Enforce maximum length of fuzz input

Remove the libfuzzer max_len option which doesn't apply to other
fuzzing engines. Enforce the maximum length directly in the fuzz
targets. For the xml target, lower the maximum when expanding entities
to avoid timeout and OOM errors.

fuzz/html.options

@@ -1,3 +1,2 @@
 [libfuzzer]
-max_len = 1000000
 timeout = 20

fuzz/regexp.c

@@ -21,6 +21,9 @@ LLVMFuzzerTestOneInput(const char *data, size_t size) {
     char *str[2] = { NULL, NULL };
     size_t numStrings;
 
+    if (size > 200)
+        return(0);
+
     numStrings = xmlFuzzExtractStrings(data, size, str, 2);
 
     /* CUR_SCHAR doesn't handle invalid UTF-8 and may cause infinite loops. */

fuzz/regexp.options

@@ -1,3 +1,2 @@
 [libfuzzer]
-max_len = 200
 timeout = 5

fuzz/schema.c

@@ -21,6 +21,9 @@ int
 LLVMFuzzerTestOneInput(const char *data, size_t size) {
     xmlSchemaParserCtxtPtr pctxt;
 
+    if (size > 50000)
+        return(0);
+
     xmlFuzzDataInit(data, size);
     xmlFuzzReadEntities();
 

fuzz/schema.options

@@ -1,3 +1,2 @@
 [libfuzzer]
-max_len = 80000
 timeout = 20

fuzz/uri.c

@@ -13,6 +13,9 @@ LLVMFuzzerTestOneInput(const char *data, size_t size) {
     char *str[2] = { NULL, NULL };
     size_t numStrings;
 
+    if (size > 10000)
+        return(0);
+
     numStrings = xmlFuzzExtractStrings(data, size, str, 2);
 
     uri = xmlParseURI(str[0]);

fuzz/uri.options

@@ -1,3 +1,2 @@
 [libfuzzer]
-max_len = 10000
 timeout = 5

fuzz/xml.c

@@ -29,13 +29,18 @@ LLVMFuzzerTestOneInput(const char *data, size_t size) {
     xmlTextReaderPtr reader;
     xmlChar *out;
     const char *docBuffer, *docUrl;
-    size_t docSize, consumed, chunkSize;
+    size_t maxSize, docSize, consumed, chunkSize;
     int opts, outSize;
 
     xmlFuzzDataInit(data, size);
     opts = xmlFuzzReadInt();
-    /* XML_PARSE_HUGE still causes timeouts. */
-    opts &= ~XML_PARSE_HUGE;
+
+    /* Lower maximum size when processing entities for now. */
+    maxSize = opts & XML_PARSE_NOENT ? 50000 : 500000;
+    if (size > maxSize) {
+        xmlFuzzDataCleanup();
+        return(0);
+    }
 
     xmlFuzzReadEntities();
     docBuffer = xmlFuzzMainEntity(&docSize);

fuzz/xml.options

@@ -1,3 +1,2 @@
 [libfuzzer]
-max_len = 80000
 timeout = 20

fuzz/xpath.c

@@ -23,6 +23,9 @@ LLVMFuzzerTestOneInput(const char *data, size_t size) {
     const char *expr, *xml;
     size_t exprSize, xmlSize;
 
+    if (size > 10000)
+        return(0);
+
     xmlFuzzDataInit(data, size);
 
     expr = xmlFuzzReadString(&exprSize);

fuzz/xpath.options

@@ -1,3 +1,2 @@
 [libfuzzer]
-max_len = 10000
 timeout = 20