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VPFMT 3C "Dec 29, 1996"
NAME
vpfmt - display error message in standard format and pass to logging and monitoring services
SYNOPSIS

#include <pfmt.h>
#include <stdarg.h>

int vpfmt(FILE *stream, long flag, const char *format, va_list ap);
DESCRIPTION

The vpfmt() function is identical to pfmt(3C), except that it is called with an argument list as defined by <stdarg.h>.

The <stdarg.h> header defines the type va_list and a set of macros for advancing through a list of arguments whose number and types may vary. The ap argument is of type va_list. This argument is used with the <stdarg.h> macros va_start(), va_arg(), and va_end(). See stdarg(3EXT). The example in the EXAMPLES section below demonstrates their use with vpfmt().

RETURN VALUES

Upon successful completion, vpfmt() returns the number of bytes transmitted. Otherwise, -1 is returned if there was a write error to stream.

EXAMPLES

Example 1 Use of vpfmt() to write an error routine.

The following example demonstrates how vpfmt() could be used to write an error() routine. The va_alist() macro is used as the parameter list in a function definition. The va_start(ap, .\|.\|.) call, where ap is of type va_list, must be invoked before any attempt to traverse and access unnamed arguments. Calls to va_arg(ap, atype) traverse the argument list. Each execution of va_arg() expands to an expression with the value and type of the next argument in the list ap, which is the same object initialized by va_start(). The atype argument is the type that the returned argument is expected to be. The va_end(ap) macro must be invoked when all desired arguments have been accessed. The argument list in ap can be traversed again if va_start() is called again after va_end(). In the example below, va_arg() is executed first to retrieve the format string passed to error(). The remaining error() arguments (arg1, arg2, ...) are passed to vpfmt() in the argument ap.

#include <pfmt.h>
#include <stdarg.h>
/*
 * error should be called like
 * error(format, arg1, ...);
 */
void error(...)
{
 va_list ap;
 char *format;
 va_start(ap, );
 format = va_arg(ap, char *);
 (void) vpfmt(stderr, MM_ERROR, format, ap);
 va_end(ap);
 (void) abort();
}
USAGE

Since vpfmt() uses gettxt(3C), it is recommended that vpfmt() not be used.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE
MT-Level MT-Safe
SEE ALSO

gettxt(3C), pfmt(3C), attributes(5), stdarg(3EXT)