don't use str{cpy,cat} in mruby and mrbc

The length of each string is known. It should be used.

1 files changed, 8 insertions, 4 deletions

diff --git a/tools/mrbc/mrbc.c b/tools/mrbc/mrbc.c
index 79fcd2bdf..735b22b1d 100644
--- a/tools/mrbc/mrbc.c
+++ b/tools/mrbc/mrbc.c
@@ -51,15 +51,19 @@ usage(const char *name)
 static char *
 get_outfilename(mrb_state *mrb, char *infile, char *ext)
 {
+  size_t infilelen;
+  size_t extlen;
   char *outfile;
   char *p;
 
-  outfile = (char*)mrb_malloc(mrb, strlen(infile) + strlen(ext) + 1);
-  strcpy(outfile, infile);
+  infilelen = strlen(infile);
+  extlen = strlen(ext);
+  outfile = (char*)mrb_malloc(mrb, infilelen + extlen + 1);
+  memcpy(outfile, infile, infilelen + 1);
   if (*ext) {
     if ((p = strrchr(outfile, '.')) == NULL)
-      p = &outfile[strlen(outfile)];
-    strcpy(p, ext);
+      p = outfile + infilelen;
+    memcpy(p, ext, extlen + 1);
   }
 
   return outfile;