r2893: added very primitive name mangling support to pvfs

(This used to be commit 749fa73544201f521d9cd3fa972b89cae99bc2c0)

1 files changed, 45 insertions, 1 deletions

diff --git a/source4/ntvfs/posix/pvfs_shortname.c b/source4/ntvfs/posix/pvfs_shortname.c
index 21c0ca6ea0..ae911ad885 100644
--- a/source4/ntvfs/posix/pvfs_shortname.c
+++ b/source4/ntvfs/posix/pvfs_shortname.c
@@ -23,6 +23,34 @@
 #include "include/includes.h"
 #include "vfs_posix.h"
 
+#define FNV1_PRIME 0x01000193
+/*the following number is a fnv1 of the string: idra@samba.org 2002 */
+#define FNV1_INIT  0xa6b93095
+
+/* 
+   hash a string of the specified length. The string does not need to be
+   null terminated 
+
+   this hash needs to be fast with a low collision rate (what hash doesn't?)
+*/
+static uint32_t mangle_hash(const char *key)
+{
+	uint32_t value;
+	codepoint_t c;
+	size_t c_size;
+
+	for (value = FNV1_INIT; 
+	     (c=next_codepoint(key, &c_size)); 
+	     key += c_size) {
+		c = toupper_w(c);
+                value *= (uint32_t)FNV1_PRIME;
+                value ^= (uint32_t)c;
+        }
+
+	/* note that we force it to a 31 bit hash, to keep within the limits
+	   of the 36^6 mangle space */
+	return value & ~0x80000000;  
+}
 
 /*
   return the short name for a component of a full name
@@ -30,7 +58,23 @@
 */
 char *pvfs_short_name_component(struct pvfs_state *pvfs, const char *name)
 {
-	return talloc_strndup(pvfs, name, 12);
+	const char *basechars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+	uint32_t hash;
+	char c1, c2;
+	const char *ext;
+
+	if (strlen(name) < 12) {
+		return talloc_strdup(pvfs, name);
+	}
+
+	hash = mangle_hash(name);
+	ext = strrchr(name, '.');
+
+	c1 = basechars[(hash/36)%36];
+	c2 = basechars[hash%36];
+
+	return talloc_asprintf(pvfs, "%.5s~%c%c%.4s", name, c1, c2, ext?ext:"");
+	
 }