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vsprintf(9f)

vsprintf(9F)                   Kernel Functions                   vsprintf(9F)

NAME
       vsprintf - 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.


DESCRIPTION
       vsprintf()  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; ex‐
       cess 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 af‐
       ter  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  conver‐
                          sion. 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 sec‐
                          ond 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
                          characters, 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  char‐
                          acter  pointer  is  NULL on SPARC, the string <null‐
                          string> is used in its place; on x86,  it  is  unde‐
                          fined.


       %                  Copy a %; no argument is converted.


RETURN VALUES
       vsprintf() returns its first parameter, buf.

CONTEXT
       vsprintf() 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 argu‐
       ments. 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 ALSO
       va_arg(9F), cmn_err(9F), ddi_binding_name(9F), ddi_get_instance(9F)


       Writing Device Drivers in Oracle Solaris 11.4

Oracle Solaris 11.4               6 May 1996                      vsprintf(9F)
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