util: use new VT ESC sequence to clear scrollback buffer

[elogind.git] / src / util.c

diff --git a/src/util.c b/src/util.c
index f0051ee28581f1aaa040cce6be46e1e7037c3ee9..a271708ba291979b17e6c4881389ad85b921ad4f 100644 (file)
--- a/src/util.c
+++ b/src/util.c
@@ -2141,7 +2141,7 @@ bool fstype_is_network(const char *fstype) {
 int chvt(int vt) {
         int fd, r = 0;
 
-        if ((fd = open("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC)) < 0)
+        if ((fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC)) < 0)
                 return -errno;
 
         if (vt < 0) {
@@ -2261,7 +2261,7 @@ int ask(char *ret, const char *replies, const char *text, ...) {
         }
 }
 
-int reset_terminal(int fd) {
+int reset_terminal_fd(int fd) {
         struct termios termios;
         int r = 0;
         long arg;
@@ -2323,6 +2323,19 @@ finish:
         return r;
 }
 
+int reset_terminal(const char *name) {
+        int fd, r;
+
+        fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return fd;
+
+        r = reset_terminal_fd(fd);
+        close_nointr_nofail(fd);
+
+        return r;
+}
+
 int open_terminal(const char *name, int mode) {
         int fd, r;
         unsigned c = 0;
@@ -2443,8 +2456,8 @@ int acquire_terminal(const char *name, bool fail, bool force, bool ignore_tiocst
                 /* We pass here O_NOCTTY only so that we can check the return
                  * value TIOCSCTTY and have a reliable way to figure out if we
                  * successfully became the controlling process of the tty */
-                if ((fd = open_terminal(name, O_RDWR|O_NOCTTY)) < 0)
-                        return -errno;
+                if ((fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC)) < 0)
+                        return fd;
 
                 /* First, try to get the tty */
                 r = ioctl(fd, TIOCSCTTY, force);
@@ -2511,7 +2524,7 @@ int acquire_terminal(const char *name, bool fail, bool force, bool ignore_tiocst
         if (notify >= 0)
                 close_nointr_nofail(notify);
 
-        if ((r = reset_terminal(fd)) < 0)
+        if ((r = reset_terminal_fd(fd)) < 0)
                 log_warning("Failed to reset terminal: %s", strerror(-r));
 
         return fd;
@@ -4413,6 +4426,88 @@ char* hostname_cleanup(char *s) {
         return s;
 }
 
+int terminal_vhangup_fd(int fd) {
+        if (ioctl(fd, TIOCVHANGUP) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int terminal_vhangup(const char *name) {
+        int fd, r;
+
+        fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return fd;
+
+        r = terminal_vhangup_fd(fd);
+        close_nointr_nofail(fd);
+
+        return r;
+}
+
+int vt_disallocate(const char *name) {
+        int fd, r;
+        unsigned u;
+
+        /* Deallocate the VT if possible. If not possible
+         * (i.e. because it is the active one), at least clear it
+         * entirely (including the scrollback buffer) */
+
+        if (!startswith(name, "/dev/"))
+                return -EINVAL;
+
+        if (!tty_is_vc(name)) {
+                /* So this is not a VT. I guess we cannot deallocate
+                 * it then. But let's at least clear the screen */
+
+                fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+                if (fd < 0)
+                        return fd;
+
+                loop_write(fd, "\033[H\033[2J", 7, false); /* clear screen */
+                close_nointr_nofail(fd);
+
+                return 0;
+        }
+
+        if (!startswith(name, "/dev/tty"))
+                return -EINVAL;
+
+        r = safe_atou(name+8, &u);
+        if (r < 0)
+                return r;
+
+        if (u <= 0)
+                return -EINVAL;
+
+        /* Try to deallocate */
+        fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return fd;
+
+        r = ioctl(fd, VT_DISALLOCATE, u);
+        close_nointr_nofail(fd);
+
+        if (r >= 0)
+                return 0;
+
+        if (errno != EBUSY)
+                return -errno;
+
+        /* Couldn't deallocate, so let's clear it fully with
+         * scrollback */
+        fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return fd;
+
+        /* Requires Linux 2.6.40 */
+        loop_write(fd, "\033[H\033[3J", 7, false); /* clear screen including scrollback */
+        close_nointr_nofail(fd);
+
+        return 0;
+}
+
 static const char *const ioprio_class_table[] = {
         [IOPRIO_CLASS_NONE] = "none",
         [IOPRIO_CLASS_RT] = "realtime",