VSPRINTF(9F)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 decimal (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 charac‐
ters, 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 argument, 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 characters from the string are copied
until a null character is encountered. If the charac‐
ter 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
May 6, 1996 VSPRINTF(9F)
