libssh  0.7.90
Data Structures | Functions
The libssh SFTP API

SFTP handling functions. More...

Data Structures

struct  sftp_statvfs_t
 SFTP statvfs structure. More...
 

Functions

int sftp_async_read (sftp_file file, void *data, uint32_t len, uint32_t id)
 Wait for an asynchronous read to complete and save the data. More...
 
int sftp_async_read_begin (sftp_file file, uint32_t len)
 Start an asynchronous read from a file using an opened sftp file handle. More...
 
void sftp_attributes_free (sftp_attributes file)
 Free a sftp attribute structure. More...
 
char * sftp_canonicalize_path (sftp_session sftp, const char *path)
 Canonicalize a sftp path. More...
 
int sftp_chmod (sftp_session sftp, const char *file, mode_t mode)
 Change permissions of a file. More...
 
int sftp_chown (sftp_session sftp, const char *file, uid_t owner, gid_t group)
 Change the file owner and group. More...
 
int sftp_close (sftp_file file)
 Close an open file handle. More...
 
int sftp_closedir (sftp_dir dir)
 Close a directory handle opened by sftp_opendir(). More...
 
int sftp_dir_eof (sftp_dir dir)
 Tell if the directory has reached EOF (End Of File). More...
 
int sftp_extension_supported (sftp_session sftp, const char *name, const char *data)
 Check if the given extension is supported. More...
 
unsigned int sftp_extensions_get_count (sftp_session sftp)
 Get the count of extensions provided by the server. More...
 
const char * sftp_extensions_get_data (sftp_session sftp, unsigned int indexn)
 Get the data of the extension provided by the server. More...
 
const char * sftp_extensions_get_name (sftp_session sftp, unsigned int indexn)
 Get the name of the extension provided by the server. More...
 
void sftp_file_set_blocking (sftp_file handle)
 Make the sftp communication for this file handle blocking. More...
 
void sftp_file_set_nonblocking (sftp_file handle)
 Make the sftp communication for this file handle non blocking. More...
 
void sftp_free (sftp_session sftp)
 Close and deallocate a sftp session. More...
 
sftp_attributes sftp_fstat (sftp_file file)
 Get information about a file or directory from a file handle. More...
 
sftp_statvfs_t sftp_fstatvfs (sftp_file file)
 Get information about a mounted file system. More...
 
int sftp_fsync (sftp_file file)
 Synchronize a file's in-core state with storage device. More...
 
int sftp_get_error (sftp_session sftp)
 Get the last sftp error. More...
 
int sftp_init (sftp_session sftp)
 Initialize the sftp session with the server. More...
 
sftp_attributes sftp_lstat (sftp_session session, const char *path)
 Get information about a file or directory. More...
 
int sftp_mkdir (sftp_session sftp, const char *directory, mode_t mode)
 Create a directory. More...
 
sftp_session sftp_new (ssh_session session)
 Start a new sftp session. More...
 
sftp_session sftp_new_channel (ssh_session session, ssh_channel channel)
 Start a new sftp session with an existing channel. More...
 
sftp_file sftp_open (sftp_session session, const char *file, int accesstype, mode_t mode)
 Open a file on the server. More...
 
sftp_dir sftp_opendir (sftp_session session, const char *path)
 Open a directory used to obtain directory entries. More...
 
ssize_t sftp_read (sftp_file file, void *buf, size_t count)
 Read from a file using an opened sftp file handle. More...
 
sftp_attributes sftp_readdir (sftp_session session, sftp_dir dir)
 Get a single file attributes structure of a directory. More...
 
char * sftp_readlink (sftp_session sftp, const char *path)
 Read the value of a symbolic link. More...
 
int sftp_rename (sftp_session sftp, const char *original, const char *newname)
 Rename or move a file or directory. More...
 
void sftp_rewind (sftp_file file)
 Rewinds the position of the file pointer to the beginning of the file. More...
 
int sftp_rmdir (sftp_session sftp, const char *directory)
 Remove a directoy. More...
 
