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--- Libc/Libc-262.3.2/stdio/printf.3
+++ Libc/Libc-583/stdio/printf.3
@@ -34,51 +34,97 @@
.\" SUCH DAMAGE.
.\"
.\" @(#)printf.3 8.1 (Berkeley) 6/4/93
-.\" $FreeBSD: src/lib/libc/stdio/printf.3,v 1.17.2.10 2001/12/14 18:33:57 ru Exp $
+.\" $FreeBSD: src/lib/libc/stdio/printf.3,v 1.58 2004/10/16 16:00:01 stefanf Exp $
.\"
-.Dd June 4, 1993
+.Dd October 16, 2004
.Dt PRINTF 3
.Os
.Sh NAME
-.Nm printf , fprintf , sprintf , snprintf , asprintf ,
-.Nm vprintf , vfprintf, vsprintf , vsnprintf , vasprintf
+.Nm asprintf ,
+.Nm fprintf ,
+.Nm printf ,
+.Nm snprintf ,
+.Nm sprintf ,
+.Nm vasprintf ,
+.Nm vfprintf,
+.Nm vprintf ,
+.Nm vsnprintf ,
+.Nm vsprintf
.Nd formatted output conversion
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdio.h
.Ft int
-.Fn printf "const char *format" ...
+.Fo asprintf
+.Fa "char **ret"
+.Fa "const char *format" ...
+.Fc
.Ft int
-.Fn fprintf "FILE *stream" "const char *format" ...
+.Fo fprintf
+.Fa "FILE *restrict stream"
+.Fa "const char *restrict format" ...
+.Fc
.Ft int
-.Fn sprintf "char *str" "const char *format" ...
+.Fo printf
+.Fa "const char *restrict format" ...
+.Fc
.Ft int
-.Fn snprintf "char *str" "size_t size" "const char *format" ...
+.Fo snprintf
+.Fa "char *restrict s"
+.Fa "size_t n"
+.Fa "const char *restrict format" ...
+.Fc
.Ft int
-.Fn asprintf "char **ret" "const char *format" ...
+.Fo sprintf
+.Fa "char *restrict s"
+.Fa "const char *restrict format" ...
+.Fc
.In stdarg.h
+.In stdio.h
.Ft int
-.Fn vprintf "const char *format" "va_list ap"
+.Fo vasprintf
+.Fa "char **ret"
+.Fa "const char *format"
+.Fa "va_list ap"
+.Fc
.Ft int
-.Fn vfprintf "FILE *stream" "const char *format" "va_list ap"
+.Fo vfprintf
+.Fa "FILE *restrict stream"
+.Fa "const char *restrict format"
+.Fa "va_list ap"
+.Fc
.Ft int
-.Fn vsprintf "char *str" "const char *format" "va_list ap"
+.Fo vprintf
+.Fa "const char *restrict format"
+.Fa "va_list ap"
+.Fc
.Ft int
-.Fn vsnprintf "char *str" "size_t size" "const char *format" "va_list ap"
+.Fo vsnprintf
+.Fa "char *restrict s"
+.Fa "size_t n"
+.Fa "const char *restrict format"
+.Fa "va_list ap"
+.Fc
.Ft int
-.Fn vasprintf "char **ret" "const char *format" "va_list ap"
+.Fo vsprintf
+.Fa "char *restrict s"
+.Fa "const char *restrict format"
+.Fa "va_list ap"
+.Fc
.Sh DESCRIPTION
The
.Fn printf
family of functions produces output according to a
-.Fa format
+.Fa format ,
as described below.
-.Fn Printf
+The
+.Fn printf
and
.Fn vprintf
+functions
write output to
-.Pa stdout ,
+.Dv stdout ,
the standard output stream;
.Fn fprintf
and
@@ -91,13 +137,19 @@
and
.Fn vsnprintf
write to the character string
-.Fa str ;
+.Fa s ;
and
.Fn asprintf
and
.Fn vasprintf
dynamically allocate a new string with
.Xr malloc 3 .
+.Pp
+Extended locale versions of these functions are documented in
+.Xr printf_l 3 .
+See
+.Xr xlocale 3
+for more information.
