src/vfs/sftpfs/file.c

   1 /* Virtual File System: SFTP file system.
   2    The internal functions: files
   3
   4    Copyright (C) 2011-2024
   5    Free Software Foundation, Inc.
   6
   7    Written by:
   8    Ilia Maslakov <il.smind@gmail.com>, 2011
   9    Slava Zanko <slavazanko@gmail.com>, 2011, 2012
  10
  11    This file is part of the Midnight Commander.
  12
  13    The Midnight Commander is free software: you can redistribute it
  14    and/or modify it under the terms of the GNU General Public License as
  15    published by the Free Software Foundation, either version 3 of the License,
  16    or (at your option) any later version.
  17
  18    The Midnight Commander is distributed in the hope that it will be useful,
  19    but WITHOUT ANY WARRANTY; without even the implied warranty of
  20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21    GNU General Public License for more details.
  22
  23    You should have received a copy of the GNU General Public License
  24    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  25  */
  26
  27 #include <config.h>
  28
  29 #include <errno.h>              /* ENOENT, EACCES */
  30
  31 #include <libssh2.h>
  32 #include <libssh2_sftp.h>
  33
  34 #include "lib/global.h"
  35 #include "lib/util.h"
  36
  37 #include "internal.h"
  38
  39 /*** global variables ****************************************************************************/
  40
  41 /*** file scope macro definitions ****************************************************************/
  42
  43 #define SFTP_FILE_HANDLER(a) ((sftpfs_file_handler_t *) a)
  44
  45 /*** file scope type declarations ****************************************************************/
  46
  47 typedef struct
  48 {
  49     vfs_file_handler_t base;    /* base class */
  50
  51     LIBSSH2_SFTP_HANDLE *handle;
  52     int flags;
  53     mode_t mode;
  54 } sftpfs_file_handler_t;
  55
  56 /*** forward declarations (file scope functions) *************************************************/
  57
  58 /*** file scope variables ************************************************************************/
  59
  60 /* --------------------------------------------------------------------------------------------- */
  61 /*** file scope functions ************************************************************************/
  62 /* --------------------------------------------------------------------------------------------- */
  63 /**
  64  * Reopen file by file handle.
  65  *
  66  * @param fh      the file handler
  67  * @param mcerror pointer to the error handler
  68  */
  69 static void
  70 sftpfs_reopen (vfs_file_handler_t *fh, GError **mcerror)
  71 {
  72     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
  73     int flags;
  74     mode_t mode;
  75
  76     g_return_if_fail (mcerror == NULL || *mcerror == NULL);
  77
  78     flags = file->flags;
  79     mode = file->mode;
  80
  81     sftpfs_close_file (fh, mcerror);
  82     sftpfs_open_file (fh, flags, mode, mcerror);
  83 }
  84
  85 /* --------------------------------------------------------------------------------------------- */
  86
  87 static int
  88 sftpfs_file__handle_error (sftpfs_super_t *super, int sftp_res, GError **mcerror)
  89 {
  90     if (sftpfs_is_sftp_error (super->sftp_session, sftp_res, LIBSSH2_FX_PERMISSION_DENIED))
  91         return -EACCES;
  92
  93     if (sftpfs_is_sftp_error (super->sftp_session, sftp_res, LIBSSH2_FX_NO_SUCH_FILE))
  94         return -ENOENT;
  95
  96     if (!sftpfs_waitsocket (super, sftp_res, mcerror))
  97         return -1;
  98
  99     return 0;
 100 }
 101
 102 /* --------------------------------------------------------------------------------------------- */
 103 /*** public functions ****************************************************************************/
 104 /* --------------------------------------------------------------------------------------------- */
 105
 106 vfs_file_handler_t *
 107 sftpfs_fh_new (struct vfs_s_inode *ino, gboolean changed)
 108 {
 109     sftpfs_file_handler_t *fh;
 110
 111     fh = g_new0 (sftpfs_file_handler_t, 1);
 112     vfs_s_init_fh (VFS_FILE_HANDLER (fh), ino, changed);
 113
 114     return VFS_FILE_HANDLER (fh);
 115 }
 116
 117 /* --------------------------------------------------------------------------------------------- */
 118 /**
 119  * Open new SFTP file.
