hexdump(1): strlen + calloc + snprintf == asprintf

[Theo Buehler]

use the libc interface instead of rolling it by hand.

Index: parse.c
===================================================================
RCS file: /var/cvs/src/usr.bin/hexdump/parse.c,v
retrieving revision 1.21
diff -u -p -r1.21 parse.c
--- parse.c     24 Aug 2016 03:13:45 -0000      1.21
+++ parse.c     24 Aug 2016 05:23:47 -0000
@@ -147,8 +147,7 @@ add(const char *fmt)
                for (savep = ++p; *p != '"';)
                        if (*p++ == 0)
                                badfmt(fmt);
-               tfu->fmt = strndup(savep, p - savep);
-               if (tfu->fmt == NULL)
+               if ((tfu->fmt = strndup(savep, p - savep)) == NULL)
                        err(1, NULL);
                escape(tfu->fmt);
                p++;
@@ -219,7 +218,6 @@ rewrite(FS *fs)
        char *p1, *p2;
        char savech, *fmtp, cs[4];
        int nconv, prec;
-       size_t len;
 
        nextpr = NULL;
        prec = 0;
@@ -408,10 +406,8 @@ rewrite(FS *fs)
                         */
                        savech = *p2;
                        p1[0] = '\0';
-                       len = strlen(fmtp) + strlen(cs) + 1;
-                       if ((pr->fmt = calloc(1, len)) == NULL)
+                       if (asprintf(&pr->fmt, "%s%s", fmtp, cs) == -1)
                                err(1, NULL);
-                       snprintf(pr->fmt, len, "%s%s", fmtp, cs);
                        *p2 = savech;
                        pr->cchar = pr->fmt + (p1 - fmtp);
                        fmtp = p2;