[lib][libc] move the io hooks into a separate struct that the handle points to

include/sys/io.h

@@ -41,25 +41,24 @@ void register_print_callback(print_callback_t *cb);
 void unregister_print_callback(print_callback_t *cb);
 
 /* the underlying handle to talk to io devices */
-typedef struct io_handle {
-    ssize_t (*write)(void *ctx, const char *buf, size_t len);
-    ssize_t (*read)(void *ctx, char *buf, size_t len);
+struct io_handle;
+typedef struct io_handle_hooks {
+    ssize_t (*write)(struct io_handle *handle, const char *buf, size_t len);
+    ssize_t (*read)(struct io_handle *handle, char *buf, size_t len);
+} io_handle_hooks_t;
 
-    void *ctx;
+#define IO_HANDLE_MAGIC 'ioh '
+
+typedef struct io_handle {
+    uint32_t magic;
+    const io_handle_hooks_t *hooks;
 } io_handle_t;
 
 /* the main console io handle */
 extern io_handle_t console_io;
 
-/* convenience routines for the above */
-static inline ssize_t io_write(const io_handle_t *io, const char *buf, size_t len)
-{
-    return io->write(io->ctx, buf, len);
-}
-
-static inline ssize_t io_read(const io_handle_t *io, char *buf, size_t len)
-{
-    return io->read(io->ctx, buf, len);
-}
+/* routines to call through the io handle */
+ssize_t io_write(io_handle_t *io, const char *buf, size_t len);
+ssize_t io_read(io_handle_t *io, char *buf, size_t len);
 
 __END_CDECLS

lib/debug/debug.c

@@ -65,7 +65,7 @@ static int __panic_stdio_fgetc(void *ctx)
     return (unsigned char)c;
 }
 
-static ssize_t __panic_stdio_read(void *ctx, char *s, size_t len)
+static ssize_t __panic_stdio_read(io_handle_t *io, char *s, size_t len)
 {
     if (len == 0)
         return 0;
@@ -77,7 +77,7 @@ static ssize_t __panic_stdio_read(void *ctx, char *s, size_t len)
     return 1;
 }
 
-static ssize_t __panic_stdio_write(void *ctx, const char *s, size_t len)
+static ssize_t __panic_stdio_write(io_handle_t *io, const char *s, size_t len)
 {
     for (size_t i = 0; i < len; i++) {
         platform_pputc(s[i]);
@@ -87,10 +87,13 @@ static ssize_t __panic_stdio_write(void *ctx, const char *s, size_t len)
 
 FILE *get_panic_fd(void)
 {
-    static io_handle_t panic_io = {
+    static const io_handle_hooks_t panic_hooks = {
         .write = __panic_stdio_write,
         .read = __panic_stdio_read,
-        .ctx = 0
+    };
+    static io_handle_t panic_io = {
+        .magic = IO_HANDLE_MAGIC,
+        .hooks = &panic_hooks
     };
     static FILE panic_fd = {
         .io = &panic_io

lib/libc/io.c

@@ -22,11 +22,10 @@
  */
 #include <sys/io.h>
 
+#include <err.h>
 #include <ctype.h>
 #include <debug.h>
-#include <stdlib.h>
-#include <printf.h>
-#include <stdio.h>
+#include <assert.h>
 #include <list.h>
 #include <string.h>
 #include <arch/ops.h>
@@ -90,13 +89,13 @@ void unregister_print_callback(print_callback_t *cb)
     spin_unlock_restore(&print_spin_lock, state, PRINT_LOCK_FLAGS);
 }
 
-static ssize_t __debug_stdio_write(void *ctx, const char *s, size_t len)
+static ssize_t __debug_stdio_write(io_handle_t *io, const char *s, size_t len)
 {
     out_count(s, len);
     return len;
 }
 
-static ssize_t __debug_stdio_read(void *ctx, char *s, size_t len)
+static ssize_t __debug_stdio_read(io_handle_t *io, char *s, size_t len)
 {
     if (len == 0)
         return 0;
@@ -109,9 +108,33 @@ static ssize_t __debug_stdio_read(void *ctx, char *s, size_t len)
 }
 
 /* global console io handle */
-io_handle_t console_io = {
+static const io_handle_hooks_t console_io_hooks = {
     .write  = __debug_stdio_write,
     .read   = __debug_stdio_read,
-    .ctx    = 0
 };
 
+io_handle_t console_io = {
+    .magic = IO_HANDLE_MAGIC,
+    .hooks  = &console_io_hooks
+};
+
+ssize_t io_write(io_handle_t *io, const char *buf, size_t len)
+{
+    DEBUG_ASSERT(io->magic == IO_HANDLE_MAGIC);
+
+    if (!io->hooks->write)
+        return ERR_NOT_SUPPORTED;
+
+    return io->hooks->write(io, buf, len);
+}
+
+ssize_t io_read(io_handle_t *io, char *buf, size_t len)
+{
+    DEBUG_ASSERT(io->magic == IO_HANDLE_MAGIC);
+
+    if (!io->hooks->read)
+        return ERR_NOT_SUPPORTED;
+
+    return io->hooks->read(io, buf, len);
+}
+