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util: use new VT ESC sequence to clear scrollback buffer

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This commit is contained in:
Lennart Poettering 2011-05-20 14:37:14 +02:00
parent b136daf5ca
commit b83bc4e9cc
1 changed files with 33 additions and 68 deletions
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101
src/util.c
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@ -4449,16 +4449,27 @@ int terminal_vhangup(const char *name) {
int vt_disallocate(const char *name) {
int fd, r;
unsigned u;
int temporary_vt, temporary_fd;
char tpath[64];
struct vt_stat vt_stat;
/* 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 (!tty_is_vc(name))
return -EIO;
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;
@ -4468,79 +4479,33 @@ int vt_disallocate(const char *name) {
return r;
if (u <= 0)
return -EIO;
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);
if (r >= 0) {
close_nointr_nofail(fd);
return 0;
}
if (errno != EBUSY) {
close_nointr_nofail(fd);
return -errno;
}
if (ioctl(fd, VT_GETSTATE, &vt_stat) < 0) {
close_nointr_nofail(fd);
return -errno;
}
if (u != vt_stat.v_active) {
close_nointr_nofail(fd);
return -EBUSY;
}
if (ioctl(fd, VT_OPENQRY, &temporary_vt) < 0) {
close_nointr_nofail(fd);
return -errno;
}
if (temporary_vt <= 0) {
close_nointr_nofail(fd);
return -EIO;
}
/* Switch to temporary VT */
snprintf(tpath, sizeof(tpath), "/dev/tty%i", temporary_vt);
char_array_0(tpath);
temporary_fd = open_terminal(tpath, O_RDWR|O_NOCTTY|O_CLOEXEC);
ioctl(fd, VT_ACTIVATE, temporary_vt);
if (temporary_fd >= 0)
close_nointr_nofail(temporary_fd);
/* Reopen /dev/tty0 */
close_nointr_nofail(fd);
fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC);
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)
r = -errno;
else {
/* Disallocate the real VT */
if (ioctl(fd, VT_DISALLOCATE, u) < 0)
r = -errno;
else
r = 0;
}
return fd;
/* Recreate original VT */
temporary_fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
/* Requires Linux 2.6.40 */
loop_write(fd, "\033[H\033[3J", 7, false); /* clear screen including scrollback */
close_nointr_nofail(fd);
if (temporary_fd >= 0) {
loop_write(temporary_fd, "\033[H\033[2J", 7, false); /* clear screen explicitly */
close_nointr_nofail(temporary_fd);
}
/* Switch back to original VT */
if (fd >= 0) {
ioctl(fd, VT_ACTIVATE, vt_stat.v_active);
close_nointr_nofail(fd);
}
return r;
return 0;
}
static const char *const ioprio_class_table[] = {