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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;
       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 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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