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.

3 files changed, 38 insertions, 11 deletions

diff --git a/kernel/serial.c b/kernel/serial.c
index 7f23298..86bbd87 100644
--- a/kernel/serial.c
+++ b/kernel/serial.c
@@ -15,10 +15,20 @@
 #define RSMODEMS  (RSBASE + 6)
 #define RSSCRATCH (RSBASE + 7)
 
-static int rsputs(char *s) {
+#define rswait()\
+  while((inb(RSLINES) & 0x20) == 0);
+
+int rsputs(char *s) {
   while(*s) {
-    while((inb(RSLINES) & 0x20) == 0);
-    outb(RSDATA, *s++);
+    rswait();
+    if(*s == '\n') {
+      outb(RSDATA, '\n');
+      rswait();
+      outb(RSDATA, '\r');
+      s++;
+    } else {
+      outb(RSDATA, *s++);
+    }
   }
 
   return 0;
@@ -46,7 +56,3 @@ void serial_init(void) {
   rsputs("[kernel] Serial monitor initialized!\n\r");
   printk("[rs] Serial port COM0 initialized!\n");
 }
-
-int sys_rsputs(char *s) {
-  return rsputs(s);
-}
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;
 }
diff --git a/kernel/traps.s b/kernel/traps.s
index 0a0d202..408a650 100644
--- a/kernel/traps.s
+++ b/kernel/traps.s
@@ -21,8 +21,8 @@ extern ticked
 ; too.
 
 %define ts_signal       6
-%define ts_sig_handlers 14
-%define ts_tss_esp0     146
+%define ts_sig_handlers 18
+%define ts_tss_esp0     150
 
 %macro SAVE 0
   pusha