From 0495bfb0d64bb2b318b629fd1c821dc8e2c8647d Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Sat, 14 Dec 2024 15:33:06 +0100
Subject: sb/printf: Add ksbprintf

Easier to add formatted strings to the string builder without
using intermediate buffers.
---
 kernel/lib/sv.h             |  1 +
 kernel/libc/include/stdio.h |  2 ++
 kernel/libc/stdio/print.c   | 41 +++++++++++++++++++++++------------------
 kernel/timer.c              | 10 ++++++----
 4 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/kernel/lib/sv.h b/kernel/lib/sv.h
index 40f33ca..9a70fb3 100644
--- a/kernel/lib/sv.h
+++ b/kernel/lib/sv.h
@@ -2,6 +2,7 @@
 #define SV_H
 #include "sb.h"
 #include <stddef.h>
+#include <stdint.h>
 
 #define SB_TO_SV(_sb)                                                          \
   (struct sv) {                                                                \
diff --git a/kernel/libc/include/stdio.h b/kernel/libc/include/stdio.h
index 60808dd..111be17 100644
--- a/kernel/libc/include/stdio.h
+++ b/kernel/libc/include/stdio.h
@@ -2,6 +2,7 @@
 #define STDIO_H
 #include <stdarg.h>
 #include <stddef.h>
+#include <lib/sb.h>
 
 void putc(const char c);
 void delete_characther(void);
@@ -9,5 +10,6 @@ int kprintf(const char *format, ...);
 int vkprintf(const char *format, va_list list);
 int ksnprintf(char *out, size_t size, const char *format, ...);
 int kbnprintf(char *out, size_t size, const char *format, ...);
+int ksbprintf(struct sb *ctx, const char *format, ...);
 
 #endif
diff --git a/kernel/libc/stdio/print.c b/kernel/libc/stdio/print.c
index 56b55ae..fdfd00f 100644
--- a/kernel/libc/stdio/print.c
+++ b/kernel/libc/stdio/print.c
@@ -1,5 +1,6 @@
 #include <assert.h>
 #include <kmalloc.h>
+#include <lib/sb.h>
 #include <log.h>
 #include <math.h>
 #include <stdio.h>
@@ -286,32 +287,36 @@ int vkcprintf(struct print_context *ctx, const char *fmt, va_list ap) {
   return rc;
 }
 
-struct bn_context {
-  char *out;
-  int size;
-};
-
-void bn_write(struct print_context *_ctx, const char *s, int l) {
-  struct bn_context *ctx = (struct bn_context *)_ctx->data;
+void sb_write(struct print_context *_ctx, const char *s, int l) {
+  struct sb *ctx = (struct sb *)_ctx->data;
   assert(ctx);
-  size_t k = min(l, ctx->size);
-  memcpy(ctx->out, s, k);
-  ctx->out += k;
-  ctx->size -= k;
+  sb_append_buffer(ctx, s, l);
 }
 
-int kbnprintf(char *out, size_t size, const char *format, ...) {
+int vksbprintf(struct sb *ctx, const char *format, va_list ap) {
   struct print_context context;
 
-  struct bn_context ctx;
-  context.data = &ctx;
-  ctx.out = out;
-  ctx.size = size;
-  context.write = bn_write;
+  context.data = ctx;
+  context.write = sb_write;
 
+  return vkcprintf(&context, format, ap);
+}
+
+int ksbprintf(struct sb *ctx, const char *format, ...) {
   va_list list;
   va_start(list, format);
-  int rc = vkcprintf(&context, format, list);
+  int rc = vksbprintf(ctx, format, list);
+  va_end(list);
+  return rc;
+}
+
+int kbnprintf(char *out, size_t size, const char *format, ...) {
+  struct sb ctx;
+  sb_init_buffer(&ctx, out, size);
+
+  va_list list;
+  va_start(list, format);
+  int rc = vksbprintf(&ctx, format, list);
   va_end(list);
   return rc;
 }
diff --git a/kernel/timer.c b/kernel/timer.c
index 6321cda..2cfd714 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -47,11 +47,13 @@ u64 timer_get_ms(void) {
 }
 
 int clock_read(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
-  if (0 != offset) {
-    return 0;
-  }
+  struct sb ctx;
+  sb_init_buffer(&ctx, buffer, len);
+  sb_set_ignore(&ctx, offset);
+
   u64 r = timer_get_ms();
-  return min(len, (u64)kbnprintf(buffer, len, "%llu", r));
+  (void)ksbprintf(&ctx, "%llu", r);
+  return sv_length(SB_TO_SV(ctx));
 }
 
 int clock_write(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
-- 
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