New 'c-*printf' modules for formatted output in C locale.

[gnulib.git] / lib / c-vasnprintf.h

diff --git a/lib/c-vasnprintf.h b/lib/c-vasnprintf.h
new file mode 100644 (file)
index 0000000..8fc1724
--- /dev/null
+++ b/lib/c-vasnprintf.h
@@ -0,0 +1,76 @@
+/* vsprintf with automatic memory allocation in C locale.
+   Copyright (C) 2002-2004, 2007-2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License along
+   with this program; if not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef _C_VASNPRINTF_H
+#define _C_VASNPRINTF_H
+
+/* Get va_list.  */
+#include <stdarg.h>
+
+/* Get size_t.  */
+#include <stddef.h>
+
+/* The __attribute__ feature is available in gcc versions 2.5 and later.
+   The __-protected variants of the attributes 'format' and 'printf' are
+   accepted by gcc versions 2.6.4 (effectively 2.7) and later.
+   We enable _GL_ATTRIBUTE_FORMAT only if these are supported too, because
+   gnulib and libintl do '#define printf __printf__' when they override
+   the 'printf' function.  */
+#if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
+# define _GL_ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
+#else
+# define _GL_ATTRIBUTE_FORMAT(spec) /* empty */
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Write formatted output to a string dynamically allocated with malloc().
+   You can pass a preallocated buffer for the result in RESULTBUF and its
+   size in *LENGTHP; otherwise you pass RESULTBUF = NULL.
+   If successful, return the address of the string (this may be = RESULTBUF
+   if no dynamic memory allocation was necessary) and set *LENGTHP to the
+   number of resulting bytes, excluding the trailing NUL.  Upon error, set
+   errno and return NULL.
+
+   When dynamic memory allocation occurs, the preallocated buffer is left
+   alone (with possibly modified contents).  This makes it possible to use
+   a statically allocated or stack-allocated buffer, like this:
+
+          char buf[100];
+          size_t len = sizeof (buf);
+          char *output = vasnprintf (buf, &len, format, args);
+          if (output == NULL)
+            ... error handling ...;
+          else
+            {
+              ... use the output string ...;
+              if (output != buf)
+                free (output);
+            }
+
+   Formatting takes place in the C locale, that is, the decimal point used in
+   floating-point formatting directives is always '.'.
+  */
+extern char *c_vasnprintf (char *resultbuf, size_t *lengthp, const char *format, va_list args)
+       _GL_ATTRIBUTE_FORMAT ((__printf__, 3, 0));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _C_VASNPRINTF_H */