[sysvinit-devel] [PATCH] automatically spawn agetty on kernel consoles

[Ludwig Nussel]

The feature is useful for developers and admins that occasionally need
to boot with e.g. console=ttyS0.
The built in default can be overridden via inittab for each device. An
entry like "S0::off:" turns off the getty on ttyS0.
---
 src/init.c |   74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 74 insertions(+), 0 deletions(-)

diff --git a/src/init.c b/src/init.c
index d379fb2..13deef7 100644
--- a/src/init.c
+++ b/src/init.c
@@ -1243,6 +1243,76 @@ void startup(CHILD *ch)
        }
 }
 
+#ifdef __linux__
+static
+void check_kernel_console()
+{
+       FILE* fp;
+       char buf[4096];
+       if ((fp = fopen("/proc/cmdline", "r")) == 0) {
+               return;
+       }
+       if (fgets(buf, sizeof(buf), fp)) {
+               char* p = buf;
+               while ((p = strstr(p, "console="))) {
+                       char* e;
+                       p += strlen("console=");
+                       for (e = p; *e; ++e) {
+                               switch (*e) {
+                                       case '-' ... '9':
+                                       case 'A' ... 'Z':
+                                       case '_':
+                                       case 'a' ... 'z':
+                                               continue;
+                               }
+                               break;
+                       }
+                       if (p != e) {
+                               CHILD* old;
+                               int dup = 0;
+                               char id[8] = {0};
+                               char dev[32] = {0};
+                               strncpy(dev, p, MIN(sizeof(dev), 
(unsigned)(e-p)));
+                               if (!strncmp(dev, "tty", 3))
+                                       strncpy(id, dev+3, sizeof(id));
+                               else
+                                       strncpy(id, dev, sizeof(id));
+
+                               for(old = newFamily; old; old = old->next) {
+                                       if (!strcmp(old->id, id)) {
+                                               dup = 1;
+                                       }
+                               }
+                               if (!dup) {
+                                       CHILD* ch = imalloc(sizeof(CHILD));
+                                       ch->action = RESPAWN;
+                                       strcpy(ch->id, id);
+                                       strcpy(ch->rlevel, "2345");
+                                       sprintf(ch->process, "/sbin/agetty -L 
-s 115200,38400,9600 %s vt102", dev);
+                                       ch->next = NULL;
+                                       for(old = family; old; old = old->next) 
{
+                                               if (strcmp(old->id, ch->id) == 
0) {
+                                                       old->new = ch;
+                                                       break;
+                                               }
+                                       }
+                                       /* add to end */
+                                       for(old = newFamily; old; old = 
old->next) {
+                                               if (!old->next) {
+                                                       old->next = ch;
+                                                       break;
+                                               }
+                                       }
+
+                                       initlog(L_VB, "added agetty on %s with 
id %s", dev, id);
+                               }
+                       }
+               }
+       }
+       fclose(fp);
+       return;
+}
+#endif
 
 /*
  *     Read the inittab file.
@@ -1455,6 +1525,10 @@ void read_inittab(void)
    */
   if (fp) fclose(fp);
 
+#ifdef __linux__
+  check_kernel_console();
+#endif
+
   /*
    *   Loop through the list of children, and see if they need to
    *   be killed. 
-- 
1.7.3.4