.Pp
These functions write the output under the control of a
.Fa format
@@ -109,20 +161,22 @@
These functions return the number of characters printed
(not including the trailing
.Ql \e0
-used to end output to strings),
+used to end output to strings) or a negative value if an output error occurs,
except for
.Fn snprintf
and
.Fn vsnprintf ,
which return the number of characters that would have been printed if the
-.Fa size
+.Fa n
were unlimited
(again, not including the final
.Ql \e0 ) .
.Pp
-.Fn Asprintf
+The
+.Fn asprintf
and
.Fn vasprintf
+functions
set
.Fa *ret
to be a pointer to a buffer sufficiently large to hold the formatted string.
@@ -133,32 +187,41 @@
.Fn asprintf
and
.Fn vasprintf
-will return -1 and set
+will return \-1 and set
.Fa ret
to be a
.Dv NULL
pointer.
.Pp
-.Fn Snprintf
+The
+.Fn snprintf
and
.Fn vsnprintf
+functions
will write at most
-.Fa size Ns \-1
+.Fa n Ns \-1
of the characters printed into the output string
(the
-.Fa size Ns 'th
+.Fa n Ns \'th
character then gets the terminating
.Ql \e0 ) ;
if the return value is greater than or equal to the
-.Fa size
+.Fa n
argument, the string was too short
and some of the printed characters were discarded.
-.Pp
-.Fn Sprintf
+The output is always null-terminated.
+.Pp
+The
+.Fn sprintf
and
.Fn vsprintf
+functions
effectively assume an infinite
-.Fa size .
+.Fa n .
+.Pp
+For those routines that write to a user-provided character string,
+that string and the format strings should not overlap, as the
+behavior is undefined.
.Pp
The format string is composed of zero or more directives:
ordinary
@@ -190,12 +253,9 @@
are accessed the results will be indeterminate.
.It
Zero or more of the following flags:
-.Bl -hyphen
-.It
-A
-.Cm #
-character
-specifying that the value should be converted to an
+.Bl -tag -width ".So \ Sc (space)"
+.It Sq Cm #
+The value should be converted to an
.Dq alternate form .
For
.Cm c , d , i , n , p , s ,
@@ -219,7 +279,7 @@
.Cm X
conversions) prepended to it.
For
-.Cm e , E , f , g ,
+.Cm a , A , e , E , f , F , g ,
and
.Cm G
conversions, the result will always contain a decimal point, even if no
@@ -231,11 +291,8 @@
.Cm G
conversions, trailing zeros are not removed from the result as they
would otherwise be.
-.It
-A
-.Cm 0
-(zero)
-character specifying zero padding.
+.It So Cm 0 Sc (zero)
+Zero padding.
For all conversions except
.Cm n ,
the converted value is padded on the left with zeros rather than blanks.
@@ -246,10 +303,9 @@
the
.Cm 0
flag is ignored.
-.It
-A negative field width flag
-.Cm \-
-indicates the converted value is to be left adjusted on the field boundary.
+.It Sq Cm \-
+A negative field width flag;
+the converted value is to be left adjusted on the field boundary.
Except for
.Cm n
conversions, the converted value is padded on the right with blanks,
@@ -259,21 +315,45 @@
overrides a
.Cm 0
if both are given.
-.It
-A space, specifying that a blank should be left before a positive number
+.It So "\ " Sc (space)
+A blank should be left before a positive number
produced by a signed conversion
-.Cm ( d , e , E , f , g , G ,
+.Cm ( a , A , d , e , E , f , F , g , G ,
or
.Cm i ) .
-.It
-A
-.Cm +
-character specifying that a sign always be placed before a
+.It Sq Cm +
+A sign must always be placed before a
number produced by a signed conversion.
A
.Cm +
overrides a space if both are used.
+.It Sq Cm '
+Decimal conversions
+.Cm ( d , u ,
+or
+.Cm i )
+or the integral portion of a floating point conversion
+.Cm ( f
+or
+.Cm F )
+should be grouped and separated by thousands using
+the non-monetary separator returned by
+.Xr localeconv 3 .
.El
+.It
+An optional separator character (
+.Cm \ , | \; | \ : | _
+) used for separating multiple values when printing an AltiVec or SSE vector,
+or other multi-value unit.
+.Pp
+NOTE: This is an extension to the
+.Fn printf
+specification.
+Behaviour of these values for
+.Fn printf
+is only defined for operating systems conforming to the
+AltiVec Technology Programming Interface Manual.
+(At time of writing this includes only Mac OS X 10.2 and later.)
.It
An optional decimal digit string specifying a minimum field width.
