gnunet-android

gnunet_disk_lib.h (20995B)

---

 /*
      This file is part of GNUnet.
      Copyright (C) 2001-2012 GNUnet e.V.
 
      GNUnet is free software: you can redistribute it and/or modify it
      under the terms of the GNU Affero General Public License as published
      by the Free Software Foundation, either version 3 of the License,
      or (at your option) any later version.
 
      GNUnet 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
      Affero General Public License for more details.
 
      You should have received a copy of the GNU Affero General Public License
      along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
      SPDX-License-Identifier: AGPL3.0-or-later
  */
 /**
  * @addtogroup libgnunetutil
  * Multi-function utilities library for GNUnet programs
  * @{
  *
  * @author Christian Grothoff
  *
  * @file
  * Disk IO APIs
  *
  * @defgroup disk  Disk library
  * Disk IO APIs
  * @{
  */
 
 #if ! defined (__GNUNET_UTIL_LIB_H_INSIDE__)
 #error "Only <gnunet_util_lib.h> can be included directly."
 #endif
 
 #ifndef GNUNET_DISK_LIB_H
 #define GNUNET_DISK_LIB_H
 
 /**
  * Handle used to manage a pipe.
  */
 struct GNUNET_DISK_PipeHandle;
 
 /**
  * Type of a handle.
  */
 enum GNUNET_FILE_Type
 {
   /**
    * Handle represents an event.
    */
   GNUNET_DISK_HANLDE_TYPE_EVENT,
 
   /**
    * Handle represents a file.
    */
   GNUNET_DISK_HANLDE_TYPE_FILE,
 
   /**
    * Handle represents a pipe.
    */
   GNUNET_DISK_HANLDE_TYPE_PIPE
 };
 
 /**
  * Handle used to access files (and pipes).
  */
 struct GNUNET_DISK_FileHandle
 {
   /**
    * File handle on Unix-like systems.
    */
   int fd;
 };
 
 
 /* we need size_t, and since it can be both unsigned int
    or unsigned long long, this IS platform dependent;
    but "stdlib.h" should be portable 'enough' to be
    unconditionally available... */
 
 #include <stdlib.h>
 #include "gnunet_configuration_lib.h"
 #include "gnunet_scheduler_lib.h"
 
 #ifdef __cplusplus
 extern "C"
 {
 #if 0                           /* keep Emacsens' auto-indent happy */
 }
 #endif
 #endif
 
 
 /**
  * Specifies how a file should be opened.
  */
 enum GNUNET_DISK_OpenFlags
 {
   /**
    * Open the file for reading
    */
   GNUNET_DISK_OPEN_READ = 1,
 
   /**
    * Open the file for writing
    */
   GNUNET_DISK_OPEN_WRITE = 2,
 
   /**
    * Open the file for both reading and writing
    */
   GNUNET_DISK_OPEN_READWRITE = 3,
 
   /**
    * Fail if file already exists
    */
   GNUNET_DISK_OPEN_FAILIFEXISTS = 4,
 
   /**
    * Truncate file if it exists
    */
   GNUNET_DISK_OPEN_TRUNCATE = 8,
 
   /**
    * Create file if it doesn't exist
    */
   GNUNET_DISK_OPEN_CREATE = 16,
 
   /**
    * Append to the file
    */
   GNUNET_DISK_OPEN_APPEND = 32
 };
 
 /**
  * Specifies what type of memory map is desired.
  */
 enum GNUNET_DISK_MapType
 {
   /**
    * Read-only memory map.
    */
   GNUNET_DISK_MAP_TYPE_READ = 1,
 
   /**
    * Write-able memory map.
    */
   GNUNET_DISK_MAP_TYPE_WRITE = 2,
 
   /**
    * Read-write memory map.
    */
   GNUNET_DISK_MAP_TYPE_READWRITE = 3
 };
 
 
 /**
  * File access permissions, UNIX-style.
  */
 enum GNUNET_DISK_AccessPermissions
 {
   /**
    * Nobody is allowed to do anything to the file.
    */
   GNUNET_DISK_PERM_NONE = 0,
 
