c++ - String written to child process corrupted? -

i want execute program in child process. program works when run directly in terminal: waits input , control+d/eof has send before processes it.

in code below program not seem receive string properly, seems if sees part or nothing @ when receives eof seems happen several times though send once.

if can tell me going wrong here?

    int main(int argc, char** argv) {       int pipes[2][2]; //pipe[0] read, pipe[1] write        #define parent_read_fd  ( pipes[1][0] )       #define parent_write_fd ( pipes[0][1] )        #define child_read_fd   ( pipes[0][0]  )       #define child_write_fd  ( pipes[1][1]  )        // pipes parent write , read       assert( (pipe(pipes[1])) == 0 );       assert( (pipe(pipes[0])) == 0 );        int pid = fork();       if(pid == 0) {           char *argv[]={"/workspace/osm/overpass/osm3s_v0.7.51/bin/osm3s_query", "--db-dir=$db_dir"};            assert( (dup2(child_read_fd, stdin_fileno)) != -1);           assert( (dup2(child_write_fd, stdout_fileno)) != -1);            close(child_read_fd);           close(child_write_fd);           close(parent_read_fd);           close(parent_write_fd);            execv(argv[0], argv);       } else if(pid > 0) {           char buffer[1000];           int count;            close(child_read_fd);           close(child_write_fd);            int query_size = strlen(query.c_str()) + 1;           int succesful_write = write(parent_write_fd, &query, query_size);           assert(succesful_write==query_size);           close(parent_write_fd);            // read child’s stdout           while( count = read(parent_read_fd, buffer, sizeof(buffer)-1) > 0){             cerr << buffer << endl;           }       } else {         cerr << "could not fork child process" << endl;         exit(exit_failure);       }     } 

the error output program example (it changes every time program run):

    line 1: parse error: unknown type "�"     line 1: parse error: empty query not allowed     line 1: parse error: unknown type "n"     line 1: parse error: empty query not allowed     line 1: parse error: unknown type "�"     ...