src/java.base/unix/native/libnio/ch/FileChannelImpl.c

*** 45,54 ****
--- 45,55 ----
  #include "jlong.h"
  #include "nio.h"
  #include "nio_util.h"
  #include "sun_nio_ch_FileChannelImpl.h"
  #include "java_lang_Integer.h"
+ #include <assert.h>
  
  static jfieldID chan_fd;        /* jobject 'fd' in sun.nio.ch.FileChannelImpl */
  
  JNIEXPORT jlong JNICALL
  Java_sun_nio_ch_FileChannelImpl_initIDs(JNIEnv *env, jclass clazz)
*** 70,87 ****
  }
  
  
  JNIEXPORT jlong JNICALL
  Java_sun_nio_ch_FileChannelImpl_map0(JNIEnv *env, jobject this,
!                                      jint prot, jlong off, jlong len)
  {
      void *mapAddress = 0;
      jobject fdo = (*env)->GetObjectField(env, this, chan_fd);
      jint fd = fdval(env, fdo);
      int protections = 0;
      int flags = 0;
  
      if (prot == sun_nio_ch_FileChannelImpl_MAP_RO) {
          protections = PROT_READ;
          flags = MAP_SHARED;
      } else if (prot == sun_nio_ch_FileChannelImpl_MAP_RW) {
          protections = PROT_WRITE | PROT_READ;
--- 71,91 ----
  }
  
  
  JNIEXPORT jlong JNICALL
  Java_sun_nio_ch_FileChannelImpl_map0(JNIEnv *env, jobject this,
!                                      jint prot, jlong off, jlong len, jboolean map_sync)
  {
      void *mapAddress = 0;
      jobject fdo = (*env)->GetObjectField(env, this, chan_fd);
      jint fd = fdval(env, fdo);
      int protections = 0;
      int flags = 0;
  
+     // should never be called with map_sync and prot == PRIVATE
+     assert((prot != sun_nio_ch_FileChannelImpl_MAP_PV) ||! map_sync);
+     
      if (prot == sun_nio_ch_FileChannelImpl_MAP_RO) {
          protections = PROT_READ;
          flags = MAP_SHARED;
      } else if (prot == sun_nio_ch_FileChannelImpl_MAP_RW) {
          protections = PROT_WRITE | PROT_READ;
*** 89,107 ****
--- 93,143 ----
      } else if (prot == sun_nio_ch_FileChannelImpl_MAP_PV) {
          protections =  PROT_WRITE | PROT_READ;
          flags = MAP_PRIVATE;
      }
  
+     // if MAP_SYNC and MAP_SHARED_VALIDATE are not defined then it is
+     // best to define them here. This ensures the code compiles on old
+     // OS releases which do not provide the relevant headers. If run
+     // on the same machine then it will work if the kernel contains
+     // the necessary support otherwise mmap should fail with an
+     // invalid argument error
+ 
+ #ifndef MAP_SYNC
+ #define MAP_SYNC 0x80000
+ #endif
+ #ifndef MAP_SHARED_VALIDATE
+ #define MAP_SHARED_VALIDATE 0x03
+ #endif
+     
+     if (map_sync) {
+         // ensure
+         //  1) this is Linux on AArch64 or x86_64
+         //  2) the mmap APIs are available/ at compile time
+ #if !defined(LINUX) || ! (defined(aarch64) || (defined(amd64) && defined(_LP64)))
+         // TODO - implement for solaris/AIX/BSD/WINDOWS and for 32 bit
+         JNU_ThrowIOException(env, "map_persistent is not implemented");
+         return IOS_THROWN;
+ #else
+         flags |= MAP_SYNC | MAP_SHARED_VALIDATE;
+ #endif
+     }
+ 
      mapAddress = mmap64(
          0,                    /* Let OS decide location */
          len,                  /* Number of bytes to map */
          protections,          /* File permissions */
          flags,                /* Changes are shared */
          fd,                   /* File descriptor of mapped file */
          off);                 /* Offset into file */
  
      if (mapAddress == MAP_FAILED) {
+         if (map_sync && errno == ENOTSUP) {
+             JNU_ThrowIOExceptionWithLastError(env, "map_persistent is not supported");
+             return IOS_THROWN;
+         }
+ 
          if (errno == ENOMEM) {
              JNU_ThrowOutOfMemoryError(env, "Map failed");
              return IOS_THROWN;
          }
          return handle(env, -1, "Map failed");