fs/proc/proc_tty.c

   1 /*
   2  * proc_tty.c -- handles /proc/tty
   3  *
   4  * Copyright 1997, Theodore Ts'o
   5  */
   6
   7 #include <asm/uaccess.h>
   8
   9 #include <linux/init.h>
  10 #include <linux/errno.h>
  11 #include <linux/sched.h>
  12 #include <linux/proc_fs.h>
  13 #include <linux/stat.h>
  14 #include <linux/tty.h>
  15 #include <asm/bitops.h>
  16
  17 extern struct tty_driver *tty_drivers;  /* linked list of tty drivers */
  18
  19 static int tty_drivers_read_proc(char *page, char **start, off_t off,
  20                                  int count, int *eof, void *data);
  21 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
  22                                 int count, int *eof, void *data);
  23
  24 /*
  25  * The /proc/tty directory inodes...
  26  */
  27 static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;
  28
  29 /*
  30  * This is the handler for /proc/tty/drivers
  31  */
  32 static int tty_drivers_read_proc(char *page, char **start, off_t off,
  33                                  int count, int *eof, void *data)
  34 {
  35         int     len = 0;
  36         off_t   begin = 0;
  37         struct tty_driver *p;
  38         char    range[20], deftype[20];
  39         char    *type;
  40
  41         for (p = tty_drivers; p; p = p->next) {
  42                 if (p->num > 1)
  43                         sprintf(range, "%d-%d", p->minor_start,
  44                                 p->minor_start + p->num - 1);
  45                 else
  46                         sprintf(range, "%d", p->minor_start);
  47                 switch (p->type) {
  48                 case TTY_DRIVER_TYPE_SYSTEM:
  49                         if (p->subtype == SYSTEM_TYPE_TTY)
  50                                 type = "system:/dev/tty";
  51                         else if (p->subtype == SYSTEM_TYPE_SYSCONS)
  52                                 type = "system:console";
  53                         else if (p->subtype == SYSTEM_TYPE_CONSOLE)
  54                                 type = "system:vtmaster";
  55                         else
  56                                 type = "system";
  57                         break;
  58                 case TTY_DRIVER_TYPE_CONSOLE:
  59                         type = "console";
  60                         break;
  61                 case TTY_DRIVER_TYPE_SERIAL:
  62                         if (p->subtype == 2)
  63                                 type = "serial:callout";
  64                         else
  65                                 type = "serial";
  66                         break;
  67                 case TTY_DRIVER_TYPE_PTY:
  68                         if (p->subtype == PTY_TYPE_MASTER)
  69                                 type = "pty:master";
  70                         else if (p->subtype == PTY_TYPE_SLAVE)
  71                                 type = "pty:slave";
  72                         else
  73                                 type = "pty";
  74                         break;
  75                 default:
  76                         sprintf(deftype, "type:%d.%d", p->type, p->subtype);
  77                         type = deftype;
  78                         break;
  79                 }
  80                 len += sprintf(page+len, "%-20s /dev/%-8s %3d %7s %s\n",
  81                                p->driver_name ? p->driver_name : "unknown",
  82                                p->name, p->major, range, type);
  83                 if (len+begin > off+count)
  84                         break;
  85                 if (len+begin < off) {
  86                         begin += len;
  87                         len = 0;
  88                 }
  89         }
  90         if (!p)
  91                 *eof = 1;
  92         if (off >= len+begin)
  93                 return 0;
  94         *start = page + (off-begin);
  95         return ((count < begin+len-off) ? count : begin+len-off);
  96 }
  97
  98 /*
  99  * This is the handler for /proc/tty/ldiscs
 100  */
 101 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
 102                                 int count, int *eof, void *data)
 103 {
 104         int     i;
 105         int     len = 0;
 106         off_t   begin = 0;
 107         struct tty_ldisc *ld;
 108
 109         for (i=0; i < NR_LDISCS; i++) {
 110                 ld = tty_ldisc_get(i);
 111                 if (ld == NULL)
 112                         continue;
 113                 len += sprintf(page+len, "%-10s %2d\n",
 114                                ld->name ? ld->name : "???", i);
 115                 tty_ldisc_put(i);
 116                 if (len+begin > off+count)
 117                         break;
 118                 if (len+begin < off) {
 119                         begin += len;
 120                         len = 0;
 121                 }
 122         }
 123         if (i >= NR_LDISCS)
 124                 *eof = 1;
 125         if (off >= len+begin)
 126                 return 0;
 127         *start = page + (off-begin);
 128         return ((count < begin+len-off) ? count : begin+len-off);
 129 }
 130
 131 /*
 132  * This function is called by tty_register_driver() to handle
 133  * registering the driver's /proc handler into /proc/tty/driver/<foo>
 134  */
 135 void proc_tty_register_driver(struct tty_driver *driver)
 136 {
 137         struct proc_dir_entry *ent;
 138
 139         if ((!driver->read_proc && !driver->write_proc) ||
 140             !driver->driver_name ||
 141             driver->proc_entry)
 142                 return;
 143
 144         ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
 145         if (!ent)
 146                 return;
 147         ent->read_proc = driver->read_proc;
 148         ent->write_proc = driver->write_proc;
 149         ent->data = driver;
 150
 151         driver->proc_entry = ent;
 152 }
 153
 154 /*
 155  * This function is called by tty_unregister_driver()
 156  */
 157 void proc_tty_unregister_driver(struct tty_driver *driver)
 158 {
 159         struct proc_dir_entry *ent;
 160
 161         ent = driver->proc_entry;
 162         if (!ent)
 163                 return;
 164
 165         remove_proc_entry(driver->driver_name, proc_tty_driver);
 166
 167         driver->proc_entry = 0;
 168 }
 169
 170 /*
 171  * Called by proc_root_init() to initialize the /proc/tty subtree
 172  */
 173 void __init proc_tty_init(void)
 174 {
 175         if (!proc_mkdir("tty", 0))
 176                 return;
 177         proc_tty_ldisc = proc_mkdir("tty/ldisc", 0);
 178         /*
 179          * /proc/tty/driver/serial reveals the exact character counts for
 180          * serial links which is just too easy to abuse for inferring
 181          * password lengths and inter-keystroke timings during password
 182          * entry.
 183          */
 184         proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, 0);
 185
 186         create_proc_read_entry("tty/ldiscs", 0, 0, tty_ldiscs_read_proc,NULL);
 187         create_proc_read_entry("tty/drivers", 0, 0, tty_drivers_read_proc,NULL);
 188 }