If the converted value has fewer characters than the field width, it will
@@ -291,9 +371,9 @@
and
.Cm X
conversions, the number of digits to appear after the decimal-point for
-.Cm e , E ,
-and
-.Cm f
+.Cm a , A , e , E , f ,
+and
+.Cm F
conversions, the maximum number of significant digits for
.Cm g
and
@@ -303,79 +383,98 @@
.Cm s
conversions.
.It
-The optional character
-.Cm h ,
-specifying that a following
-.Cm d , i , o , u , x ,
+An optional length modifier, that specifies the size of the argument.
+The following length modifiers are valid for the
+.Cm d , i , n , o , u , x ,
or
.Cm X
-conversion corresponds to a
-.Vt short int
-or
-.Vt unsigned short int
-argument, or that a following
+conversion:
+.Bl -column ".Cm q Em (deprecated)" ".Vt signed char" ".Vt unsigned long long" ".Vt long long *"
+.It Sy Modifier Ta Cm d , i Ta Cm o , u , x , X Ta Cm n
+.It Cm hh Ta Vt "signed char" Ta Vt "unsigned char" Ta Vt "signed char *"
+.It Cm h Ta Vt short Ta Vt "unsigned short" Ta Vt "short *"
+.It Cm l No (ell) Ta Vt long Ta Vt "unsigned long" Ta Vt "long *"
+.It Cm ll No (ell ell) Ta Vt "long long" Ta Vt "unsigned long long" Ta Vt "long long *"
+.It Cm j Ta Vt intmax_t Ta Vt uintmax_t Ta Vt "intmax_t *"
+.It Cm t Ta Vt ptrdiff_t Ta (see note) Ta Vt "ptrdiff_t *"
+.It Cm z Ta (see note) Ta Vt size_t Ta (see note)
+.It Cm q Em (deprecated) Ta Vt quad_t Ta Vt u_quad_t Ta Vt "quad_t *"
+.El
+.Pp
+Note:
+the
+.Cm t
+modifier, when applied to a
+.Cm o , u , x ,
+or
+.Cm X
+conversion, indicates that the argument is of an unsigned type
+equivalent in size to a
+.Vt ptrdiff_t .
+The
+.Cm z
+modifier, when applied to a
+.Cm d
+or
+.Cm i
+conversion, indicates that the argument is of a signed type equivalent in
+size to a
+.Vt size_t .
+Similarly, when applied to an
.Cm n
-conversion corresponds to a pointer to a
-.Vt short int
-argument.
-.It
-The optional character
-.Cm l
-(ell) specifying that a following
-.Cm d , i , o , u , x ,
-or
-.Cm X
-conversion applies to a pointer to a
-.Vt long int
-or
-.Vt unsigned long int
-argument, or that a following
-.Cm n
-conversion corresponds to a pointer to a
-.Vt long int
-argument.
-.It
-The optional characters
-.Cm ll
-(ell ell) specifying that a following
-.Cm d , i , o , u , x ,
-or
-.Cm X
-conversion applies to a pointer to a
-.Vt long long int
-or
-.Vt unsigned long long int
-argument, or that a following
-.Cm n
-conversion corresponds to a pointer to a
-.Vt long long int
-argument.
-.It
-The optional character
-.Cm q ,
-specifying that a following
-.Cm d , i , o , u , x ,
-or
-.Cm X
-conversion corresponds to a
-.Vt quad int
-or
-.Vt unsigned quad int
-argument, or that a following
-.Cm n
-conversion corresponds to a pointer to a
-.Vt quad int
-argument.
-.It
-The character
-.Cm L
-specifying that a following
-.Cm e , E , f , g ,
+conversion, it indicates that the argument is a pointer to a signed type
+equivalent in size to a
+.Vt size_t .
+.Pp
+The following length modifier is valid for the
+.Cm a , A , e , E , f , F , g ,
or
.Cm G
-conversion corresponds to a
-.Vt long double
-argument.
