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Diffstat (limited to 'tools/virtiofsd/fuse.h')
| -rw-r--r-- | tools/virtiofsd/fuse.h | 1275 |
1 files changed, 1275 insertions, 0 deletions
diff --git a/tools/virtiofsd/fuse.h b/tools/virtiofsd/fuse.h new file mode 100644 index 0000000000..883f6e59fb --- /dev/null +++ b/tools/virtiofsd/fuse.h @@ -0,0 +1,1275 @@ +/* + FUSE: Filesystem in Userspace + Copyright (C) 2001-2007 Miklos Szeredi <miklos@szeredi.hu> + + This program can be distributed under the terms of the GNU LGPLv2. + See the file COPYING.LIB. +*/ + +#ifndef FUSE_H_ +#define FUSE_H_ + +/** @file + * + * This file defines the library interface of FUSE + * + * IMPORTANT: you should define FUSE_USE_VERSION before including this header. + */ + +#include "fuse_common.h" + +#include <fcntl.h> +#include <time.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/statvfs.h> +#include <sys/uio.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/* ----------------------------------------------------------- * + * Basic FUSE API * + * ----------------------------------------------------------- */ + +/** Handle for a FUSE filesystem */ +struct fuse; + +/** + * Readdir flags, passed to ->readdir() + */ +enum fuse_readdir_flags { + /** + * "Plus" mode. + * + * The kernel wants to prefill the inode cache during readdir. The + * filesystem may honour this by filling in the attributes and setting + * FUSE_FILL_DIR_FLAGS for the filler function. The filesystem may also + * just ignore this flag completely. + */ + FUSE_READDIR_PLUS = (1 << 0), +}; + +enum fuse_fill_dir_flags { + /** + * "Plus" mode: all file attributes are valid + * + * The attributes are used by the kernel to prefill the inode cache + * during a readdir. + * + * It is okay to set FUSE_FILL_DIR_PLUS if FUSE_READDIR_PLUS is not set + * and vice versa. + */ + FUSE_FILL_DIR_PLUS = (1 << 1), +}; + +/** Function to add an entry in a readdir() operation + * + * The *off* parameter can be any non-zero value that enables the + * filesystem to identify the current point in the directory + * stream. It does not need to be the actual physical position. A + * value of zero is reserved to indicate that seeking in directories + * is not supported. + * + * @param buf the buffer passed to the readdir() operation + * @param name the file name of the directory entry + * @param stat file attributes, can be NULL + * @param off offset of the next entry or zero + * @param flags fill flags + * @return 1 if buffer is full, zero otherwise + */ +typedef int (*fuse_fill_dir_t) (void *buf, const char *name, + const struct stat *stbuf, off_t off, + enum fuse_fill_dir_flags flags); +/** + * Configuration of the high-level API + * + * This structure is initialized from the arguments passed to + * fuse_new(), and then passed to the file system's init() handler + * which should ensure that the configuration is compatible with the + * file system implementation. + */ +struct fuse_config { + /** + * If `set_gid` is non-zero, the st_gid attribute of each file + * is overwritten with the value of `gid`. + */ + int set_gid; + unsigned int gid; + + /** + * If `set_uid` is non-zero, the st_uid attribute of each file + * is overwritten with the value of `uid`. + */ + int set_uid; + unsigned int uid; + + /** + * If `set_mode` is non-zero, the any permissions bits set in + * `umask` are unset in the st_mode attribute of each file. + */ + int set_mode; + unsigned int umask; + + /** + * The timeout in seconds for which name lookups will be + * cached. + */ + double entry_timeout; + + /** + * The timeout in seconds for which a negative lookup will be + * cached. This means, that if file did not exist (lookup + * retuned ENOENT), the lookup will only be redone after the + * timeout, and the file/directory will be assumed to not + * exist until then. A value of zero means that negative + * lookups are not cached. + */ + double negative_timeout; + + /** + * The timeout in seconds for which file/directory attributes + * (as returned by e.g. the `getattr` handler) are cached. + */ + double attr_timeout; + + /** + * Allow requests to be interrupted + */ + int intr; + + /** + * Specify which signal number to send to the filesystem when + * a request is interrupted. The default is hardcoded to + * USR1. + */ + int intr_signal; + + /** + * Normally, FUSE assigns inodes to paths only for as long as + * the kernel is aware of them. With this option inodes are + * instead remembered for at least this many seconds. This + * will require more memory, but may be necessary when using + * applications that make use of inode numbers. + * + * A number of -1 means that inodes will be remembered for the + * entire life-time of the file-system process. + */ + int remember; + + /** + * The default behavior is that if an open file is deleted, + * the file is renamed to a hidden file (.fuse_hiddenXXX), and + * only removed when the file is finally released. This + * relieves the filesystem implementation of having to deal + * with this problem. This option disables the hiding + * behavior, and files are removed immediately in an unlink + * operation (or in a rename operation which overwrites an + * existing file). + * + * It is recommended that you not use the hard_remove + * option. When hard_remove is set, the following libc + * functions fail on unlinked files (returning errno of + * ENOENT): read(2), write(2), fsync(2), close(2), f*xattr(2), + * ftruncate(2), fstat(2), fchmod(2), fchown(2) + */ + int hard_remove; + + /** + * Honor the st_ino field in the functions getattr() and + * fill_dir(). This value is used to fill