Defined EOF as -1 in stdio.h.

Implemented the sprintf() library function in lib/stdio.c which uses the
vsprintf() function.

Implemented a very primative controlling TTY for each process. This is
achieved by a switch in the sys_puts system call which uses the 'ctty'
element of the process' task structure to determine an appropriate I/O
channel. A negative ctty value doesn't equate to any I/O channel
effectively disabling the process' output.

Added the sys_ctty system call which allows a process to set it's own
ctty value.

Removed the sys_rsputs system call. Output to serial is now performed by
the process first setting it's ctty value to 1, then invoking sys_puts.

1 files changed, 23 insertions, 2 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index c2256c1..986c4dd 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -3,13 +3,28 @@
 #include <kernel/sched.h>
 #include <signal.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <sys/types.h>
 #include <time.h>
 #include <unistd.h>
 
 int sys_puts(char *s) {
-  printk("[%04x] ", ctask->pid);
-  return printk(s);
+  char buf[8];
+  sprintf(buf, "[%04x] ", ctask->pid);
+
+  if(ctask->ctty < 0)
+    return EOF;
+
+  switch(ctask->ctty) {
+    case 1:
+      rsputs(buf);
+      return rsputs(s);
+      break;
+    default:
+      printk("%s", buf);
+      return printk(s);
+      break;
+  }
 }
 
 time_t sys_time(void) {
@@ -56,6 +71,12 @@ int sys_pause(void) {
   return -1;
 }
 
+int sys_ctty(int ctty) {
+  ctask->ctty = ctty;
+
+  return 0;
+}
+
 int sys_dummy(void) {
   return -ENOSYS;
 }