root/src/vfs/sftpfs/file.c

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DEFINITIONS

This source file includes following definitions.
  1. sftpfs_reopen
  2. sftpfs_file__handle_error
  3. sftpfs_fh_new
  4. sftpfs_open_file
  5. sftpfs_fstat
  6. sftpfs_read_file
  7. sftpfs_write_file
  8. sftpfs_close_file
  9. sftpfs_lseek

   1 /* Virtual File System: SFTP file system.
   2    The internal functions: files
   3 
   4    Copyright (C) 2011-2021
   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>
  30 #include <libssh2.h>
  31 #include <libssh2_sftp.h>
  32 
  33 #include "lib/global.h"
  34 #include "lib/util.h"
  35 
  36 #include "internal.h"
  37 
  38 /*** global variables ****************************************************************************/
  39 
  40 /*** file scope macro definitions ****************************************************************/
  41 
  42 #define SFTP_FILE_HANDLER(a) ((sftpfs_file_handler_t *) a)
  43 
  44 /*** file scope type declarations ****************************************************************/
  45 
  46 typedef struct
  47 {
  48     vfs_file_handler_t base;    /* base class */
  49 
  50     LIBSSH2_SFTP_HANDLE *handle;
  51     int flags;
  52     mode_t mode;
  53 } sftpfs_file_handler_t;
  54 
  55 /*** file scope variables ************************************************************************/
  56 
  57 /* --------------------------------------------------------------------------------------------- */
  58 /*** file scope functions ************************************************************************/
  59 /* --------------------------------------------------------------------------------------------- */
  60 /**
  61  * Reopen file by file handle.
  62  *
  63  * @param fh      the file handler
  64  * @param mcerror pointer to the error handler
  65  */
  66 static void
  67 sftpfs_reopen (vfs_file_handler_t * fh, GError ** mcerror)
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  68 {
  69     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
  70     int flags;
  71     mode_t mode;
  72 
  73     g_return_if_fail (mcerror == NULL || *mcerror == NULL);
  74 
  75     flags = file->flags;
  76     mode = file->mode;
  77 
  78     sftpfs_close_file (fh, mcerror);
  79     sftpfs_open_file (fh, flags, mode, mcerror);
  80 }
  81 
  82 /* --------------------------------------------------------------------------------------------- */
  83 
  84 static int
  85 sftpfs_file__handle_error (sftpfs_super_t * super, int sftp_res, GError ** mcerror)
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  86 {
  87     if (sftpfs_is_sftp_error (super->sftp_session, sftp_res, LIBSSH2_FX_PERMISSION_DENIED))
  88         return -EACCES;
  89 
  90     if (sftpfs_is_sftp_error (super->sftp_session, sftp_res, LIBSSH2_FX_NO_SUCH_FILE))
  91         return -ENOENT;
  92 
  93     if (!sftpfs_waitsocket (super, sftp_res, mcerror))
  94         return -1;
  95 
  96     return 0;
  97 }
  98 
  99 /* --------------------------------------------------------------------------------------------- */
 100 /*** public functions ****************************************************************************/
 101 /* --------------------------------------------------------------------------------------------- */
 102 
 103 vfs_file_handler_t *
 104 sftpfs_fh_new (struct vfs_s_inode * ino, gboolean changed)
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 105 {
 106     sftpfs_file_handler_t *fh;
 107 
 108     fh = g_new0 (sftpfs_file_handler_t, 1);
 109     vfs_s_init_fh (VFS_FILE_HANDLER (fh), ino, changed);
 110 
 111     return VFS_FILE_HANDLER (fh);
 112 }
 113 
 114 /* --------------------------------------------------------------------------------------------- */
 115 /**
 116  * Open new SFTP file.
