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  1. JDK
  2. JDK-8272877

Java VM warning messages are not printed using the vfprintf hook

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    • OS:
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      Description

      ADDITIONAL SYSTEM INFORMATION :
      OS: Red Hat Enterprise Linux 8
      JDK: JDK 8 Update 301, JDK 11.0.12, JDK 16.0.2

      I have reproduced this issue in the above environment.
      But I think this issue probably will occur on any OS.

      A DESCRIPTION OF THE PROBLEM :
      JNI_CreateJavaVM can create a Java VM with a vfprintf hook by specifying vfprintf option.
      https://docs.oracle.com/javase/8/docs/technotes/guides/jni/spec/invocation.html#JNI_CreateJavaVM

      But Java VM warning messages such as the following are not comletely printed using the vfprintf hook.

      Java HotSpot(TM) 64-Bit Server VM warning: <message>

      "Java HotSpot(TM) 64-Bit Server VM warning: " (with no newline) is printed using the vfprintf hook.
      But the rest part of the message (with a newline) is printed to the stderr.

      [example]
      Specify the following Java VM options to cause a Java VM warning message.

      -XX:+UnlockDiagnosticVMOptions -XX:+LogCompilation -XX:LogFile=not_existing_directory/compilation.log
      (`not_existing_directory` is a not-existing directory.)

      The above Java VM options cause the following warning message.

      Java HotSpot(TM) 64-Bit Server VM warning: Cannot open file not_existing_directory/compilation.log due to No such file or directory

      If a vfprintf hook is not specified when creating a Java VM, the whole message is printed to the stderr.
      If a vfprintf hook is specified when creating a Java VM, "Java HotSpot(TM) 64-Bit Server VM warning: " (with no newline) is printed using the vfprintf hook and "Cannot open file not_existing_directory/compilation.log due to No such file or directory" (with a newline) is printed to the stderr.

      I think the cause of this issue is the following warning function.
      https://github.com/openjdk/jdk/blob/master/src/hotspot/share/utilities/debug.cpp#L116

      "<Java VM name> warning: " is printed using the jio_fprintf function.
      And the rest part of the message is printed using the vfprintf function and the fputc function.
      The jio_fprintf function uses the vfprintf hook to print messages if the vfprintf hook is specified.
      But the vfprintf function does not using the vfprintf hook.

      I think the rest part of the message should also be printed using the jio_fprintf function or the jio_vfprintf function instead of the vfprintf function or the fputc function.

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      1. Compile create_jvm.c (the attached source code)
      JDK 8
      > gcc -Wall -O3 -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -L $JAVA_HOME/jre/lib/amd64/server -l jvm -o create_jvm create_jvm.c
      JDK 11 or JDK 16
      > gcc -Wall -O3 -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -L $JAVA_HOME/lib/server -l jvm -o create_jvm create_jvm.c

      2. Run the compiled program
      (The first argument is the log file name used by the vfptintf hook.)
      JDK 8
      > export LD_LIBRARY_PATH=$JAVA_HOME/jre/lib/amd64/server
      > ./create_jvm.c jvm.log
      JDK 11 or JDK 16
      > export LD_LIBRARY_PATH=$JAVA_HOME/lib/server
      > ./create_jvm.c jvm.log


      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      The whole of the following Java VM warning message is printed to the jvm.log.

      Java HotSpot(TM) 64-Bit Server VM warning: Cannot open file not_existing_directory/compilation.log due to No such file or directory

      ACTUAL -
      The following message (with no newline) is printed to the jvm.log.

      Java HotSpot(TM) 64-Bit Server VM warning:

      And the following message is printed to the stderr.

      Cannot open file not_existing_directory/compilation.log due to No such file or directory

      [note]
      The content of the jvm.log file is the following.

      Java HotSpot(TM) 64-Bit Server VM warning: Warning: Cannot open log file: not_existing_directory/compilation.log
      Warning: Forcing option -XX:LogFile=/tmp/compilation.log

      "Java HotSpot(TM) 64-Bit Server VM warning: " (with no newline) is printed using the jio_fprintf function at the warning function.
      The following messages are printed using the jio_print function or the jio_printf function at the defaultStream::open_file function.

      Warning: Cannot open log file: not_existing_directory/compilation.log
      Warning: Forcing option -XX:LogFile=/tmp/compilation.log

      "Java HotSpot(TM) 64-Bit Server VM warning: " is not finished a newline.
      So, the next message "Warning: Cannot open log file: not_existing_directory/compilation.log" is printed the same line.


      ---------- BEGIN SOURCE ----------
      /* create_jvm.c */
      #include <stdio.h>
      #include <stdlib.h>
      #include <jni.h>

      static jint (JNICALL my_vfprintf)(FILE *, const char *, va_list);

      static FILE *log_file;

      int main(int argc, char *argv[]) {
        JavaVM *vm;
        JNIEnv *env;
        JavaVMInitArgs vm_args;
        JavaVMOption options[4];

        vm_args.version = JNI_VERSION_1_8;
        vm_args.options = options;
        vm_args.nOptions = 4;
        vm_args.ignoreUnrecognized = JNI_FALSE;

        options[0].optionString = "vfprintf";
        options[0].extraInfo = (void *) my_vfprintf;
        options[1].optionString = "-XX:+UnlockDiagnosticVMOptions";
        options[2].optionString = "-XX:+LogCompilation";
        options[3].optionString = "-XX:LogFile=not_existing_directory/compilation.log";

        fprintf(stdout, "Start\n");

        if (argc <= 1) {
          fprintf(stderr, "Usage: %s <log_file>\n", argv[0]);
          exit(1);
        }

        if ((log_file = fopen(argv[1], "w")) == NULL) {
          fprintf(stderr, "Failed to open file\n");
          exit(1);
        }

        if (JNI_CreateJavaVM(&vm, (void **) &env, &vm_args) != JNI_OK) {
          fprintf(stderr, "Failed to create Java VM\n");
          fclose(log_file);
          exit(1);
        }

        if ((*vm)->DestroyJavaVM(vm) != JNI_OK) {
          fprintf(stderr, "Failed to destroy Java VM\n");
          fclose(log_file);
          exit(1);
        }

        fclose(log_file);

        fprintf(stdout, "Done\n");
        return 0;
      }

      jint (JNICALL my_vfprintf)(FILE *fp, const char *format, va_list args) {
        return vfprintf(log_file, format, args);
      }

      ---------- END SOURCE ----------

      FREQUENCY : always


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            Assignee:
            sswsharm swati sharma
            Reporter:
            webbuggrp Webbug Group
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              Updated:
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