Add dprintf() and vdprintf() from POSIX.1-2008. Like getline(),

dprintf() is a simple wrapper around another function, so we may as
well implement it. But also like getline(), we can't prototype it by
default right now because it would break too many ports.

1 files changed, 76 insertions, 27 deletions

diff --git a/lib/libc/stdio/printf.3 b/lib/libc/stdio/printf.3
index 98e26dc..27d5bf0 100644
--- a/lib/libc/stdio/printf.3
+++ b/lib/libc/stdio/printf.3
@@ -32,16 +32,17 @@
 .\"     @(#)printf.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd October 16, 2004
+.Dd March 3, 2009
 .Dt PRINTF 3
 .Os
 .Sh NAME
-.Nm printf , fprintf , sprintf , snprintf , asprintf ,
-.Nm vprintf , vfprintf, vsprintf , vsnprintf , vasprintf
+.Nm printf , fprintf , sprintf , snprintf , asprintf , dprintf ,
+.Nm vprintf , vfprintf, vsprintf , vsnprintf , vasprintf, vdprintf
 .Nd formatted output conversion
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
+.Fd "#define _WITH_DPRINTF"
 .In stdio.h
 .Ft int
 .Fn printf "const char * restrict format" ...
@@ -53,6 +54,8 @@
 .Fn snprintf "char * restrict str" "size_t size" "const char * restrict format" ...
 .Ft int
 .Fn asprintf "char **ret" "const char *format" ...
+.Ft int
+.Fn dprintf "int" "const char * restrict format" ...
 .In stdarg.h
 .Ft int
 .Fn vprintf "const char * restrict format" "va_list ap"
@@ -64,6 +67,8 @@
 .Fn vsnprintf "char * restrict str" "size_t size" "const char * restrict format" "va_list ap"
 .Ft int
 .Fn vasprintf "char **ret" "const char *format" "va_list ap"
+.Ft int
+.Fn vdprintf "int fd" "const char * restrict format" "va_list ap"
 .Sh DESCRIPTION
 The
 .Fn printf
@@ -83,6 +88,10 @@ and
 .Fn vfprintf
 write output to the given output
 .Fa stream ;
+.Fn dprintf
+and
+.Fn vdprintf
+write output to the given file descriptor;
 .Fn sprintf ,
 .Fn snprintf ,
 .Fn vsprintf ,
@@ -771,6 +780,57 @@ for later interpolation by
 Always use the proper secure idiom:
 .Pp
 .Dl "snprintf(buffer, sizeof(buffer), \*q%s\*q, string);"
+.Sh COMPATIBILITY
+Many application writers used the name
+.Va dprintf
+before the
+.Fn dprintf
+function was introduced in
+.St -p1003.1 ,
+so a prototype is not provided by default in order to avoid
+compatibility problems.
+Applications that wish to use the
+.Fn dprintf
+function described herein should either request a strict
+.St -p1003.1-2008
+environment by defining the macro
+.Dv _POSIX_C_SOURCE
+to the value 200809 or greater, or by defining the macro
+.Dv _WITH_DPRINTF ,
+prior to the inclusion of
+.In stdio.h .
+For compatibility with GNU libc, defining either
+.Dv _BSD_SOURCE
+or
+.Dv _GNU_SOURCE
+prior to the inclusion of
+.In stdio.h
+will also make
+.Fn dprintf
+available.
+.Pp
+The conversion formats
+.Cm \&%D , \&%O ,
+and
+.Cm %U
+are not standard and
+are provided only for backward compatibility.
+The effect of padding the
+.Cm %p
+format with zeros (either by the
+.Cm 0
+flag or by specifying a precision), and the benign effect (i.e., none)
+of the
+.Cm #
+flag on
+.Cm %n
+and
+.Cm %p
+conversions, as well as other
+nonsensical combinations such as
+.Cm %Ld ,
+are not standard; such combinations
+should be avoided.
 .Sh ERRORS
 In addition to the errors documented for the
 .Xr write 2
@@ -810,7 +870,13 @@ With the same reservation, the
 and
 .Fn vsnprintf
 functions conform to
-.St -isoC-99 .
+.St -isoC-99 ,
+while
+.Fn dprintf
+and
+.Fn vdprintf
+conform to
+.St -p1003.1-2008 .
 .Sh HISTORY
 The functions
 .Fn asprintf
@@ -828,30 +894,13 @@ from
 .An Todd C. Miller Aq Todd.Miller@courtesan.com
 for
 .Ox 2.3 .
-.Sh BUGS
-The conversion formats
-.Cm \&%D , \&%O ,
-and
-.Cm %U
-are not standard and
-are provided only for backward compatibility.
-The effect of padding the
-.Cm %p
-format with zeros (either by the
-.Cm 0
-flag or by specifying a precision), and the benign effect (i.e., none)
-of the
-.Cm #
-flag on
-.Cm %n
+The
+.Fn dprintf
 and
-.Cm %p
-conversions, as well as other
-nonsensical combinations such as
-.Cm %Ld ,
-are not standard; such combinations
-should be avoided.
-.Pp
+.Fn vdprintf
+functions were added in
+.Fx 8.0 .
+.Sh BUGS
 The
 .Nm
 family of functions do not correctly handle multibyte characters in the