[DynInst_API:] ReplaceFunction doesn't work

[Valéria Quadros <valeriaquadros@xxxxxxxxx>]

Hello, 
  I have a code which is supposed to change the behavior of a function (write call). I generated a shared library with the new write method and link it against my mutatee. When I compile and execute the mutator, everything seems to be ok; however, the new write method is not called. The library code is:

#include<stdio.h>
#include<sys/types.h>

ssize_t myWrite(int fd, const void *buf, size_t count) {
    fprintf(stderr, "hello");
    return 0;
}

 The library was generated with the commands:
gcc -fPIC -g -c -Wall myLib.c -o myLibObj.o
gcc -shared -Wl,-soname,libmyLib.so.1 -o libmyLib.so.1 myLibObj.o -lc -ldl

 The mutatte code is:

#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main() {
    int fd = open("wwopen.txt" , O_WRONLY|O_CREAT, 0666);

    int res = write(fd, "see you", 7);

    printf("Written %d bytes", res);

    return 1;
}

It was compiled with the command:
gcc -g -o wwopen wwopen.c libmyLib.so.1

The mutator code is:
#include<stdio.h>

#include "BPatch.h"
#include "BPatch_process.h"
#include "BPatch_function.h"
#include "BPatch_Vector.h"
#include "BPatch_thread.h"

bool replaceWrite(BPatch_process *app, BPatch_image *appImage, int rate) {
    int res;
    char name[128];
    unsigned int i;

    BPatch_Vector<BPatch_function *> myFuncs;
    appImage->findFunction("myWrite", myFuncs);
    fprintf(stderr, "myWrite size: %d\n", myFuncs.size());
    BPatch_Vector<BPatch_localVar *> *myparams = myFuncs[0]->getParams();
    fprintf(stderr, "\nParams size: %d", myparams->size());
    
    // (1) Locate the write call
    BPatch_Vector<BPatch_function *> writeFuncs;
    appImage->findFunction("write", writeFuncs);
    if(writeFuncs.size() == 0) {
        fprintf(stderr, "ERROR: Unable to find function for write()\n");
        return false;
    }
    fprintf(stderr, "\nWrite size: %d\n", writeFuncs.size());

    for(i = 0; i < writeFuncs.size(); i++) {
        writeFuncs[i]->getName(name, 128);
        fprintf(stderr, "\nIsShared1: %d", writeFuncs[i]->isSharedLib());
        fprintf(stderr, "\nWrite1 name: %s\n", name);

        BPatch_Vector<BPatch_localVar *> *params = writeFuncs[i]->getParams();
        fprintf(stderr, "\nParams size: %d", params->size());
    }

    res = app->replaceFunction(*writeFuncs[0], *myFuncs[0]);

    fprintf(stderr, "\nReplace res: %d", res);

    return true;
}

pid_t createDynProcess(const char *path, const char **argv, int rate) {
    BPatch bPatch;
    bool res;
    
    BPatch_process *app = bPatch.processCreate(path, argv);
    if(!app) {
        perror("createProcess");
        return -1;
    }
    fprintf(stderr, "\nPassei do processCreate");
    BPatch_image *appImage = app->getImage();

    res = app->loadLibrary("libmyLib.so.1", true);
    if(res == true)
        fprintf(stderr, "\nOK - library loaded");
    else
        fprintf(stderr, "\nNon-OK");

    fprintf(stderr, "\nInstrumenting write...\n");
    res = replaceWrite(app, appImage, rate);
    if (!res) {
        fprintf(stderr, "ERROR: failed to instrument mutatee\n");
        return -1;
    }

    // Continue the execution...
    fprintf(stderr, "\nContinuing execution and waiting for termination\n");
    res = app->continueExecution();
    fprintf(stderr, "\nContinue Execution: %d", res);
    while (!app->isTerminated())
        bPatch.waitForStatusChange();
    printf("\nDone.\n");

    return app->getPid();
}

int main() {
    const char *procArgv[2];
    procArgv[0] = const_cast<char*>("wwopen_temp.txt");
    procArgv[1] = NULL;
    int rate = 2;

    int pid = createDynProcess(strdup("/home/valeria/dyn_write_test/wwopen"), procArgv, rate);

    return pid;
}

It was compiled with the command:
g++ -Wall -I /usr/local/dyninst/include -L /usr/local/dyninst/i386-unknown-linux2.4/lib -ldyninstAPI -g -o teste teste.C

 I don't know where the mistake is. I hope somebody can help me.

Best regard, Valeria