+conversion:
+.Bl -column ".Sy Modifier" ".Cm a , A , e , E , f , F , g , G"
+.It Sy Modifier Ta Cm a , A , e , E , f , F , g , G
+.It Cm l No (ell) Ta Vt double
+(ignored, same behavior as without it)
+.It Cm L Ta Vt "long double"
+.El
+.Pp
+The following length modifier is valid for the
+.Cm c
+or
+.Cm s
+conversion:
+.Bl -column ".Sy Modifier" ".Vt wint_t" ".Vt wchar_t *"
+.It Sy Modifier Ta Cm c Ta Cm s
+.It Cm l No (ell) Ta Vt wint_t Ta Vt "wchar_t *"
+.El
+.Pp
+The AltiVec Technology Programming Interface Manual also defines five additional length modifiers
+which can be used (in place of the conventional length modifiers) for the printing of AltiVec or SSE vectors:
+.Bl -tag -compact
+.It Cm v
+Treat the argument as a vector value, unit length will be determined by the conversion
+specifier (default = 16 8-bit units for all integer conversions,
+4 32-bit units for floating point conversions).
+.It Cm vh, hv
+Treat the argument as a vector of 8 16-bit units.
+.It Cm vl, lv
+Treat the argument as a vector of 4 32-bit units.
+.El
+.Pp
+NOTE: The vector length specifiers are extensions to the
+.Fn printf
+specification.
+Behaviour of these values for
+.Fn printf
+is only defined for operating systems conforming to the
+AltiVec Technology Programming Interface Manual.
+(At time of writing this includes only Mac OS X 10.2 and later.)
+.Pp
+As a further extension, for SSE2 64-bit units:
+.Bl -tag -compact
+.It Cm vll, llv
+Treat the argument as a vector of 2 64-bit units.
+.El
.It
A character that specifies the type of conversion to be applied.
.El
@@ -393,11 +492,12 @@
A negative field width is treated as a left adjustment flag followed by a
positive field width; a negative precision is treated as though it were
missing.
-If a single format directive mixes positional (nn$)
+If a single format directive mixes positional
+.Pq Li nn$
and non-positional arguments, the results are undefined.
.Pp
The conversion specifiers and their meanings are:
-.Bl -tag -width "diouxX"
+.Bl -tag -width ".Cm diouxX"
.It Cm diouxX
The
.Vt int
@@ -415,11 +515,11 @@
.Cm X )
notation.
The letters
-.Cm abcdef
+.Dq Li abcdef
are used for
.Cm x
conversions; the letters
-.Cm ABCDEF
+.Dq Li ABCDEF
are used for
.Cm X
conversions.
@@ -428,7 +528,7 @@
the left with zeros.
.It Cm DOU
The
-.Vt long int
+.Vt "long int"
argument is converted to signed decimal, unsigned octal, or unsigned
decimal, as if the format had been
.Cm ld , lo ,
@@ -440,7 +540,9 @@
The
.Vt double
argument is rounded and converted in the style
-.Oo \- Oc Ns d Ns Cm \&. Ns ddd Ns Cm e Ns \\*[Pm]dd
+.Sm off
+.Oo \- Oc Ar d Li \&. Ar ddd Li e \\*[Pm] Ar dd
+.Sm on
where there is one digit before the
decimal-point character
and the number of digits after it is equal to the precision;
@@ -450,17 +552,38 @@
An
.Cm E
conversion uses the letter
-.Cm E
+.Ql E
(rather than
-.Cm e )
+.Ql e )
to introduce the exponent.
The exponent always contains at least two digits; if the value is zero,
the exponent is 00.
-.It Cm f
+.Pp
+For
+.Cm a , A , e , E , f , F , g ,
+and
+.Cm G
+conversions, positive and negative infinity are represented as
+.Li inf
+and
+.Li -inf
+respectively when using the lowercase conversion character, and
+.Li INF
+and
+.Li -INF
+respectively when using the uppercase conversion character.
+Similarly, NaN is represented as
+.Li nan
+when using the lowercase conversion, and
+.Li NAN
+when using the uppercase conversion.
+.It Cm fF
The
.Vt double
argument is rounded and converted to decimal notation in the style
-.Oo \- Oc Ns ddd Ns Cm \&. Ns ddd ,
+.Sm off
+.Oo \- Oc Ar ddd Li \&. Ar ddd ,
+.Sm on
where the number of digits after the decimal-point character
is equal to the precision specification.
If the precision is missing, it is taken as 6; if the precision is
@@ -474,6 +597,8 @@
or
.Cm e
(or
+.Cm F
+or
.Cm E
for
.Cm G
@@ -483,19 +608,90 @@
it is treated as 1.