   /**
    * Owner can read.
    */
   GNUNET_DISK_PERM_USER_READ = 1,
 
   /**
    * Owner can write.
    */
   GNUNET_DISK_PERM_USER_WRITE = 2,
 
   /**
    * Owner can execute.
    */
   GNUNET_DISK_PERM_USER_EXEC = 4,
 
   /**
    * Group can read.
    */
   GNUNET_DISK_PERM_GROUP_READ = 8,
 
   /**
    * Group can write.
    */
   GNUNET_DISK_PERM_GROUP_WRITE = 16,
 
   /**
    * Group can execute.
    */
   GNUNET_DISK_PERM_GROUP_EXEC = 32,
 
   /**
    * Everybody can read.
    */
   GNUNET_DISK_PERM_OTHER_READ = 64,
 
   /**
    * Everybody can write.
    */
   GNUNET_DISK_PERM_OTHER_WRITE = 128,
 
   /**
    * Everybody can execute.
    */
   GNUNET_DISK_PERM_OTHER_EXEC = 256
 };
 
 
 /**
  * Constants for specifying how to seek.  Do not change values or order,
  * some of the code depends on the specific numeric values!
  */
 enum GNUNET_DISK_Seek
 {
   /**
    * Seek an absolute position (from the start of the file).
    */
   GNUNET_DISK_SEEK_SET = 0,
 
   /**
    * Seek a relative position (from the current offset).
    */
   GNUNET_DISK_SEEK_CUR = 1,
 
   /**
    * Seek an absolute position from the end of the file.
    */
   GNUNET_DISK_SEEK_END = 2
 };
 
 
 /**
  * Enumeration identifying the two ends of a pipe.
  */
 enum GNUNET_DISK_PipeEnd
 {
   /**
    * The reading-end of a pipe.
    */
   GNUNET_DISK_PIPE_END_READ = 0,
 
   /**
    * The writing-end of a pipe.
    */
   GNUNET_DISK_PIPE_END_WRITE = 1
 };
 
 
 /**
  * Checks whether a handle is invalid
  *
  * @param h handle to check
  * @return #GNUNET_YES if invalid, #GNUNET_NO if valid
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_handle_invalid (const struct GNUNET_DISK_FileHandle *h);
 
 
 /**
  * Check that fil corresponds to a filename
  * (of a file that exists and that is not a directory).
  *
  * @param fil filename to check
  * @return #GNUNET_YES if yes, #GNUNET_NO if not a file, #GNUNET_SYSERR if something
  * else (will print an error message in that case, too).
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_test (const char *fil);
 
 
 /**
  * Check that fil corresponds to a filename and the file has read permissions.
  *
  * @param fil filename to check
  * @return #GNUNET_YES if yes, #GNUNET_NO if file doesn't exist or
  *         has no read permissions, #GNUNET_SYSERR if something else
  *         (will print an error message in that case, too).
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_test_read (const char *fil);
 
 
 /**
  * Move a file out of the way (create a backup) by renaming it to "orig.NUM~"
  * where NUM is the smallest number that is not used yet.
  *
  * @param fil name of the file to back up
  * @return the backup file name (must be freed by caller)
  */
 char*
 GNUNET_DISK_file_backup (const char *fil);
 
 
 /**
  * Move the read/write pointer in a file
  * @param h handle of an open file
  * @param offset position to move to
  * @param whence specification to which position the offset parameter relates to
  * @return the new position on success, #GNUNET_SYSERR otherwise
  */
 off_t
 GNUNET_DISK_file_seek (const struct GNUNET_DISK_FileHandle *h,
                        off_t offset,
                        enum GNUNET_DISK_Seek whence);
 
 
 /**
  * Get the size of the file (or directory) of the given file (in
  * bytes).
  *
  * @param filename name of the file or directory
  * @param size set to the size of the file (or,
  *             in the case of directories, the sum
  *             of all sizes of files in the directory)
  * @param include_symbolic_links should symbolic links be
  *        included?
  * @param single_file_mode #GNUNET_YES to only get size of one file
  *        and return #GNUNET_SYSERR for directories.
  * @return #GNUNET_SYSERR on error, #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_size (const char *filename,
                        uint64_t *size,
                        int include_symbolic_links,
                        int single_file_mode);
 
 
 /**
  * Obtain some unique identifiers for the given file
  * that can be used to identify it in the local system.
  * This function is used between GNUnet processes to
  * quickly check if two files with the same absolute path
  * are actually identical.  The two processes represent
  * the same peer but may communicate over the network
  * (and the file may be on an NFS volume).  This function
  * may not be supported on all operating systems.
  *
  * @param filename name of the file
  * @param dev set to the device ID
  * @param ino set to the inode ID
  * @return #GNUNET_OK on success
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_get_identifiers (const char *filename,
                                   uint64_t *dev,
                                   uint64_t *ino);
 
