AK: Add conversion functions for packed DOS time format

This also adjusts the FATFS code to use the new functions and removes
the now redundant old conversion functions.

7 files changed, 98 insertions, 39 deletions

diff --git a/AK/CMakeLists.txt b/AK/CMakeLists.txt
index 8ce72a78c9..1188c0f916 100644
--- a/AK/CMakeLists.txt
+++ b/AK/CMakeLists.txt
@@ -4,6 +4,7 @@ set(AK_SOURCES
     CircularBuffer.cpp
     DeprecatedFlyString.cpp
     DeprecatedString.cpp
+    DOSPackedTime.cpp
     Error.cpp
     FloatingPointStringConversions.cpp
     FlyString.cpp
diff --git a/AK/DOSPackedTime.cpp b/AK/DOSPackedTime.cpp
new file mode 100644
index 0000000000..28d869f444
--- /dev/null
+++ b/AK/DOSPackedTime.cpp
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2022, Undefine <undefine@undefine.pl>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/DOSPackedTime.h>
+
+namespace AK {
+
+Time time_from_packed_dos(DOSPackedDate date, DOSPackedTime time)
+{
+    if (date.value == 0)
+        return Time();
+
+    return Time::from_timestamp(first_dos_year + date.year, date.month, date.day, time.hour, time.minute, time.second * 2, 0);
+}
+
+DOSPackedDate to_packed_dos_date(unsigned year, unsigned month, unsigned day)
+{
+    DOSPackedDate date;
+    date.year = year - first_dos_year;
+    date.month = month;
+    date.day = day;
+
+    return date;
+}
+
+DOSPackedTime to_packed_dos_time(unsigned hour, unsigned minute, unsigned second)
+{
+    DOSPackedTime time;
+    time.hour = hour;
+    time.minute = minute;
+    time.second = second / 2;
+
+    return time;
+}
+
+}
diff --git a/AK/DOSPackedTime.h b/AK/DOSPackedTime.h
new file mode 100644
index 0000000000..3dd46aa10e
--- /dev/null
+++ b/AK/DOSPackedTime.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2022, Undefine <undefine@undefine.pl>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Time.h>
+#include <AK/Types.h>
+
+namespace AK {
+
+union DOSPackedTime {
+    u16 value;
+    struct {
+        u16 second : 5;
+        u16 minute : 6;
+        u16 hour : 5;
+    };
+};
+static_assert(sizeof(DOSPackedTime) == 2);
+
+union DOSPackedDate {
+    u16 value;
+    struct {
+        u16 day : 5;
+        u16 month : 4;
+        u16 year : 7;
+    };
+};
+static_assert(sizeof(DOSPackedDate) == 2);
+
+inline constexpr u16 first_dos_year = 1980;
+
+Time time_from_packed_dos(DOSPackedDate, DOSPackedTime);
+DOSPackedDate to_packed_dos_date(unsigned year, unsigned month, unsigned day);
+DOSPackedTime to_packed_dos_time(unsigned hour, unsigned minute, unsigned second);
+
+}
+
+#if USING_AK_GLOBALLY
+using AK::DOSPackedDate;
+using AK::DOSPackedTime;
+using AK::time_from_packed_dos;
+using AK::to_packed_dos_date;
+using AK::to_packed_dos_time;
+#endif
diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt
index 7236baa021..036c84f7d6 100644
--- a/Kernel/CMakeLists.txt
+++ b/Kernel/CMakeLists.txt
@@ -480,6 +480,7 @@ elseif("${SERENITY_ARCH}" STREQUAL "aarch64")
 endif()
 
 set(AK_SOURCES
+    ../AK/DOSPackedTime.cpp
     ../AK/GenericLexer.cpp
     ../AK/Hex.cpp
     ../AK/MemoryStream.cpp
diff --git a/Kernel/FileSystem/FATFS/Definitions.h b/Kernel/FileSystem/FATFS/Definitions.h
index d0f47c57f5..938fc064b3 100644
--- a/Kernel/FileSystem/FATFS/Definitions.h
+++ b/Kernel/FileSystem/FATFS/Definitions.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/DOSPackedTime.h>
 #include <AK/EnumBits.h>
 #include <AK/Types.h>
 
