RFR: JDK-8320005 : Native library suffix impact on hotspot code in AIX [v2]

[suchismith1993]

On Tue, 28 Nov 2023 11:08:43 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> > > > > i would have to repeat the line 1132 and 1139 in os_aix.cpp again , if the condition fails for .so files, because i have to reload it again and check if the .a exists. In the shared code i had repeat less number of lines i believe. Do you suggest moving lines 1132 to 1139 to another function then ?
> > > > 
> > > > 
> > > > @tstuefe Any suggestion on this ?
> > > 
> > > 
> > > ```
> > > --- a/src/hotspot/os/aix/os_aix.cpp
> > > +++ b/src/hotspot/os/aix/os_aix.cpp
> > > @@ -1108,7 +1108,7 @@ bool os::dll_address_to_library_name(address addr, char* buf,
> > >    return true;
> > >  }
> > >  
> > > -void *os::dll_load(const char *filename, char *ebuf, int ebuflen) {
> > > +static void* dll_load_inner(const char *filename, char *ebuf, int ebuflen) {
> > >  
> > >    log_info(os)("attempting shared library load of %s", filename);
> > >  
> > > @@ -1158,6 +1158,35 @@ void *os::dll_load(const char *filename, char *ebuf, int ebuflen) {
> > >    return nullptr;
> > >  }
> > >  
> > > +void* os::dll_load(const char *filename, char *ebuf, int ebuflen) {
> > > +
> > > +  void* result = nullptr;
> > > +
> > > +  // First try using *.so suffix; failing that, retry with *.a suffix.
> > > +  const size_t len = strlen(filename);
> > > +  constexpr size_t safety = 3 + 1;
> > > +  constexpr size_t bufsize = len + safety;
> > > +  char* buf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
> > > +  strcpy(buf, filename);
> > > +  char* const dot = strrchr(buf, '.');
> > > +
> > > +  assert(dot != nullptr, "Attempting to load a shared object without extension? %s", filename);
> > > +  assert(strcmp(dot, ".a") == 0 || strcmp(dot, ".so") == 0,
> > > +      "Attempting to load a shared object that is neither *.so nor *.a", filename);
> > > +
> > > +  sprintf(dot, ".so");
> > > +  result = dll_load_inner(buf, ebuf, ebuflen);
> > > +
> > > +  if (result == nullptr) {
> > > +    sprintf(dot, ".a");
> > > +    result = dll_load_inner(buf, ebuf, ebuflen);
> > > +  }
> > > +
> > > +  FREE_C_HEAP_ARRAY(char, buf);
> > > +
> > > +  return result;
> > > +}
> > > +
> > > ```
> > 
> > 
> > @tstuefe as discussed with @TheRealMDoerr do you think using default argument will help ? Either we pass agent object as 3rd parameter or an empty character buffer(and not const chat*) which would be spcifically used to copy the alternate filename to it using strcpy so that it is reflected in the jvmagent code ?
> 
> A third parameter for what?

@tstuefe  
3rd parameter to pass the either of 2 things: 
1. The JvmTiAgent object "agent", so that after shifting the save_library_signature to os_aix,we can still access the agent object.-> For this i tried importing jvm/prims header file, but i get segmentation faults during build . Not sure if i am doing it the right way.
2. Pass a character buffer(and not const char*) where we copy the modified filename back to it and then use it in jvmAgent. code.

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PR Comment: https://git.openjdk.org/jdk/pull/16604#issuecomment-1829634847