int sftp_seek (sftp_file file, uint32_t new_offset)
 Seek to a specific location in a file. More...
 
int sftp_seek64 (sftp_file file, uint64_t new_offset)
 Seek to a specific location in a file. More...
 
int sftp_server_init (sftp_session sftp)
 Intialize the sftp server. More...
 
sftp_session sftp_server_new (ssh_session session, ssh_channel chan)
 Create a new sftp server session. More...
 
int sftp_server_version (sftp_session sftp)
 Get the version of the SFTP protocol supported by the server. More...
 
int sftp_setstat (sftp_session sftp, const char *file, sftp_attributes attr)
 Set file attributes on a file, directory or symbolic link. More...
 
sftp_attributes sftp_stat (sftp_session session, const char *path)
 Get information about a file or directory. More...
 
sftp_statvfs_t sftp_statvfs (sftp_session sftp, const char *path)
 Get information about a mounted file system. More...
 
void sftp_statvfs_free (sftp_statvfs_t statvfs_o)
 Free the memory of an allocated statvfs. More...
 
int sftp_symlink (sftp_session sftp, const char *target, const char *dest)
 Create a symbolic link. More...
 
unsigned long sftp_tell (sftp_file file)
 Report current byte position in file. More...
 
uint64_t sftp_tell64 (sftp_file file)
 Report current byte position in file. More...
 
int sftp_unlink (sftp_session sftp, const char *file)
 Unlink (delete) a file. More...
 
int sftp_utimes (sftp_session sftp, const char *file, const struct timeval *times)
 Change the last modification and access time of a file. More...
 
ssize_t sftp_write (sftp_file file, const void *buf, size_t count)
 Write to a file using an opened sftp file handle. More...
 

Server responses

Responses returned by the sftp server.

#define SSH_FX_OK   0
 No error.
 
#define SSH_FX_EOF   1
 End-of-file encountered.
 
#define SSH_FX_NO_SUCH_FILE   2
 File doesn't exist.
 
#define SSH_FX_PERMISSION_DENIED   3
 Permission denied.
 
#define SSH_FX_FAILURE   4
 Generic failure.
 
#define SSH_FX_BAD_MESSAGE   5
 Garbage received from server.
 
#define SSH_FX_NO_CONNECTION   6
 No connection has been set up.
 
#define SSH_FX_CONNECTION_LOST   7
 There was a connection, but we lost it.
 
#define SSH_FX_OP_UNSUPPORTED   8
 Operation not supported by the server.
 
#define SSH_FX_INVALID_HANDLE   9
 Invalid file handle.
 
#define SSH_FX_NO_SUCH_PATH   10
 No such file or directory path exists.
 
#define SSH_FX_FILE_ALREADY_EXISTS   11
 An attempt to create an already existing file or directory has been made.
 
#define SSH_FX_WRITE_PROTECT   12
 We are trying to write on a write-protected filesystem.
 
#define SSH_FX_NO_MEDIA   13
 No media in remote drive.
 

Detailed Description

SFTP handling functions.

SFTP commands are channeled by the ssh sftp subsystem. Every packet is sent/read using a sftp_packet type structure. Related to these packets, most of the server answers are messages having an ID and a message specific part. It is described by sftp_message when reading a message, the sftp system puts it into the queue, so the process having asked for it can fetch it, while continuing to read for other messages (it is unspecified in which order messages may be sent back to the client

Function Documentation

◆ sftp_async_read()

int sftp_async_read ( sftp_file  file,
void *  data,
uint32_t  len,
uint32_t  id 
)

Wait for an asynchronous read to complete and save the data.

Parameters
fileThe opened sftp file handle to be read from.
dataPointer to buffer to recieve read data.
lenSize of the buffer in bytes. It should be bigger or equal to the length parameter of the sftp_async_read_begin() call.
idThe identifier returned by the sftp_async_read_begin() function.
Returns
Number of bytes read, 0 on EOF, SSH_ERROR if an error occured, SSH_AGAIN if the file is opened in nonblocking mode and the request hasn't been executed yet.
Warning
A call to this function with an invalid identifier will never return.
See also
sftp_async_read_begin()

References ssh_channel_poll().

