Traps And Signals; Trap Handling - HP Guardian Errors Manual

21 Traps and Signals

Certain critical problems can cause a process to be unable to continue executing. These are typically
the result of coding errors, but other conditions, such as the lack of a system resource (for example,
memory), can also prevent normal process execution. Such conditions are reported as traps to
TNS processes and as signals to TNS/R native processes.A trap is a software mechanism that
stops process execution.A signal is a software interrupt that can notify a process of other events,
such as timer expiration, as well as of critical error conditions.
The set of signals that are used in the Guardian environment is known as TNS/R native signals.
This set is a subset of a larger set of signals used in the Open System Services (OSS) environment.
Most of the TNS/R native signals are caused by the same conditions that cause traps to occur in
TNS processes. TNS processes in the Guardian environment do not receive signals, except under
rare circumstances that cause a trap 8 to be generated.
In this section, equivalent trap and signal conditions are described together.Signals are commonly
referred to by name, where each name is a literal that stands for a 32-bit signal number.
Table 16 lists the TNS/R native signals by name, in alphabetic order, along with their signal
numbers, the equivalent trap numbers, and brief trap descriptions.
Table 16 TNS/R Native Signal Names, Signal Numbers, Trap Numbers, and Trap Descriptions
Signal Name
SIGABRT
SIGALRM
SIGFPE
SIGILL
SIGLIMIT
SIGMEMERR
SIGMEMMGR
SIGNOMEM
SIGSEGV
SIGSTK
SIGTIMEOUT
other signals

Trap Handling

When a trap occurs, control passes to the Debug or Inspect debugger by default. However, by
using the ARMTRAP system procedure, a program can specify a trap handler to be executed when
the trap occurs or, alternatively, that a trap causes the program to abend. The actions of a trap
handler typically include either terminating the process or, in certain cases, resuming execution.
For information about the Debug and Inspect debuggers, refer to the Debug Manual and the Inspect
Manual.
For a description of the ARMTRAP procedure, see the Guardian Procedure Calls Reference Manual.
For an explanation of how to create your own trap handler with ARMTRAP, see the Guardian
Programmer's Guide.
Signal Number Trap Number
6D none
14D none
8D 2
4D 1
27D 5
22D 13
24D 1 1
23D 12
1 1D 0
25D 3
26D 4
-- 8
Trap Description
(not available to TNS processes)
(not available to TNS processes)
Arithmetic overflow
Instruction failure
Limits exceeded
Uncorrectable memory error
Memory manager read error
No memory available
Illegal address reference
Stack overflow
Process loop-timer timeout
(signal delivered to TNS process)
Trap Handling 271