

 nocache:

        /*
         * We don't have the information to hand so rely on traditional
         * methods. The very slow getcwd, which spawns a process on some
         * systems, or the not quite so bad getwd.
         */

        if (!SMB_VFS_GETWD(conn,s)) {
                DEBUG(0, ("vfs_GetWd: SMB_VFS_GETWD call failed: %s\n",
                          strerror(errno)));
                return NULL;
        }

        if (lp_getwd_cache() && VALID_STAT(st)) {
                key = vfs_file_id_from_sbuf(conn, &st);

                memcache_add(smbd_memcache(), GETWD_CACHE,
                             data_blob_const(&key, sizeof(key)),
                             data_blob_const(s, strlen(s)+1));
        }

        result = talloc_strdup(ctx, s);
        if (result == NULL) {
                errno = ENOMEM;
        }
        return result;
}

/*******************************************************************
 Reduce a file name, removing .. elements and checking that
 it is below dir in the heirachy. This uses realpath.
********************************************************************/

NTSTATUS check_reduced_name(connection_struct *conn, const char *fname)
{
#ifdef REALPATH_TAKES_NULL
        bool free_resolved_name = True;
#else
        char resolved_name_buf[PATH_MAX+1];
        bool free_resolved_name = False;
#endif
        char *resolved_name = NULL;
        char *p = NULL;

        DEBUG(3,("reduce_name [%s] [%s]\n", fname, conn->connectpath));

#ifdef REALPATH_TAKES_NULL
        resolved_name = SMB_VFS_REALPATH(conn,fname,NULL);
#else
        resolved_name = SMB_VFS_REALPATH(conn,fname,resolved_name_buf);
#endif

        if (!resolved_name) {
                switch (errno) {
                        case ENOTDIR:
                                DEBUG(3,("reduce_name: Component not a directory in getting realpath for %s\n", fname));
                                return map_nt_error_from_unix(errno);
                        case ENOENT:
                        {
                                TALLOC_CTX *ctx = talloc_tos();
                                char *tmp_fname = NULL;
                                char *last_component = NULL;
                                /* Last component didn't exist. Remove it and try and canonicalise the directory. */

                                tmp_fname = talloc_strdup(ctx, fname);
                                if (!tmp_fname) {
                                        return NT_STATUS_NO_MEMORY;
                                }
                                p = strrchr_m(tmp_fname, '/');
                                if (p) {
                                        *p++ = '\0';
                                        last_component = p;
                                } else {
                                        last_component = tmp_fname;
                                        tmp_fname = talloc_strdup(ctx,
                                                        ".");
                                        if (!tmp_fname) {
                                                return NT_STATUS_NO_MEMORY;
                                        }
                                }

#ifdef REALPATH_TAKES_NULL
                                resolved_name = SMB_VFS_REALPATH(conn,tmp_fname,NULL);
#else
                                resolved_name = SMB_VFS_REALPATH(conn,tmp_fname,resolved_name_buf);
#endif
                                if (!resolved_name) {
                                        DEBUG(3,("reduce_name: couldn't get realpath for %s\n", fname));
                                        return map_nt_error_from_unix(errno);
                                }
                                tmp_fname = talloc_asprintf(ctx,
                                                "%s/%s",
                                                resolved_name,
                                                last_component);
                                if (!tmp_fname) {
                                        return NT_STATUS_NO_MEMORY;
                                }
#ifdef REALPATH_TAKES_NULL
                                SAFE_FREE(resolved_name);
                                resolved_name = SMB_STRDUP(tmp_fname);
                                if (!resolved_name) {
                                        DEBUG(0,("reduce_name: malloc fail for %s\n", tmp_fname));
                                        return NT_STATUS_NO_MEMORY;
                                }
#else
                                safe_strcpy(resolved_name_buf, tmp_fname, PATH_MAX);
                                resolved_name = resolved_name_buf;
#endif
                                break;
                        }
                        default:
                                DEBUG(1,("reduce_name: couldn't get realpath for %s\n", fname));
                                return map_nt_error_from_unix(errno);
                }
        }

        DEBUG(10,("reduce_name realpath [%s] -> [%s]\n", fname, resolved_name));

        if (*resolved_name != '/') {
                DEBUG(0,("reduce_name: realpath doesn't return absolute paths !\n"));
                if (free_resolved_name) {
                        SAFE_FREE(resolved_name);
                }
                return NT_STATUS_OBJECT_NAME_INVALID;
        }

        /* Check for widelinks allowed. */
        if (!lp_widelinks(SNUM(conn))) {
                    const char *conn_rootdir;

                    conn_rootdir = SMB_VFS_CONNECTPATH(conn, fname);
                    if (conn_rootdir == NULL) {
                            DEBUG(2, ("check_reduced_name: Could not get conn_rootdir\n"));
                            if (free_resolved_name) {
                                    SAFE_FREE(resolved_name);
                            }
                            return NT_STATUS_ACCESS_DENIED;
                    }

                    if (strncmp(conn_rootdir, resolved_name,
                                strlen(conn_rootdir)) != 0) {
                            DEBUG(2, ("reduce_name: Bad access attempt: %s is "
                                      "a symlink outside the share path",
                                      fname));
                            if (free_resolved_name) {
                                    SAFE_FREE(resolved_name);
                            }
                            return NT_STATUS_ACCESS_DENIED;
                    }
        }

        /* Check if we are allowing users to follow symlinks */
        /* Patch from David Clerc <David.Clerc@cui.unige.ch>
                University of Geneva */

#ifdef S_ISLNK
        if (!lp_symlinks(SNUM(conn))) {
                SMB_STRUCT_STAT statbuf;
                if ( (SMB_VFS_LSTAT(conn,fname,&statbuf) != -1) &&
                                (S_ISLNK(statbuf.st_ex_mode)) ) {
                        if (free_resolved_name) {
                                SAFE_FREE(resolved_name);
                        }
                        DEBUG(3,("reduce_name: denied: file path name %s is a symlink\n",resolved_name));
                        return NT_STATUS_ACCESS_DENIED;
                }
        }
#endif

        DEBUG(3,("reduce_name: %s reduced to %s\n", fname, resolved_name));
        if (free_resolved_name) {
                SAFE_FREE(resolved_name);
        }
        return NT_STATUS_OK;
}