◆ sftp_async_read_begin()

int sftp_async_read_begin ( sftp_file  file,
uint32_t  len 
)

Start an asynchronous read from a file using an opened sftp file handle.

Its goal is to avoid the slowdowns related to the request/response pattern of a synchronous read. To do so, you must call 2 functions:

sftp_async_read_begin() and sftp_async_read().

The first step is to call sftp_async_read_begin(). This function returns a request identifier. The second step is to call sftp_async_read() using the returned identifier.

Parameters
fileThe opened sftp file handle to be read from.
lenSize to read in bytes.
Returns
An identifier corresponding to the sent request, < 0 on error.
Warning
When calling this function, the internal offset is updated corresponding to the len parameter.
A call to sftp_async_read_begin() sends a request to the server. When the server answers, libssh allocates memory to store it until sftp_async_read() is called. Not calling sftp_async_read() will lead to memory leaks.
See also
sftp_async_read()
sftp_open()

References ssh_buffer_free(), and ssh_buffer_new().

◆ sftp_attributes_free()

void sftp_attributes_free ( sftp_attributes  file)

Free a sftp attribute structure.

Parameters
fileThe sftp attribute structure to free.

References ssh_string_free().

◆ sftp_canonicalize_path()

char* sftp_canonicalize_path ( sftp_session  sftp,
const char *  path 
)

Canonicalize a sftp path.

Parameters
sftpThe sftp session handle.
pathThe path to be canonicalized.
Returns
The canonicalize path, NULL on error.

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_chmod()

int sftp_chmod ( sftp_session  sftp,
const char *  file,
mode_t  mode 
)

Change permissions of a file.

Parameters
sftpThe sftp session handle.
fileThe file which owner and group should be changed.
modeSpecifies the permissions to use. It is modified by the process's umask in the usual way: The permissions of the created file are (mode & ~umask)
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

◆ sftp_chown()

int sftp_chown ( sftp_session  sftp,
const char *  file,
uid_t  owner,
gid_t  group 
)

Change the file owner and group.

Parameters
sftpThe sftp session handle.
fileThe file which owner and group should be changed.
ownerThe new owner which should be set.
groupThe new group which should be set.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

◆ sftp_close()

int sftp_close ( sftp_file  file)

Close an open file handle.

Parameters
fileThe open sftp file handle to close.
Returns
Returns SSH_NO_ERROR or SSH_ERROR if an error occured.
See also
sftp_open()

References ssh_string_free().

◆ sftp_closedir()

int sftp_closedir ( sftp_dir  dir)

Close a directory handle opened by sftp_opendir().

Parameters
dirThe sftp directory handle to close.
Returns
Returns SSH_NO_ERROR or SSH_ERROR if an error occured.

References ssh_buffer_free(), and ssh_string_free().

◆ sftp_dir_eof()

int sftp_dir_eof ( sftp_dir  dir)

Tell if the directory has reached EOF (End Of File).

Parameters
dirThe sftp directory handle.
Returns
1 if the directory is EOF, 0 if not.
See also
sftp_readdir()

◆ sftp_extension_supported()

int sftp_extension_supported ( sftp_session  sftp,
const char *  name,
const char *  data 
)

Check if the given extension is supported.

Parameters
sftpThe sftp session to use.
nameThe name of the extension.
dataThe data of the extension.
Returns
1 if supported, 0 if not.

Example:

sftp_extension_supported(sftp, "statvfs@openssh.com", "2");

References sftp_extensions_get_count(), sftp_extensions_get_data(), and sftp_extensions_get_name().

◆ sftp_extensions_get_count()

unsigned int sftp_extensions_get_count ( sftp_session  sftp)

Get the count of extensions provided by the server.

Parameters
sftpThe sftp session to use.
Returns
The count of extensions provided by the server, 0 on error or not available.