 
 /**
  * Create an (empty) temporary file on disk.  If the given name is not
  * an absolute path, the current 'TMPDIR' will be prepended.  In any case,
  * 6 random characters will be appended to the name to create a unique
  * filename.
  *
  * @param pd project data to use to determine paths
  * @param t component to use for the name;
  *        does NOT contain "XXXXXX" or "/tmp/".
  * @return NULL on error, otherwise name of fresh
  *         file on disk in directory for temporary files
  */
 char *
 GNUNET_DISK_mktemp (const struct GNUNET_OS_ProjectData *pd,
                     const char *t);
 
 
 /**
  * Create an (empty) temporary directory on disk.  If the given name is not an
  * absolute path, the current 'TMPDIR' will be prepended.  In any case, 6
  * random characters will be appended to the name to create a unique name.
  *
  * @param pd project data to use to determine paths
  * @param t component to use for the name;
  *        does NOT contain "XXXXXX" or "/tmp/".
  * @return NULL on error, otherwise name of freshly created directory
  */
 char *
 GNUNET_DISK_mkdtemp (const struct GNUNET_OS_ProjectData *pd,
                      const char *t);
 
 
 /**
  * Open a file.  Note that the access permissions will only be
  * used if a new file is created and if the underlying operating
  * system supports the given permissions.
  *
  * @param fn file name to be opened
  * @param flags opening flags, a combination of GNUNET_DISK_OPEN_xxx bit flags
  * @param perm permissions for the newly created file, use
  *             #GNUNET_DISK_PERM_NONE if a file could not be created by this
  *             call (because of flags)
  * @return IO handle on success, NULL on error
  */
 struct GNUNET_DISK_FileHandle *
 GNUNET_DISK_file_open (const char *fn,
                        enum GNUNET_DISK_OpenFlags flags,
                        enum GNUNET_DISK_AccessPermissions perm);
 
 
 /**
  * Get the size of an open file.
  *
  * @param fh open file handle
  * @param size where to write size of the file
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_handle_size (struct GNUNET_DISK_FileHandle *fh,
                               off_t *size);
 
 
 /**
  * Flags for #GNUNET_DISK_pipe().
  */
 enum GNUNET_DISK_PipeFlags
 {
 
   /**
    * No special options, use non-blocking read/write operations.
    */
   GNUNET_DISK_PF_NONE,
 
   /**
    * Configure read end to block when reading if set.
    */
   GNUNET_DISK_PF_BLOCKING_READ = 1,
 
   /**
    * Configure write end to block when writing if set.
    */
   GNUNET_DISK_PF_BLOCKING_WRITE = 2,
 
   /**
    * Configure both pipe ends for blocking operations if set.
    */
   GNUNET_DISK_PF_BLOCKING_RW = GNUNET_DISK_PF_BLOCKING_READ
                                | GNUNET_DISK_PF_BLOCKING_WRITE
 
 };
 
 
 /**
  * Creates an interprocess channel
  *
  * @param pf how to configure the pipe
  * @return handle to the new pipe, NULL on error
  */
 struct GNUNET_DISK_PipeHandle *
 GNUNET_DISK_pipe (enum GNUNET_DISK_PipeFlags pf);
 
 
 /**
  * Creates a pipe object from a couple of file descriptors.
  * Useful for wrapping existing pipe FDs.
  *
  * @param pf how to configure the pipe
  * @param fd an array of two fd values. One of them may be -1 for read-only or write-only pipes
  * @return handle to the new pipe, NULL on error
  */
 struct GNUNET_DISK_PipeHandle *
 GNUNET_DISK_pipe_from_fd (enum GNUNET_DISK_PipeFlags pf,
                           int fd[2]);
 
 
 /**
  * Closes an interprocess channel
  * @param p pipe
  * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_pipe_close (struct GNUNET_DISK_PipeHandle *p);
 
 
 /**
  * Closes one half of an interprocess channel
  *
  * @param p pipe to close end of
  * @param end which end of the pipe to close
  * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_pipe_close_end (struct GNUNET_DISK_PipeHandle *p,
                             enum GNUNET_DISK_PipeEnd end);
 
