From a2303665fc2ffe517eafee5995ac343facd546ec Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Mon, 1 May 2023 19:31:15 +0200
Subject: [PATCH] libos: Add os:: print(), println(), eprint(), and eprintln()

---
 libluna/include/luna/String.h |  3 +-
 libos/include/os/File.h       |  5 +++
 libos/src/File.cpp            | 59 +++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/libluna/include/luna/String.h b/libluna/include/luna/String.h
index c8e7000b..2140fffb 100644
--- a/libluna/include/luna/String.h
+++ b/libluna/include/luna/String.h
@@ -38,6 +38,7 @@ class String
 
     static Result<String> format(const String& fmt, ...);
     static Result<String> format(StringView fmt, ...);
+    static Result<String> vformat(StringView fmt, va_list ap);
 
     static Result<String> from_cstring(const char* str);
 
@@ -94,6 +95,4 @@ class String
     usize m_length { 0 };
 
     void empty();
-
-    static Result<String> vformat(StringView fmt, va_list ap);
 };
diff --git a/libos/include/os/File.h b/libos/include/os/File.h
index ab770058..7f9f9156 100644
--- a/libos/include/os/File.h
+++ b/libos/include/os/File.h
@@ -66,4 +66,9 @@ namespace os
 
         int m_fd { -1 };
     };
+
+    Result<void> print(StringView fmt, ...);
+    Result<void> println(StringView fmt, ...);
+    Result<void> eprint(StringView fmt, ...);
+    Result<void> eprintln(StringView fmt, ...);
 }
diff --git a/libos/src/File.cpp b/libos/src/File.cpp
index 2f6be82a..33c1dd49 100644
--- a/libos/src/File.cpp
+++ b/libos/src/File.cpp
@@ -193,4 +193,63 @@ namespace os
     {
         fcntl(m_fd, F_SETFD, FD_CLOEXEC);
     }
+
+    // FIXME: Do not allocate memory for printing.
+    Result<void> print_impl(SharedPtr<File> f, StringView fmt, va_list ap)
+    {
+        auto str = TRY(String::vformat(fmt, ap));
+        return f->write(str.view());
+    }
+
+    Result<void> print(StringView fmt, ...)
+    {
+        va_list ap;
+        va_start(ap, fmt);
+
+        auto rc = print_impl(File::standard_output(), fmt, ap);
+
+        va_end(ap);
+
+        return rc;
+    }
+
+    Result<void> println(StringView fmt, ...)
+    {
+        va_list ap;
+        va_start(ap, fmt);
+
+        auto rc = print_impl(File::standard_output(), fmt, ap);
+
+        va_end(ap);
+
+        TRY(rc);
+
+        return File::standard_output()->write("\n"_sv);
+    }
+
+    Result<void> eprint(StringView fmt, ...)
+    {
+        va_list ap;
+        va_start(ap, fmt);
+
+        auto rc = print_impl(File::standard_error(), fmt, ap);
+
+        va_end(ap);
+
+        return rc;
+    }
+
+    Result<void> eprintln(StringView fmt, ...)
+    {
+        va_list ap;
+        va_start(ap, fmt);
+
+        auto rc = print_impl(File::standard_error(), fmt, ap);
+
+        va_end(ap);
+
+        TRY(rc);
+
+        return File::standard_error()->write("\n"_sv);
+    }
 }