in the st_ino field + * in the stat(2), lstat(2), fstat(2) functions and the d_ino + * field in the readdir(2) function. The filesystem does not + * have to guarantee uniqueness, however some applications + * rely on this value being unique for the whole filesystem. + * + * Note that this does *not* affect the inode that libfuse + * and the kernel use internally (also called the "nodeid"). + */ + int use_ino; + + /** + * If use_ino option is not given, still try to fill in the + * d_ino field in readdir(2). If the name was previously + * looked up, and is still in the cache, the inode number + * found there will be used. Otherwise it will be set to -1. + * If use_ino option is given, this option is ignored. + */ + int readdir_ino; + + /** + * This option disables the use of page cache (file content cache) + * in the kernel for this filesystem. This has several affects: + * + * 1. Each read(2) or write(2) system call will initiate one + * or more read or write operations, data will not be + * cached in the kernel. + * + * 2. The return value of the read() and write() system calls + * will correspond to the return values of the read and + * write operations. This is useful for example if the + * file size is not known in advance (before reading it). + * + * Internally, enabling this option causes fuse to set the + * `direct_io` field of `struct fuse_file_info` - overwriting + * any value that was put there by the file system. + */ + int direct_io; + + /** + * This option disables flushing the cache of the file + * contents on every open(2). This should only be enabled on + * filesystems where the file data is never changed + * externally (not through the mounted FUSE filesystem). Thus + * it is not suitable for network filesystems and other + * intermediate filesystems. + * + * NOTE: if this option is not specified (and neither + * direct_io) data is still cached after the open(2), so a + * read(2) system call will not always initiate a read + * operation. + * + * Internally, enabling this option causes fuse to set the + * `keep_cache` field of `struct fuse_file_info` - overwriting + * any value that was put there by the file system. + */ + int kernel_cache; + + /** + * This option is an alternative to `kernel_cache`. Instead of + * unconditionally keeping cached data, the cached data is + * invalidated on open(2) if if the modification time or the + * size of the file has changed since it was last opened. + */ + int auto_cache; + + /** + * The timeout in seconds for which file attributes are cached + * for the purpose of checking if auto_cache should flush the + * file data on open. + */ + int ac_attr_timeout_set; + double ac_attr_timeout; + + /** + * If this option is given the file-system handlers for the + * following operations will not receive path information: + * read, write, flush, release, fsync, readdir, releasedir, + * fsyncdir, lock, ioctl and poll. + * + * For the truncate, getattr, chmod, chown and utimens + * operations the path will be provided only if the struct + * fuse_file_info argument is NULL. + */ + int nullpath_ok; + + /** + * The remaining options are used by libfuse internally and + * should not be touched. + */ + int show_help; + char *modules; + int debug; +}; + + +/** + * The file system operations: + * + * Most of these should work very similarly to the well known UNIX + * file system operations. A major exception is that instead of + * returning an error in 'errno', the operation should return the + * negated error value (-errno) directly. + * + * All methods are optional, but some are essential for a useful + * filesystem (e.g. getattr). Open, flush, release, fsync, opendir, + * releasedir, fsyncdir, access, create, truncate, lock, init and + * destroy are special purpose methods, without which a full featured + * filesystem can still be implemented. + * + * In general, all methods are expected to perform any necessary + * permission checking. However, a filesystem may delegate this task + * to the kernel by passing the `default_permissions` mount option to + * `fuse_new()`. In this case, methods will only be called if + * the kernel's permission check has succeeded. + * + * Almost all operations take a path which can be of any length. + */ +struct fuse_operations { + /** Get file attributes. + * + * Similar to stat(). The 'st_dev' and 'st_blksize' fields are + * ignored. The 'st_ino' field is ignored except if the 'use_ino' + * mount option is given. In that case it is passed to userspace, + * but libfuse and the kernel will still assign a different + * inode for internal use (called the "nodeid"). + * + * `fi` will always be NULL if the file is not currently open, but + * may also be NULL if the file is open. + */ + int (*getattr) (const char *, struct stat *, struct fuse_file_info *fi); + + /** Read the target of a symbolic link + * + * The buffer should be filled with a null terminated string. The + * buffer size argument includes the space for the terminating + * null character. If the linkname is too long to fit in the + * buffer, it should be truncated. The return value should be 0 + * for success. + */ + int (*readlink) (const char *, char *, size_t); + + /** Create a file node + * + * This is called for creation of all non-directory, non-symlink + * nodes. If the filesystem defines a create() method, then for + * regular files that will be called instead. + */ + int (*mknod) (const char *, mode_t, dev_t); + + /** Create a directory + * + * Note that the mode argument may not have the type specification + * bits set, i.e. S_ISDIR(mode) can be false. To obtain the + * correct