srcsrqt_r Subroutine

Purpose

Sends a request to a subsystem.

Library

System Resource Controller Library (libsrc.a)

Syntax

#include <spc.h>

srcsrqt_r(Host, SubsystemName, SubsystemPID, RequestLength,
             SubsystemRequest, ReplyLength, ReplyBuffer, StartItAlso,
             Continued, SRCHandle)
char * Host, * SubsystemName;
char * SubsystemRequest, * ReplyBuffer;
pid_t  SubsystemPID,
int,  StartItAlso, * Continued;
short  RequestLength, * ReplyLength;
char ** SRCHandle;

Description

The srcsrqt_r subroutine sends a request to a subsystem, waits for a response and returns one or more replies to the caller. The format of the request and the reply is determined by the caller and the subsystem.

Note: For each NEWREQUEST, the srcsrqt_r subroutine creates its own socket to send a request to the subsystem. The socket that this function opens remains open until an error or an end packet is received.

This system is threadsafe and reentrant.

Two types of continuation are returned by the srcsrqt_r subroutine:

Item Description
No continuation ReplyBuffer->srchdr.continued is set to the END constant.
Reply continuation ReplyBuffer->srchdr.continued is not set to the END constant, but to a positive value agreed upon by the calling process and the subsystem. The packet is returned to the caller.

Parameters

Item Description
SubsystemPID The process ID of the subsystem.
Host Specifies the foreign host on which this subsystem request is to be sent. If the host is null, the request is sent to the subsystem on the local host.
SubsystemName Specifies the name of the subsystem to which this request is to be sent. You must specify a SubsystemName if you do not specify a SubsystemPID.
RequestLength Specifies the length, in bytes, of the request to be sent to the subsystem. The maximum length is 2000 bytes.
SubsystemRequest Points to the subsystem request packet.
ReplyLength Specifies the maximum length, in bytes, of the reply to be received from the subsystem. On return from the srcsrqt subroutine, the ReplyLength parameter is set to the actual length of the subsystem reply packet.
ReplyBuffer Points to a buffer for the receipt of the reply packet from the subsystem.
StartItAlso Specifies whether the subsystem should be started if it is nonactive. When nonzero, the System Resource Controller (SRC) attempts to start a nonactive subsystem, and then passes the request to the subsystem.
Continued Specifies whether this call to the srcsrqt subroutine is a continuation of a previous request. If the Continued parameter is set to NEWREQUEST, a request for it is sent to the subsystem and the subsystem is notified that a response is expected. Under normal circumstances, the calling process should never set Continued to any value other than NEWREQUEST. The last response from the subsystem will set Continued to END. The caller must continue to call the srcsrqt_r subroutine until END is received. Otherwise, the socket will not be closed and the internal buffers freed. As an alternative, set Continued=SRC_CLOSE to discard the remaining data, close the socket, and free the internal buffers.
SRCHandle Identifies a request and its associated responses. Set to NULL by the caller for a NEWREQUEST. The srcsrqt_r subroutine saves a value in SRCHandle to allow srcsrqt_r continuation calls to use the same socket and internal buffers. The SRCHandle parameter should not be changed by the caller except for NEWREQUESTs.

Return Values

If the srcsrqt_r subroutine is successful, the value SRC_OK is returned.

Error Codes

The srcsrqt_r subroutine fails and returns the corresponding error code if one of the following error conditions is detected:

Item Description
SRC_BADSOCK The request could not be passed to the subsystem because of a socket failure.
SRC_CONT The subsystem uses signals. The request cannot complete.
SRC_DMNA The SRC daemon is not active.
SRC_INET_AUTHORIZED_HOST The local host is not in the remote /etc/hosts.equiv file.
SRC_INET_INVALID_HOST On the remote host, the local host is not known.
SRC_INVALID_USER The user is not root or group system.
SRC_MMRY An SRC component could not allocate the memory it needs.
SRC_NOCONTINUE The Continued parameter was not set to NEWREQUEST, and no continuation is currently active.
SRC_NORPLY The request timed out waiting for a response.
SRC_NSVR The subsystem is not active.
SRC_REQLEN2BIG The RequestLength is greater than the maximum 2000 bytes.
SRC_SOCK There is a problem with SRC socket communications.
SRC_STPG The request was not passed to the subsystem. The subsystem is stopping.
SRC_UDP The SRC port is not defined in the /etc/services file.
SRC_UHOST The foreign host is not known.

Examples

  1. To request long subsystem status, enter: 
    int cont=NEWREQUEST;
int rc;
short replen;
short reqlen;
char *handle;
struct
{
    struct srchdr srchdr;
    struct statcode statcode[20];
} statbuf;
struct subreq subreq;
 
subreq.action=STATUS;
subreq.object=SUBSYSTEM;
subreq.parm1=LONGSTAT;
strcpy(subreq.objname,"srctest");
replen=sizeof(statbuf);
reqlen=sizeof(subreq);
rc=srcsrqt_r("MaryC", "srctest", 0, reqlen, &subreq, &replen,
&statbuf, SRC_NO, &cont, &handle);

    This entry gets long status of the subsystem srctest on the MaryC machine. The subsystem keeps sending status packets until statbuf.srchdr.cont=END.

  2. To start a subserver, enter: 
    int cont=NEWREQUEST;
int rc;
short replen;
short reqlen;
struct
char *handle;
struct
{
    struct srchdr srchdr;
    struct statcode statcode[20];
} statbuf;
struct subreq subreq;
 
subreq.action=START;
subreq.object=1234;
replen=sizeof(statbuf);
reqlen=sizeof(subreq);
rc=srcsrqt_r("", "", 987, reqlen, &subreq, &replen, &statbuf,
SRC_NO, &cont, &handle);

    This entry starts the subserver with the code point of 1234, but only if the subsystem is already active.

  3. To start a subserver and a subsystem, enter: 
    int cont=NEWREQUEST;
int rc;
short replen;
short reqlen;
char *handle;
struct
{
    struct srchdr srchdr;
    struct statcode statcode[20];
} statbuf;
struct subreq subreq;
subreq.action=START;
subreq.object=1234;
replen=sizeof(statbuf);
reqlen=sizeof(subreq);
rc=srcsrqt("", "", 987, reqlen, &subreq, &replen, &statbuf, SRC_YES, &cont, &handle);

    This entry starts the subserver with the code point of 1234. If the subsystem to which this subserver belongs is not active, the subsystem is started.

Files

Item Description
/etc/services Defines sockets and protocols used for Internet services.
/dev/SRC Specifies the AF_UNIX socket file.
/dev/.SRC-unix Specifies the location for temporary socket files.