fs: Improve documentation for FS API

Simple improvements in text and formatting of the documentation
the the FS API.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
This commit is contained in:
Dominik Ermel 2020-09-23 15:04:07 +00:00 committed by Carles Cufí
commit 81dc347b84
2 changed files with 131 additions and 125 deletions

View file

@ -133,23 +133,24 @@ struct fs_statvfs {
* @brief File System interface structure * @brief File System interface structure
* *
* @param open Opens or creates a file, depending on flags given * @param open Opens or creates a file, depending on flags given
* @param read Reads items of data of size bytes long * @param read Reads nbytes number of bytes
* @param write Writes items of data of size bytes long * @param write Writes nbytes number of bytes
* @param lseek Moves the file position to a new location in the file * @param lseek Moves the file position to a new location in the file
* @param tell Retrieves the current position in the file * @param tell Retrieves the current position in the file
* @param truncate Truncates the file to the new length * @param truncate Truncates/expands the file to the new length
* @param sync Flush the cache of an open file * @param sync Flushes the cache of an open file
* @param close Flushes the associated stream and closes the file * @param close Flushes the associated stream and closes the file
* @param opendir Opens an existing directory specified by the path * @param opendir Opens an existing directory specified by the path
* @param readdir Reads directory entries of a open directory * @param readdir Reads directory entries of an open directory
* @param closedir Closes an open directory * @param closedir Closes an open directory
* @param mount Mount a file system * @param mount Mounts a file system
* @param unmount Unmount a file system * @param unmount Unmounts a file system
* @param unlink Deletes the specified file or directory * @param unlink Deletes the specified file or directory
* @param rename Renames a file or directory * @param rename Renames a file or directory
* @param mkdir Creates a new directory using specified path * @param mkdir Creates a new directory using specified path
* @param stat Checks the status of a file or directory specified by the path * @param stat Checks the status of a file or directory specified by the path
* @param statvfs Returns the total and available space in the filesystem volume * @param statvfs Returns the total and available space on the file system
* volume
*/ */
struct fs_file_system_t { struct fs_file_system_t {
/* File operations */ /* File operations */
@ -202,56 +203,59 @@ struct fs_file_system_t {
#endif #endif
/** /**
* @brief File open * @brief Open or create file
* *
* Opens or creates, if does not exist, file depending on flags provided * Opens or possibly creates a file and associates a stream with it.
* and associates a stream with it.
* *
* @param zfp Pointer to file object * @details
* @param file_name The name of file to open * @p flags can be 0 or a binary combination of one or more of the following
* identifiers:
* - @c FS_O_READ open for read
* - @c FS_O_WRITE open for write
* - @c FS_O_RDWR open for read/write (<tt>FS_O_READ | FS_O_WRITE</tt>)
* - @c FS_O_CREATE create file if it does not exist
* - @c FS_O_APPEND move to end of file before each write
*
* If @p flags are set to 0 the function will attempt to open an existing file
* with no read/write access; this may be used to e.g. check if the file exists.
*
* @param zfp Pointer to a file object
* @param file_name The name of a file to open
* @param flags The mode flags * @param flags The mode flags
* *
* @p flags can be empty, or combination of one or more of following flags: * @retval 0 on success;
* FS_O_READ open for read * @retval -EINVAL when a bad file name is given;
* FS_O_WRITE open for write * @retval -ENOENT when the file path is not possible (bad mount point);
* FS_O_RDWR open for read/write (<tt>FS_O_READ | FS_O_WRITE</tt>) * @retval <0 an other negative errno code, depending on a file system back-end.
* FS_O_CREATE create file if it does not exist
* FS_O_APPEND move to end of file before each write
*
* @retval 0 Success
* @retval -EINVAL when bad file name is given
* @retval -NOENT when file path is not possible (bad mount point)
* @retval other negative error code, depending on file system back-end.
*/ */
int fs_open(struct fs_file_t *zfp, const char *file_name, fs_mode_t flags); int fs_open(struct fs_file_t *zfp, const char *file_name, fs_mode_t flags);
/** /**
* @brief File close * @brief Close file
* *
* Flushes the associated stream and closes * Flushes the associated stream and closes the file.
