TarStream: Refactor the API to get rid of that awful method in Result

That method being try_set_value_with_specific_error()

kernel/src/main.cpp

@@ -55,7 +55,7 @@ Result<void> init()
     Scheduler::init();
 
     TarStream::Entry entry;
-    while (TRY(g_initrd.read_next_entry().try_set_value_with_specific_error(entry, 0)))
+    while (TRY(g_initrd.read_next_entry(entry)))
     {
         if (entry.type == TarStream::EntryType::RegularFile)
         {

luna/include/luna/Result.h

@@ -115,14 +115,6 @@ template <typename T> class Result
         return m_value.try_move_value(ref);
     }
 
-    // FIXME: Please remove this.
-    Result<bool> try_set_value_with_specific_error(T& ref, int error)
-    {
-        if (has_error() && m_error != error) return release_error();
-
-        return m_value.try_set_value(ref);
-    }
-
     T release_value()
     {
         expect(has_value(), "Result::release_value() called on a Result that holds an error");

luna/include/luna/TarStream.h

@@ -29,7 +29,7 @@ class TarStream
 
     void initialize(void* base, usize size);
 
-    Result<Entry> read_next_entry();
+    Result<bool> read_next_entry(Entry& out);
 
     void rewind();
 
@@ -58,9 +58,9 @@ class TarStream
         char prefix[155];
     };
 
-    Result<void> find_valid_header(TarHeader* out, bool& success);
+    void find_valid_header(TarHeader* out, bool& success);
 
-    Result<void> read_header(TarHeader* out);
+    void read_header(TarHeader* out, bool& success);
     Result<Entry> parse_header(const TarHeader* hdr);
 
     void* m_base;

luna/src/TarStream.cpp

@@ -22,13 +22,17 @@ void TarStream::rewind()
     m_offset = 0;
 }
 
-Result<void> TarStream::read_header(TarHeader* out)
+void TarStream::read_header(TarHeader* out, bool& success)
 {
-    if ((m_offset + 512) > m_size) return err(0);
+    if ((m_offset + 512) > m_size)
+    {
+        success = false;
+        return;
+    };
     memcpy(out, m_pos, sizeof(TarHeader));
     m_pos = offset_ptr(m_pos, 512);
     m_offset += 512;
-    return {};
+    success = true;
 }
 
 Result<TarStream::Entry> TarStream::parse_header(const TarStream::TarHeader* hdr)
@@ -61,30 +65,31 @@ Result<TarStream::Entry> TarStream::parse_header(const TarStream::TarHeader* hdr
     return entry;
 }
 
-Result<void> TarStream::find_valid_header(TarStream::TarHeader* out, bool& success)
+void TarStream::find_valid_header(TarStream::TarHeader* out, bool& success)
 {
     success = false;
     while (true)
     {
-        TRY(read_header(out));
+        read_header(out, success);
+        if (!success) return;
         if (!memcmp(out->magic, "ustar", 5))
         {
             success = true;
-            return {};
+            return;
         }
     }
 }
 
-// FIXME: How do we know whether an error is an error or just EOF? Returning an error code of 0 as EOF seems a bit
-// clunky to me...
-Result<TarStream::Entry> TarStream::read_next_entry()
+Result<bool> TarStream::read_next_entry(Entry& out)
 {
     bool success;
     TarHeader header;
-    auto rc = find_valid_header(&header, success);
-    if (!success) return rc.release_error();
+    find_valid_header(&header, success);
+    if (!success) return false;
 
-    return parse_header(&header);
+    out = TRY(parse_header(&header));
+
+    return true;
 }
 
 usize TarStream::read_contents(const Entry& entry, void* buf, usize offset, usize length) const