CPC_SETERRHNDLR(3CPC) CPU Performance Counters Library Functions

NAME

cpc_seterrhndlr - control libcpc error reporting

SYNOPSIS

cc [ flag... ] file... -lcpc [ library... ]
#include <libcpc.h>

typedef void(cpc_errhndlr_t)(cpc_t *cpc, const char *fn, int subcode,
const char *fmt, va_list ap);


void cpc_seterrhndlr(cpc_t *cpc, cpc_errhndlr_t *errfn);

DESCRIPTION

For the convenience of programmers instrumenting their code, several
libcpc(3LIB) functions automatically emit to stderr error messages that
attempt to provide a more detailed explanation of their error return
values. While this can be useful for simple programs, some applications
might want to report their errors differently, for example, to a window
or to a log file.


The cpc_seterrhndlr() function allows the caller to provide an alternate
function for reporting errors. The type signature is shown in the
SYNOPSIS. The fn argument is passed the library function name that
detected the error, an integer subcode indicating the specific error
condition that has occurred, and the format string fmt that contains a
textual description of the integer subcode. The format string fmt and
argument pointer ap can be passed directly to vsnprintf(3C) or similar
varargs-based function for formatting.


The integer subcodes are provided to allow programs to recognize error
conditions while using libcpc. The fmt string is provided as a
convenience for easy printing. The error subcodes are:

CPC_INVALID_EVENT

A specified event is not supported by the processor.


CPC_INVALID_PICNUM

The counter number does not fall in the range of available counters.


CPC_INVALID_ATTRIBUTE

A specified attribute is not supported by the processor.


CPC_ATTRIBUTE_OUT_OF_RANGE

The value of an attribute is outside the range supported by the
processor.


CPC_RESOURCE_UNAVAIL

A hardware resource necessary for completing an operation was
unavailable.


CPC_PIC_NOT_CAPABLE

The requested counter cannot count an assigned event.


CPC_REQ_INVALID_FLAGS

One or more requests has invalid flags.


CPC_CONFLICTING_REQS

The requests in a set cannot be programmed onto the hardware at the
same time.


CPC_ATTR_REQUIRES_PRIVILEGE

A request contains an attribute which requires the cpc_cpu privilege,
which the process does not have.


The default printing routine can be restored by calling the routine with
an errfn argument of NULL.

EXAMPLES

Example 1: Debugging example.

The following example produces error messages only when debugging the
program containing it, or when the cpc_bind_curlwp(), cpc_bind_cpu(), or
cpc_bind_pctx() functions are reporting an error when binding a
cpc_set_t.


int debugging;
void
myapp_errfn(const char *fn, int subcode, const char *fmt, va_list ap)
{
if (strncmp(fn, "cpc_bind", 8) != 0 && !debugging)
return;
(void) fprintf(stderr, "myapp: cpc_%s(): ", fn);
(void) vfprintf(stderr, fmt, ap);
}

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
|MT-Level | Safe |
+--------------------+-----------------+

SEE ALSO

vsnprintf(3C), cpc_bind_curlwp(3CPC), libcpc(3LIB), attributes(7)

March 10, 2023 CPC_SETERRHNDLR(3CPC)