[util] Add util::format replacement for snprintf

The printf library I have been using, while useful, has way more than I
need in it, and had comparably huge stack space requirements. This
change adds a new util::format() which is a replacement for snprintf,
but with only the features used by kernel logging.

The logger has been changed to use it, as well as the few instances of
snprintf in the interrupt handling code before calling kassert.

Also part of this change: the logger's (now vestigial) immediate output
handling code is removed, as well as the "sequence" field on log
message headers.

src/kernel/logger.cpp

@@ -1,6 +1,7 @@
 #include <new>
 #include <string.h>
 
+#include <util/format.h>
 #include <util/no_construct.h>
 
 #include "assert.h"
@@ -8,7 +9,6 @@
 #include "memory.h"
 #include "objects/system.h"
 #include "objects/thread.h"
-#include "printf/printf.h"
 
 static uint8_t log_buffer[128 * 1024];
 
@@ -18,9 +18,6 @@ static uint8_t log_buffer[128 * 1024];
 static util::no_construct<log::logger> __g_logger_storage;
 log::logger &g_logger = __g_logger_storage.value;
 
-// For printf.c
-extern "C" void putchar_(char c) {}
-
 
 namespace log {
 
@@ -33,19 +30,15 @@ const char *logger::s_area_names[] = {
     nullptr
 };
 
-logger::logger(logger::immediate_cb output) :
-    m_buffer(nullptr, 0),
-    m_immediate(output),
-    m_sequence(0)
+logger::logger() :
+    m_buffer(nullptr, 0)
 {
     memset(&m_levels, 0, sizeof(m_levels));
     s_log = this;
 }
 
-logger::logger(uint8_t *buffer, size_t size, logger::immediate_cb output) :
-    m_buffer(buffer, size),
-    m_immediate(output),
-    m_sequence(0)
+logger::logger(uint8_t *buffer, size_t size) :
+    m_buffer(buffer, size)
 {
     memset(&m_levels, 0, sizeof(m_levels));
     s_log = this;
@@ -64,20 +57,13 @@ logger::output(level severity, logs area, const char *fmt, va_list args)
     header->bytes = sizeof(entry);
     header->area = area;
     header->severity = severity;
-    header->sequence = m_sequence++;
 
-    size_t mlen = vsnprintf(header->message, sizeof(buffer) - sizeof(entry) - 1, fmt, args);
+    size_t mlen = util::vformat({header->message, sizeof(buffer) - sizeof(entry) - 1}, fmt, args);
     header->message[mlen] = 0;
     header->bytes += mlen + 1;
 
     util::scoped_lock lock {m_lock};
 
-    if (m_immediate) {
-        buffer[header->bytes] = 0;
-        m_immediate(area, severity, header->message);
-        return;
-    }
-
     uint8_t *out;
     size_t n = m_buffer.reserve(header->bytes, reinterpret_cast<void**>(&out));
     if (n < header->bytes) {
@@ -94,13 +80,14 @@ logger::output(level severity, logs area, const char *fmt, va_list args)
 size_t
 logger::get_entry(void *buffer, size_t size)
 {
-
     util::scoped_lock lock {m_lock};
 
     void *out;
     size_t out_size = m_buffer.get_block(&out);
     if (out_size == 0 || out == 0) {
+        lock.release();
         m_event.wait();
+        lock.reacquire();
         out_size = m_buffer.get_block(&out);
 
         if (out_size == 0 || out == 0)
@@ -155,5 +142,5 @@ void fatal(logs area, const char *fmt, ...)
 
 void logger_init()
 {
-    new (&g_logger) log::logger(log_buffer, sizeof(log_buffer), nullptr);
+    new (&g_logger) log::logger(log_buffer, sizeof(log_buffer));
 }