* the file.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_close(struct fs_file_t *zfp); int fs_close(struct fs_file_t *zfp);
/** /**
* @brief File unlink * @brief Unlink file
* *
* Deletes the specified file or directory * Deletes the specified file or directory
* *
* @param path Path to the file or directory to delete * @param path Path to the file or directory to delete
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_unlink(const char *path); int fs_unlink(const char *path);
/** /**
* @brief File o directory rename * @brief Rename file or directory
* *
* Performs a rename and / or move of the specified source path to the * Performs a rename and / or move of the specified source path to the
* specified destination. The source path can refer to either a file or a * specified destination. The source path can refer to either a file or a
@ -261,87 +265,88 @@ int fs_unlink(const char *path);
* directory. If an object already exists at the specified destination path, * directory. If an object already exists at the specified destination path,
* this function causes it to be unlinked prior to the rename (i.e., the * this function causes it to be unlinked prior to the rename (i.e., the
* destination gets clobbered). * destination gets clobbered).
* @note Current implementation does not allow moving files between mount
* points.
* *
* @param from The source path. * @param from The source path
* @param to The destination path. * @param to The destination path
* *
* @retval 0 Success; * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_rename(const char *from, const char *to); int fs_rename(const char *from, const char *to);
/** /**
* @brief File read * @brief Read file
* *
* Reads items of data of size bytes long. * Reads up to @p size bytes of data to @p ptr pointed buffer, returns number
* of bytes read. A returned value may be lower than @p size if there were
* fewer bytes available than requested.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* @param ptr Pointer to the data buffer * @param ptr Pointer to the data buffer
* @param size Number of bytes to be read * @param size Number of bytes to be read
* *
* @return Number of bytes read. On success, it will be equal to number of * @retval >=0 a number of bytes read, on success;
* items requested to be read. Returns less than number of bytes * @retval <0 a negative errno code on error.
* requested if there are not enough bytes available in file. Will return
* -ERRNO code on error.
*/ */
ssize_t fs_read(struct fs_file_t *zfp, void *ptr, size_t size); ssize_t fs_read(struct fs_file_t *zfp, void *ptr, size_t size);
/** /**
* @brief File write * @brief Write file
* *
* Writes items of data of size bytes long. * Attempts to write @p size number of bytes to the specified file.
* If a negative value is returned from the function, the file pointer has not
* been advanced.
* If the function returns a non-negative number that is lower than @p size,
* the global @c errno variable should be checked for an error code,
* as the device may have no free space for data.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* @param ptr Pointer to the data buffer * @param ptr Pointer to the data buffer
* @param size Number of bytes to be write * @param size Number of bytes to be written
* *
* @return Number of bytes written. On success, it will be equal to the number * @retval >=0 a number of bytes written, on success;
* of bytes requested to be written. Any other value, indicates an error. Will * @retval <0 a negative errno code on error.
* return -ERRNO code on error.
* In the case where -ERRNO is returned, the file pointer will not be
* advanced because it couldn't start the operation.
* In the case where it is able to write, but is not able to complete writing
* all of the requested number of bytes, then it is because the disk got full.
* In that case, it returns less number of bytes written than requested, but
* not a negative -ERRNO value as in regular error case.
*/ */
ssize_t fs_write(struct fs_file_t *zfp, const void *ptr, size_t size); ssize_t fs_write(struct fs_file_t *zfp, const void *ptr, size_t size);
/** /**
* @brief File seek * @brief Seek file
* *
* Moves the file position to a new location in the file. The offset is added * Moves the file position to a new location in the file. The @p offset is added
* to file position based on the 'whence' parameter. * to file position based on the @p whence parameter.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* @param offset Relative location to move the file pointer to * @param offset Relative location to move the file pointer to
* @param whence Relative location from where offset is to be calculated. * @param whence Relative location from where offset is to be calculated.
* - FS_SEEK_SET = from beginning of file * - @c FS_SEEK_SET for the beginning of the file;
* - FS_SEEK_CUR = from current position, * - @c FS_SEEK_CUR for the current position;
* - FS_SEEK_END = from end of file. * - @c FS_SEEK_END for the end of the file.
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ENOTSUP if underlying file system does not support seeking * @retval -ENOTSUP if not supported by underlying file system driver;
* @retval < 0 negative errno code * @retval <0 an other negative errno code on error.
*/ */
int fs_seek(struct fs_file_t *zfp, off_t offset, int whence); int fs_seek(struct fs_file_t *zfp, off_t offset, int whence);
/** /**
* @brief Get current file position. * @brief Get current file position.
* *
* Retrieves the current position in the file. * Retrieves and returns the current position in the file stream.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* *
* @retval >= 0 position Current position in file * @retval >= 0 a current position in file;
* @retval -ENOTSUP if underlying file system does not support seeking * @retval -ENOTSUP if not supported by underlying file system driver;
* @retval < 0 negative errno code * @retval <0 an other negative errno code on error.
* Current revision does not validate the file object. *
* The current revision does not validate the file object.
