CODEWITHSUNDEEP
c++cexecunistd.hexecl
JAM AICA
JAM AICA

Reputation: 91

Exec fails due to Bad Address

I have a serious problem with exec.I've tried both options with list(execl) and array(execv) but the problem remains.I'll give the function in which i try to make the call.

#include <unistd.h>
#include <sys/types.h>
void MyFunc(string aparams[],char* infile,char* outfile,int k,int points){

int mcount=3;
char* offset= new char[5];
sprintf(offset,"%d",k);
char* pntr=new char[5];
sprintf(pntr,"%d",points);
char* *wparams=new char*[mcount];
for (int i = 0; i < mcount; i++) {
    wparams[i] = new char[aparams[i].length() + 1];
    strcpy(wparams[i], aparams[i].c_str());
}
char *cwd; 
cwd=(char*)malloc(255); 
getcwd(cwd,255); 
strcat(cwd,"/"); 
strcat(cwd,wparams[0]);
cout << cwd << endl;
execl(cwd,wparams[0],"-i",infile,"-o",outfile,"-f",offset,"-n",pntr,"-a",wparams[1],wparams[2],wparams[3],(char*) NULL);    

cout << "exec failed" << endl;
perror("The problem in exec is:");
exit(3);

}

aparams[0] contains a string with the name of an executable file,let's say "test".I compiled -> g++ test.cpp -o test -> so I got this executable. The other positions of aparams contain some arguments for the test program.

So,test never runs(when I run it from command line it's ok) and perror shows the message "The problem in exec is: Bad Address."

I've also tried to cast all arguments(const char*) but nothing changed. Is it a problem with arguments? Or it's a matter of the executable?

Upvotes: 1

Views: 1970

Answers (2)

Wilfredo Pomier
Wilfredo Pomier

Reputation: 1121

Your problem is in this line:

execl(cwd, 
    wparams[0], 
    "-i", infile, "-o", outfile, "-f", offset, "-n", pntr, 
    "-a", wparams[1], wparams[2], wparams[3], (char*) NULL);

You're trying to send wparams[3], which doesn't exists! It's the 4th element of wparam array and you explicitly defined it as array[3] in the initialization of your variable mcount.

Upvotes: 1

Criticize SE actions means ban
Criticize SE actions means ban

Reputation: 58868

mcount is 3, so wparams points to an array with three elements - wparams[0], wparams[1] and wparams[2].

Then you access wparams[3] which is invalid and contains garbage.

Don't try to access array elements that don't exist.

Upvotes: 3

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