 120  *
 121  * @param fh      the file handler
 122  * @param flags   flags (see man 2 open)
 123  * @param mode    mode (see man 2 open)
 124  * @param mcerror pointer to the error handler
 125  * @return TRUE if connection was created successfully, FALSE otherwise
 126  */
 127
 128 gboolean
 129 sftpfs_open_file (vfs_file_handler_t *fh, int flags, mode_t mode, GError **mcerror)
 130 {
 131     unsigned long sftp_open_flags = 0;
 132     int sftp_open_mode = 0;
 133     gboolean do_append = FALSE;
 134     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 135     sftpfs_super_t *super = SFTP_SUPER (fh->ino->super);
 136     char *name;
 137     const GString *fixfname;
 138
 139     (void) mode;
 140     mc_return_val_if_error (mcerror, FALSE);
 141
 142     name = vfs_s_fullpath (vfs_sftpfs_ops, fh->ino);
 143     if (name == NULL)
 144         return FALSE;
 145
 146     if ((flags & O_CREAT) != 0 || (flags & O_WRONLY) != 0)
 147     {
 148         sftp_open_flags = (flags & O_WRONLY) != 0 ? LIBSSH2_FXF_WRITE : 0;
 149         sftp_open_flags |= (flags & O_CREAT) != 0 ? LIBSSH2_FXF_CREAT : 0;
 150         if ((flags & O_APPEND) != 0)
 151         {
 152             sftp_open_flags |= LIBSSH2_FXF_APPEND;
 153             do_append = TRUE;
 154         }
 155         sftp_open_flags |= (flags & O_TRUNC) != 0 ? LIBSSH2_FXF_TRUNC : 0;
 156
 157         sftp_open_mode = LIBSSH2_SFTP_S_IRUSR |
 158             LIBSSH2_SFTP_S_IWUSR | LIBSSH2_SFTP_S_IRGRP | LIBSSH2_SFTP_S_IROTH;
 159     }
 160     else
 161         sftp_open_flags = LIBSSH2_FXF_READ;
 162
 163     fixfname = sftpfs_fix_filename (name);
 164
 165     while (TRUE)
 166     {
 167         int libssh_errno;
 168
 169         file->handle =
 170             libssh2_sftp_open_ex (super->sftp_session, fixfname->str, fixfname->len,
 171                                   sftp_open_flags, sftp_open_mode, LIBSSH2_SFTP_OPENFILE);
 172         if (file->handle != NULL)
 173             break;
 174
 175         libssh_errno = libssh2_session_last_errno (super->session);
 176         if (libssh_errno != LIBSSH2_ERROR_EAGAIN)
 177         {
 178             sftpfs_ssherror_to_gliberror (super, libssh_errno, mcerror);
 179             g_free (name);
 180             return FALSE;
 181         }
 182     }
 183
 184     g_free (name);
 185
 186     file->flags = flags;
 187     file->mode = mode;
 188
 189     if (do_append)
 190     {
 191         struct stat file_info = {
 192             .st_dev = 0
 193         };
 194         /* In case of
 195
 196            struct stat file_info = { 0 };
 197
 198            gcc < 4.7 [1] generates the following:
 199
 200            error: missing initializer [-Werror=missing-field-initializers]
 201            error: (near initialization for 'file_info.st_dev') [-Werror=missing-field-initializers]
 202
 203            [1] http://stackoverflow.com/questions/13373695/how-to-remove-the-warning-in-gcc-4-6-missing-initializer-wmissing-field-initi/27461062#27461062
 204          */
 205
 206         if (sftpfs_fstat (fh, &file_info, mcerror) == 0)
 207             libssh2_sftp_seek64 (file->handle, file_info.st_size);
 208     }
 209     return TRUE;
 210 }
 211
 212 /* --------------------------------------------------------------------------------------------- */
 213 /**
 214  * Stats the file specified by the file descriptor.
 215  *
 216  * @param data    file handler
 217  * @param buf     buffer for store stat-info
 218  * @param mcerror pointer to the error handler
 219  * @return 0 if success, negative value otherwise
 220  */
 221
 222 int
 223 sftpfs_fstat (void *data, struct stat *buf, GError **mcerror)
 224 {
 225     int res;
 226     LIBSSH2_SFTP_ATTRIBUTES attrs;
 227     vfs_file_handler_t *fh = VFS_FILE_HANDLER (data);
 228     sftpfs_file_handler_t *sftpfs_fh = (sftpfs_file_handler_t *) data;
 229     struct vfs_s_super *super = VFS_FILE_HANDLER_SUPER (fh);
 230     sftpfs_super_t *sftpfs_super = SFTP_SUPER (super);
 231
 232     mc_return_val_if_error (mcerror, -1);
 233
 234     if (sftpfs_fh->handle == NULL)
 235         return -1;
 236
 237     do
 238     {
 239         int err;
 240
 241         res = libssh2_sftp_fstat_ex (sftpfs_fh->handle, &attrs, 0);
 242         if (res >= 0)
 243             break;
 244
 245         err = sftpfs_file__handle_error (sftpfs_super, res, mcerror);
 246         if (err < 0)
 247             return err;
 248     }
 249     while (res == LIBSSH2_ERROR_EAGAIN);
 250
 251     sftpfs_attr_to_stat (&attrs, buf);
 252
 253     return 0;
 254 }
 255
 256 /* --------------------------------------------------------------------------------------------- */
 257 /**
 258  * Read up to 'count' bytes from the file descriptor 'fh' to the buffer starting at 'buffer'.
