Use static buffers for mprintf and debug_printf, cut down on library dependencies

init/Makefile

@@ -5,8 +5,8 @@ $(eval $(call add_lib,libprocess))
 $(eval $(call add_lib,libstring))
 $(eval $(call add_lib,libdebugconsole))
 $(eval $(call add_lib,libaux))
-$(eval $(call add_lib,libmalloc))
 $(eval $(call add_lib,libkb))
+$(eval $(call add_lib,libmalloc))
 
 cflags += -DPRINTF_INCLUDE_CONFIG_H=1
 

init/init.c

@@ -1,7 +1,6 @@
 #include <debugconsole.h>
 #include <kb.h>
 #include <limits.h>
-#include <malloc.h>
 #include <process.h>
 #include <stddef.h>
 #include <stdint.h>

libaux/mprintf.c

@@ -1,28 +1,38 @@
-#include <malloc.h>
 #include <mprintf.h>
 #include <printf.h>
 #include <process_self.h>
 #include <stdarg.h>
+#include <stdatomic.h>
 #include <streams.h>
 #include <string.h>
 #include <system.h>
 
+static char mprintf_buffer[MPRINTF_BUF_MAX];
+static atomic_flag mprintf_buffer_lock1 = ATOMIC_FLAG_INIT;
+
+static void mprintf_buffer_lock (void) {
+  while (atomic_flag_test_and_set_explicit (&mprintf_buffer_lock1, memory_order_acquire)) {
+#if defined(__x86_64__)
+    __asm__ volatile ("pause" ::: "memory");
+#endif
+  }
+}
+
+static void mprintf_buffer_unlock (void) {
+  atomic_flag_clear_explicit (&mprintf_buffer_lock1, memory_order_release);
+}
+
 void mprintf (const char* fmt, ...) {
   va_list args;
   va_start (args, fmt);
 
-  char* buf = malloc (MPRINTF_BUF_MAX);
+  mprintf_buffer_lock ();
 
-  if (buf == NULL) {
-    va_end (args);
-    return;
-  }
-
-  memset (buf, 0, MPRINTF_BUF_MAX);
-  int len = vsnprintf (buf, MPRINTF_BUF_MAX, fmt, args);
+  int len = vsnprintf (mprintf_buffer, MPRINTF_BUF_MAX, fmt, args);
 
   va_end (args);
 
-  stream_write (process_get_pgid (), STREAM_OUT, buf, len);
-  free (buf);
+  stream_write (process_get_pgid (), STREAM_OUT, mprintf_buffer, len);
+
+  mprintf_buffer_unlock ();
 }

libdebugconsole/debugconsole.c

@@ -1,10 +1,25 @@
 #include <debugconsole.h>
 #include <devices.h>
-#include <malloc.h>
 #include <printf.h>
+#include <stdatomic.h>
 #include <stddef.h>
 #include <system.h>
 
+static char debug_printf_buffer[DEBUG_PRINTF_MAX];
+static atomic_flag debug_printf_buffer_lock = ATOMIC_FLAG_INIT;
+
+static void debugconsole_printf_buffer_lock (void) {
+  while (atomic_flag_test_and_set_explicit (&debug_printf_buffer_lock, memory_order_acquire)) {
+#if defined(__x86_64__)
+    __asm__ volatile ("pause" ::: "memory");
+#endif
+  }
+}
+
+static void debugconsole_printf_buffer_unlock (void) {
+  atomic_flag_clear_explicit (&debug_printf_buffer_lock, memory_order_release);
+}
+
 int debugconsole_print (const char* string, size_t len) {
   return device_do ("debugconsole", DEBUGCONSOLE_PUTSTR, (void*)string, (void*)&len, NULL, NULL);
 }
@@ -13,18 +28,13 @@ void debug_printf (const char* fmt, ...) {
   va_list args;
   va_start (args, fmt);
 
-  char* buf = malloc (DEBUG_PRINTF_MAX);
+  debugconsole_printf_buffer_lock ();
 
-  if (buf == NULL) {
-    va_end (args);
-    return;
-  }
-
-  buf[0] = '\0';
-  int len = vsnprintf (buf, DEBUG_PRINTF_MAX, fmt, args);
+  int len = vsnprintf (debug_printf_buffer, DEBUG_PRINTF_MAX, fmt, args);
 
   va_end (args);
 
-  debugconsole_print (buf, len);
-  free (buf);
+  debugconsole_print (debug_printf_buffer, len);
+
+  debugconsole_printf_buffer_unlock ();
 }

mailtest/Makefile

@@ -2,7 +2,6 @@ include ../make/ufuncs.mk
 
 $(eval $(call add_lib,libprocess))
 $(eval $(call add_lib,libstring))
-$(eval $(call add_lib,libmalloc))
 $(eval $(call add_lib,libdebugconsole))
 $(eval $(call add_lib,libaux))
 

mailtest/mailtest.c

@@ -23,10 +23,11 @@ void app_main (void) {
     char recv_buffer[1024];
 
     for (;;) {
+      debug_printf ("Waiting...\n");
       memset (recv_buffer, 0, sizeof (recv_buffer));
       mail_receive (recv_buffer, sizeof (recv_buffer));
 
-      debug_printf ("%s\n", recv_buffer);
+      debug_printf ("Recv: %s\n", recv_buffer);
     }
   } else if (strcmp (commandbuf, "send") == 0) {
     if (env_get (process_get_pgid (), "payload", (void*)payloadbuf, sizeof (payloadbuf)) != ST_OK) {