From 35d98182c5b86c25eb4e7fd18fc68f240683960b Mon Sep 17 00:00:00 2001
From: Franklin Wei <frankhwei536@gmail.com>
Date: Sun, 1 Mar 2015 14:40:30 -0500
Subject: vprintf and panic formatting

---
 include/kernel/panic.h |  2 +-
 include/stdio.h        |  5 ++++-
 kernel/panic.c         |  7 ++++++-
 libc/stdio.c           | 37 +++++++++++++++++++++++++++++++++++++
 4 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/include/kernel/panic.h b/include/kernel/panic.h
index db53e8e..7baeaa9 100644
--- a/include/kernel/panic.h
+++ b/include/kernel/panic.h
@@ -1 +1 @@
-void panic(const char*, ...);
+void panic(const char*, ...) __attribute__ ((format (printf, 1, 2)));
diff --git a/include/stdio.h b/include/stdio.h
index 49966cf..9bed898 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -1,4 +1,7 @@
-int printf(const char* fmt, ...)  __attribute__ ((format (printf, 1, 2)));;
+#include <stdarg.h>
+
+int vprintf(const char* fmt, va_list);
+int printf(const char* fmt, ...)  __attribute__ ((format (printf, 1, 2)));
 int puts(const char*);
 int putchar(int);
 
diff --git a/kernel/panic.c b/kernel/panic.c
index 3a2ddf1..42b54d7 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -1,10 +1,15 @@
 #include "panic.h"
+#include <stdarg.h>
 #include <stdio.h>
 
 __attribute__((noreturn)) void panic(const char *str, ...)
 {
     /* no printf formatting for now */
-    printf("KERNEL PANIC: %s", str);
+    printf("KERNEL PANIC: ");
+    va_list ap;
+    va_start(ap, str);
+    vprintf(str, ap);
+    va_end(ap);
     for(;;)
     {
         asm("cli");
diff --git a/libc/stdio.c b/libc/stdio.c
index 8219d11..6359c47 100644
--- a/libc/stdio.c
+++ b/libc/stdio.c
@@ -82,3 +82,40 @@ int printf(const char *fmt, ...)
     va_end(ap);
     return 0;
 }
+
+int vprintf(const char *fmt, va_list ap)
+{
+    while(*fmt)
+    {
+        char ch = *fmt++;
+        switch(ch)
+        {
+        case '%':
+        {
+            switch(*fmt++)
+            {
+            case 'c':
+                putchar(va_arg(ap, int));
+                break;
+            case 's':
+                puts(va_arg(ap, const char*));
+                break;
+            case 'x':
+                print_hex(va_arg(ap, unsigned));
+                break;
+            case 'd':
+                puts(itoa(va_arg(ap, unsigned), 10));
+                break;
+            default:
+                puts("printf: unknown format\n");
+                break;
+            }
+            break;
+        }
+        default:
+            putchar(ch);
+            break;
+        }
+    }
+    return 0;
+}
-- 
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