Adding an asprintf implementation for portability. Should add a (v)snprintf implementation later.

This commit was SVN r1971.

src/util/asprintf.c

@@ -0,0 +1,51 @@
+/*
+ * $HEADER$
+ */
+
+/*
+ * Simple implementation of asprintf based on vsnprintf.
+ *
+ * Assumes that vsnprintf returns the required number of characters when
+ * supplied with a null buffer (as specified in C99).
+ */
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+ * Need to implement ompi_vsnprintf for platforms that don't have a
+ * working vsnprintf.
+ *
+ * For now, assume a working vsnprintf...
+ */
+
+#define ompi_vsnprintf vsnprintf
+
+int ompi_asprintf(char **ptr, const char *fmt, ...)
+{
+    int length;
+    size_t size;
+    va_list ap;
+
+    /* find the required size */
+    va_start(ap, fmt);
+    length = ompi_vsnprintf(NULL, (size_t) 0, fmt, ap);
+    size = (size_t) length + 1;
+    va_end(ap);
+
+    /* allocate a buffer */
+    *ptr = (char *) malloc(size);
+    if (*ptr == NULL) {
+        errno = ENOMEM;
+        return -1;
+    }
+
+    /* fill the buffer */
+    va_start(ap, fmt);
+    length = ompi_vsnprintf(*ptr, size, fmt, ap);
+    va_end(ap);
+
+    return length;
+}