Error Handling

This chapter describes error handling and debugging.

1. Overview

Tmax APIs set an error number based on the situation in which an error occurs. Error messages help the user to find the cause of the errors. In order to know the system call level error information, refer to the error messages and APIs defined in tuxinc/Uunix.h.

Tmax provides CLH, which displays information on the console, to help find the problems that occur in the Tmax system, not at the application level.

For more information about error messages that can occur during the operation of the Tmax system, refer to Tmax Message Reference Guide.

2. API Level Error Processing

The return value of the Tmax API failure differs depending on the API. The error number of each error situation is set in tperrno.

2.1. tpstrerror

The tpstrerror function displays a message corresponding to an error number. It is available on both servers and clients. When an error occurs while using Tmax APIs, the error code is stored in the global variable tperrno. The tpstrerror() function displays a message corresponding to the error code in tperrno.

Prototype

# include <atmi.h>
char *tpstrerror (int tperrno)

Parameter

Parameter Description

tperrno

The error code for which the message will be displayed.
Return Value

Value Description

Error message

A message corresponding to the error code, if available.

NULL

No message is available for the error code.

Parameter	Description
tperrno	The error code for which the message will be displayed.

Value	Description
Error message	A message corresponding to the error code, if available.
NULL	No message is available for the error code.

Example

#include <stdio.h>
#include <usrinc/atmi.h>

void main(int argc, char *argv[])
{
    int ret;
    char buf;
    TPSTART_T *tpinfo;

    tpinfo = (TPSTART_T *)tpalloc(“TPSTART”, NULL, sizeof(TPSTART_T));

    if (tpinfo==NULL) { error processing }
    strcpy(tpinfo->dompwd, “tuxedo”);

    if (tpstart(tpinfo) == -1){
        printf(“tpstart fail , err = %s\n”, tpstrerror(tperrno));
        exit(1);
    }

    buf = (char *)tpalloc(“CARRAY”, NULL, 20);
    if (buf==NULL) {error processing };
    data process....

    tpfree((char *) buf);
    tpend();
}

3. System Level Error Processing

Tmax APIs use many system calls. To check a specific system call error generated due an operating system or platform error or to port error messages to heterogeneous platforms, the error messages can be integrated and managed by using the API explained in the following.

The following is the location of the header file.

TMAXDIR/tuxinc/Uunix.h

3.1. Uunixerr

Uunixerr is a variable to set an integrated error code when an error occurs while invoking a system call.

int Uunixerr

3.2. Uunix_err

The Uunix_err function prints a system error message to stderr when an ATMI API call fails and tperrno is set to TPEOS.

Prototype

# include <Uunix.h>
void Uunix_err (char *msg)

Parameter

Parameter	Description
msg	The message to prepend to the system error message. Typically, this is the program name. One of the following is printed: UCLOSE, UCREAT, UEXEC, UFCTNL, UFORK, ULSEEK, UMSGCTL, UMSGGET, UMSGSND, UMSGRCV, UOPEN, UPLOCK, UREAD, USEMCTL, USEMGET, USEMOP, USHMCTL, USHMGET, USHMAT, USHMDT, USTAT, UWRITE, USBRK, USYSMUL, UWAIT, UKILL, UTIME, UMKDIR, ULINK, UUNLINK, UUNAME, UNLIST

Description

msg

The message to prepend to the system error message. Typically, this is the program name.

One of the following is printed:

UCLOSE, UCREAT, UEXEC, UFCTNL, UFORK, ULSEEK, UMSGCTL, UMSGGET, UMSGSND, UMSGRCV, UOPEN, UPLOCK, UREAD, USEMCTL, USEMGET, USEMOP, USHMCTL, USHMGET, USHMAT, USHMDT, USTAT, UWRITE, USBRK, USYSMUL, UWAIT, UKILL, UTIME, UMKDIR, ULINK, UUNLINK, UUNAME, UNLIST

Example

ret=tmaxreadenv("NO THAT FILE", "TMAX");
if (ret<0) {
   Uunix_err("myprog");
   exit(1);
}

The result is as follows:

mypog: UOPEN

3.3. Ustrerror

The Ustrerror function returns the integrated error message corresponding to a system error code (errno).

