The files
 
 asnprintf.c 
 printf-args.c
 printf-args.h
 printf-parse.c
 printf-parse.h
 vasnprintf.c
 vasnprintf.h

are taken from the vasnprintf module of the GNUlib package, which can
be found at: 

 http://www.gnu.org/software/gnulib/

All files have been modified to include g-gnulib.h. 

vasnprintf.c has also been modified to include support for long long 
printing if the system printf doesn't. This code is protected by 
#ifndef HAVE_LONG_LONG_FORMAT.

Code has been added to printf-args.[ch], printf-parse.c and vasnprintf.c
to support printing of __int64 values with the I64 format modifier. This
is protected by #ifdef HAVE_INT64_AND_I64.

The files

 printf.h 
 printf.c
 g-gnulib.h

have been written by me. printf.[hc] contain implementations of the  
remaining functions in the printf family based on vasnprintf. 
g-gnulib.h is included by all source files in order to move all
exported functions to the _g_gnulib namespace, replace malloc by
g_malloc and make sure that snprintf is only used if it implements 
C99 return value semantics. 

Matthias Clasen
November 1, 2003

To update:
* Create an empty directory, put a configure.ac file into it.
* Run gnulib-tool --lgpl=2 --import --lib=libgnu --source-base=lib \
  --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=. \
  --no-conditional-dependencies --no-libtool --macro-prefix=gl \
  isnand-nolibm isnanf-nolibm isnanl-nolibm printf-frexpl \
  signbit vasnprintf
* Then pick out the files that are already in glib/gnulib subdirectory
  (the rest of the files are not needed):

asnprintf.c
c++defs.h
float+.h
fpucw.h
gnulib_math.h.in (rename from math.in.h)
isnan.c
isnand.c
isnand-nolibm.h
isnanf.c
isnanf-nolibm.h
isnanl.c
isnanl-nolibm.h
printf-args.c
printf-args.h
printf-frexp.c
printf-frexp.h
printf-frexpl.c
printf-frexpl.h
printf-parse.c
printf-parse.h
signbitd.c
signbitf.c
signbitl.c
vasnprintf.c
vasnprintf.h
verify.h
xsize.h

* Then look at the glib-gnulib.patch and re-introduce custom glib changes
  contained in that patch.
* If gnulib_math.h.in got some new @variables@, these will have to be
  somehow set in meson.build, otherwise meson would warn about them
  at configure stage

LRN
June 06, 2018