directory type bits use mode|S_IFDIR + * */ + int (*mkdir) (const char *, mode_t); + + /** Remove a file */ + int (*unlink) (const char *); + + /** Remove a directory */ + int (*rmdir) (const char *); + + /** Create a symbolic link */ + int (*symlink) (const char *, const char *); + + /** Rename a file + * + * *flags* may be `RENAME_EXCHANGE` or `RENAME_NOREPLACE`. If + * RENAME_NOREPLACE is specified, the filesystem must not + * overwrite *newname* if it exists and return an error + * instead. If `RENAME_EXCHANGE` is specified, the filesystem + * must atomically exchange the two files, i.e. both must + * exist and neither may be deleted. + */ + int (*rename) (const char *, const char *, unsigned int flags); + + /** Create a hard link to a file */ + int (*link) (const char *, const char *); + + /** Change the permission bits of a file + * + * `fi` will always be NULL if the file is not currenlty open, but + * may also be NULL if the file is open. + */ + int (*chmod) (const char *, mode_t, struct fuse_file_info *fi); + + /** Change the owner and group of a file + * + * `fi` will always be NULL if the file is not currenlty open, but + * may also be NULL if the file is open. + * + * Unless FUSE_CAP_HANDLE_KILLPRIV is disabled, this method is + * expected to reset the setuid and setgid bits. + */ + int (*chown) (const char *, uid_t, gid_t, struct fuse_file_info *fi); + + /** Change the size of a file + * + * `fi` will always be NULL if the file is not currenlty open, but + * may also be NULL if the file is open. + * + * Unless FUSE_CAP_HANDLE_KILLPRIV is disabled, this method is + * expected to reset the setuid and setgid bits. + */ + int (*truncate) (const char *, off_t, struct fuse_file_info *fi); + + /** Open a file + * + * Open flags are available in fi->flags. The following rules + * apply. + * + * - Creation (O_CREAT, O_EXCL, O_NOCTTY) flags will be + * filtered out / handled by the kernel. + * + * - Access modes (O_RDONLY, O_WRONLY, O_RDWR, O_EXEC, O_SEARCH) + * should be used by the filesystem to check if the operation is + * permitted. If the ``-o default_permissions`` mount option is + * given, this check is already done by the kernel before calling + * open() and may thus be omitted by the filesystem. + * + * - When writeback caching is enabled, the kernel may send + * read requests even for files opened with O_WRONLY. The + * filesystem should be prepared to handle this. + * + * - When writeback caching is disabled, the filesystem is + * expected to properly handle the O_APPEND flag and ensure + * that each write is appending to the end of the file. + * + * - When writeback caching is enabled, the kernel will + * handle O_APPEND. However, unless all changes to the file + * come through the kernel this will not work reliably. The + * filesystem should thus either ignore the O_APPEND flag + * (and let the kernel handle it), or return an error + * (indicating that reliably O_APPEND is not available). + * + * Filesystem may store an arbitrary file handle (pointer, + * index, etc) in fi->fh, and use this in other all other file + * operations (read, write, flush, release, fsync). + * + * Filesystem may also implement stateless file I/O and not store + * anything in fi->fh. + * + * There are also some flags (direct_io, keep_cache) which the + * filesystem may set in fi, to change the way the file is opened. + * See fuse_file_info structure in <fuse_common.h> for more details. + * + * If this request is answered with an error code of ENOSYS + * and FUSE_CAP_NO_OPEN_SUPPORT is set in + * `fuse_conn_info.capable`, this is treated as success and + * future calls to open will also succeed without being send + * to the filesystem process. + * + */ + int (*open) (const char *, struct fuse_file_info *); + + /** Read data from an open file + * + * Read should return exactly the number of bytes requested except + * on EOF or error, otherwise the rest of the data will be + * substituted with zeroes. An exception to this is when the + * 'direct_io' mount option is specified, in which case the return + * value of the read system call will reflect the return value of + * this operation. + */ + int (*read) (const char *, char *, size_t, off_t, + struct fuse_file_info *); + + /** Write data to an open file + * + * Write should return exactly the number of bytes requested + * except on error. An exception to this is when the 'direct_io' + * mount option is specified (see read operation). + * + * Unless FUSE_CAP_HANDLE_KILLPRIV is disabled, this method is + * expected to reset the setuid and setgid bits. + */ + int (*write) (const char *, const char *, size_t, off_t, + struct fuse_file_info *); + + /** Get file system statistics + * + * The 'f_favail', 'f_fsid' and 'f_flag' fields are ignored + */ + int (*statfs) (const char *, struct statvfs *); + + /** Possibly flush cached data + * + * BIG NOTE: This is not equivalent to fsync(). It's not a + * request to sync dirty data. + * + * Flush is called on each close() of a file descriptor, as opposed to + * release which is called on the close of the last file descriptor for + * a file. Under Linux, errors returned by flush() will be passed to + * userspace as errors from close(), so flush() is a good place to write + * back any cached dirty data. However, many applications ignore errors + * on close(), and on non-Linux systems, close() may succeed even if flush() + * returns an error. For these reasons, filesystems should not assume + * that errors returned by flush will ever be noticed or even + * delivered. + * + * NOTE: The flush() method may be called more than once for each + * open(). This happens if more than one file descriptor refers to an + * open file handle, e.g. due to dup(), dup2() or fork() calls. It is + * not possible to determine if a flush is final, so each flush should + * be treated equally. Multiple write-flush sequences are relatively + * rare, so this shouldn't be a problem. + * + * Filesystems shouldn't assume that flush will be called at any + * particular point. It may be called more times than expected, or not + * at all. + * + * [close]: http://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html + */ + int (*flush) (const char *, struct fuse_file_info *); + + /** Release an open file + * + * Release is called when there are no more references to an open + * file: all file descriptors are closed and all memory mappings + * are unmapped. + * + * For every open() call there will be exactly one release() call + * with the same flags and file handle. It is possible to + * have a file opened more than once, in which case only the last + * release will mean, that no more reads/writes will happen on the + * file. The return value of release is ignored. + */ + int (*release) (const char *, struct fuse_file_info *); + + /** Synchronize file contents + * + * If the datasync parameter is non-zero, then only the user data + * should be flushed, not the meta data. + */ + int (*fsync) (const char *, int, struct fuse_file_info *); + + /** Set extended attributes */ + int (*setxattr) (const char *, const char *, const char *, size_t, int); + + /** Get extended attributes */ + int (*getxattr) (const char *, const char *, char *, size_t); + + /** List extended attributes */ + int (*listxattr) (const char *, char *, size_t); + + /** Remove extended attributes */ + int (*removexattr) (const char *, const char *); + + /** Open directory + * + * Unless the 'default_permissions' mount option is given, + * this method should check if opendir is permitted for this + * directory. Optionally opendir may also return an arbitrary + * filehandle in the fuse_file_info structure, which will be + * passed to readdir, releasedir and fsyncdir. + */ + int (*opendir) (const char *, struct fuse_file_info *); + + /** Read directory + * + * The filesystem may choose between two modes of operation: + * + * 1) The readdir implementation ignores the offset parameter, and + * passes zero to the filler function's offset. The filler + * function will not return '1' (unless an error happens), so the + * whole directory is read in a single readdir operation. + * + * 2) The readdir implementation keeps track of the offsets of the + * directory entries. It uses the offset parameter and always + * passes non-zero offset to the filler function. When the buffer + * is full (or an error happens) the filler function will return + * '1'. + */ + int (*readdir) (const char *, void *, fuse_fill_dir_t, off_t, + struct fuse_file_info *, enum fuse_readdir_flags); + + /** Release directory + */ + int (*releasedir) (const char *, struct fuse_file_info *); + + /** Synchronize directory contents + * + * If the datasync parameter is non-zero, then only the user data + * should be flushed, not the meta data + */ + int (*fsyncdir) (const char *, int, struct fuse_file_info *); + + /** + * Initialize filesystem + * + * The return value will passed in the `private_data` field of + * `struct fuse_context` to all file operations, and as a + * parameter to the destroy() method. It overrides the initial + * value provided to fuse_main() / fuse_new(). + */ + void *(*init) (struct fuse_conn_info *conn, + struct fuse_config *cfg); + + /** + * Clean up filesystem + * + * Called on filesystem exit. + */ + void (*destroy) (void *private_data); + + /** + * Check file access permissions + * + * This will be called for the access() system call. If the + * 'default_permissions' mount option is given, this method is not + * called. + * + * This method is not called under Linux kernel versions 2.4.x + */ + int (*access) (const char *, int); + + /** + * Create and open a file + * + * If the file does not exist, first create it with the specified + * mode, and then open it. + * + * If this method is not implemented or under Linux kernel + * versions earlier than 2.6.15, the mknod() and open() methods + * will be called instead. + */ + int (*create) (const char *, mode_t, struct fuse_file_info *); + + /** + * Perform POSIX file locking operation + * + * The cmd argument will be either F_GETLK, F_SETLK or F_SETLKW. + * + * For the meaning of fields in 'struct flock' see the man page + * for fcntl(2). The l_whence field will always be set to + * SEEK_SET. + * + * For checking lock ownership, the 'fuse_file_info->owner' + * argument must be used. + * + * For F_GETLK operation, the library will first check currently + * held locks, and if a conflicting lock is found it will return + * information without calling this method. This ensures, that + * for local locks the l_pid field is correctly filled in. The + * results may not be accurate in case of race conditions and in + * the presence of hard links, but it's unlikely that an + * application would rely on accurate GETLK results in these + * cases. If a conflicting lock is not found, this method will be + * called, and the filesystem may fill out l_pid by a meaningful + * value, or it may leave this field zero. + * + * For F_SETLK and F_SETLKW the l_pid field will be set to the pid + * of the process performing the locking operation. + * + * Note: if this method is not implemented, the kernel will still + * allow file locking to work locally. Hence it is only + * interesting for network filesystems