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libjio/libjio/libjio.h  view on Meta::CPAN

/*
 * Core functions
 */

/** Open a file.
 *
 * Takes the same parameters as the UNIX open(2), with an additional one for
 * internal flags.
 *
 * The only supported internal flag is J_LINGER, which enables lingering
 * transactions.
 *
 * @param name path to the file to open
 * @param flags flags to pass to open(2)
 * @param mode mode to pass to open(2)
 * @param jflags journal flags
 * @returns a new jfs_t that identifies the open file on success, or NULL on
 *	error
 * @see jclose(), open()
 * @ingroup basic
 */
jfs_t *jopen(const char *name, int flags, int mode, unsigned int jflags);

/** Close a file opened with jopen().
 *
 * After a call to this function, the memory allocated for the open file will
 * be freed.
 *
 * If there was an autosync thread started for this file, it will be stopped.
 *
 * @param fs open file
 * @returns 0 on success, -1 on error
 * @see jopen(), jfs_autosync_start()
 * @ingroup basic
 */
int jclose(jfs_t *fs);

/** Sync a file. Makes sense only when using lingering transactions.
 *
 * @param fs open file
 * @returns 0 on success, -1 on error
 * @ingroup basic
 */
int jsync(jfs_t *fs);

/** Create a new transaction.
 *
 * Note that the final flags to use in the transaction will be the result of
 * ORing the flags parameter with fs' flags.
 *
 * @param fs open file the transaction will apply to
 * @param flags transaction flags
 * @returns a new transaction (must be freed using jtrans_free())
 * @see jtrans_free()
 * @ingroup basic
 */
jtrans_t *jtrans_new(jfs_t *fs, unsigned int flags);

/** Add a write operation to a transaction.
 *
 * A write operation consists of a buffer, its length, and the offset to write
 * it to.
 *
 * The file will not be touched (not even locked) until commit time, where the
 * first count bytes of buf will be written at offset.
 *
 * Operations will be applied in order, and overlapping operations are
 * permitted, in which case the latest one will prevail.
 *
 * The buffer will be copied internally and can be free()d right after this
 * function returns.
 *
 * @param ts transaction
 * @param buf buffer to write
 * @param count how many bytes from the buffer to write
 * @param offset offset to write at
 * @returns 0 on success, -1 on error
 * @ingroup basic
 */
int jtrans_add_w(jtrans_t *ts, const void *buf, size_t count, off_t offset);

/** Add a read operation to a transaction.
 *
 * An operation consists of a buffer, its length, and the offset to read it
 * from.
 *
 * The file will not be touched (not even locked) until commit time, where the
 * first count bytes at offset will be read into buf.
 *
 * Note that if there is not enough data in the file to read the specified
 * amount of bytes, the commit will fail, so do not attempt to read beyond EOF
 * (you can use jread() for that purpose).
 *
 * Operations will be applied in order, and overlapping operations are
 * permitted, in which case the latest one will prevail.
 *
 * In case of an error in jtrans_commit(), the contents of the buffer are
 * undefined.
 *
 * @param ts transaction
 * @param buf buffer to read to
 * @param count how many bytes to read
 * @param offset offset to read at
 * @returns 0 on success, -1 on error
 * @ingroup basic
 * @see jread()
 */
int jtrans_add_r(jtrans_t *ts, void *buf, size_t count, off_t offset);

/** Commit a transaction.
 * 
 * All the operations added to it using jtrans_add_w()/jtrans_add_r() will be
 * written to/read from disk, in the same order they were added.
 *
 * After this function returns successfully, all the data can be trusted to be
 * on the disk. The commit is atomic with regards to other processes using
 * libjio, but not accessing directly to the file.
 *
 * @param ts transaction
 * @returns 0 on success, or -1 if there was an error but atomic warranties
 * 	were preserved, or -2 if there was an error and there is a possible
 * 	break of atomic warranties (which is an indication of a severe
 * 	underlying condition).
 * @ingroup basic
 */
ssize_t jtrans_commit(jtrans_t *ts);