Referenced by sftp_extension_supported().

◆ sftp_extensions_get_data()

const char* sftp_extensions_get_data ( sftp_session  sftp,
unsigned int  indexn 
)

Get the data of the extension provided by the server.

This is normally the version number of the extension.

Parameters
sftpThe sftp session to use.
indexnThe index number of the extension data you want.
Returns
The data of the extension.

Referenced by sftp_extension_supported().

◆ sftp_extensions_get_name()

const char* sftp_extensions_get_name ( sftp_session  sftp,
unsigned int  indexn 
)

Get the name of the extension provided by the server.

Parameters
sftpThe sftp session to use.
indexnThe index number of the extension name you want.
Returns
The name of the extension.

Referenced by sftp_extension_supported().

◆ sftp_file_set_blocking()

void sftp_file_set_blocking ( sftp_file  handle)

Make the sftp communication for this file handle blocking.

Parameters
[in]handleThe file handle to set blocking.

◆ sftp_file_set_nonblocking()

void sftp_file_set_nonblocking ( sftp_file  handle)

Make the sftp communication for this file handle non blocking.

Parameters
[in]handleThe file handle to set non blocking.

◆ sftp_free()

void sftp_free ( sftp_session  sftp)

Close and deallocate a sftp session.

Parameters
sftpThe sftp session handle to free.

References ssh_channel_free(), and ssh_channel_send_eof().

◆ sftp_fstat()

sftp_attributes sftp_fstat ( sftp_file  file)

Get information about a file or directory from a file handle.

Parameters
fileThe sftp file handle to get the stat information.
Returns
The sftp attributes structure of the file or directory, NULL on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_new().

◆ sftp_fstatvfs()

sftp_statvfs_t sftp_fstatvfs ( sftp_file  file)

Get information about a mounted file system.

Parameters
fileAn opened file.
Returns
A statvfs structure or NULL on error.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_fsync()

int sftp_fsync ( sftp_file  file)

Synchronize a file's in-core state with storage device.

This calls the "fsync@openssh.com" extention. You should check if the extensions is supported using:

int supported = sftp_extension_supported(sftp, "fsync@openssh.com", "1");
Parameters
fileThe opened sftp file handle to sync
Returns
0 on success, < 0 on error with ssh and sftp error set.

References ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_get_error()

int sftp_get_error ( sftp_session  sftp)

Get the last sftp error.

Use this function to get the latest error set by a posix like sftp function.

Parameters
sftpThe sftp session where the error is saved.
Returns
The saved error (see server responses), < 0 if an error in the function occured.
See also
Server responses

◆ sftp_init()

int sftp_init ( sftp_session  sftp)

Initialize the sftp session with the server.

Parameters
sftpThe sftp session to initialize.
Returns
0 on success, < 0 on error with ssh error set.
See also
sftp_new()

References ssh_buffer_new().

◆ sftp_lstat()

sftp_attributes sftp_lstat ( sftp_session  session,
const char *  path 
)

Get information about a file or directory.

Identical to sftp_stat, but if the file or directory is a symbolic link, then the link itself is stated, not the file that it refers to.

Parameters
sessionThe sftp session handle.
pathThe path to the file or directory to obtain the information.
Returns
The sftp attributes structure of the file or directory, NULL on error with ssh and sftp error set.
See also
sftp_get_error()

◆ sftp_mkdir()

int sftp_mkdir ( sftp_session  sftp,
const char *  directory,
mode_t  mode 
)

Create a directory.

Parameters
sftpThe sftp session handle.
directoryThe directory to create.
modeSpecifies the permissions to use. It is modified by the process's umask in the usual way: The permissions of the created file are (mode & ~umask)
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_new()

sftp_session sftp_new ( ssh_session  session)

Start a new sftp session.

Parameters
sessionThe ssh session to use.
Returns
A new sftp session or NULL on error.
See also
sftp_free()

References ssh_channel_free(), ssh_channel_new(), and ssh_channel_open_session().

