Initial commit

- create subsystem system using clone syscall, shared memory, shared
  file descriptors
- printk-like logging facility (TODO: console loglevel)
- initcall system (like linux kernel)

TODO: determine license
factors: linker.ld, linux kernel licensing (some ideas are more
  liberally taken rather than paraphrased)

1 files changed, 69 insertions, 0 deletions

diff --git a/init/log.c b/init/log.c
new file mode 100644
index 0000000..3cdaa06
--- /dev/null
+++ b/init/log.c
@@ -0,0 +1,69 @@
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/file.h>
+#include <unistd.h>
+
+#include <log.h>
+#include <util.h>
+
+static const char *colors[] = {
+    [0] = ANSI_BLINK ANSI_REVERSE ANSI_BOLD ANSI_RED,
+    [1] = ANSI_REVERSE ANSI_BOLD ANSI_RED,
+    [2] = ANSI_BOLD ANSI_RED,
+    [3] = ANSI_RED,
+    [4] = ANSI_BOLD,
+    [5] = ANSI_BRIGHT_WHITE,
+    [6] = ANSI_RESET,
+    [7] = ANSI_ITALIC ANSI_BRIGHT_BLUE,
+};
+
+int console_lock = 0;
+
+int print(const char *fmt, ...)
+{
+    int loglevel = 5;
+    if(fmt[0] == LOG_SOH_ASCII) {
+        loglevel = (fmt[1] - 0x30) % 10;
+        fmt += 2;
+    }
+
+    char buf[512];
+
+    va_list ap;
+    va_start(ap, fmt);
+    vsnprintf(buf, 512, fmt, ap);
+    va_end(ap);
+    buf[512 - 1] = '\0';
+
+    size_t colon = 0;
+    for(; colon < strlen(buf); ++colon) {
+        if(buf[colon] == ':')
+            break;
+    }
+
+    /* spin lock, at the cost of architecture portability */
+    __asm__(".spin_lock:");
+    __asm__("mov rax, 1");
+    __asm__("xchg rax, [console_lock]");
+    __asm__("test rax, rax");
+    __asm__("jnz .spin_lock");
+
+    if(buf[colon] == ':') {
+        writeputs(ANSI_RESET);
+        writeputs(colors[loglevel]);
+        writeputs(ANSI_YELLOW);
+        write(STDOUT_FILENO, buf, colon);
+        writeputs(ANSI_RESET);
+    }
+    writeputs(colors[loglevel]);
+    if(colon && *(buf + colon)) {
+        writeputs(buf + colon);
+    } else {
+        writeputs(buf);
+    }
+    writeputs(ANSI_RESET);
+
+    console_lock = 0;
+    return 0;
+}