/** Rollback a transaction.
 *
 * This function atomically undoes a previous committed transaction. After its
 * successful return, the data can be trusted to be on disk. The read
 * operations will be ignored.
 *
 * Use with care.
 *
 * @param ts transaction
 * @returns the same as jtrans_commit()
 * @see jtrans_commit()
 * @ingroup basic
 */
ssize_t jtrans_rollback(jtrans_t *ts);

/** Free a transaction structure.
 *

libjio/libjio/libjio.h  view on Meta::CPAN

 */
ssize_t jread(jfs_t *fs, void *buf, size_t count);

/** Read from the file at the given offset. Works just like UNIX pread(2).
 *
 * @param fs file to read from
 * @param buf buffer used to store the data
 * @param count maximum number of bytes to read
 * @param offset offset to read at
 * @returns number of bytes read on success, or -1 on error
 * @see pread(2)
 * @ingroup unix
 */
ssize_t jpread(jfs_t *fs, void *buf, size_t count, off_t offset);

/** Read from the file into multiple buffers. Works just like UNIX readv(2).
 *
 * @param fs file to read from
 * @param vector buffers used to store the data
 * @param count maximum number of bytes to read
 * @returns number of bytes read on success, or -1 on error
 * @see readv(2)
 * @ingroup unix
 */
ssize_t jreadv(jfs_t *fs, const struct iovec *vector, int count);

/** Write to the file. Works just like UNIX write(2).
 *
 * @param fs file to write to
 * @param buf buffer used to read the data from
 * @param count maximum number of bytes to write
 * @returns number of bytes written on success, or -1 on error
 * @see write(2)
 * @ingroup unix
 */
ssize_t jwrite(jfs_t *fs, const void *buf, size_t count);

/** Write to the file at the given offset. Works just like UNIX pwrite(2).
 *
 * @param fs file to write to
 * @param buf buffer used to read the data from
 * @param count maximum number of bytes to write
 * @param offset offset to write at
 * @returns number of bytes written on success, or -1 on error
 * @see pwrite(2)
 * @ingroup unix
 */
ssize_t jpwrite(jfs_t *fs, const void *buf, size_t count, off_t offset);

/** Write to the file from multiple buffers. Works just like UNIX writev(2).
 *
 * @param fs file to write to
 * @param vector buffers used to read the data from
 * @param count maximum number of bytes to write
 * @returns number of bytes written on success, or -1 on error
 * @see writev(2)
 * @ingroup unix
 */
ssize_t jwritev(jfs_t *fs, const struct iovec *vector, int count);

/** Truncates the file to the given length. Works just like UNIX ftruncate(2).
 *
 * @param fs file to truncate
 * @param length lenght to truncate to
 * @returns 0 on success, -1 on error
 * @see ftruncate(2)
 * @ingroup unix
 */
int jtruncate(jfs_t *fs, off_t length);

/** Reposition read/write file offset. Works just like UNIX lseek(2).
 *
 * @param fs file to change the offset to
 * @param offset offset to set
 * @param whence where to count offset from, can be SEEK_SET to count from the
 *	beginning of the file, SEEK_CUR to count from the current position, or
 *	SEEK_END to count from the end.
 * @returns the new offset counted from the beginning of the file, or -1 on
 *	error.
 * @ingroup unix
 */
off_t jlseek(jfs_t *fs, off_t offset, int whence);


/*
 * ANSI C stdio wrappers
 */

jfs_t *jfopen(const char *path, const char *mode);

int jfclose(jfs_t *stream);

jfs_t *jfreopen(const char *path, const char *mode, jfs_t *stream);

size_t jfread(void *ptr, size_t size, size_t nmemb, jfs_t *stream);

size_t jfwrite(const void *ptr, size_t size, size_t nmemb, jfs_t *stream);

int jfileno(jfs_t *stream);

int jfeof(jfs_t *stream);

void jclearerr(jfs_t *stream);

int jferror(jfs_t *stream);

int jfseek(jfs_t *stream, long offset, int whence);

long jftell(jfs_t *stream);

void jrewind(jfs_t *stream);

FILE *jfsopen(jfs_t *stream, const char *mode);


/*
 * jopen() flags.
 *
 * Internally used also for jtrans_t flags.
 */

/** Don't lock the file before operating on it.
 *
 * @see jopen()
 * @ingroup basic */
#define J_NOLOCK	1

/** No need to read rollback information.
 *