◆ sftp_new_channel()

sftp_session sftp_new_channel ( ssh_session  session,
ssh_channel  channel 
)

Start a new sftp session with an existing channel.

Parameters
sessionThe ssh session to use.
channelAn open session channel with subsystem already allocated
Returns
A new sftp session or NULL on error.
See also
sftp_free()

◆ sftp_open()

sftp_file sftp_open ( sftp_session  session,
const char *  file,
int  accesstype,
mode_t  mode 
)

Open a file on the server.

Parameters
sessionThe sftp session handle.
fileThe file to be opened.
accesstypeIs one of O_RDONLY, O_WRONLY or O_RDWR which request opening the file read-only,write-only or read/write. Acesss may also be bitwise-or'd with one or more of the following: O_CREAT - If the file does not exist it will be created. O_EXCL - When used with O_CREAT, if the file already exists it is an error and the open will fail. O_TRUNC - If the file already exists it will be truncated.
modeMode specifies the permissions to use if a new file is created. It is modified by the process's umask in the usual way: The permissions of the created file are (mode & ~umask)
Returns
A sftp file handle, NULL on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_opendir()

sftp_dir sftp_opendir ( sftp_session  session,
const char *  path 
)

Open a directory used to obtain directory entries.

Parameters
sessionThe sftp session handle to open the directory.
pathThe path of the directory to open.
Returns
A sftp directory handle or NULL on error with ssh and sftp error set.
See also
sftp_readdir
sftp_closedir

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_read()

ssize_t sftp_read ( sftp_file  file,
void *  buf,
size_t  count 
)

Read from a file using an opened sftp file handle.

Parameters
fileThe opened sftp file handle to be read from.
bufPointer to buffer to recieve read data.
countSize of the buffer in bytes.
Returns
Number of bytes written, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), and ssh_buffer_new().

◆ sftp_readdir()

sftp_attributes sftp_readdir ( sftp_session  session,
sftp_dir  dir 
)

Get a single file attributes structure of a directory.

Parameters
sessionThe sftp session handle to read the directory entry.
dirThe opened sftp directory handle to read from.
Returns
A file attribute structure or NULL at the end of the directory.
See also
sftp_opendir()
sftp_attribute_free()
sftp_closedir()

References ssh_buffer_new().

◆ sftp_readlink()

char* sftp_readlink ( sftp_session  sftp,
const char *  path 
)

Read the value of a symbolic link.

Parameters
sftpThe sftp session handle.
pathSpecifies the path name of the symlink to be read.
Returns
The target of the link, NULL on error.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_rename()

int sftp_rename ( sftp_session  sftp,
const char *  original,
const char *  newname 
)

Rename or move a file or directory.

Parameters
sftpThe sftp session handle.
originalThe original url (source url) of file or directory to be moved.
newnameThe new url (destination url) of the file or directory after the move.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), and ssh_buffer_new().

◆ sftp_rewind()

void sftp_rewind ( sftp_file  file)

Rewinds the position of the file pointer to the beginning of the file.

Parameters
fileOpen sftp file handle.

◆ sftp_rmdir()

int sftp_rmdir ( sftp_session  sftp,
const char *  directory 
)

Remove a directoy.

Parameters
sftpThe sftp session handle.
directoryThe directory to remove.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), and ssh_buffer_new().

◆ sftp_seek()

int sftp_seek ( sftp_file  file,
uint32_t  new_offset 
)

Seek to a specific location in a file.

Parameters
fileOpen sftp file handle to seek in.
new_offsetOffset in bytes to seek.
Returns
0 on success, < 0 on error.

◆ sftp_seek64()

int sftp_seek64 ( sftp_file  file,
uint64_t  new_offset 
)

Seek to a specific location in a file.

This is the 64bit version.

Parameters
fileOpen sftp file handle to seek in.
new_offsetOffset in bytes to seek.
Returns
0 on success, < 0 on error.

