1.1 --- a/src/share/vm/memory/filemap.cpp Tue Nov 27 07:57:57 2012 -0800
1.2 +++ b/src/share/vm/memory/filemap.cpp Wed Nov 28 08:17:59 2012 -0500
1.3 @@ -25,6 +25,7 @@
1.4 #include "precompiled.hpp"
1.5 #include "classfile/classLoader.hpp"
1.6 #include "classfile/symbolTable.hpp"
1.7 +#include "classfile/altHashing.hpp"
1.8 #include "memory/filemap.hpp"
1.9 #include "runtime/arguments.hpp"
1.10 #include "runtime/java.hpp"
1.11 @@ -82,8 +83,37 @@
1.12 close();
1.13 }
1.14
1.15 +// Fill in the fileMapInfo structure with data about this VM instance.
1.16
1.17 -// Fill in the fileMapInfo structure with data about this VM instance.
1.18 +// This method copies the vm version info into header_version. If the version is too
1.19 +// long then a truncated version, which has a hash code appended to it, is copied.
1.20 +//
1.21 +// Using a template enables this method to verify that header_version is an array of
1.22 +// length JVM_IDENT_MAX. This ensures that the code that writes to the CDS file and
1.23 +// the code that reads the CDS file will both use the same size buffer. Hence, will
1.24 +// use identical truncation. This is necessary for matching of truncated versions.
1.25 +template <int N> static void get_header_version(char (&header_version) [N]) {
1.26 + assert(N == JVM_IDENT_MAX, "Bad header_version size");
1.27 +
1.28 + const char *vm_version = VM_Version::internal_vm_info_string();
1.29 + const int version_len = (int)strlen(vm_version);
1.30 +
1.31 + if (version_len < (JVM_IDENT_MAX-1)) {
1.32 + strcpy(header_version, vm_version);
1.33 +
1.34 + } else {
1.35 + // Get the hash value. Use a static seed because the hash needs to return the same
1.36 + // value over multiple jvm invocations.
1.37 + unsigned int hash = AltHashing::murmur3_32(8191, (const jbyte*)vm_version, version_len);
1.38 +
1.39 + // Truncate the ident, saving room for the 8 hex character hash value.
1.40 + strncpy(header_version, vm_version, JVM_IDENT_MAX-9);
1.41 +
1.42 + // Append the hash code as eight hex digits.
1.43 + sprintf(&header_version[JVM_IDENT_MAX-9], "%08x", hash);
1.44 + header_version[JVM_IDENT_MAX-1] = 0; // Null terminate.
1.45 + }
1.46 +}
1.47
1.48 void FileMapInfo::populate_header(size_t alignment) {
1.49 _header._magic = 0xf00baba2;
1.50 @@ -95,13 +125,7 @@
1.51 // invoked with.
1.52
1.53 // JVM version string ... changes on each build.
1.54 - const char *vm_version = VM_Version::internal_vm_info_string();
1.55 - if (strlen(vm_version) < (JVM_IDENT_MAX-1)) {
1.56 - strcpy(_header._jvm_ident, vm_version);
1.57 - } else {
1.58 - fail_stop("JVM Ident field for shared archive is too long"
1.59 - " - truncated to <%s>", _header._jvm_ident);
1.60 - }
1.61 + get_header_version(_header._jvm_ident);
1.62
1.63 // Build checks on classpath and jar files
1.64 _header._num_jars = 0;
1.65 @@ -434,8 +458,9 @@
1.66 fail_continue("The shared archive file has a bad magic number.");
1.67 return false;
1.68 }
1.69 - if (strncmp(_header._jvm_ident, VM_Version::internal_vm_info_string(),
1.70 - JVM_IDENT_MAX-1) != 0) {
1.71 + char header_version[JVM_IDENT_MAX];
1.72 + get_header_version(header_version);
1.73 + if (strncmp(_header._jvm_ident, header_version, JVM_IDENT_MAX-1) != 0) {
1.74 fail_continue("The shared archive file was created by a different"
1.75 " version or build of HotSpot.");
1.76 return false;
