[or-cvs] Add a tor_memmem function

[nickm@xxxxxxxx (Nick Mathewson)]

Update of /home/or/cvsroot/tor/src/common
In directory moria:/tmp/cvs-serv19901/src/common

Modified Files:
	compat.c compat.h 
Log Message:
Add a tor_memmem function

Index: compat.c
===================================================================
RCS file: /home/or/cvsroot/tor/src/common/compat.c,v
retrieving revision 1.52
retrieving revision 1.53
diff -u -d -r1.52 -r1.53
--- compat.c	12 Jun 2005 04:33:26 -0000	1.52
+++ compat.c	18 Jun 2005 02:17:11 -0000	1.53
@@ -13,7 +13,9 @@
  * the platform.
  **/
 
-/* This is required on rh7 to make strptime not complain. */
+/* This is required on rh7 to make strptime not complain.
+ * We also need it to make memmem get defined (where available)
+ */
 #define _GNU_SOURCE
 
 #include "orconfig.h"
@@ -134,6 +136,38 @@
   return r;
 }
 
+/** Given <b>hlen</b> bytes at <b>haystack</b> and <b>nlen</b> bytes at
+ * <b>needle</b>, return a pointer to the first occurence of the needle
+ * within the haystack, or NULL if there is no such occurrence.
+ *
+ * Requires that nlen be greater than zero.
+ */
+const void *
+tor_memmem(const void *haystack, size_t hlen, const void *needle, size_t nlen)
+{
+#if defined(HAVE_MEMMEM) && (!defined(__GNUC__) || __GNUC__ >= 2)
+  tor_assert(nlen);
+  return memmem(haystack, hlen, needle, nlen);
+#else
+  /* This isn't as fast as the GLIBC implementation, but it doesn't need to be. */
+  const void *p, *end;
+  char first;
+  tor_assert(nlen);
+
+  p = haystack;
+  end = haystack + hlen;
+  first = *(const char*)needle;
+  while ((p = memchr(p, first, end-p))) {
+    if (end-p >= nlen)
+      return NULL;
+    if (!memcmp(p, needle, nlen))
+      return p;
+    ++p;
+  }
+  return NULL;
+#endif
+}
+
 /** Take a filename and return a pointer to its final element.  This
  * function is called on __FILE__ to fix a MSVC nit where __FILE__
  * contains the full path to the file.  This is bad, because it

Index: compat.h
===================================================================
RCS file: /home/or/cvsroot/tor/src/common/compat.h,v
retrieving revision 1.30
retrieving revision 1.31
diff -u -d -r1.30 -r1.31
--- compat.h	9 Jun 2005 19:03:31 -0000	1.30
+++ compat.h	18 Jun 2005 02:17:11 -0000	1.31
@@ -87,6 +87,9 @@
      CHECK_PRINTF(3,4);
 int tor_vsnprintf(char *str, size_t size, const char *format, va_list args);
 
+const void *tor_memmem(const void *haystack, size_t hlen, const void *needle,
+                       size_t nlen);
+
 #define TOR_ISAPLHA(c)   isalpha((int)(unsigned char)(c))
 #define TOR_ISALNUM(c)   isalnum((int)(unsigned char)(c))
 #define TOR_ISSPACE(c)   isspace((int)(unsigned char)(c))