 259  *
 260  * @param fh      file handler
 261  * @param buffer  buffer for data
 262  * @param count   data size
 263  * @param mcerror pointer to the error handler
 264  *
 265  * @return 0 on success, negative value otherwise
 266  */
 267
 268 ssize_t
 269 sftpfs_read_file (vfs_file_handler_t *fh, char *buffer, size_t count, GError **mcerror)
 270 {
 271     ssize_t rc;
 272     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 273     sftpfs_super_t *super;
 274
 275     mc_return_val_if_error (mcerror, -1);
 276
 277     if (fh == NULL)
 278     {
 279         mc_propagate_error (mcerror, 0, "%s",
 280                             _("sftp: No file handler data present for reading file"));
 281         return -1;
 282     }
 283
 284     super = SFTP_SUPER (VFS_FILE_HANDLER_SUPER (fh));
 285
 286     do
 287     {
 288         int err;
 289
 290         rc = libssh2_sftp_read (file->handle, buffer, count);
 291         if (rc >= 0)
 292             break;
 293
 294         err = sftpfs_file__handle_error (super, (int) rc, mcerror);
 295         if (err < 0)
 296             return err;
 297     }
 298     while (rc == LIBSSH2_ERROR_EAGAIN);
 299
 300     fh->pos = (off_t) libssh2_sftp_tell64 (file->handle);
 301
 302     return rc;
 303 }
 304
 305 /* --------------------------------------------------------------------------------------------- */
 306
 307 /**
 308  * Write up to 'count' bytes from  the buffer starting at 'buffer' to the descriptor 'fh'.
 309  *
 310  * @param fh      file handler
 311  * @param buffer  buffer for data
 312  * @param count   data size
 313  * @param mcerror pointer to the error handler
 314  *
 315  * @return 0 on success, negative value otherwise
 316  */
 317
 318 ssize_t
 319 sftpfs_write_file (vfs_file_handler_t *fh, const char *buffer, size_t count, GError **mcerror)
 320 {
 321     ssize_t rc;
 322     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 323     sftpfs_super_t *super = SFTP_SUPER (VFS_FILE_HANDLER_SUPER (fh));
 324
 325     mc_return_val_if_error (mcerror, -1);
 326
 327     fh->pos = (off_t) libssh2_sftp_tell64 (file->handle);
 328
 329     do
 330     {
 331         int err;
 332
 333         rc = libssh2_sftp_write (file->handle, buffer, count);
 334         if (rc >= 0)
 335             break;
 336
 337         err = sftpfs_file__handle_error (super, (int) rc, mcerror);
 338         if (err < 0)
 339             return err;
 340     }
 341     while (rc == LIBSSH2_ERROR_EAGAIN);
 342
 343     return rc;
 344 }
 345
 346 /* --------------------------------------------------------------------------------------------- */
 347
 348 /**
 349  * Close a file descriptor.
 350  *
 351  * @param fh      file handler
 352  * @param mcerror pointer to the error handler
 353  *
 354  * @return 0 on success, negative value otherwise
 355  */
 356
 357 int
 358 sftpfs_close_file (vfs_file_handler_t *fh, GError **mcerror)
 359 {
 360     int ret;
 361
 362     mc_return_val_if_error (mcerror, -1);
 363
 364     ret = libssh2_sftp_close (SFTP_FILE_HANDLER (fh)->handle);
 365
 366     return ret == 0 ? 0 : -1;
 367 }
 368
 369 /* --------------------------------------------------------------------------------------------- */
 370
 371 /**
 372  * Reposition the offset of the open file associated with the file descriptor.
 373  *
 374  * @param fh      file handler
 375  * @param offset  file offset
 376  * @param whence  method of seek (at begin, at current, at end)
 377  * @param mcerror pointer to the error handler
 378  *
 379  * @return 0 on success, negative value otherwise
 380  */
 381
 382 off_t
 383 sftpfs_lseek (vfs_file_handler_t *fh, off_t offset, int whence, GError **mcerror)
 384 {
 385     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 386
 387     mc_return_val_if_error (mcerror, 0);
 388
 389     switch (whence)
 390     {
 391     case SEEK_SET:
 392         /* Need reopen file because:
 393            "You MUST NOT seek during writing or reading a file with SFTP, as the internals use
 394            outstanding packets and changing the "file position" during transit will results in
 395            badness." */
 396         if (fh->pos > offset || offset == 0)
 397         {
 398             sftpfs_reopen (fh, mcerror);
 399             mc_return_val_if_error (mcerror, 0);
 400         }
 401         fh->pos = offset;
 402         break;
 403     case SEEK_CUR:
 404         fh->pos += offset;
 405         break;
 406     case SEEK_END:
 407         if (fh->pos > fh->ino->st.st_size - offset)
 408         {
 409             sftpfs_reopen (fh, mcerror);
 410             mc_return_val_if_error (mcerror, 0);
 411         }
 412         fh->pos = fh->ino->st.st_size - offset;
 413         break;
 414     default:
 415         break;
 416     }
 417
 418     libssh2_sftp_seek64 (file->handle, fh->pos);
 419     fh->pos = (off_t) libssh2_sftp_tell64 (file->handle);
 420
 421     return fh->pos;
 422 }
 423
 424 /* --------------------------------------------------------------------------------------------- */