Style
.Cm e
-is used if the exponent from its conversion is less than -4 or greater than
+is used if the exponent from its conversion is less than \-4 or greater than
or equal to the precision.
Trailing zeros are removed from the fractional part of the result; a
decimal point appears only if it is followed by at least one digit.
+.It Cm aA
+The
+.Vt double
+argument is rounded and converted to hexadecimal notation in the style
+.Sm off
+.Oo \- Oc Li 0x Ar h Li \&. Ar hhhp Oo \\*[Pm] Oc Ar d ,
+.Sm on
+where the number of digits after the hexadecimal-point character
+is equal to the precision specification.
+If the precision is missing, it is taken as enough to represent
+the floating-point number exactly, and no rounding occurs.
+If the precision is zero, no hexadecimal-point character appears.
+The
+.Cm p
+is a literal character
+.Ql p ,
+and the exponent consists of a positive or negative sign
+followed by a decimal number representing an exponent of 2.
+The
+.Cm A
+conversion uses the prefix
+.Dq Li 0X
+(rather than
+.Dq Li 0x ) ,
+the letters
+.Dq Li ABCDEF
+(rather than
+.Dq Li abcdef )
+to represent the hex digits, and the letter
+.Ql P
+(rather than
+.Ql p )
+to separate the mantissa and exponent.
+.Pp
+Note that there may be multiple valid ways to represent floating-point
+numbers in this hexadecimal format.
+For example,
+.Li 0x3.24p+0 , 0x6.48p-1
+and
+.Li 0xc.9p-2
+are all equivalent.
+The format chosen depends on the internal representation of the
+number, but the implementation guarantees that the length of the
+mantissa will be minimized.
+Zeroes are always represented with a mantissa of 0 (preceded by a
+.Ql -
+if appropriate) and an exponent of
+.Li +0 .
+.It Cm C
+Treated as
+.Cm c
+with the
+.Cm l
+(ell) modifier.
.It Cm c
The
.Vt int
argument is converted to an
-.Vt unsigned char ,
+.Vt "unsigned char" ,
and the resulting character is written.
+.Pp
+If the
+.Cm l
+(ell) modifier is used, the
+.Vt wint_t
+argument shall be converted to a
+.Vt wchar_t ,
+and the (potentially multi-byte) sequence representing the
+single wide character is written, including any shift sequences.
+If a shift sequence is used, the shift state is also restored
+to the original state after the character.
+.It Cm S
+Treated as
+.Cm s
+with the
+.Cm l
+(ell) modifier.
.It Cm s
The
-.Vt char *
+.Vt "char *"
argument is expected to be a pointer to an array of character type (pointer
to a string).
Characters from the array are written up to (but not including)
@@ -509,9 +705,34 @@
the size of the array, the array must contain a terminating
.Dv NUL
character.
+.Pp
+If the
+.Cm l
+(ell) modifier is used, the
+.Vt "wchar_t *"
+argument is expected to be a pointer to an array of wide characters
+(pointer to a wide string).
+For each wide character in the string, the (potentially multi-byte)
+sequence representing the
+wide character is written, including any shift sequences.
+If any shift sequence is used, the shift state is also restored
+to the original state after the string.
+Wide characters from the array are written up to (but not including)
+a terminating wide
+.Dv NUL
+character;
+if a precision is specified, no more than the number of bytes specified are
+written (including shift sequences).
+Partial characters are never written.
+If a precision is given, no null character
+need be present; if the precision is not specified, or is greater than
+the number of bytes required to render the multibyte representation of
+the string, the array must contain a terminating wide
+.Dv NUL
+character.
.It Cm p
The
-.Vt void *
+.Vt "void *"
pointer argument is printed in hexadecimal (as if by
.Ql %#x
or
@@ -519,7 +740,7 @@
.It Cm n
The number of characters written so far is stored into the
integer indicated by the
-.Vt int *
+.Vt "int *"
(or variant) pointer argument.
No argument is converted.
.It Cm %
@@ -532,8 +753,13 @@
.Ql %% .
.El
.Pp
+The decimal point
+character is defined in the program's locale (category
+.Dv LC_NUMERIC ) .
+.Pp
In no case does a non-existent or small field width cause truncation of
-a field; if the result of a conversion is wider than the field width, the
+a numeric field; if the result of a conversion is wider than the field
+width, the
field is expanded to contain the conversion result.
