diff options
Diffstat (limited to 'debian/clear_console.c')
| -rw-r--r-- | debian/clear_console.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/debian/clear_console.c b/debian/clear_console.c new file mode 100644 index 0000000..4cd3f26 --- /dev/null +++ b/debian/clear_console.c @@ -0,0 +1,291 @@ +/* +Copyright (C) 2006-2019 Canonical Ltd. + +clear_console and it's man page are free software; you can redistribute it +and/or modify it under the terms of the GNU General Public License as +published by the Free Software Foundation; either version 2, or (at your +option) any later version. +*/ + +#include <stdlib.h> +#include <stdio.h> +#include <fcntl.h> +#include <string.h> +#include <getopt.h> +#include <errno.h> +#include <unistd.h> +#include <sys/ioctl.h> +#if defined(__linux) +#include <linux/kd.h> +#include <linux/vt.h> +#elif defined(__FreeBSD_kernel__) +#include <sys/consio.h> +#include <sys/kbio.h> +#endif + +#include <curses.h> +#include <term.h> + +#define VERSION "0.1" + +char* progname; +int quiet = 0; + +void usage() +{ + fprintf(stderr, "Usage: %s [option]\n", progname); + fprintf(stderr, "valid options are:\n"); + fprintf(stderr, "\t-q --quiet don't print error messages\n"); + fprintf(stderr, "\t-h --help display this help text and exit\n"); + fprintf(stderr, "\t-V --version display version information and exit\n"); +} + +const struct option opts[] = +{ + /* operations */ + {"help", no_argument, 0, 'h'}, + {"version", no_argument, 0, 'V'}, + {"quiet", no_argument, 0, 'q'}, + {0, 0, 0, 0} +}; + +static int putch(int c) +{ + return putchar(c); +} + + +/* taken from console-utils, lib/misc-console-utils.c */ + +int is_a_console(int fd) +{ +#if defined(__linux__) + char arg; +#elif defined(__FreeBSD_kernel__) + int arg; +#endif + + arg = 0; + return (ioctl(fd, KDGKBTYPE, &arg) == 0 + && ((arg == KB_OTHER) || (arg == KB_101) || (arg == KB_84))); +} + +static int open_a_console(char *fnam) +{ + int fd; + + /* try read-only */ + fd = open(fnam, O_RDWR); + + /* if failed, try read-only */ + if (fd < 0 && errno == EACCES) + fd = open(fnam, O_RDONLY); + + /* if failed, try write-only */ + if (fd < 0 && errno == EACCES) + fd = open(fnam, O_WRONLY); + + /* if failed, fail */ + if (fd < 0) + return -1; + + /* if not a console, fail */ + if (! is_a_console(fd)) + { + close(fd); + return -1; + } + + /* success */ + return fd; +} + +/* + * Get an fd for use with kbd/console ioctls. + * We try several things because opening /dev/console will fail + * if someone else used X (which does a chown on /dev/console). + * + * if tty_name is non-NULL, try this one instead. + */ + +int get_console_fd(char* tty_name) +{ + int fd; + + if (tty_name) + { + if (-1 == (fd = open_a_console(tty_name))) + return -1; + else + return fd; + } + + fd = open_a_console("/dev/tty"); + if (fd >= 0) + return fd; + + fd = open_a_console("/dev/tty0"); + if (fd >= 0) + return fd; + + fd = open_a_console("/dev/console"); + if (fd >= 0) + return fd; + + for (fd = 0; fd < 3; fd++) + if (is_a_console(fd)) + return fd; + +#if 0 + fprintf(stderr, + _("Couldnt get a file descriptor referring to the console\n")); +#endif + return -1; /* total failure */ +} + + +int is_pseudo_tty(int fd) +{ + char *tty = ttyname(fd); + + if (!tty) + { + if (!quiet) + perror("ttyname"); + return 0; + } + + if (strlen(tty) >= 9 && !strncmp(tty, "/dev/pts/", 9)) + return 1; + + if (strlen(tty) >= 8 && !strncmp(tty, "/dev/tty", 8) + && tty[8] >= 'a' && tty[8] <= 'z') + return 1; + + return 0; +} + +int clear_console(int fd) +{ + int num, tmp_num; +#if defined(__linux__) + struct vt_stat vtstat; +#endif + + /* Linux console secure erase (since 2.6.39), this is sufficient there; + other terminals silently ignore this code. If they don't and write junk + instead, well, we're clearing the screen anyway. + */ + write(1, "\e[3J", 4); + + /* clear screen */ + setupterm((char *) 0, 1, (int *) 0); + if (tputs(clear_screen, lines > 0 ? lines : 1, putch) == ERR) + { + exit(1); + } + + if (is_pseudo_tty(STDIN_FILENO)) + return 0; + + if (!strcmp(getenv("TERM"), "screen")) + return 0; + + /* get current vt */ +#if defined(__linux__) + if (ioctl(fd, VT_GETSTATE, &vtstat) < 0) +#elif defined(__FreeBSD_kernel__) + if (ioctl(fd, VT_ACTIVATE, &num) < 0) +#endif + { + if (!quiet) + fprintf(stderr, "%s: cannot get VTstate\n", progname); + exit(1); + } +#if defined(__linux__) + num = vtstat.v_active; +#endif + tmp_num = (num == 6 ? 5 : 6); + + /* switch vt to clear the scrollback buffer */ + if (ioctl(fd, VT_ACTIVATE, tmp_num)) + { + if (!quiet) + perror("chvt: VT_ACTIVATE"); + exit(1); + } + + if (ioctl(fd, VT_WAITACTIVE, tmp_num)) + { + if (!quiet) + perror("VT_WAITACTIVE"); + exit(1); + } + + /* switch back */ + if (ioctl(fd, VT_ACTIVATE, num)) + { + if (!quiet) + perror("chvt: VT_ACTIVATE"); + exit(1); + } + + if (ioctl(fd, VT_WAITACTIVE, num)) + { + if (!quiet) + perror("VT_WAITACTIVE"); + exit(1); + } + return 0; +} + +int main (int argc, char* argv[]) +{ + int fd; + int result; /* option handling */ + int an_option; + + if ((progname = strrchr(argv[0], '/')) == NULL) + progname = argv[0]; + else + progname++; + + while (1) + { + result = getopt_long(argc, argv, "Vhq", opts, &an_option); + + if (result == EOF) + break; + + switch (result) + { + case 'V': + fprintf(stdout, "%s: Version %s\n", progname, VERSION); + exit (0); + case 'h': + usage(); + exit (0); + + case 'q': + quiet = 1; + } + } + + if (optind < argc) + { + if (!quiet) + fprintf(stderr, "%s: no non-option arguments are valid", progname); + exit(1); + } + + if ((fd = get_console_fd(NULL)) == -1) + { + if (!quiet) + fprintf(stderr, "%s: terminal is not a console\n", progname); + exit(1); + } + + clear_console(fd); + + return 0; +} |