c++ - Read/Write bytes within two processes (apps) using virtual serial communication on Android -

i have written c/c++ application (ndk) android can open virtual port serial communication. writes , reads bytes port within same process. far working , didn´t have root device in order this. simple programm following:

int fd = open("/dev/ptmx", o_rdwr | o_noctty); if (fd == -1) {     logw("error opening file");      return 1; }  grantpt(fd); unlockpt(fd);  char* pts_name = ptsname(fd); logi("ptsname: %s\n", pts_name);  char* inputbyte = "this test\n";  char byte;  int numofbyteswritten = write(fd, inputbyte, strlen(inputbyte)); logi("number of bytes written: %d\n", numofbyteswritten);  while (read(fd, &byte, 1) == 1) { logi("byte: %c\n", byte); }  close(fd); 

now problem if want same thing within 2 processes (two apps) doesn´t work. 1 process opens /dev/ptmx, , other process should open /dev/pts directory. everytime slave tries open /dev/pts directory error "error opening file" (-1). have rooted device , still not working. have sleep function after opening /dev/ptmx directory in order wait slave.

what should do? ideas?

i have solved problem post solution in case else interested:

(1) phone should rooted.

(2) master opens port in form "/dev/pts/n" (variable pts_name in example) n number. port given by:

int fd = open("/dev/ptmx", o_rdwr | o_noctty);   if (fd == -1) {      logw("error opening file");      return 1;   }   char* pts_name = ptsname(fd);   logi("ptsname: %s\n", pts_name); 

(3) give permissions port (this can done programmatically or adb shell). shell be:

• su
• chmod 666 pts_name (for example chmod 666 /dev/pts/4).

(4) execute slave opens port. example int fd = open("/dev/pts/4", o_rdwr);

(5) voilà!