Option cachée dans Logcat

Logcat.cpp

            case 'Q':
                /* this is a *hidden* option used to start a version of logcat                 */
                /* in an emulated device only. it basically looks for androidboot.logcat=      */
                /* on the kernel command line. If something is found, it extracts a log filter */
                /* and uses it to run the program. If nothing is found, the program should     */
                /* quit immediately                                                            */
#define  KERNEL_OPTION  "androidboot.logcat="
#define  CONSOLE_OPTION "androidboot.console="
                {
                    int          fd;
                    char*        logcat;
                    char*        console;
                    int          force_exit = 1;
                    static char  cmdline[1024];

                    fd = open("/proc/cmdline", O_RDONLY);
                    if (fd >= 0) {
                        int  n = read(fd, cmdline, sizeof(cmdline)-1 );
                        if (n < 0) n = 0;
                        cmdline[n] = 0;
                        close(fd);
                    } else {
                        cmdline[0] = 0;
                    }

                    logcat  = strstr( cmdline, KERNEL_OPTION );
                    console = strstr( cmdline, CONSOLE_OPTION );
                    if (logcat != NULL) {
                        char*  p = logcat + sizeof(KERNEL_OPTION)-1;;
                        char*  q = strpbrk( p, " \t\n\r" );;

                        if (q != NULL)
                            *q = 0;

                        forceFilters = p;
                        force_exit   = 0;
                    }
                    /* if nothing found or invalid filters, exit quietly */
                    if (force_exit)
                        exit(0);

                    /* redirect our output to the emulator console */
                    if (console) {
                        char*  p = console + sizeof(CONSOLE_OPTION)-1;
                        char*  q = strpbrk( p, " \t\n\r" );
                        char   devname[64];
                        int    len;

                        if (q != NULL) {
                            len = q - p;
                        } else
                            len = strlen(p);

                        len = snprintf( devname, sizeof(devname), "/dev/%.*s", len, p );
                        fprintf(stderr, "logcat using %s (%d)\n", devname, len);
                        if (len < (int)sizeof(devname)) {
                            fd = open( devname, O_WRONLY );
                            if (fd >= 0) {
                                dup2(fd, 1);
                                dup2(fd, 2);
                                close(fd);
                            }
                        }
                    }
                }
                break;