brlapi_connection(3)

NAME
brlapi_connection - Before calling any other function of the library, calling brlapi_openConnection() is needed to establish a connection to BrlAPI 's server. When the connection is not needed any more, brlapi_closeConnection() must be called to close the connection.

SYNOPSIS

  Data Structures
struct brlapi_connectionSettings_t
Settings structure for BrlAPI connection.

  Macros
#define BRLAPI_SOCKETPORTNUM 4101
#define BRLAPI_SOCKETPORT '4101'
#define BRLAPI_SOCKETPATH '/var/lib/BrlAPI'
#define BRLAPI_ETCDIR '/etc'
#define BRLAPI_AUTHKEYFILE 'brlapi.key'
#define BRLAPI_DEFAUTH_KEYFILE 'keyfile:' BRLAPI_ETCDIR '/' BRLAPI_AUTHKEYFILE
#define BRLAPI_DEFAUTH_POLKIT ''
#define BRLAPI_DEFAUTH BRLAPI_DEFAUTH_KEYFILE BRLAPI_DEFAUTH_POLKIT
#define BRLAPI_SETTINGS_INITIALIZER { NULL, NULL }

  Typedefs
typedef int brlapi_fileDescriptor

  Functions
brlapi_fileDescriptor BRLAPI_STDCALL brlapi_openConnection (const brlapi_connectionSettings_t *desiredSettings, brlapi_connectionSettings_t *actualSettings)
brlapi_fileDescriptor BRLAPI_STDCALL brlapi__openConnection (brlapi_handle_t *handle, const brlapi_connectionSettings_t *desiredSettings, brlapi_connectionSettings_t *actualSettings)
void BRLAPI_STDCALL brlapi_closeConnection (void)
void BRLAPI_STDCALL brlapi__closeConnection (brlapi_handle_t *handle)

Detailed Description

Macro Definition Documentation

  #define BRLAPI_AUTHKEYFILE 'brlapi.key'
Default name of the file containing BrlAPI 's authorization key

This name is relative to BRLAPI_ETCDIR

  #define BRLAPI_DEFAUTH BRLAPI_DEFAUTH_KEYFILE BRLAPI_DEFAUTH_POLKIT

  #define BRLAPI_DEFAUTH_KEYFILE 'keyfile:' BRLAPI_ETCDIR '/' BRLAPI_AUTHKEYFILE
Default authorization setting

  #define BRLAPI_DEFAUTH_POLKIT ''

  #define BRLAPI_ETCDIR '/etc'
brltty 's settings directory

This is where authorization key and driver-dependent key names are found for instance.

  #define BRLAPI_SETTINGS_INITIALIZER { NULL, NULL }
Allows to initialize a structure of type brlapi_connectionSettings_t * with default values.

  #define BRLAPI_SOCKETPATH '/var/lib/BrlAPI'
Default unix path on which connections to BrlAPI can be established

  #define BRLAPI_SOCKETPORT '4101'

  #define BRLAPI_SOCKETPORTNUM 4101
Default port number on which connections to BrlAPI can be established

Typedef Documentation

  typedef int brlapi_fileDescriptor

Function Documentation

  void BRLAPI_STDCALL brlapi__closeConnection (brlapi_handle_t * handle)

  brlapi_fileDescriptor BRLAPI_STDCALL brlapi__openConnection (brlapi_handle_t * handle, const brlapi_connectionSettings_t * desiredSettings, brlapi_connectionSettings_t * actualSettings)

  void BRLAPI_STDCALL brlapi_closeConnection (void)
Cleanly close the socket

This function locks until a closing acknowledgement is received from the server. The socket is then freed, so the file descriptor brlapi_openConnection() gave has no meaning any more

  brlapi_fileDescriptor BRLAPI_STDCALL brlapi_openConnection (const brlapi_connectionSettings_t * desiredSettings, brlapi_connectionSettings_t * actualSettings)
Open a socket and connect it to BrlAPI 's server

This function first loads an authorization key as specified in settings. It then creates a TCP socket and connects it to the specified machine, on the specified port. It writes the authorization key on the socket and waits for acknowledgement.

Returns
    the file descriptor, or -1 on error

Note
    The file descriptor is returned in case the client wants to communicate with the server without using libbrlapi functions. If it uses them however, it won't have to pass the file descriptor later, since the library keeps a copy of it. But that also means that brlapi_openConnection() may be called several times, but libbrlapi functions will always work with the last call's descriptor

Example:

    if (brlapi_openConnection(&settings,&settings)<0) {
     fprintf(stderr,"couldn't connect to BrlAPI at %s: %s,
      settings.host, brlapi_strerror(&brlapi_error));
     exit(1);
    }

Errors:
    BrlAPI might not be on this TCP port, the host name might not be resolvable, the authorization may fail,...

Parameters
    desiredSettings this gives the desired connection parameters, as described in brlapi_connectionSettings_t. If NULL, defaults values are used, so that it is generally a good idea to give NULL as default, and only fill a brlapi_connectionSettings_t structure when the user gave parameters to the program for instance;
    actualSettings if not NULL, parameters which were actually used are stored here, if the application ever needs them.

See also
    brlapi_connectionSettings_t brlapi_writePacket() brlapi_readPacketHeader() brlapi_readPacketContent() brlapi_readPacket()

Author

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