using popen in fanotify, system hangs while handling fanotify events

Question

i am use Fanotify sample code to handle file open and close events. In handle_events() function i am called my function checkFileIsExecutable(). after calling function my system is hang and need to hard restart. i am providing my function which is use to check executable file or not. i am added my hanging code as a reference please chck it and help me to solve this problem.

checkFileIsExecutable(const char *filepath)
{
        string data;
        FILE* stream;
        char buffer[64];
        char res[64];

        if(sFileName.empty())
        {
                return "error";
        }

        string cmd("file ");
        cmd.append(filepath);

        cout<< "Going to execute cmd: "<< cmd.c_str()) <<endl;

        stream = popen(cmd.c_str(), "r");             //here my code is hangs 
        if(stream)
        {
                while(!feof(stream))
                {
                        if(fgets(buffer, 64, stream) != NULL)
                        {
                               data.append(buffer);
                        }
                }
                pclose(stream);
         }

         strcpy(res, data.c_str());

        if(0 == strcasecmp(res, "executable"))
        {
                cout << "File is executable\n" << endl;
                return true;
        }

       return false;
}

error code:

Going to execute cmd:file /root/Test/access hangs....

the `fgets` is *sufficient*, break the loop if it returns `NULL`. If the stream goes to an *error* condition then `feof` will not be true but `ferror` will be. — Antti Haapala -- Слава Україні, May 10 '20 at 17:17
thanks @AnttiHaapala but still my question is why popen() is stuck on this line, stream = popen(cmd.c_str(), "r"); — Dhiraj, May 10 '20 at 19:00
Please provide a [mre], a minimal **full** program that produces the same behaviour — Antti Haapala -- Слава Україні, May 11 '20 at 05:11
please use following [example](http://man7.org/linux/man-pages/man7/fanotify.7.html) and in handle_events() function, call checkFileIsExecutable() function after two line. `path[path_len] = '\0'; printf("File %s\n", path); bool ret = checkFileIsExecutable(path); // Here` to produces behaviour. — Dhiraj, May 11 '20 at 08:09
@AnttiHaapala, i am add logs and check last log which is before popen() function. — Dhiraj, May 11 '20 at 09:09

using popen in fanotify, system hangs while handling fanotify events

0 Answers0