.Sh EXAMPLES
To print a date and time in the form
@@ -564,21 +790,111 @@
#include <stdarg.h>
char *newfmt(const char *fmt, ...)
{
- char *p;
- va_list ap;
- if ((p = malloc(128)) == NULL)
- return (NULL);
- va_start(ap, fmt);
- (void) vsnprintf(p, 128, fmt, ap);
- va_end(ap);
- return (p);
+ char *p;
+ va_list ap;
+ if ((p = malloc(128)) == NULL)
+ return (NULL);
+ va_start(ap, fmt);
+ (void) vsnprintf(p, 128, fmt, ap);
+ va_end(ap);
+ return (p);
}
.Ed
+.Sh SECURITY CONSIDERATIONS
+The
+.Fn sprintf
+and
+.Fn vsprintf
+functions are easily misused in a manner which enables malicious users
+to arbitrarily change a running program's functionality through
+a buffer overflow attack.
+Because
+.Fn sprintf
+and
+.Fn vsprintf
+assume an infinitely long string,
+callers must be careful not to overflow the actual space;
+this is often hard to assure.
+For safety, programmers should use the
+.Fn snprintf
+interface instead.
+For example:
+.Bd -literal
+void
+foo(const char *arbitrary_string, const char *and_another)
+{
+ char onstack[8];
+
+#ifdef BAD
+ /*
+ * This first sprintf is bad behavior. Do not use sprintf!
+ */
+ sprintf(onstack, "%s, %s", arbitrary_string, and_another);
+#else
+ /*
+ * The following two lines demonstrate better use of
+ * snprintf().
+ */
+ snprintf(onstack, sizeof(onstack), "%s, %s", arbitrary_string,
+ and_another);
+#endif
+}
+.Ed
+.Pp
+The
+.Fn printf
+and
+.Fn sprintf
+family of functions are also easily misused in a manner
+allowing malicious users to arbitrarily change a running program's
+functionality by either causing the program
+to print potentially sensitive data
+.Dq "left on the stack" ,
+or causing it to generate a memory fault or bus error
+by dereferencing an invalid pointer.
+.Pp
+.Cm %n
+can be used to write arbitrary data to potentially carefully-selected
+addresses.
+Programmers are therefore strongly advised to never pass untrusted strings
+as the
+.Fa format
+argument, as an attacker can put format specifiers in the string
+to mangle your stack,
+leading to a possible security hole.
+This holds true even if the string was built using a function like
+.Fn snprintf ,
+as the resulting string may still contain user-supplied conversion specifiers
+for later interpolation by
+.Fn printf .
+.Pp
+Always use the proper secure idiom:
+.Pp
+.Dl "snprintf(buffer, sizeof(buffer), \*q%s\*q, string);"
+.Sh ERRORS
+In addition to the errors documented for the
+.Xr write 2
+system call, the
+.Fn printf
+family of functions may fail if:
+.Bl -tag -width Er
+.It Bq Er EILSEQ
+An invalid wide character code was encountered.
+.It Bq Er ENOMEM
+Insufficient storage space is available.
+.El
.Sh SEE ALSO
.Xr printf 1 ,
-.Xr scanf 3
+.Xr fmtcheck 3 ,
+.Xr printf_l 3 ,
+.Xr scanf 3 ,
+.Xr setlocale 3 ,
+.Xr stdarg 3 ,
+.Xr wprintf 3
.Sh STANDARDS
-The
+Subject to the caveats noted in the
+.Sx BUGS
+section below, the
.Fn fprintf ,
.Fn printf ,
.Fn sprintf ,
@@ -588,7 +904,15 @@
.Fn vsprintf
functions
conform to
-.St -isoC .
+.St -ansiC
+and
+.St -isoC-99 .
+With the same reservation, the
+.Fn snprintf
+and
+.Fn vsnprintf
+functions conform to
+.St -isoC-99 .
.Sh HISTORY
The functions
.Fn asprintf
@@ -630,14 +954,8 @@
are not standard; such combinations
should be avoided.
.Pp
-Because
-.Fn sprintf
-and
-.Fn vsprintf
-assume an infinitely long string,
-callers must be careful not to overflow the actual space;
-this is often hard to assure.
-For safety, programmers should use the
-.Fn snprintf
-interface instead.
-Unfortunately, this interface is not portable.
+The
+.Nm
+family of functions do not correctly handle multibyte characters in the
+.Fa format
+argument.