 117  *
 118  * @param fh      the file handler
 119  * @param flags   flags (see man 2 open)
 120  * @param mode    mode (see man 2 open)
 121  * @param mcerror pointer to the error handler
 122  * @return TRUE if connection was created successfully, FALSE otherwise
 123  */
 124 
 125 gboolean
 126 sftpfs_open_file (vfs_file_handler_t * fh, int flags, mode_t mode, GError ** mcerror)
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 127 {
 128     unsigned long sftp_open_flags = 0;
 129     int sftp_open_mode = 0;
 130     gboolean do_append = FALSE;
 131     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 132     sftpfs_super_t *super = SFTP_SUPER (fh->ino->super);
 133     char *name;
 134 
 135     (void) mode;
 136     mc_return_val_if_error (mcerror, FALSE);
 137 
 138     name = vfs_s_fullpath (sftpfs_class, fh->ino);
 139     if (name == NULL)
 140         return FALSE;
 141 
 142     if ((flags & O_CREAT) != 0 || (flags & O_WRONLY) != 0)
 143     {
 144         sftp_open_flags = (flags & O_WRONLY) != 0 ? LIBSSH2_FXF_WRITE : 0;
 145         sftp_open_flags |= (flags & O_CREAT) != 0 ? LIBSSH2_FXF_CREAT : 0;
 146         if ((flags & O_APPEND) != 0)
 147         {
 148             sftp_open_flags |= LIBSSH2_FXF_APPEND;
 149             do_append = TRUE;
 150         }
 151         sftp_open_flags |= (flags & O_TRUNC) != 0 ? LIBSSH2_FXF_TRUNC : 0;
 152 
 153         sftp_open_mode = LIBSSH2_SFTP_S_IRUSR |
 154             LIBSSH2_SFTP_S_IWUSR | LIBSSH2_SFTP_S_IRGRP | LIBSSH2_SFTP_S_IROTH;
 155     }
 156     else
 157         sftp_open_flags = LIBSSH2_FXF_READ;
 158 
 159     while (TRUE)
 160     {
 161         const GString *fixfname;
 162         int libssh_errno;
 163 
 164         fixfname = sftpfs_fix_filename (name);
 165 
 166         file->handle =
 167             libssh2_sftp_open_ex (super->sftp_session, fixfname->str, fixfname->len,
 168                                   sftp_open_flags, sftp_open_mode, LIBSSH2_SFTP_OPENFILE);
 169         if (file->handle != NULL)
 170             break;
 171 
 172         libssh_errno = libssh2_session_last_errno (super->session);
 173         if (libssh_errno != LIBSSH2_ERROR_EAGAIN)
 174         {
 175             sftpfs_ssherror_to_gliberror (super, libssh_errno, mcerror);
 176             g_free (name);
 177             return FALSE;
 178         }
 179     }
 180 
 181     g_free (name);
 182 
 183     file->flags = flags;
 184     file->mode = mode;
 185 
 186     if (do_append)
 187     {
 188         struct stat file_info = {
 189             .st_dev = 0
 190         };
 191         /* In case of
 192 
 193            struct stat file_info = { 0 };
 194 
 195            gcc < 4.7 [1] generates the following:
 196 
 197            error: missing initializer [-Werror=missing-field-initializers]
 198            error: (near initialization for 'file_info.st_dev') [-Werror=missing-field-initializers]
 199 
 200            [1] http://stackoverflow.com/questions/13373695/how-to-remove-the-warning-in-gcc-4-6-missing-initializer-wmissing-field-initi/27461062#27461062
 201          */
 202 
 203         if (sftpfs_fstat (fh, &file_info, mcerror) == 0)
 204             libssh2_sftp_seek64 (file->handle, file_info.st_size);
 205     }
 206     return TRUE;
 207 }
 208 
 209 /* --------------------------------------------------------------------------------------------- */
 210 /**
 211  * Stats the file specified by the file descriptor.
 212  *
 213  * @param data    file handler
 214  * @param buf     buffer for store stat-info
 215  * @param mcerror pointer to the error handler
 216  * @return 0 if success, negative value otherwise
 217  */
 218 
 219 int
 220 sftpfs_fstat (void *data, struct stat *buf, GError ** mcerror)
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 221 {
 222     int res;
 223     LIBSSH2_SFTP_ATTRIBUTES attrs;
 224     vfs_file_handler_t *fh = VFS_FILE_HANDLER (data);
 225     sftpfs_file_handler_t *sftpfs_fh = (sftpfs_file_handler_t *) data;
 226     struct vfs_s_super *super = VFS_FILE_HANDLER_SUPER (fh);
 227     sftpfs_super_t *sftpfs_super = SFTP_SUPER (super);
 228 
 229     mc_return_val_if_error (mcerror, -1);
 230 
 231     if (sftpfs_fh->handle == NULL)
 232         return -1;
 233 
 234     do
 235     {
 236         int err;
 237 
 238         res = libssh2_sftp_fstat_ex (sftpfs_fh->handle, &attrs, 0);
 239         if (res >= 0)
 240             break;
 241 
 242         err = sftpfs_file__handle_error (sftpfs_super, res, mcerror);
 243         if (err < 0)
 244             return err;
 245     }
 246     while (res == LIBSSH2_ERROR_EAGAIN);
 247 
 248     sftpfs_attr_to_stat (&attrs, buf);
 249 
 250     return 0;
 251 }
 252 
 253 /* --------------------------------------------------------------------------------------------- */
 254 /**
 255  * Read up to 'count' bytes from the file descriptor 'fh' to the buffer starting at 'buffer'.