 
 /**
  * Detaches one of the ends from the pipe.
  * Detached end is a fully-functional FileHandle, it will
  * not be affected by anything you do with the pipe afterwards.
  * Each end of a pipe can only be detched from it once (i.e.
  * it is not duplicated).
  *
  * @param p pipe to detach an end from
  * @param end which end of the pipe to detach
  * @return Detached end on success, NULL on failure
  * (or if that end is not present or is closed).
  */
 struct GNUNET_DISK_FileHandle *
 GNUNET_DISK_pipe_detach_end (struct GNUNET_DISK_PipeHandle *p,
                              enum GNUNET_DISK_PipeEnd end);
 
 /**
  * Close an open file.
  *
  * @param h file handle
  * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_close (struct GNUNET_DISK_FileHandle *h);
 
 
 /**
  * Get the handle to a particular pipe end
  *
  * @param p pipe
  * @param n end to access
  * @return handle for the respective end
  */
 const struct GNUNET_DISK_FileHandle *
 GNUNET_DISK_pipe_handle (const struct GNUNET_DISK_PipeHandle *p,
                          enum GNUNET_DISK_PipeEnd n);
 
 
 /**
  * Update POSIX permissions mask of a file on disk.  If both arguments
  * are #GNUNET_NO, the file is made world-read-write-executable (777).
  * Does nothing on W32.
  *
  * @param fn name of the file to update
  * @param require_uid_match #GNUNET_YES means 700
  * @param require_gid_match #GNUNET_YES means 770 unless @a require_uid_match is set
  */
 void
 GNUNET_DISK_fix_permissions (const char *fn,
                              int require_uid_match,
                              int require_gid_match);
 
 
 /**
  * Get a handle from a native integer FD.
  *
  * @param fno native integer file descriptor
  * @return file handle corresponding to the descriptor
  */
 struct GNUNET_DISK_FileHandle *
 GNUNET_DISK_get_handle_from_int_fd (int fno);
 
 
 /**
  * Get a handle from a native FD.
  *
  * @param fd native file descriptor
  * @return file handle corresponding to the descriptor
  */
 struct GNUNET_DISK_FileHandle *
 GNUNET_DISK_get_handle_from_native (FILE *fd);
 
 
 /**
  * Read the contents of a binary file into a buffer.
  *
  * @param h handle to an open file
  * @param result the buffer to write the result to
  * @param len the maximum number of bytes to read
  * @return the number of bytes read on success, #GNUNET_SYSERR on failure
  */
 ssize_t
 GNUNET_DISK_file_read (const struct GNUNET_DISK_FileHandle *h,
                        void *result,
                        size_t len);
 
 
 /**
  * Read the contents of a binary file into a buffer.
  *
  * @param fn file name
  * @param result the buffer to write the result to
  * @param len the maximum number of bytes to read
  * @return number of bytes read, #GNUNET_SYSERR on failure
  */
 ssize_t
 GNUNET_DISK_fn_read (const char *fn,
                      void *result,
                      size_t len);
 
 
 /**
  * Write a buffer to a file.
  *
  * @param h handle to open file
  * @param buffer the data to write
  * @param n number of bytes to write
  * @return number of bytes written on success, #GNUNET_SYSERR on error
  */
 ssize_t
 GNUNET_DISK_file_write (const struct GNUNET_DISK_FileHandle *h,
                         const void *buffer,
                         size_t n);
 
 
 /**
  * Write a buffer to a file, blocking, if necessary.
  *
  * @param h handle to open file
  * @param buffer the data to write
  * @param n number of bytes to write
  * @return number of bytes written on success, #GNUNET_SYSERR on error
  */
 ssize_t
 GNUNET_DISK_file_write_blocking (const struct GNUNET_DISK_FileHandle *h,
                                  const void *buffer,
                                  size_t n);
 
 
 /**
  * Write a buffer to a file atomically.  The directory is created if
  * necessary.  Fail if @a filename already exists or if not exactly @a buf
  * with @a buf_size bytes could be written to @a filename.
  *
  * @param fn file name
  * @param buf the data to write
  * @param buf_size number of bytes to write from @a buf
  * @param mode file permissions
  * @return #GNUNET_OK on success,
  *         #GNUNET_NO if a file existed under @a filename
  *         #GNUNET_SYSERR on failure
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_fn_write (const char *fn,
                       const void *buf,
                       size_t buf_size,
                       enum GNUNET_DISK_AccessPermissions mode);
 
 
 /**
  * Copy a file.
  *
  * @param src file to copy
  * @param dst destination file name
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_copy (const char *src,
                        const char *dst);
 