*/ */
off_t fs_tell(struct fs_file_t *zfp); off_t fs_tell(struct fs_file_t *zfp);
/** /**
* @brief Change the size of an open file * @brief Truncate or extend an open file to a given size
* *
* Truncates the file to the new length if it is shorter than the current * Truncates the file to the new length if it is shorter than the current
* size of the file. Expands the file if the new length is greater than the * size of the file. Expands the file if the new length is greater than the
@ -349,30 +354,30 @@ off_t fs_tell(struct fs_file_t *zfp);
* *
* @note In the case of expansion, if the volume got full during the * @note In the case of expansion, if the volume got full during the
* expansion process, the function will expand to the maximum possible length * expansion process, the function will expand to the maximum possible length
* and returns success. Caller should check if the expanded size matches the * and return success. Caller should check if the expanded size matches the
* requested length. * requested length.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* @param length New size of the file in bytes * @param length New size of the file in bytes
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_truncate(struct fs_file_t *zfp, off_t length); int fs_truncate(struct fs_file_t *zfp, off_t length);
/** /**
* @brief Flushes any cached write of an open file * @brief Flush cached write data buffers of an open file
* *
* This function can be used to flush the cache of an open file. This can * The function flushes the cache of an open file; it can be invoked to ensure
* be called to ensure data gets written to the storage media immediately. * data gets written to the storage media immediately, e.g. to avoid data loss
* This may be done to avoid data loss if power is removed unexpectedly. * in case if power is removed unexpectedly.
* Note that closing a file will cause caches to be flushed correctly so it * @note Closing a file will cause caches to be flushed correctly so the
* need not be called if the file is being closed. * function need not be called when the file is being closed.
* *
* @param zfp Pointer to the file object * @param zfp Pointer to the file object
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_sync(struct fs_file_t *zfp); int fs_sync(struct fs_file_t *zfp);
@ -383,8 +388,8 @@ int fs_sync(struct fs_file_t *zfp);
* *
* @param path Path to the directory to create * @param path Path to the directory to create
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error
*/ */
int fs_mkdir(const char *path); int fs_mkdir(const char *path);
@ -396,15 +401,16 @@ int fs_mkdir(const char *path);
* @param zdp Pointer to the directory object * @param zdp Pointer to the directory object
* @param path Path to the directory to open * @param path Path to the directory to open
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_opendir(struct fs_dir_t *zdp, const char *path); int fs_opendir(struct fs_dir_t *zdp, const char *path);
/** /**
* @brief Directory read entry * @brief Directory read entry
* *
* Reads directory entries of a open directory. * Reads directory entries of an open directory. In end-of-dir condition,
* the function will return 0 and set the <tt>entry->name[0]</tt> to 0.
* *
* @note: Most existing underlying file systems do not generate POSIX * @note: Most existing underlying file systems do not generate POSIX
* special directory entries "." or "..". For consistency the * special directory entries "." or "..". For consistency the
@ -414,10 +420,8 @@ int fs_opendir(struct fs_dir_t *zdp, const char *path);
* @param zdp Pointer to the directory object * @param zdp Pointer to the directory object
* @param entry Pointer to zfs_dirent structure to read the entry into * @param entry Pointer to zfs_dirent structure to read the entry into
* *
* @retval 0 Success * @retval 0 on success or end-of-dir;;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
* @return In end-of-dir condition, this will return 0 and set
* entry->name[0] = 0
*/ */
int fs_readdir(struct fs_dir_t *zdp, struct fs_dirent *entry); int fs_readdir(struct fs_dir_t *zdp, struct fs_dirent *entry);
@ -428,8 +432,8 @@ int fs_readdir(struct fs_dir_t *zdp, struct fs_dirent *entry);
* *
* @param zdp Pointer to the directory object * @param zdp Pointer to the directory object
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_closedir(struct fs_dir_t *zdp); int fs_closedir(struct fs_dir_t *zdp);
@ -442,53 +446,54 @@ int fs_closedir(struct fs_dir_t *zdp);
* *
* @param mp Pointer to the fs_mount_t structure * @param mp Pointer to the fs_mount_t structure
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 a negative errno code on error.
*/ */
int fs_mount(struct fs_mount_t *mp); int fs_mount(struct fs_mount_t *mp);
/** /**
* @brief Unmount filesystem * @brief Unmount filesystem
* *
* Perform steps needed for unmounting a file system like * Perform steps needed to unmount a file system like
* calling the file system specific unmount function and removing * calling the file system specific unmount function and removing
* the mount point from mounted file system list. * the mount point from mounted file system list.