and similar. + */ + int (*lock) (const char *, struct fuse_file_info *, int cmd, + struct flock *); + + /** + * Change the access and modification times of a file with + * nanosecond resolution + * + * This supersedes the old utime() interface. New applications + * should use this. + * + * `fi` will always be NULL if the file is not currenlty open, but + * may also be NULL if the file is open. + * + * See the utimensat(2) man page for details. + */ + int (*utimens) (const char *, const struct timespec tv[2], + struct fuse_file_info *fi); + + /** + * Map block index within file to block index within device + * + * Note: This makes sense only for block device backed filesystems + * mounted with the 'blkdev' option + */ + int (*bmap) (const char *, size_t blocksize, uint64_t *idx); + + /** + * Ioctl + * + * flags will have FUSE_IOCTL_COMPAT set for 32bit ioctls in + * 64bit environment. The size and direction of data is + * determined by _IOC_*() decoding of cmd. For _IOC_NONE, + * data will be NULL, for _IOC_WRITE data is out area, for + * _IOC_READ in area and if both are set in/out area. In all + * non-NULL cases, the area is of _IOC_SIZE(cmd) bytes. + * + * If flags has FUSE_IOCTL_DIR then the fuse_file_info refers to a + * directory file handle. + * + * Note : the unsigned long request submitted by the application + * is truncated to 32 bits. + */ + int (*ioctl) (const char *, unsigned int cmd, void *arg, + struct fuse_file_info *, unsigned int flags, void *data); + + /** + * Poll for IO readiness events + * + * Note: If ph is non-NULL, the client should notify + * when IO readiness events occur by calling + * fuse_notify_poll() with the specified ph. + * + * Regardless of the number of times poll with a non-NULL ph + * is received, single notification is enough to clear all. + * Notifying more times incurs overhead but doesn't harm + * correctness. + * + * The callee is responsible for destroying ph with + * fuse_pollhandle_destroy() when no longer in use. + */ + int (*poll) (const char *, struct fuse_file_info *, + struct fuse_pollhandle *ph, unsigned *reventsp); + + /** Write contents of buffer to an open file + * + * Similar to the write() method, but data is supplied in a + * generic buffer. Use fuse_buf_copy() to transfer data to + * the destination. + * + * Unless FUSE_CAP_HANDLE_KILLPRIV is disabled, this method is + * expected to reset the setuid and setgid bits. + */ + int (*write_buf) (const char *, struct fuse_bufvec *buf, off_t off, + struct fuse_file_info *); + + /** Store data from an open file in a buffer + * + * Similar to the read() method, but data is stored and + * returned in a generic buffer. + * + * No actual copying of data has to take place, the source + * file descriptor may simply be stored in the buffer for + * later data transfer. + * + * The buffer must be allocated dynamically and stored at the + * location pointed to by bufp. If the buffer contains memory + * regions, they too must be allocated using malloc(). The + * allocated memory will be freed by the caller. + */ + int (*read_buf) (const char *, struct fuse_bufvec **bufp, + size_t size, off_t off, struct fuse_file_info *); + /** + * Perform BSD file locking operation + * + * The op argument will be either LOCK_SH, LOCK_EX or LOCK_UN + * + * Nonblocking requests will be indicated by ORing LOCK_NB to + * the above operations + * + * For more information see the flock(2) manual page. + * + * Additionally fi->owner will be set to a value unique to + * this open file. This same value will be supplied to + * ->release() when the file is released. + * + * Note: if this method is not implemented, the kernel will still + * allow file locking to work locally. Hence it is only + * interesting for network filesystems and similar. + */ + int (*flock) (const char *, struct fuse_file_info *, int op); + + /** + * Allocates space for an open file + * + * This function ensures that required space is allocated for specified + * file. If this function returns success then any subsequent write + * request to specified range is guaranteed not to fail because of lack + * of space on the file system media. + */ + int (*fallocate) (const char *, int, off_t, off_t, + struct fuse_file_info *); + + /** + * Copy a range of data from one file to another + * + * Performs an optimized copy between two file descriptors without the + * additional cost of transferring data through the FUSE kernel module + * to user space (glibc) and then back into the FUSE filesystem again. + * + * In case this method is not implemented, glibc falls back to reading + * data from the source and writing to the destination. Effectively + * doing an inefficient copy of the data. + */ + ssize_t (*copy_file_range) (const char *path_in, + struct fuse_file_info *fi_in, + off_t offset_in, const char *path_out, + struct fuse_file_info *fi_out, + off_t offset_out, size_t size, int flags); + + /** + * Find next data or hole after the specified offset + */ + off_t (*lseek) (const char *, off_t off, int whence, struct fuse_file_info *); +}; + +/** Extra context that may be needed by some filesystems + * + * The uid, gid and pid fields are not filled in case of a writepage + * operation. + */ +struct fuse_context { + /** Pointer to the fuse object */ + struct fuse *fuse; + + /** User ID of the calling process */ + uid_t uid; + + /** Group ID of the calling process */ + gid_t gid; + + /** Process ID of the calling thread */ + pid_t pid; + + /** Private filesystem data */ + void *private_data; + + /** Umask of the calling process */ + mode_t umask; +}; + +/** + * Main function of FUSE. + * + * This