From bcca3d183930eeaf3d024476f39d1d8fccf2ebab Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Tue, 10 Dec 2024 12:23:05 +0100
Subject: kernel: Add kbnprintf

Like snprintf but without null termination
---
 kernel/libc/include/stdio.h |  1 +
 kernel/libc/stdio/print.c   | 41 ++++++++++++++++++++++++++++++++++-------
 2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/kernel/libc/include/stdio.h b/kernel/libc/include/stdio.h
index 0c6a0a3..60808dd 100644
--- a/kernel/libc/include/stdio.h
+++ b/kernel/libc/include/stdio.h
@@ -8,5 +8,6 @@ void delete_characther(void);
 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, ...);
 
 #endif
diff --git a/kernel/libc/stdio/print.c b/kernel/libc/stdio/print.c
index d4ec48a..56b55ae 100644
--- a/kernel/libc/stdio/print.c
+++ b/kernel/libc/stdio/print.c
@@ -286,6 +286,36 @@ 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;
+  assert(ctx);
+  size_t k = min(l, ctx->size);
+  memcpy(ctx->out, s, k);
+  ctx->out += k;
+  ctx->size -= k;
+}
+
+int kbnprintf(char *out, size_t size, const char *format, ...) {
+  struct print_context context;
+
+  struct bn_context ctx;
+  context.data = &ctx;
+  ctx.out = out;
+  ctx.size = size;
+  context.write = bn_write;
+
+  va_list list;
+  va_start(list, format);
+  int rc = vkcprintf(&context, format, list);
+  va_end(list);
+  return rc;
+}
+
 struct sn_context {
   char *out;
   int size;
@@ -304,19 +334,16 @@ void sn_write(struct print_context *_ctx, const char *s, int l) {
 int ksnprintf(char *out, size_t size, const char *format, ...) {
   struct print_context context;
 
-  struct sn_context *ctx = context.data = kmalloc(sizeof(struct sn_context));
-  if (!ctx) {
-    return -1;
-  }
-  ctx->out = out;
-  ctx->size = size;
+  struct sn_context ctx;
+  context.data = &ctx;
+  ctx.out = out;
+  ctx.size = size;
   context.write = sn_write;
 
   va_list list;
   va_start(list, format);
   int rc = vkcprintf(&context, format, list);
   va_end(list);
-  kfree(ctx);
   return rc;
 }
 
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