Add option to disable the cache. Add a new bitfield in the engine struct that will govern options relating to engine internals.

clamd/clamd.c

@@ -338,6 +338,9 @@ int main(int argc, char **argv)
 	break;
     }
 
+    if (optget(opts, "disable-cache")->enabled)
+        cl_engine_set_num(engine, CL_ENGINE_DISABLE_CACHE, 1);
+
     /* load the database(s) */
     dbdir = optget(opts, "DatabaseDirectory")->strarg;
     logg("#Reading databases from %s\n", dbdir);

clamscan/manager.c

@@ -567,6 +567,9 @@ int scanmanager(const struct optstruct *opts)
 	return 2;
     }
 
+    if (optget(opts, "disable-cache")->enabled)
+        cl_engine_set_num(engine, CL_ENGINE_DISABLE_CACHE, 1);
+
     if(optget(opts, "detect-pua")->enabled) {
 	dboptions |= CL_DB_PUA;
 	if((opt = optget(opts, "exclude-pua"))->enabled) {

etc/clamd.conf.sample

@@ -246,6 +246,13 @@ Example
 # when the LeaveTemporaryFiles option is enabled.
 #ForceToDisk yes
 
+# This option allows you to disable the caching feature of the engine. By
+# default, the engine will store an MD5 in a cache of any files that are
+# not flagged as virus or that hit limits checks. Disabling the cache will
+# have a negative performance impact on large scans.
+# Default: no
+#DisableCache yes
+
 ##
 ## Executable files
 ##

libclamav/cache.c

@@ -743,6 +743,11 @@ int cli_cache_init(struct cl_engine *engine) {
     struct CACHE *cache;
     unsigned int i, j;
 
+    if (engine->engine_options & ENGINE_OPTIONS_DISABLE_CACHE) {
+        cli_dbgmsg("cli_cache_init: Caching disabled.\n");
+        return 0;
+    }
+
     if(!engine) {
 	cli_errmsg("cli_cache_init: mpool malloc fail\n");
 	return 1;
@@ -777,6 +782,10 @@ void cli_cache_destroy(struct cl_engine *engine) {
     struct CACHE *cache;
     unsigned int i;
 
+    if (engine->engine_options & ENGINE_OPTIONS_DISABLE_CACHE) {
+        return;
+    }
+
     if(!engine || !(cache = engine->cache))
 	return;
 
@@ -813,6 +822,11 @@ void cache_add(unsigned char *md5, size_t size, cli_ctx *ctx) {
     uint32_t level;
     struct CACHE *c;
 
+    if (ctx->engine->engine_options & ENGINE_OPTIONS_DISABLE_CACHE) {
+        cli_dbgmsg("cache_add: Caching disabled. Not adding sample to cache.\n");
+        return;
+    }
+
     if(!ctx || !ctx->engine || !ctx->engine->cache)
        return;
 
@@ -851,6 +865,11 @@ void cache_remove(unsigned char *md5, size_t size, const struct cl_engine *engin
     unsigned int key = getkey(md5);
     struct CACHE *c;
 
+    if (engine->engine_options & ENGINE_OPTIONS_DISABLE_CACHE) {
+        cli_dbgmsg("cache_remove: Caching disabled.\n");
+        return;
+    }
+
     if(!engine || !engine->cache)
        return;
 
@@ -886,6 +905,11 @@ int cache_check(unsigned char *hash, cli_ctx *ctx) {
     cli_md5_ctx md5;
     int ret;
 
+    if (ctx->engine->engine_options & ENGINE_OPTIONS_DISABLE_CACHE) {
+        cli_dbgmsg("cache_check: Caching disabled. Returning CL_VIRUS.\n");
+        return CL_VIRUS;
+    }
+
     if(!ctx || !ctx->engine || !ctx->engine->cache)
        return CL_VIRUS;
 

libclamav/clamav.h

@@ -194,7 +194,8 @@ enum cl_engine_field {
     CL_ENGINE_MAX_HTMLNOTAGS,       /* uint64_t */
     CL_ENGINE_MAX_SCRIPTNORMALIZE,  /* uint64_t */
     CL_ENGINE_MAX_ZIPTYPERCG,       /* uint64_t */
-    CL_ENGINE_FORCETODISK           /* uint32_t */
+    CL_ENGINE_FORCETODISK,          /* uint32_t */
+    CL_ENGINE_DISABLE_CACHE         /* uint32_t */
 };
 
 enum bytecode_security {
@@ -232,6 +233,13 @@ extern int cl_engine_addref(struct cl_engine *engine);
 
 extern int cl_engine_free(struct cl_engine *engine);
 
+extern void cli_cache_disable(void);
+
+extern int cli_cache_enable(struct cl_engine *engine);
+
+/* For the new engine_options bit field in the engine */
+#define ENGINE_OPTIONS_NONE             0
+#define ENGINE_OPTIONS_DISABLE_CACHE    1
 
 /* CALLBACKS */
 

libclamav/others.c

@@ -490,6 +490,15 @@ int cl_engine_set_num(struct cl_engine *engine, enum cl_engine_field field, long
 	    if (num == CL_BYTECODE_MODE_TEST)
 		cli_infomsg(NULL, "bytecode engine in test mode\n");
 	    break;
+    case CL_ENGINE_DISABLE_CACHE:
+        if (num) {
+            engine->engine_options |= ENGINE_OPTIONS_DISABLE_CACHE;
+        } else {
+            engine->engine_options &= ~(ENGINE_OPTIONS_DISABLE_CACHE);
+            if (!(engine->cache))
+                cli_cache_init(engine);
+        }
+        break;
 	default:
 	    cli_errmsg("cl_engine_set_num: Incorrect field number\n");
 	    return CL_EARG;

libclamav/others.h

@@ -193,6 +193,7 @@ struct cl_engine {
     uint32_t ac_maxdepth;
     char *tmpdir;
     uint32_t keeptmp;
+    uint64_t engine_options;
 
     /* Limits */
     uint64_t maxscansize;  /* during the scanning of archives this size
@@ -307,6 +308,7 @@ struct cl_settings {
     uint32_t bytecode_timeout;
     enum bytecode_mode bytecode_mode;
     char *pua_cats;
+    uint64_t engine_options;
 
     /* callbacks */
     clcb_pre_cache cb_pre_cache;

shared/optparser.c

@@ -253,6 +253,8 @@ const struct clam_option __clam_options[] = {
 
     { "SelfCheck", NULL, 0, TYPE_NUMBER, MATCH_NUMBER, 600, NULL, 0, OPT_CLAMD, "This option specifies the time intervals (in seconds) in which clamd\nshould perform a database check.", "600" },
 
+    { "DisableCache", "disable-cache", 0, TYPE_BOOL, MATCH_BOOL, 0, NULL, 0, OPT_CLAMD | OPT_CLAMSCAN, "This option allows you to disable clamd's caching feature.", "no" },
+
     { "VirusEvent", NULL, 0, TYPE_STRING, NULL, -1, NULL, 0, OPT_CLAMD, "Execute a command when a virus is found. In the command string %v will be\nreplaced with the virus name. Additionally, two environment variables will\nbe defined: $CLAM_VIRUSEVENT_FILENAME and $CLAM_VIRUSEVENT_VIRUSNAME.", "/usr/bin/mailx -s \"ClamAV VIRUS ALERT: %v\" alert < /dev/null" },
 
     { "ExitOnOOM", NULL, 0, TYPE_BOOL, MATCH_BOOL, 0, NULL, 0, OPT_CLAMD, "Stop the daemon when libclamav reports an out of memory condition.", "yes" },