vsprintf(9F) Kernel Functions for Drivers vsprintf(9F)NAMEvsprintf - format characters in memory
SYNOPSIS
#include <sys/varargs.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
char *vsprintf(char *buf, const char *fmt, va_list ap);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
PARAMETERS
buf Pointer to a character string.
fmt Pointer to a character string.
ap Pointer to a variable argument list.
DESCRIPTIONvsprintf() builds a string in buf under the control of the format fmt.
The format is a character string with either plain characters, which
are simply copied into buf, or conversion specifications, each of which
converts zero or more arguments, again copied into buf. The results
are unpredictable if there are insufficient arguments for the format;
excess arguments are simply ignored. It is the user's responsibility to
ensure that enough storage is available for buf.
ap contains the list of arguments used by the conversion specifications
in fmt. ap is a variable argument list and must be initialized by call‐
ing va_start(9F). va_end(9F) is used to clean up and must be called
after each traversal of the list. Multiple traversals of the argument
list, each bracketed by va_start(9F) and va_end(9F), are possible.
Each conversion specification is introduced by the % character, after
which the following appear in sequence:
An optional decimal digit specifying a minimum field width for numeric
conversion. The converted value will be right-justified and padded with
leading zeroes if it has fewer characters than the minimum.
An optional l (ll) specifying that a following d, D, o, O, x, X, or u
conversion character applies to a long (long long) integer argument. An
l (ll) before any other conversion character is ignored.
A character indicating the type of conversion to be applied:
d,D,o,O,x,X,u
The integer argument is converted to signed decimal (d, D),
unsigned octal (o, O), unsigned hexadecimal (x, X) or unsigned dec‐
imal (u), respectively, and copied. The letters abcdef are used for
x conversion. The letters ABCDEF are used for X conversion.
c
The character value of the argument is copied.
b
This conversion uses two additional arguments. The first is an
integer, and is converted according to the base specified in the
second argument. The second argument is a character string in the
form <base>[<arg>...]. The base supplies the conversion base for
the first argument as a binary value; \10 gives octal, \20 gives
hexadecimal. Each subsequent <arg> is a sequence of characters, the
first of which is the bit number to be tested, and subsequent char‐
acters, up to the next bit number or terminating null, supply the
name of the bit.
A bit number is a binary-valued character in the range 1-32. For
each bit set in the first argument, and named in the second argu‐
ment, the bit names are copied, separated by commas, and bracketed
by < and >. Thus, the following function call would generate
reg=3<BitTwo,BitOne>\n in buf.
vsprintf(buf, "reg=%b\n", 3, "\10\2BitTwo\1BitOne")
s
The argument is taken to be a string (character pointer), and char‐
acters from the string are copied until a null character is encoun‐
tered. If the character pointer is NULL on SPARC, the string
<nullstring> is used in its place; on x86, it is undefined.
%
Copy a %; no argument is converted.
RETURN VALUESvsprintf() returns its first parameter, buf.
CONTEXTvsprintf() can be called from user, kernel, or interrupt context.
EXAMPLES
Example 1: Using vsprintf()
In this example, xxerror() accepts a pointer to a dev_info_t structure
dip, an error level level, a format fmt, and a variable number of
arguments. The routine uses vsprintf() to format the error message in
buf. Note that va_start(9F) and va_end(9F) bracket the call to
vsprintf(). instance, level, name, and buf are then passed to
cmn_err(9F).
#include <sys/varargs.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#define MAX_MSG 256
void
xxerror(dev_info_t *dip, int level, const char *fmt, ...)
{
va_list ap;
int instance;
char buf[MAX_MSG],
*name;
instance = ddi_get_instance(dip);
name = ddi_binding_name(dip);
/* format buf using fmt and arguments contained in ap */
va_start(ap, fmt);
vsprintf(buf, fmt, ap);
va_end(ap);
/* pass formatted string to cmn_err(9F) */
cmn_err(level, "%s%d: %s", name, instance, buf);
}
SEE ALSOcmn_err(9F), ddi_binding_name(9F), ddi_get_instance(9F), va_arg(9F)
Writing Device Drivers
SunOS 5.10 6 May 1996 vsprintf(9F)
