bluethoothctl with C

Server Mode (Playback from external BT source)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

int main()
{
    int pfds[2];
    int status;
    pid_t pid;

    if ( pipe(pfds) == -1 )
    {
        perror("pipe error\n");
        exit(1);
    }

    pid = fork();
    if ( pid == 0 ) //child, run the bluetoothctl command
    {
        close(STDIN_FILENO);
        dup2( pfds[0], STDIN_FILENO );
        close( pfds[1] );
        execl("/usr/bin/bluetoothctl", "bluetoothctl", (char*) NULL);
        exit(0);

    }
    else //father, send the command to bluetoothctl
    {
        close(STDOUT_FILENO);
        dup2( pfds[1], STDOUT_FILENO );
        write(STDOUT_FILENO, "power on\n", strlen("power off\n"));
        sleep(1);
        write(STDOUT_FILENO, "agent on\n", strlen("agent on\n"));
        write(STDOUT_FILENO, "default-agent\n", strlen("default-agent\n"));
        write(STDOUT_FILENO, "pairable on\n", strlen("pairable on\n"));
        write(STDOUT_FILENO, "pair A8:87:B3:1E:D9:66\n", strlen("pair A8:87:B3:1E:D9:66\n"));
        write(STDOUT_FILENO, "trust A8:87:B3:1E:D9:66\n", strlen("trust A8:87:B3:1E:D9:66\n"));
        write(STDOUT_FILENO, "connect A8:87:B3:1E:D9:66\n", strlen("connect A8:87:B3:1E:D9:66\n"));
        sleep(2);
        write(STDOUT_FILENO, "exit\n", strlen("exit\n"));
        write(STDOUT_FILENO, "connect A8:87:B3:1E:D9:66\n", strlen("connect A8:87:B3:1E:D9:66\n"));
        close( pfds[0] );
        waitpid((pid_t)pid, &status, 0);
        exit(0);
    }
}

ref:Bluetooth A2DP



無法啟動 power on

[bluetooth]# power on
Failed to set power on: org.bluez.Error.Blocked

查找原因

$ sudo systemctl status bluetooth.service
● bluetooth.service - Bluetooth service
   Loaded: loaded (/lib/systemd/system/bluetooth.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2021-02-22 17:08:08 CST; 1min 55s ago
     Docs: man:bluetoothd(8)
 Main PID: 4723 (bluetoothd)
   Status: "Running"
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/bluetooth.service
           └─4723 /usr/lib/bluetooth/bluetoothd

 二  22 17:08:08 hello-W230ST systemd[1]: Starting Bluetooth service...
 二  22 17:08:08 hello-W230ST bluetoothd[4723]: Bluetooth daemon 5.48
 二  22 17:08:08 hello-W230ST systemd[1]: Started Bluetooth service.
 二  22 17:08:08 hello-W230ST bluetoothd[4723]: Starting SDP server
 二  22 17:08:08 hello-W230ST bluetoothd[4723]: Bluetooth management interface 1.14 initialized
 二  22 17:08:08 hello-W230ST bluetoothd[4723]: Failed to set mode: Blocked through rfkill (0x12)
 二  22 17:08:08 hello-W230ST bluetoothd[4723]: Endpoint registered: sender=:1.91 path=/MediaEndpoint/A2DPSource
 二  22 17:08:08 hello-W230ST bluetoothd[4723]: Endpoint registered: sender=:1.91 path=/MediaEndpoint/A2DPSink
 二  22 17:09:55 hello-W230ST bluetoothd[4723]: Failed to set mode: Blocked through rfkill (0x12)

$ sudo systemctl restart bluetooth.service  <-沒用

$ sudo rfkill list
0: hci0: Bluetooth
        Soft blocked: yes <- 被block住了@@?
        Hard blocked: no
1: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no

解決

$ sudo rfkill unblock bluetooth


$ sudo rfkill list
0: hci0: Bluetooth
        Soft blocked: no
        Hard blocked: no
1: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no

ref:
1. Cannot unblock soft-blocked bluetooth

2. PIPES, FORKS, & DUP