[EagerAppCDS] 1. fix strlen usage 2. change the impl of bootclasspath…

… check in cds

Summary: 1. strlen: conversion from 'size_t' to 'int', possible loss of data
2. change the impl of checking boot classpath value when replaying in cds

Test Plan: windows build
           ci jtreg cds

Reviewed-by: lei.yul, lingjun-cg

Issue: dragonwell-project#559

CR:

hotspot/src/share/vm/classfile/classLoaderExt.hpp

@@ -133,7 +133,7 @@ class ClassLoaderExt: public ClassLoader { // AllStatic
   static void append_boot_classpath(ClassPathEntry* new_entry) {
 #if INCLUDE_CDS
     if (UseAppCDS) {
-      if (CDSIgnoreBootClasspathAppend) {
+      if (CDSIgnoreBootClasspathDiff) {
         warning("AppCDS is still enabled, but bootstrap classpath has been appended");
       } else {
         warning("UseAppCDS is disabled because bootstrap classpath has been appended");

hotspot/src/share/vm/classfile/sharedClassUtil.cpp

@@ -39,19 +39,6 @@
 #include "runtime/java.hpp"
 #include "runtime/os.hpp"
 
-AgentEntry* SharedClassUtil::_agentlib_head = NULL;
-AgentEntry* SharedClassUtil::_agentlib_tail = NULL;
-
-AgentEntry::AgentEntry(const char* name) {
-  char* copy = NEW_C_HEAP_ARRAY(char, strlen(name)+1, mtInternal);
-  strcpy(copy, name);
-  _name = copy;
-  _next = NULL;
-}
-
-AgentEntry::~AgentEntry() {
-  FREE_C_HEAP_ARRAY(char, _name, mtInternal);
-}
 
 class ManifestStream: public ResourceObj {
   private:
@@ -151,9 +138,9 @@ ClassPathSegment* SharedPathsMiscInfoExt::to_sorted_segments(const char* path, i
   }
   ClassPathSegment *cps = NEW_RESOURCE_ARRAY(ClassPathSegment, max_seg_num + 1);
 
-  int len = strlen(path);
+  size_t len = strlen(path);
   //not use i < len,but use i<= len for processing the last segment conveniently
-  for (int i = 0, j = 0; i <= len; i++) {
+  for (uint i = 0, j = 0; i <= len; i++) {
     if (i == len || path[i] == os::path_separator()[0]) {
       //i == j mean a empty string
       if (i != j) {
@@ -229,29 +216,6 @@ bool SharedPathsMiscInfoExt::check(jint type, const char* path) {
   return true;
 }
 
-void SharedClassUtil::append_lib_in_bootclasspath(const char* path) {
-  if(*path == '\0') return;
-  AgentEntry* agent_entry = new AgentEntry(path);
-  if (_agentlib_head == NULL) {
-    _agentlib_head = agent_entry;
-    _agentlib_tail = agent_entry;
-  } else {
-    _agentlib_tail->set_next(agent_entry);
-    _agentlib_tail = agent_entry;
-  }
-}
-
-bool SharedClassUtil::is_appended_boot_cp(const char* path, int len) {
-  AgentEntry* e = _agentlib_head;
-  while(e != NULL) {
-    if (strncmp(e->name(), path, len) == 0) {
-      return true;
-    }
-    e = e->next();
-  }
-  return false;
-}
-
 void SharedClassUtil::update_shared_classpath(ClassPathEntry *cpe, SharedClassPathEntry* e,
                                               time_t timestamp, long filesize, TRAPS) {
   e->_timestamp = timestamp;

hotspot/src/share/vm/classfile/sharedClassUtil.hpp

@@ -107,28 +107,9 @@ class SharedClassPathEntryExt: public SharedClassPathEntry {
   }
 };
 
