100% unit test coverage

scan_asn1rawint.c

@@ -3,19 +3,48 @@
 size_t scan_asn1rawint(const char* src,const char* max,size_t len,long* l) {
   size_t i;
   long m;
-  if (src>=max) return 0;		// 0 bytes input buffer
-  if (*src<0) m=-1; else m=0;		// negative number?
+  if (src>=max || max-src<len)
+    return 0;		// input buffer too small
+  m=(*src>>7);	// -1 if negative, 0 otherwise
+//  if (*src<0) m=-1; else m=0;		// negative number?
   if (len>1 && *src==m) {
     // we want to catch things like 00 01
     // but a leading 0 byte is needed for 00 a0 because otherwise it would be -96
-    if ((src[1]>>7)==m) return 0;	// non-minimal encoding
-    if (len>sizeof(m)+1) return 0;	// value too large, does not fit
+    if ((src[1]>>7)==m)
+      return 0;	// non-minimal encoding
+    if (len>sizeof(m)+1)
+      return 0;	// value too large, does not fit
   } else
-    if (len>sizeof(m)) return 0;	// value too large, does not fit
-  if (src+len>max) return 0;		// input buffer not sufficient
+    if (len>sizeof(m))
+      return 0;	// value too large, does not fit
   for (i=0; i<len; ++i) {
     m=(m<<8)|(unsigned char)src[i];
   }
   *l=m;
   return len;
 }
+
+#ifdef UNITTEST
+#include <assert.h>
+#include <string.h>
+
+int main() {
+  char buf[10];
+  long l;
+  assert(scan_asn1rawint(buf, buf, 0, &l) == 0);	// no input
+  assert(scan_asn1rawint(buf, buf+10, 0, &l) == 0);	// no input
+  strcpy(buf,"\x01");
+  assert(scan_asn1rawint(buf, buf+10, 1, &l) == 1 && l == 1);	// OK
+  memcpy(buf,"\x00\x01",2);
+  assert(scan_asn1rawint(buf, buf+10, 1, &l) == 1 && l == 0);	// OK
+  assert(scan_asn1rawint(buf, buf+10, 2, &l) == 0);	// non-minimal
+  memcpy(buf,"\xa0",1);
+  assert(scan_asn1rawint(buf, buf+10, 1, &l) == 1 && l == -96);	// OK
+  memcpy(buf,"\x00\xa0",2);
+  assert(scan_asn1rawint(buf, buf+10, 2, &l) == 2 && l == 160);	// OK
+  memcpy(buf,"\x01\x02\x03\x04\x05\x06\x07\x08\x09",9);
+  assert(scan_asn1rawint(buf, buf+10, 9, &l) == 0);	// value too large, not representable
+  memcpy(buf,"\xff\x01\x02\x03\x04\x05\x06\x07\x08\x09",10);
+  assert(scan_asn1rawint(buf, buf+10, 10, &l) == 0);	// value too large, not representable
+}
+#endif