◆ sftp_server_init()

int sftp_server_init ( sftp_session  sftp)

Intialize the sftp server.

Parameters
sftpThe sftp session to init.
Returns
0 on success, < 0 on error.

◆ sftp_server_new()

sftp_session sftp_server_new ( ssh_session  session,
ssh_channel  chan 
)

Create a new sftp server session.

Parameters
sessionThe ssh session to use.
chanThe ssh channel to use.
Returns
A new sftp server session.

◆ sftp_server_version()

int sftp_server_version ( sftp_session  sftp)

Get the version of the SFTP protocol supported by the server.

Parameters
sftpThe sftp session handle.
Returns
The server version.

◆ sftp_setstat()

int sftp_setstat ( sftp_session  sftp,
const char *  file,
sftp_attributes  attr 
)

Set file attributes on a file, directory or symbolic link.

Parameters
sftpThe sftp session handle.
fileThe file which attributes should be changed.
attrThe file attributes structure with the attributes set which should be changed.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), and ssh_string_from_char().

◆ sftp_stat()

sftp_attributes sftp_stat ( sftp_session  session,
const char *  path 
)

Get information about a file or directory.

Parameters
sessionThe sftp session handle.
pathThe path to the file or directory to obtain the information.
Returns
The sftp attributes structure of the file or directory, NULL on error with ssh and sftp error set.
See also
sftp_get_error()

◆ sftp_statvfs()

sftp_statvfs_t sftp_statvfs ( sftp_session  sftp,
const char *  path 
)

Get information about a mounted file system.

Parameters
sftpThe sftp session handle.
pathThe pathname of any file within the mounted file system.
Returns
A statvfs structure or NULL on error.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), ssh_string_free(), and ssh_string_from_char().

◆ sftp_statvfs_free()

void sftp_statvfs_free ( sftp_statvfs_t  statvfs_o)

Free the memory of an allocated statvfs.

Parameters
statvfs_oThe statvfs to free.

◆ sftp_symlink()

int sftp_symlink ( sftp_session  sftp,
const char *  target,
const char *  dest 
)

Create a symbolic link.

Parameters
sftpThe sftp session handle.
targetSpecifies the target of the symlink.
destSpecifies the path name of the symlink to be created.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), ssh_buffer_new(), and ssh_get_openssh_version().

◆ sftp_tell()

unsigned long sftp_tell ( sftp_file  file)

Report current byte position in file.

Parameters
fileOpen sftp file handle.
Returns
The offset of the current byte relative to the beginning of the file associated with the file descriptor. < 0 on error.

◆ sftp_tell64()

uint64_t sftp_tell64 ( sftp_file  file)

Report current byte position in file.

Parameters
fileOpen sftp file handle.
Returns
The offset of the current byte relative to the beginning of the file associated with the file descriptor. < 0 on error.

◆ sftp_unlink()

int sftp_unlink ( sftp_session  sftp,
const char *  file 
)

Unlink (delete) a file.

Parameters
sftpThe sftp session handle.
fileThe file to unlink/delete.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

References ssh_buffer_free(), and ssh_buffer_new().

◆ sftp_utimes()

int sftp_utimes ( sftp_session  sftp,
const char *  file,
const struct timeval *  times 
)

Change the last modification and access time of a file.

Parameters
sftpThe sftp session handle.
fileThe file which owner and group should be changed.
timesA timeval structure which contains the desired access and modification time.
Returns
0 on success, < 0 on error with ssh and sftp error set.
See also
sftp_get_error()

◆ sftp_write()

ssize_t sftp_write ( sftp_file  file,
const void *  buf,
size_t  count 
)

Write to a file using an opened sftp file handle.

Parameters
fileOpen sftp file handle to write to.
bufPointer to buffer to write data.
countSize of buffer in bytes.
Returns
Number of bytes written, < 0 on error with ssh and sftp error set.
See also
sftp_open()
sftp_read()
sftp_close()

References ssh_buffer_free(), ssh_buffer_get_len(), and ssh_buffer_new().