* *
*
* @param mp Pointer to the fs_mount_t structure * @param mp Pointer to the fs_mount_t structure
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 negative errno code on error.
*/ */
int fs_unmount(struct fs_mount_t *mp); int fs_unmount(struct fs_mount_t *mp);
/** /**
* @brief Mount point read entry * @brief Get path of mount point at index
* *
* Read mount point entry * This function iterates through the list of mount points and returns
* the directory name of the mount point at the given @p index.
* On success @p index is incremented and @p name is set to the mount directory
* name. If a mount point with the given @p index does not exist, @p name will
* be set to @c NULL.
* *
* @param number Pointer to mount point number * @param index Pointer to mount point index
* @param name Pointer to mount point name * @param name Pointer to pointer to path name
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval -ENOENT if there is no mount point with given index.
* @return On success \p number is incremented and \p name is set to mount
* point name. In case no mount point exists for the given \p number
* -ENOENT is returned and \p name is set to NULL.
*/ */
int fs_readmount(int *number, const char **name); int fs_readmount(int *index, const char **name);
/** /**
* @brief File or directory status * @brief File or directory status
* *
* Checks the status of a file or directory specified by the path * Checks the status of a file or directory specified by the @p path.
* @note The file on a storage device may not be updated until it is closed.
* *
* @param path Path to the file or directory * @param path Path to the file or directory
* @param entry Pointer to zfs_dirent structure to fill if file or directory * @param entry Pointer to the zfs_dirent structure to fill if the file or
* exists. * directory exists.
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 negative errno code on error.
*/ */
int fs_stat(const char *path, struct fs_dirent *entry); int fs_stat(const char *path, struct fs_dirent *entry);
@ -498,10 +503,11 @@ int fs_stat(const char *path, struct fs_dirent *entry);
* Returns the total and available space in the file system volume. * Returns the total and available space in the file system volume.
* *
* @param path Path to the mounted directory * @param path Path to the mounted directory
* @param stat Pointer to zfs_statvfs structure to receive the fs statistics * @param stat Pointer to the zfs_statvfs structure to receive the fs
* statistics
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 negative errno code on error.
*/ */
int fs_statvfs(const char *path, struct fs_statvfs *stat); int fs_statvfs(const char *path, struct fs_statvfs *stat);
@ -510,11 +516,11 @@ int fs_statvfs(const char *path, struct fs_statvfs *stat);
* *
* Register file system with virtual file system. * Register file system with virtual file system.
* *
* @param type Type of file system (ex: FS_FATFS) * @param type Type of file system (ex: @c FS_FATFS)
* @param fs Pointer to File system * @param fs Pointer to File system
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 negative errno code on error.
*/ */
int fs_register(int type, const struct fs_file_system_t *fs); int fs_register(int type, const struct fs_file_system_t *fs);
@ -523,11 +529,11 @@ int fs_register(int type, const struct fs_file_system_t *fs);
* *
* Unregister file system from virtual file system. * Unregister file system from virtual file system.
* *
* @param type Type of file system (ex: FS_FATFS) * @param type Type of file system (ex: @c FS_FATFS)
* @param fs Pointer to File system * @param fs Pointer to File system
* *
* @retval 0 Success * @retval 0 on success;
* @retval -ERRNO errno code if error * @retval <0 negative errno code on error.
*/ */
int fs_unregister(int type, const struct fs_file_system_t *fs); int fs_unregister(int type, const struct fs_file_system_t *fs);

View file

@ -682,7 +682,7 @@ unmount_err:
return rc; return rc;
} }
int fs_readmount(int *number, const char **name) int fs_readmount(int *index, const char **name)
{ {
sys_dnode_t *node; sys_dnode_t *node;
int rc = -ENOENT; int rc = -ENOENT;
@ -694,7 +694,7 @@ int fs_readmount(int *number, const char **name)
k_mutex_lock(&mutex, K_FOREVER); k_mutex_lock(&mutex, K_FOREVER);
SYS_DLIST_FOR_EACH_NODE(&fs_mnt_list, node) { SYS_DLIST_FOR_EACH_NODE(&fs_mnt_list, node) {
if (*number == cnt) { if (*index == cnt) {
itr = CONTAINER_OF(node, struct fs_mount_t, node); itr = CONTAINER_OF(node, struct fs_mount_t, node);
break; break;
} }
@ -707,7 +707,7 @@ int fs_readmount(int *number, const char **name)
if (itr != NULL) { if (itr != NULL) {
rc = 0; rc = 0;
*name = itr->mnt_point; *name = itr->mnt_point;
++(*number); ++(*index);
} }
return rc; return rc;