simplify vasprintf implementation

the old implementation preallocated a buffer in order to try to avoid
calling vsnprintf more than once. not only did this potentially lead
to memory fragmentation from trimming with realloc; it also pulled in
realloc/free, which otherwise might not be needed in a static linked
program.

diff --git a/src/stdio/vasprintf.c b/src/stdio/vasprintf.c
index 68b7246..08251bc 100644 (file)
--- a/src/stdio/vasprintf.c
+++ b/src/stdio/vasprintf.c
@@ -3,26 +3,13 @@
 #include <stdarg.h>
 #include <stdlib.h>
 
-#define GUESS 240U
-
 int vasprintf(char **s, const char *fmt, va_list ap)
 {
        va_list ap2;
-       char *a;
-       int l=GUESS;
-
-       if (!(a=malloc(GUESS))) return -1;
-
        va_copy(ap2, ap);
-       l=vsnprintf(a, GUESS, fmt, ap2);
+       int l = vsnprintf(0, 0, fmt, ap2);
        va_end(ap2);
 
-       if (l<GUESS) {
-               char *b = realloc(a, l+1U);
-               *s = b ? b : a;
-               return l;
-       }
-       free(a);
        if (l<0 || !(*s=malloc(l+1U))) return -1;
        return vsnprintf(*s, l+1U, fmt, ap);
 }