 256  *
 257  * @param fh      file handler
 258  * @param buffer  buffer for data
 259  * @param count   data size
 260  * @param mcerror pointer to the error handler
 261  *
 262  * @return 0 on success, negative value otherwise
 263  */
 264 
 265 ssize_t
 266 sftpfs_read_file (vfs_file_handler_t * fh, char *buffer, size_t count, GError ** mcerror)
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 267 {
 268     ssize_t rc;
 269     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 270     sftpfs_super_t *super;
 271 
 272     mc_return_val_if_error (mcerror, -1);
 273 
 274     if (fh == NULL)
 275     {
 276         mc_propagate_error (mcerror, 0, "%s",
 277                             _("sftp: No file handler data present for reading file"));
 278         return -1;
 279     }
 280 
 281     super = SFTP_SUPER (VFS_FILE_HANDLER_SUPER (fh));
 282 
 283     do
 284     {
 285         int err;
 286 
 287         rc = libssh2_sftp_read (file->handle, buffer, count);
 288         if (rc >= 0)
 289             break;
 290 
 291         err = sftpfs_file__handle_error (super, (int) rc, mcerror);
 292         if (err < 0)
 293             return err;
 294     }
 295     while (rc == LIBSSH2_ERROR_EAGAIN);
 296 
 297     fh->pos = (off_t) libssh2_sftp_tell64 (file->handle);
 298 
 299     return rc;
 300 }
 301 
 302 /* --------------------------------------------------------------------------------------------- */
 303 
 304 /**
 305  * Write up to 'count' bytes from  the buffer starting at 'buffer' to the descriptor 'fh'.
 306  *
 307  * @param fh      file handler
 308  * @param buffer  buffer for data
 309  * @param count   data size
 310  * @param mcerror pointer to the error handler
 311  *
 312  * @return 0 on success, negative value otherwise
 313  */
 314 
 315 ssize_t
 316 sftpfs_write_file (vfs_file_handler_t * fh, const char *buffer, size_t count, GError ** mcerror)
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 317 {
 318     ssize_t rc;
 319     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 320     sftpfs_super_t *super = SFTP_SUPER (VFS_FILE_HANDLER_SUPER (fh));
 321 
 322     mc_return_val_if_error (mcerror, -1);
 323 
 324     fh->pos = (off_t) libssh2_sftp_tell64 (file->handle);
 325 
 326     do
 327     {
 328         int err;
 329 
 330         rc = libssh2_sftp_write (file->handle, buffer, count);
 331         if (rc >= 0)
 332             break;
 333 
 334         err = sftpfs_file__handle_error (super, (int) rc, mcerror);
 335         if (err < 0)
 336             return err;
 337     }
 338     while (rc == LIBSSH2_ERROR_EAGAIN);
 339 
 340     return rc;
 341 }
 342 
 343 /* --------------------------------------------------------------------------------------------- */
 344 
 345 /**
 346  * Close a file descriptor.
 347  *
 348  * @param fh      file handler
 349  * @param mcerror pointer to the error handler
 350  *
 351  * @return 0 on success, negative value otherwise
 352  */
 353 
 354 int
 355 sftpfs_close_file (vfs_file_handler_t * fh, GError ** mcerror)
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 356 {
 357     int ret;
 358 
 359     mc_return_val_if_error (mcerror, -1);
 360 
 361     ret = libssh2_sftp_close (SFTP_FILE_HANDLER (fh)->handle);
 362 
 363     return ret == 0 ? 0 : -1;
 364 }
 365 
 366 /* --------------------------------------------------------------------------------------------- */
 367 
 368 /**
 369  * Reposition the offset of the open file associated with the file descriptor.
 370  *
 371  * @param fh      file handler
 372  * @param offset  file offset
 373  * @param whence  method of seek (at begin, at current, at end)
 374  * @param mcerror pointer to the error handler
 375  *
 376  * @return 0 on success, negative value otherwise
 377  */
 378 
 379 off_t
 380 sftpfs_lseek (vfs_file_handler_t * fh, off_t offset, int whence, GError ** mcerror)
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 381 {
 382     sftpfs_file_handler_t *file = SFTP_FILE_HANDLER (fh);
 383 
 384     mc_return_val_if_error (mcerror, 0);
 385 
 386     switch (whence)
 387     {
 388     case SEEK_SET:
 389         /* Need reopen file because:
 390            "You MUST NOT seek during writing or reading a file with SFTP, as the internals use
 391            outstanding packets and changing the "file position" during transit will results in
 392            badness." */
 393         if (fh->pos > offset || offset == 0)
 394         {
 395             sftpfs_reopen (fh, mcerror);
 396             mc_return_val_if_error (mcerror, 0);
 397         }
 398         fh->pos = offset;
 399         break;
 400     case SEEK_CUR:
 401         fh->pos += offset;
 402         break;
 403     case SEEK_END:
 404         if (fh->pos > fh->ino->st.st_size - offset)
 405         {
 406             sftpfs_reopen (fh, mcerror);
 407             mc_return_val_if_error (mcerror, 0);
 408         }
 409         fh->pos = fh->ino->st.st_size - offset;
 410         break;
 411     default:
 412         break;
 413     }
 414 
 415     libssh2_sftp_seek64 (file->handle, fh->pos);
 416     fh->pos = (off_t) libssh2_sftp_tell64 (file->handle);
 417 
 418     return fh->pos;
 419 }
 420 
 421 /* --------------------------------------------------------------------------------------------- */

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