C99-snprintf provides a portable implementation of snprintf, vsnprintf, asprintf, and vasprintf. It should be fully C99 compliant, with the exceptions that it doesn't provide wide character support and that %a and %A conversions aren't supported. C99-snprintf should be buildable with any ANSI C compiler, it doesn't require libc functionality other than malloc (for vasprintf) and the stdarg or varargs macros, and it has no other prerequisites.
The snprintf and vsnprintf functions are part of the C99 standard library. However, they weren't included in the C89/C90 standards and some systems don't provide C99 compliant implementations of these functions. For example, if the ouput buffer isn't big enough to hold the full conversion result, IRIX up to the current release 6.5.30 and glibc up to 2.0.x don't return the same value as with a sufficiently sized buffer (which makes it impossible to precompute the required buffer size), and some older systems (such as 64-bit Solaris 7) ignore the specified buffer size and overrun the buffer if it's too small. The asprintf and vasprintf functions aren't standardized at all. They're included with recent releases of glibc and BSD's libc, but they aren't available on other systems, such as System V (e.g., Solaris).
So, if any of these functions are used, portable software should include replacement code which is used in case the functions aren't available or don't work correctly on the target system. This library can be included with software packages in order to provide such replacement functions.
With GNU Autoconf 2.60 or newer
Add snprintf.c to your project files. If you're using GNU Automake, you could use a line such as foo_LDADD = $(LIBOBJS) (where foo is the name of your program) in your Makefile.am.
Add snprintf.m4 to your m4 include directory or to your acinclude.m4 file. If you're using neither, you can simply include the contents of snprintf.m4 in your configure.ac file.
For each replacement function which might be needed in your project, call the according Autoconf macro in your configure.ac file. That is, in order to have all four replacement functions available if needed:
The required replacement functions should be declared in some header file included throughout your project files:
#include < config.h >
#include < stdarg.h >
int rpl_vsnprintf(char *, size_t, const char *, va_list);
int rpl_snprintf(char *, size_t, const char *, ...);
int rpl_vasprintf(char **, const char *, va_list);
int rpl_asprintf(char **, const char *, ...);
#endif /* HAVE_STDARG_H */
Without GNU Autoconf
If you're not using GNU Autoconf, omit the steps 2 and 3 from the above instructions. Instead:
The following preprocessor macros should be defined to 1 if the feature or file in question is available on the target system (though basic functionality should be available as long as HAVE_STDARG_H and HAVE_STDLIB_H are defined correctly):
The calls to the functions which should be replaced must be redefined throughout the project files:
#define vsnprintf rpl_vsnprintf
#define snprintf rpl_snprintf
#define vasprintf rpl_vasprintf
#define asprintf rpl_asprintf
What's New in This Release:
· Fixed the detection of infinite floating point values on IRIX (and possibly other systems) and applied another few minor cleanups.