@@ -54,38 +55,18 @@ enum class FATAttributes : u8 {
 
 AK_ENUM_BITWISE_OPERATORS(FATAttributes);
 
-union FATPackedTime {
-    u16 value;
-    struct {
-        u16 second : 5;
-        u16 minute : 6;
-        u16 hour : 5;
-    };
-};
-static_assert(sizeof(FATPackedTime) == 2);
-
-union FATPackedDate {
-    u16 value;
-    struct {
-        u16 day : 5;
-        u16 month : 4;
-        u16 year : 7;
-    };
-};
-static_assert(sizeof(FATPackedDate) == 2);
-
 struct [[gnu::packed]] FATEntry {
     char filename[8];
     char extension[3];
     FATAttributes attributes;
     u8 unused1;
     u8 creation_time_seconds;
-    FATPackedTime creation_time;
-    FATPackedDate creation_date;
-    FATPackedDate last_accessed_date;
+    DOSPackedTime creation_time;
+    DOSPackedDate creation_date;
+    DOSPackedDate last_accessed_date;
     u16 first_cluster_high;
-    FATPackedTime modification_time;
-    FATPackedDate modification_date;
+    DOSPackedTime modification_time;
+    DOSPackedDate modification_date;
     u16 first_cluster_low;
     u32 file_size;
 };
diff --git a/Kernel/FileSystem/FATFS/Inode.cpp b/Kernel/FileSystem/FATFS/Inode.cpp
index 65358de119..0dcd95468c 100644
--- a/Kernel/FileSystem/FATFS/Inode.cpp
+++ b/Kernel/FileSystem/FATFS/Inode.cpp
@@ -31,9 +31,9 @@ FATInode::FATInode(FATFS& fs, FATEntry entry, NonnullOwnPtr<KString> filename)
         .uid = 0,
         .gid = 0,
         .link_count = 0,
-        .atime = fat_date_time(m_entry.last_accessed_date, { 0 }),
-        .ctime = fat_date_time(m_entry.creation_date, m_entry.creation_time),
-        .mtime = fat_date_time(m_entry.modification_date, m_entry.modification_time),
+        .atime = time_from_packed_dos(m_entry.last_accessed_date, { 0 }),
+        .ctime = time_from_packed_dos(m_entry.creation_date, m_entry.creation_time),
+        .mtime = time_from_packed_dos(m_entry.modification_date, m_entry.modification_time),
         .dtime = {},
         .block_count = 0,
         .block_size = 0,
@@ -186,14 +186,6 @@ ErrorOr<NonnullOwnPtr<KString>> FATInode::compute_filename(FATEntry& entry, Vect
     VERIFY_NOT_REACHED();
 }
 
-Time FATInode::fat_date_time(FATPackedDate date, FATPackedTime time)
-{
-    if (date.value == 0)
-        return Time();
-
-    return Time::from_timestamp(first_fat_year + date.year, date.month, date.day, time.hour, time.minute, time.second * 2, 0);
-}
-
 StringView FATInode::byte_terminated_string(StringView string, u8 fill_byte)
 {
     if (auto index = string.find_last_not(fill_byte); index.has_value())
diff --git a/Kernel/FileSystem/FATFS/Inode.h b/Kernel/FileSystem/FATFS/Inode.h
index 699df808bb..f2505470be 100644
--- a/Kernel/FileSystem/FATFS/Inode.h
+++ b/Kernel/FileSystem/FATFS/Inode.h
@@ -39,14 +39,11 @@ private:
     static constexpr u8 lfn_entry_character_termination = 0x00;
     static constexpr u8 lfn_entry_unused_byte = 0xFF;
 
-    static constexpr u16 first_fat_year = 1980;
-
     static constexpr u8 normal_filename_length = 8;
     static constexpr u8 normal_extension_length = 3;
 
     static ErrorOr<NonnullOwnPtr<KString>> compute_filename(FATEntry&, Vector<FATLongFileNameEntry> const& = {});
     static StringView byte_terminated_string(StringView, u8);
-    static Time fat_date_time(FATPackedDate, FATPackedTime);
 
     ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list();
     ErrorOr<NonnullOwnPtr<KBuffer>> read_block_list();