 
 /**
  * Scan a directory for files.
  *
  * @param dir_name the name of the directory
  * @param callback the method to call for each file
  * @param callback_cls closure for @a callback
  * @return the number of files found, -1 on error
  */
 int
 GNUNET_DISK_directory_scan (const char *dir_name,
                             GNUNET_FileNameCallback callback,
                             void *callback_cls);
 
 /**
  * Find all files matching a glob pattern.
  *
  * Currently, the glob_pattern only supports asterisks in the last
  * path component.
  *
  * @param glob_pattern the glob pattern to search for
  * @param callback the method to call for each file
  * @param callback_cls closure for @a callback
  * @return the number of files found, -1 on error
  */
 int
 GNUNET_DISK_glob (const char *glob_pattern,
                   GNUNET_FileNameCallback callback,
                   void *callback_cls);
 
 
 /**
  * Create the directory structure for storing
  * a file.
  *
  * @param filename name of a file in the directory
  * @returns #GNUNET_OK on success, #GNUNET_SYSERR on failure,
  *          #GNUNET_NO if directory exists but is not writeable
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_directory_create_for_file (const char *filename);
 
 
 /**
  * Test if @a fil is a directory and listable. Optionally, also check if the
  * directory is readable.  Will not print an error message if the directory does
  * not exist.  Will log errors if #GNUNET_SYSERR is returned (i.e., a file exists
  * with the same name).
  *
  * @param fil filename to test
  * @param is_readable #GNUNET_YES to additionally check if @a fil is readable;
  *          #GNUNET_NO to disable this check
  * @return #GNUNET_YES if yes, #GNUNET_NO if not; #GNUNET_SYSERR if it
  *           does not exist or `stat`ed
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_directory_test (const char *fil,
                             int is_readable);
 
 
 /**
  * Remove all files in a directory (rm -rf). Call with caution.
  *
  * @param filename the file to remove
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_directory_remove (const char *filename);
 
 
 /**
  * Remove the directory given under @a option in
  * section [PATHS] in configuration under @a cfg_filename
  *
  * @param pd project data to use to determine paths
  * @param cfg_filename configuration file to parse
  * @param option option with the dir name to purge
  */
 void
 GNUNET_DISK_purge_cfg_dir (const struct GNUNET_OS_ProjectData *pd,
                            const char *cfg_filename,
                            const char *option);
 
 
 /**
  * Implementation of "mkdir -p"
  *
  * @param dir the directory to create
  * @returns #GNUNET_SYSERR on failure, #GNUNET_OK otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_directory_create (const char *dir);
 
 
 /**
  * @brief Removes special characters as ':' from a filename.
  * @param fn the filename to canonicalize
  */
 void
 GNUNET_DISK_filename_canonicalize (char *fn);
 
 
 /**
  * @brief Change owner of a file
  * @param filename file to change
  * @param user new owner of the file
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_change_owner (const char *filename,
                                const char *user);
 
 
 /**
  * Opaque handle for a memory-mapping operation.
  */
 struct GNUNET_DISK_MapHandle;
 
 
 /**
  * Map a file into memory.
  *
  * @param h open file handle
  * @param m handle to the new mapping (will be set)
  * @param access access specification, GNUNET_DISK_MAP_TYPE_xxx
  * @param len size of the mapping
  * @return pointer to the mapped memory region, NULL on failure
  */
 void *
 GNUNET_DISK_file_map (const struct GNUNET_DISK_FileHandle *h,
                       struct GNUNET_DISK_MapHandle **m,
                       enum GNUNET_DISK_MapType access,
                       size_t len);
 
 
 /**
  * Unmap a file
  *
  * @param h mapping handle
  * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_unmap (struct GNUNET_DISK_MapHandle *h);
 
 
 /**
  * Write file changes to disk
  *
  * @param h handle to an open file
  * @return #GNUNET_OK on success, #GNUNET_SYSERR otherwise
  */
 enum GNUNET_GenericReturnValue
 GNUNET_DISK_file_sync (const struct GNUNET_DISK_FileHandle *h);
 
 
 #if 0                           /* keep Emacsens' auto-indent happy */
 {
 #endif
 #ifdef __cplusplus
 }
 #endif
 
 /* ifndef GNUNET_DISK_LIB_H */
 #endif
 
 /** @} */  /* end of group */
 
 /** @} */ /* end of group addition */
 
 /* end of gnunet_disk_lib.h */