Prototype

# include <Uunix.h>
char * Ustrerror(int err);

Parameter

Parameter Description

err

The integrated error number for which the error message is to be retrieved.
Return Value

If the function call is successful, the pointer address to the integrated error message corresponding to the errno is returned.

One of the following is returned as a char * type pointer:
- UCLOSE, UCREAT, UEXEC, UFCTNL, UFORK, ULSEEK, UMSGCTL, UMSGGET, UMSGSND, UMSGRCV, UOPEN, UPLOCK, UREAD, USEMCTL, USEMGET, USEMOP, USHMCTL, USHMGET, USHMAT, USHMDT, USTAT, UWRITE, USBRK, USYSMUL, UWAIT, UKILL, UTIME, UMKDIR, ULINK, UUNLINK, UUNAME, UNLIST

Parameter	Description
err	The integrated error number for which the error message is to be retrieved.

Example

ret=tmaxreadenv("NO THAT FILE", "TMAX");
if (ret<0)
{
    printf("%d->%s\n", Uunixerr, Ustrerror(Uunixerr));
   exit(1);
}

The result is as follows:

11->UOPEN

4. Debug

4.1. Debug CLH

If changing clh.dbg, which is located in TMAXDIR/bin, to clh, all the messages handled in CLH can be checked. The original clh file must be backed up.

/home/navis/tmax/bin> tmboot

TMBOOT for node(aix5l) is starting:
Welcome to Tmax demo system: it will expire 2002/9/15
Today: 2002/7/16
        TMBOOT: TMM is starting: Tue Jul 16 22:39:13 2002
        TMBOOT: CLL is starting: Tue Jul 16 22:39:13 2002
        TMBOOT: CLH is starting: Tue Jul 16 22:39:13 2002
COM: waiting for TMM reply
LIB: read 96 bytes
(I) CLH Current Tmax Configuration:
                Number of client handler(MINCLH) = 1
                Supported maximum user per node = 3944
                Supported maximum user per handler = 3944
LIB: read 96 bytes
CLH: bootpid = 31202
        TMBOOT: SVR(sub) is starting: Tue Jul 16 22:39:13 2002
        TMBOOT: SVR(svr2) is starting: Tue Jul 16 22:39:13 2002
CLH: request_from_server: clh = 0, ind = 0, fd = 8
CLH: msg from server: msgtype = 101, svcname = , len = 0
CLH: register_from_server, spri = 32, svri = 0, maxtms = 32
CLH: reply_to_server: clh = 0, ind = 32, fd =8
CLH: msg to server: msgtype = 1101, svcname = , len = 0
CLH: request_from_server: clh = 0, ind = 0, fd = 9
CLH: msg from server: msgtype = 135, svcname = , len = 0
...

4.2. Debug Library

The libsvrd.a and libsvr.so libraries exist in the TMAXDIR/lib directory. If these libraries are used instead of libsvr.a and libsvr.so, various data values are displayed on the console screen that help the user grasp the flow in the server library and find the point where the error occurred. For libsvrd.so, only the name must be changed. libsvrd.a must be recompiled.

/oracle/navis/tmax385/lib> tmboot

TMBOOT for node(tmaxc1) is starting:
Welcome to Tmax demo system: it will expire 2002/9/30
...
GETOPT1: -b 255859
GETOPT1: -s svr2
GETOPT1: -d -1
SVR: delay = -1, _use_lock = 1
COM: waiting for TMM reply
LIB: read 96 bytes
register_to_tmm success
init_shm(78990, 139364) success
init_svctab success
SVR: my info--1 32 0 0 -3
init_clh success
LIB: read 96 bytes
register_to_clh success
init_txinfo success
check_node success
_tmax_init = 1
GETOPT1: -b 255859
GETOPT1: -s fdltest
GETOPT1: -d -1
SVR: delay = -1, _use_lock = 1
COM: waiting for TMM reply
LIB: read 96 bytes
register_to_tmm success
...