Re: [DynInst_API:] Deleting the snippets after reattaching

[Bill Williams <bill@xxxxxxxxxxx>]

On 11/10/2014 04:08 AM, shruti wrote:
> Hi,
>
> We are developing the dynamic instrumentation tool using dyninst API's.
>
> Please help me on this.
>
> In the following code I am attaching to process,inserting the printf
> snippet and detaching from it. Again I am reattaching to the same
> process for the sake of deleting the snippet inserted previously.
> But I am not able to delete the snippet. Is there any possible ways to
> delete the snippet after reattaching to it.
Detaching and reattaching is not implemented in the way you want, and 
even if it were, this approach wouldn't work--the two BPatch_processes 
for the two different attach times don't know about each other's 
instrumentation state.
Ordinarily, we'd recommend continuing the process with a 
waitAndHandleEvents() loop until you reach some callback where you want 
to remove instrumentation or the process is terminated. Is there a 
reason that approach wouldn't work for your use case?
--bw

> void usage() {
>          cout<<"Please enter the pid and function name"<<endl;
> }
>
> int main(int argc , char *argv[])
> {
>          BPatch bpatch;
>          int pid;
>          bool ret;
>          if (argc != 3) {
>                  usage();
>                  exit(1);
>          }
>
>          pid=atoi(argv[1]);
>
>          cout<<"The attached pid is "<<pid<<endl;
>          cout<<"the function name is "<<argv[2]<<endl;
>          BPatch_process *appProc = bpatch.processAttach("",pid);
>          BPatch_image *img = appProc->getImage();
>          bpatch.setTrampRecursive(true);
>          std::vector<BPatch_function *> printFuncs;
>          img->findFunction(argv[2],printFuncs);
>          if (printFuncs.size() == 0) {
>                  cout<<"Unable to find function "<<argv[2]<<endl;
>                  return -1;
>          } else {
>                   std::vector<BPatch_point *> *points;
>
>                  std::vector<BPatch_snippet *> printArgs;
>                  BPatch_snippet *fmt = new BPatch_constExpr("hello
> world\n");
>                  printArgs.push_back(fmt);
>
>                  std::vector<BPatch_function *> printfFuncs;
>                  img->findFunction("printf", printfFuncs);
>                  BPatch_funcCallExpr printfCall(*(printfFuncs[0]),
> printArgs);
>                  points = printFuncs[0]->findPoint(BPatch_entry);
>                  if ((*points).size() == 0) {
>                          return false;
>                  } else {
>                          cout<<"Got the points "<<endl;
>                  }
>                  BPatchSnippetHandle *ptr;
>                  ptr=appProc->insertSnippet(printfCall, *points);
>                  if(!ptr)
>                  {
>                          cout<<"Failed to insert the snippet"<<endl;
>                  } else {
>                          cout<<"Snippet is inserted successfully"<<endl;
>                  }
>        }
>          appProc->detach(true);
>          cout<<"Done."<<endl;
>
>          cout<<"Reattaching will be done again for deletion"<<endl;
>          BPatch_process *appProc1 = bpatch.processAttach("", pid);
>          BPatch_image *img1 = appProc1->getImage();
>          if(img1) {
>                  cout<<"Successfully got the image again"<<endl;
>          } else {
>                  cout<<"failed to get the image"<<endl;
>          }
>
>          std::vector<BPatch_function *> printFuncs1;
>          img->findFunction(argv[2],printFuncs1);
>          if (printFuncs1.size() == 0) {
>                  cout<<"Unable to find function "<<argv[2]<<endl;
>                  return -1;
>          } else {
>                   std::vector<BPatch_point *> *points1;
>
>                  std::vector<BPatch_function *> printfFuncs1;
>                  img->findFunction("printf", printfFuncs1);
>                  points1 = printFuncs1[0]->findPoint(BPatch_entry);
>                  if ((*points1).size() == 0) {
>                          return false;
>                  } else {
>                          cout<<"Got the points 2nd time"<<endl;
>                  }
>
>                  BPatch_point pt=*(*points1)[0];
>                  BPatch_Vector<BPatchSnippetHandle *> childSnippets =
> pt.getCurrentSnippets(BPatch_callBefore);
>                  if(childSnippets.size()==0){
>                          cout<<" No snippets were found "<<endl;
>                  } else {
>                          cout<<"The snippet size is "
> <<childSnippets.size()<<endl;
>                  }
>                  sleep(50);
>                   bool ret=appProc->deleteSnippet(childSnippets[0]);
>                if(ret)
>                {
>                          cout<<"The snippet is deleted"<<endl;
>                } else {
>                        cout<<"Failed to delete the snippet"<<endl;
>                }
>
>
>                  BPatch_point po=*(*points1)[0];
>
>
>                  bool check=appProc1->removeFunctionCall(po);
>                  if(check) {
>                          cout<<"success"<<endl;
>                  } else {
>                          cout<<"failure"<<endl;
>                  }
>
>          }
>          appProc1->detach(true);
>          cout<<"Done for second time."<<endl;
>          return 0;
> }
>
>
> Thanks,
> Shruthi
>
> _______________________________________________
> Dyninst-api mailing list
> Dyninst-api@xxxxxxxxxxx
> https://lists.cs.wisc.edu/mailman/listinfo/dyninst-api

--
--bw

Bill Williams
Paradyn Project
bill@xxxxxxxxxxx