-class AgentEntry: public CHeapObj<mtInternal> {
-private:
-  char* _name;
-  AgentEntry* _next;
-public:
-  const char* name()  { return _name; }
-  AgentEntry* next() { return _next; }
-  AgentEntry(const char* name);
-  void set_next(AgentEntry* entry) {
-    _next = entry;
-  }
-  ~AgentEntry();
-};
 
 class SharedClassUtil : AllStatic {
-private:
-  static AgentEntry* _agentlib_head;
-  static AgentEntry* _agentlib_tail;
 public:
-  static void append_lib_in_bootclasspath(const char* path);
-  static bool is_appended_boot_cp(const char* path, int len);
-
   static SharedPathsMiscInfo* allocate_shared_paths_misc_info() {
     return new SharedPathsMiscInfoExt();
   }

hotspot/src/share/vm/classfile/sharedPathsMiscInfo.cpp

@@ -112,23 +112,11 @@ bool SharedPathsMiscInfo::check(jint type, const char* path) {
   switch (type) {
   case BOOT:
     if (strcmp(path, Arguments::get_sysclasspath()) != 0) {
-      char* sys_cp = Arguments::get_sysclasspath();
-      int path_len = strlen(path);
-      int sys_cp_len = strlen(sys_cp);
-      if(path_len >= sys_cp_len || strncmp(path, sys_cp, path_len) != 0 || !EagerAppCDS || !CDSIgnoreBootClasspathAppend) {
-        return fail("[BOOT classpath mismatch, actual: -Dsun.boot.class.path=", sys_cp);
+      if(!EagerAppCDS || !CDSIgnoreBootClasspathDiff) {
+        return fail("[BOOT classpath mismatch, actual: -Dsun.boot.class.path=", Arguments::get_sysclasspath());
       } else {
-        int start = path_len;
-        int end = start + 1;
-        while(end <= sys_cp_len) {
-          if(end == sys_cp_len || sys_cp[end] == os::path_separator()[0]) {
-            if (!SharedClassUtil::is_appended_boot_cp(sys_cp + start + 1, end - start - 1)) {
-              return fail("[BOOT classpath mismatch, actual: -Dsun.boot.class.path=", sys_cp);
-            }
-          }
-          start = end;
-          end++;
-        }
+        warning("The Boot classpath is different from the one used in profiling.");
+        return true;
       }
     }
     break;

hotspot/src/share/vm/prims/jvmtiEnv.cpp

@@ -449,7 +449,6 @@ JvmtiEnv::AddToBootstrapClassLoaderSearch(const char* segment) {
   jvmtiPhase phase = get_phase();
   if (phase == JVMTI_PHASE_ONLOAD) {
     Arguments::append_sysclasspath(segment);
-    SharedClassUtil::append_lib_in_bootclasspath(segment);
     return JVMTI_ERROR_NONE;
   } else if (use_version_1_0_semantics()) {
     // This JvmtiEnv requested version 1.0 semantics and this function
@@ -479,7 +478,6 @@ JvmtiEnv::AddToBootstrapClassLoaderSearch(const char* segment) {
       tty->print_cr("[Opened %s]", zip_entry->name());
     }
     ClassLoaderExt::append_boot_classpath(zip_entry);
-    SharedClassUtil::append_lib_in_bootclasspath(segment);
     return JVMTI_ERROR_NONE;
   } else {
     return JVMTI_ERROR_WRONG_PHASE;

hotspot/src/share/vm/runtime/globals_ext.hpp

@@ -172,7 +172,7 @@
                                                                             \
   product(bool, IgnoreAppCDSDirCheck, false,                                \
           "Ignore non-empty dir check in AppCDS")                           \
-  product(bool, CDSIgnoreBootClasspathAppend, false,                        \
+  product(bool, CDSIgnoreBootClasspathDiff, false,                        \
           "keep AppCDS on after appending boot classpath")                  \
                                                                             \
   product(bool, SuppressAppCDSErrors, false,                                \