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Technical Reference: Base Operating System and Extensions, Volume 2
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:
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
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:
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
- 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.
- 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.
- 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
/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. |
Related Information
The src_err_msg_r (src_err_msg_r Subroutine), srcsbuf_r (srcsbuf_r Subroutine), srcrrqs_r (srcrrqs_r Subroutine), srcstat_r
(srcstat_r Subroutine), and srcstattxt_r (srcstattxt_r Subroutine) subroutines.
List of SRC Subroutines in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.
Programming Subsystem Communication with the SRC in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.
System Resource Controller (SRC) Overview for
Programmers in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.
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