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/*
Unix SMB/CIFS implementation.
POSIX NTVFS backend - 8.3 name routines
Copyright (C) Andrew Tridgell 2004
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#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
TODO: this is obviously not very useful in its current form !
*/
char *pvfs_short_name_component(struct pvfs_state *pvfs, const char *name)
{
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:"");
}
/*
return the short name for a given entry in a directory
TODO: this is obviously not very useful in its current form !
*/
char *pvfs_short_name(struct pvfs_state *pvfs, TALLOC_CTX *mem_ctx, struct pvfs_filename *name)
{
char *p = strrchr(name->full_name, '/');
char *ret = pvfs_short_name_component(pvfs, p+1);
talloc_steal(mem_ctx, ret);
return ret;
}
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