is for the lazy. This is all that has to be called from the + * main() function. + * + * This function does the following: + * - parses command line options, and handles --help and + * --version + * - installs signal handlers for INT, HUP, TERM and PIPE + * - registers an exit handler to unmount the filesystem on program exit + * - creates a fuse handle + * - registers the operations + * - calls either the single-threaded or the multi-threaded event loop + * + * Most file systems will have to parse some file-system specific + * arguments before calling this function. It is recommended to do + * this with fuse_opt_parse() and a processing function that passes + * through any unknown options (this can also be achieved by just + * passing NULL as the processing function). That way, the remaining + * options can be passed directly to fuse_main(). + * + * fuse_main() accepts all options that can be passed to + * fuse_parse_cmdline(), fuse_new(), or fuse_session_new(). + * + * Option parsing skips argv[0], which is assumed to contain the + * program name. This element must always be present and is used to + * construct a basic ``usage: `` message for the --help + * output. argv[0] may also be set to the empty string. In this case + * the usage message is suppressed. This can be used by file systems + * to print their own usage line first. See hello.c for an example of + * how to do this. + * + * Note: this is currently implemented as a macro. + * + * The following error codes may be returned from fuse_main(): + * 1: Invalid option arguments + * 2: No mount point specified + * 3: FUSE setup failed + * 4: Mounting failed + * 5: Failed to daemonize (detach from session) + * 6: Failed to set up signal handlers + * 7: An error occured during the life of the file system + * + * @param argc the argument counter passed to the main() function + * @param argv the argument vector passed to the main() function + * @param op the file system operation + * @param private_data Initial value for the `private_data` + * field of `struct fuse_context`. May be overridden by the + * `struct fuse_operations.init` handler. + * @return 0 on success, nonzero on failure + * + * Example usage, see hello.c + */ +/* + int fuse_main(int argc, char *argv[], const struct fuse_operations *op, + void *private_data); +*/ +#define fuse_main(argc, argv, op, private_data) \ + fuse_main_real(argc, argv, op, sizeof(*(op)), private_data) + +/* ----------------------------------------------------------- * + * More detailed API * + * ----------------------------------------------------------- */ + +/** + * Print available options (high- and low-level) to stdout. This is + * not an exhaustive list, but includes only those options that may be + * of interest to an end-user of a file system. + * + * The function looks at the argument vector only to determine if + * there are additional modules to be loaded (module=foo option), + * and attempts to call their help functions as well. + * + * @param args the argument vector. + */ +void fuse_lib_help(struct fuse_args *args); + +/** + * Create a new FUSE filesystem. + * + * This function accepts most file-system independent mount options + * (like context, nodev, ro - see mount(8)), as well as the + * FUSE-specific mount options from mount.fuse(8). + * + * If the --help option is specified, the function writes a help text + * to stdout and returns NULL. + * + * Option parsing skips argv[0], which is assumed to contain the + * program name. This element must always be present and is used to + * construct a basic ``usage: `` message for the --help output. If + * argv[0] is set to the empty string, no usage message is included in + * the --help output. + * + * If an unknown option is passed in, an error message is written to + * stderr and the function returns NULL. + * + * @param args argument vector + * @param op the filesystem operations + * @param op_size the size of the fuse_operations structure + * @param private_data Initial value for the `private_data` + * field of `struct fuse_context`. May be overridden by the + * `struct fuse_operations.init` handler. + * @return the created FUSE handle + */ +#if FUSE_USE_VERSION == 30 +struct fuse *fuse_new_30(struct fuse_args *args, const struct fuse_operations *op, + size_t op_size, void *private_data); +#define fuse_new(args, op, size, data) fuse_new_30(args, op, size, data) +#else +struct fuse *fuse_new(struct fuse_args *args, const struct fuse_operations *op, + size_t op_size, void *private_data); +#endif + +/** + * Mount a FUSE file system. + * + * @param mountpoint the mount point path + * @param f the FUSE handle + * + * @return 0 on success, -1 on failure. + **/ +int fuse_mount(struct fuse *f, const char *mountpoint); + +/** + * Unmount a FUSE file system. + * + * See fuse_session_unmount() for additional information. + * + * @param f the FUSE handle + **/ +void fuse_unmount(struct fuse *f); + +/** + * Destroy the FUSE handle. + * + * NOTE: This function does not unmount the filesystem. If this is + * needed, call fuse_unmount() before calling this function. + * + * @param f the FUSE handle + */ +void fuse_destroy(struct fuse *f); + +/** + * FUSE event loop. + * + * Requests from the kernel are processed, and the appropriate + * operations are called. + * + * For a description of the return value and the conditions when the + * event loop exits, refer to the documentation of + * fuse_session_loop(). + * + * @param f the FUSE handle + * @return see fuse_session_loop() + * + * See also: fuse_loop_mt() + */ +int fuse_loop(struct fuse *f); + +/** + * Flag session as