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6924920: Class Data Sharing limit on the java version string can create failures

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Truncate the java version string and add a hash value if it is too long.

Reviewed-by: dholmes, coleenp
This commit is contained in:
Harold Seigel 2012-11-28 08:17:59 -05:00
parent 8c32bcb315
commit ef28e7a277
1 changed files with 35 additions and 10 deletions
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45
hotspot/src/share/vm/memory/filemap.cpp
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@ -25,6 +25,7 @@
#include "precompiled.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/altHashing.hpp"
#include "memory/filemap.hpp"
#include "runtime/arguments.hpp"
#include "runtime/java.hpp"
@ -82,9 +83,38 @@ void FileMapInfo::fail_continue(const char *msg, ...) {
close();
}
// Fill in the fileMapInfo structure with data about this VM instance.
// This method copies the vm version info into header_version. If the version is too
// long then a truncated version, which has a hash code appended to it, is copied.
//
// Using a template enables this method to verify that header_version is an array of
// length JVM_IDENT_MAX. This ensures that the code that writes to the CDS file and
// the code that reads the CDS file will both use the same size buffer. Hence, will
// use identical truncation. This is necessary for matching of truncated versions.
template <int N> static void get_header_version(char (&header_version) [N]) {
assert(N == JVM_IDENT_MAX, "Bad header_version size");
const char *vm_version = VM_Version::internal_vm_info_string();
const int version_len = (int)strlen(vm_version);
if (version_len < (JVM_IDENT_MAX-1)) {
strcpy(header_version, vm_version);
} else {
// Get the hash value. Use a static seed because the hash needs to return the same
// value over multiple jvm invocations.
unsigned int hash = AltHashing::murmur3_32(8191, (const jbyte*)vm_version, version_len);
// Truncate the ident, saving room for the 8 hex character hash value.
strncpy(header_version, vm_version, JVM_IDENT_MAX-9);
// Append the hash code as eight hex digits.
sprintf(&header_version[JVM_IDENT_MAX-9], "%08x", hash);
header_version[JVM_IDENT_MAX-1] = 0; // Null terminate.
}
}
void FileMapInfo::populate_header(size_t alignment) {
_header._magic = 0xf00baba2;
_header._version = _current_version;
@ -95,13 +125,7 @@ void FileMapInfo::populate_header(size_t alignment) {
// invoked with.
// JVM version string ... changes on each build.
const char *vm_version = VM_Version::internal_vm_info_string();
if (strlen(vm_version) < (JVM_IDENT_MAX-1)) {
strcpy(_header._jvm_ident, vm_version);
} else {
fail_stop("JVM Ident field for shared archive is too long"
" - truncated to <%s>", _header._jvm_ident);
}
get_header_version(_header._jvm_ident);
// Build checks on classpath and jar files
_header._num_jars = 0;
@ -434,8 +458,9 @@ bool FileMapInfo::validate() {
fail_continue("The shared archive file has a bad magic number.");
return false;
}
if (strncmp(_header._jvm_ident, VM_Version::internal_vm_info_string(),
JVM_IDENT_MAX-1) != 0) {
char header_version[JVM_IDENT_MAX];
get_header_version(header_version);
if (strncmp(_header._jvm_ident, header_version, JVM_IDENT_MAX-1) != 0) {
fail_continue("The shared archive file was created by a different"
" version or build of HotSpot.");
return false;