1 files changed, 158 insertions, 0 deletions

diff --git a/fs/proc/proc_tty.c b/fs/proc/proc_tty.c
index 83adcc869437..dc44f94022f1 100644
--- a/fs/proc/proc_tty.c
+++ b/fs/proc/proc_tty.c
@@ -12,7 +12,10 @@
 #include <linux/proc_fs.h>
 #include <linux/stat.h>
 #include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/console.h>
 #include <linux/seq_file.h>
+#include <linux/fdtable.h>
 #include <linux/bitops.h>
 
 /*
@@ -137,6 +140,160 @@ static const struct file_operations proc_tty_drivers_operations = {
 };
 
 /*
+ * The device ID of file descriptor 0 of the current reading
+ * task if a character device...
+ */
+static dev_t current_dev;
+
+/*
+ * This is the handler for /proc/tty/consoles
+ */
+static int show_console_dev(struct seq_file *m, void *v)
+{
+        const struct tty_driver *driver;
+        struct console *con;
+        int index, len;
+        char flags[10];
+        dev_t dev;
+
+        if (v == SEQ_START_TOKEN)
+                return 0;
+        con = (struct console *)v;
+        if (!con)
+                return 0;
+        driver = con->device(con, &index);
+        if (!driver)
+                return 0;
+        dev = MKDEV(driver->major, driver->minor_start) + index;
+
+        index = 0;
+        if (con->flags & CON_ENABLED)
+                flags[index++] = 'E';
+        if (con->flags & CON_CONSDEV)
+                flags[index++] = 'C';
+        if (con->flags & CON_BOOT)
+                flags[index++] = 'B';
+        if (con->flags & CON_PRINTBUFFER)
+                flags[index++] = 'p';
+        if (con->flags & CON_BRL)
+                flags[index++] = 'b';
+        if (con->flags & CON_ANYTIME)
+                flags[index++] = 'a';
+        if (current_dev == dev)
+                flags[index++] = '*';
+        flags[index] = 0;
+
+        seq_printf(m, "%s%d%n", con->name, con->index, &len);
+        len = 21 - len;
+        if (len < 1)
+                len = 1;
+        seq_printf(m, "%*c", len, ' ');
+        seq_printf(m, "%c%c%c (%s)%n", con->read ? 'R' : '-',
+                        con->write ? 'W' : '-', con->unblank ? 'U' : '-',
+                        flags, &len);
+        len = 13 - len;
+        if (len < 1)
+                len = 1;
+        seq_printf(m, "%*c%4d:%d\n", len, ' ', MAJOR(dev), MINOR(dev));
+
+        return 0;
+}
+
+/* iterator for consoles */
+static void *c_start(struct seq_file *m, loff_t *pos)
+{
+        struct console *con;
+        loff_t off = 0;
+
+        if (*pos == 0)
+                return SEQ_START_TOKEN;
+
+        acquire_console_sem();
+        for (con = console_drivers; con; con = con->next) {
+                if (!con->device)
+                        continue;
+                if (++off == *pos)
+                        break;
+        }
+        release_console_sem();
+
+        return con;
+}
+
+static void *c_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        struct console *con;
+
+        acquire_console_sem();
+        if (v == SEQ_START_TOKEN)
+                con = console_drivers;
+        else
+                con = ((struct console *)v)->next;
+        for (; con; con = con->next) {
+                if (!con->device)
+                        continue;
+                ++*pos;
+                break;
+        }
+        release_console_sem();
+
+        return con;
+}
+
+static void c_stop(struct seq_file *m, void *v)
+{
+}
+
+static const struct seq_operations tty_consoles_op = {
+        .start  = c_start,
+        .next   = c_next,
+        .stop   = c_stop,
+        .show   = show_console_dev
+};
+
+/*
+ * Used for open /proc/tty/consoles. Before this detect
+ * the device ID of file descriptor 0 of the current
+ * reading task if a character device...
+ */
+static int tty_consoles_open(struct inode *inode, struct file *file)
+{
+        struct files_struct *curfiles;
+
+        current_dev = 0;
+        curfiles = get_files_struct(current);
+        if (curfiles) {
+                const struct file *curfp;
+                spin_lock(&curfiles->file_lock);
+                curfp = fcheck_files(curfiles, 0);
+                if (curfp && curfp->private_data) {
+                        const struct inode *inode;
+                        dget(curfp->f_dentry);
+                        inode = curfp->f_dentry->d_inode;
+                        if (S_ISCHR(inode->i_mode)) {
+                                struct tty_struct *tty;
+                                tty = (struct tty_struct *)curfp->private_data;
+                                if (tty && tty->magic == TTY_MAGIC) {
+                                        tty = tty_pair_get_tty(tty);
+                                        current_dev = tty_devnum(tty);
+                                }
+                        }
+                        dput(curfp->f_dentry);
+                }
+                spin_unlock(&curfiles->file_lock);
+                put_files_struct(curfiles);
+        }
+        return seq_open(file, &tty_consoles_op);
+}
+
+static const struct file_operations proc_tty_consoles_operations = {
+        .open           = tty_consoles_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+};
+
+/*
  * This function is called by tty_register_driver() to handle
  * registering the driver's /proc handler into /proc/tty/driver/<foo>
  */
@@ -186,4 +343,5 @@ void __init proc_tty_init(void)
         proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR|S_IXUSR, NULL);
         proc_create("tty/ldiscs", 0, NULL, &tty_ldiscs_proc_fops);
         proc_create("tty/drivers", 0, NULL, &proc_tty_drivers_operations);
+        proc_create("tty/consoles", 0, NULL, &proc_tty_consoles_operations);
 }