terminated + * + * This function will cause any running event loops to exit on + * the next opportunity. + * + * @param f the FUSE handle + */ +void fuse_exit(struct fuse *f); + +/** + * FUSE event loop with multiple threads + * + * Requests from the kernel are processed, and the appropriate + * operations are called. Request are processed in parallel by + * distributing them between multiple threads. + * + * For a description of the return value and the conditions when the + * event loop exits, refer to the documentation of + * fuse_session_loop(). + * + * Note: using fuse_loop() instead of fuse_loop_mt() means you are running in + * single-threaded mode, and that you will not have to worry about reentrancy, + * though you will have to worry about recursive lookups. In single-threaded + * mode, FUSE will wait for one callback to return before calling another. + * + * Enabling multiple threads, by using fuse_loop_mt(), will cause FUSE to make + * multiple simultaneous calls into the various callback functions given by your + * fuse_operations record. + * + * If you are using multiple threads, you can enjoy all the parallel execution + * and interactive response benefits of threads, and you get to enjoy all the + * benefits of race conditions and locking bugs, too. Ensure that any code used + * in the callback function of fuse_operations is also thread-safe. + * + * @param f the FUSE handle + * @param config loop configuration + * @return see fuse_session_loop() + * + * See also: fuse_loop() + */ +#if FUSE_USE_VERSION < 32 +int fuse_loop_mt_31(struct fuse *f, int clone_fd); +#define fuse_loop_mt(f, clone_fd) fuse_loop_mt_31(f, clone_fd) +#else +int fuse_loop_mt(struct fuse *f, struct fuse_loop_config *config); +#endif + +/** + * Get the current context + * + * The context is only valid for the duration of a filesystem + * operation, and thus must not be stored and used later. + * + * @return the context + */ +struct fuse_context *fuse_get_context(void); + +/** + * Get the current supplementary group IDs for the current request + * + * Similar to the getgroups(2) system call, except the return value is + * always the total number of group IDs, even if it is larger than the + * specified size. + * + * The current fuse kernel module in linux (as of 2.6.30) doesn't pass + * the group list to userspace, hence this function needs to parse + * "/proc/$TID/task/$TID/status" to get the group IDs. + * + * This feature may not be supported on all operating systems. In + * such a case this function will return -ENOSYS. + * + * @param size size of given array + * @param list array of group IDs to be filled in + * @return the total number of supplementary group IDs or -errno on failure + */ +int fuse_getgroups(int size, gid_t list[]); + +/** + * Check if the current request has already been interrupted + * + * @return 1 if the request has been interrupted, 0 otherwise + */ +int fuse_interrupted(void); + +/** + * Invalidates cache for the given path. + * + * This calls fuse_lowlevel_notify_inval_inode internally. + * + * @return 0 on successful invalidation, negative error value otherwise. + * This routine may return -ENOENT to indicate that there was + * no entry to be invalidated, e.g., because the path has not + * been seen before or has been forgotten; this should not be + * considered to be an error. + */ +int fuse_invalidate_path(struct fuse *f, const char *path); + +/** + * The real main function + * + * Do not call this directly, use fuse_main() + */ +int fuse_main_real(int argc, char *argv[], const struct fuse_operations *op, + size_t op_size, void *private_data); + +/** + * Start the cleanup thread when using option "remember". + * + * This is done automatically by fuse_loop_mt() + * @param fuse struct fuse pointer for fuse instance + * @return 0 on success and -1 on error + */ +int fuse_start_cleanup_thread(struct fuse *fuse); + +/** + * Stop the cleanup thread when using option "remember". + * + * This is done automatically by fuse_loop_mt() + * @param fuse struct fuse pointer for fuse instance + */ +void fuse_stop_cleanup_thread(struct fuse *fuse); + +/** + * Iterate over cache removing stale entries + * use in conjunction with "-oremember" + * + * NOTE: This is already done for the standard sessions + * + * @param fuse struct fuse pointer for fuse instance + * @return the number of seconds until the next cleanup + */ +int fuse_clean_cache(struct fuse *fuse); + +/* + * Stacking API + */ + +/** + * Fuse filesystem object + * + * This is opaque object represents a filesystem layer + */ +struct fuse_fs; + +/* + * These functions call the relevant filesystem operation, and return + * the result. + * + * If the operation is not defined, they return -ENOSYS, with the + * exception of fuse_fs_open, fuse_fs_release, fuse_fs_opendir, + * fuse_fs_releasedir and fuse_fs_statfs, which return 0. + */ + +int fuse_fs_getattr(struct fuse_fs *fs, const char *path, struct stat *buf, + struct fuse_file_info *fi); +int fuse_fs_rename(struct fuse_fs *fs, const char *oldpath, + const char *newpath, unsigned int flags); +int fuse_fs_unlink(struct fuse_fs *fs, const char *path); +int fuse_fs_rmdir(struct fuse_fs *fs, const char *path); +int fuse_fs_symlink(struct fuse_fs *fs, const char *linkname, + const char *path); +int fuse_fs_link(struct fuse_fs *fs, const char *oldpath, const char *newpath); +int fuse_fs_release(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi); +int fuse_fs_open(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi); +int fuse_fs_read(struct fuse_fs *fs, const char *path, char *buf, size_t size, + off_t off, struct fuse_file_info *fi); +int fuse_fs_read_buf(struct fuse_fs *fs, const char *path, + struct fuse_bufvec **bufp, size_t size, off_t off, + struct fuse_file_info *fi); +int fuse_fs_write(struct fuse_fs *fs, const char *path, const char *buf, + size_t size, off_t off, struct fuse_file_info *fi); +int fuse_fs_write_buf(struct fuse_fs *fs, const char *path, + struct fuse_bufvec *buf, off_t off, + struct fuse_file_info *fi); +int fuse_fs_fsync(struct fuse_fs *fs, const char *path, int datasync, + struct fuse_file_info *fi); +int fuse_fs_flush(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi); +int fuse_fs_statfs(struct fuse_fs *fs, const char *path, struct statvfs *buf); +int fuse_fs_opendir(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi); +int fuse_fs_readdir(struct fuse_fs *fs, const char *path, void *buf, + fuse_fill_dir_t filler, off_t off, + struct fuse_file_info *fi, enum fuse_readdir_flags flags); +int fuse_fs_fsyncdir(struct fuse_fs *fs, const char *path, int datasync, + struct fuse_file_info *fi); +int fuse_fs_releasedir(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi); +int fuse_fs_create(struct fuse_fs *fs, const char *path, mode_t mode, + struct fuse_file_info *fi); +int fuse_fs_lock(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi, int cmd, struct flock *lock); +int fuse_fs_flock(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi, int op); +int fuse_fs_chmod(struct fuse_fs *fs, const char *path, mode_t mode, + struct fuse_file_info *fi); +int fuse_fs_chown(struct fuse_fs *fs, const char *path, uid_t uid, gid_t gid, + struct fuse_file_info *fi); +int fuse_fs_truncate(struct fuse_fs *fs, const char *path, off_t size, + struct fuse_file_info *fi); +int fuse_fs_utimens(struct fuse_fs *fs, const char *path, + const struct timespec tv[2], struct fuse_file_info *fi); +int fuse_fs_access(struct fuse_fs *fs, const char *path, int mask); +int fuse_fs_readlink(struct fuse_fs *fs, const char *path, char *buf, + size_t len); +int fuse_fs_mknod(struct fuse_fs *fs, const char *path, mode_t mode, + dev_t rdev); +int fuse_fs_mkdir(struct fuse_fs *fs, const char *path, mode_t mode); +int fuse_fs_setxattr(struct fuse_fs *fs, const char *path, const char *name, + const char *value, size_t size, int flags); +int fuse_fs_getxattr(struct fuse_fs *fs, const char *path, const char *name, + char *value, size_t size); +int fuse_fs_listxattr(struct fuse_fs *fs, const char *path, char *list, + size_t size); +int fuse_fs_removexattr(struct fuse_fs *fs, const char *path, + const char *name); +int fuse_fs_bmap(struct fuse_fs *fs, const char *path, size_t blocksize, + uint64_t *idx); +int fuse_fs_ioctl(struct fuse_fs *fs, const char *path, unsigned int cmd, + void *arg, struct fuse_file_info *fi, unsigned int flags, + void *data); +int fuse_fs_poll(struct fuse_fs *fs, const char *path, + struct fuse_file_info *fi, struct fuse_pollhandle *ph, + unsigned *reventsp); +int fuse_fs_fallocate(struct fuse_fs *fs, const char *path, int mode, + off_t offset, off_t length, struct fuse_file_info *fi); +ssize_t fuse_fs_copy_file_range(struct fuse_fs *fs, const char *path_in, + struct fuse_file_info *fi_in, off_t off_in, + const char *path_out, + struct fuse_file_info *fi_out, off_t off_out, + size_t len, int flags); +off_t fuse_fs_lseek(struct fuse_fs *fs, const char *path, off_t off, int whence, + struct fuse_file_info *fi); +void fuse_fs_init(struct fuse_fs *fs, struct fuse_conn_info *conn, + struct fuse_config *cfg); +void fuse_fs_destroy(struct fuse_fs *fs); + +int fuse_notify_poll(struct fuse_pollhandle *ph); + +/** + * Create a new fuse filesystem object + * + * This is usually called from the factory of a fuse module to create + * a new instance of a filesystem. + * + * @param op the filesystem operations + * @param op_size the size of the fuse_operations structure + * @param private_data Initial value for the `private_data` + * field of `struct fuse_context`. May be overridden by the + * `struct fuse_operations.init` handler. + * @return a new filesystem object + */ +struct fuse_fs *fuse_fs_new(const struct fuse_operations *op, size_t op_size, + void *private_data); + +/** + * Factory for creating filesystem objects + * + * The function may use and remove options from 'args' that belong + * to this module. + * + * For now the 'fs' vector always contains exactly one filesystem. + * This is the filesystem which will be below the newly created + * filesystem in the stack. + * + * @param args the command line arguments + * @param fs NULL terminated filesystem object vector + * @return the new filesystem object + */ +typedef struct fuse_fs *(*fuse_module_factory_t)(struct fuse_args *args, + struct fuse_fs *fs[]); +/** + * Register filesystem module + * + * If the "-omodules=*name*_:..." option is present, filesystem + * objects are created and pushed onto the stack with the *factory_* + * function. + * + * @param name_ the name of this filesystem module + * @param factory_ the factory function for this filesystem module + */ +#define FUSE_REGISTER_MODULE(name_, factory_) \ + fuse_module_factory_t fuse_module_ ## name_ ## _factory = factory_ + +/** Get session from fuse object */ +struct fuse_session *fuse_get_session(struct fuse *f); + +/** + * Open a FUSE file descriptor and set up the mount for the given + * mountpoint and flags. + * + * @param mountpoint reference to the mount in the file system + * @param options mount options + * @return the FUSE file descriptor or -1 upon error + */ +int fuse_open_channel(const char *mountpoint, const char *options); + +#ifdef __cplusplus +} +#endif + +#endif /* FUSE_H_ */ |