From d8c59a292b86a77d71fad708d758d1e340447b55 Mon Sep 17 00:00:00 2001
From: David Keller <davidkeller@tuta.io>
Date: Fri, 26 Dec 2025 19:55:16 +0100
Subject: [PATCH 1/2] feat: add #read_greedy method

---
 src/io.cr        | 22 ++++++++++++++++++++++
 src/io/memory.cr |  5 +++++
 2 files changed, 27 insertions(+)

diff --git a/src/io.cr b/src/io.cr
index 4b94d2f29baa..4193a823ea76 100644
--- a/src/io.cr
+++ b/src/io.cr
@@ -548,6 +548,28 @@ abstract class IO
     count
   end
 
+  # Similar to `#read`, but with the additional guarantee that either
+  # the buffer will be entirely filled or the EOF will be reached while trying.
+  #
+  # Calling this method may result in multiple read calls if necessary.
+  #
+  # ```
+  # io = IO::Memory.new "123451234"
+  # slice = Bytes.new(5)
+  # io.read_greedy(slice) # => 5
+  # slice                 # => Bytes[49, 50, 51, 52, 53]
+  # io.read_greedy(slice) # => 4
+  # ```
+  def read_greedy(slice : Bytes) : Int32
+    count = slice.size
+    while slice.size > 0
+      read_bytes = read(slice)
+      return slice_total_size &- slice.size if read_bytes == 0
+      slice += read_bytes
+    end
+    count
+  end
+
   # Reads the rest of this `IO` data as a `String`.
   #
   # ```
diff --git a/src/io/memory.cr b/src/io/memory.cr
index 493db2de3cd7..9678c241fc47 100644
--- a/src/io/memory.cr
+++ b/src/io/memory.cr
@@ -175,6 +175,11 @@ class IO::Memory < IO
     end
   end
 
+  def read_greedy(slice : Bytes) : Int32
+    # IO::Memory is always greedy
+    read(slice)
+  end
+
   def peek : Bytes
     check_open
 

From 4e9f608d1d460c5775c76a52435855103d95eefd Mon Sep 17 00:00:00 2001
From: David Keller <davidkeller@tuta.io>
Date: Mon, 5 Jan 2026 19:39:08 +0100
Subject: [PATCH 2/2] add specs, fix pr issues

---
 spec/std/io/io_spec.cr | 11 +++++++++++
 src/io.cr              |  2 +-
 src/io/memory.cr       |  5 -----
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/spec/std/io/io_spec.cr b/spec/std/io/io_spec.cr
index abff1cef0a7e..dfe944e98000 100644
--- a/spec/std/io/io_spec.cr
+++ b/spec/std/io/io_spec.cr
@@ -486,6 +486,17 @@ describe IO do
         IO.same_content?(io1, io2).should be_false
       end
     end
+
+    it "combines multiple reads using #read_greedy" do
+      bytes = Bytes.new 7
+
+      io = SimpleIOMemory.new("Hello World", max_read: 2)
+      io.read_greedy(bytes).should eq(7)
+      bytes.should eq("Hello W".to_slice)
+      io.read_greedy(bytes).should eq(4)
+      bytes[0, 4].should eq("orld".to_slice)
+      io.read_greedy(bytes).should eq(0)
+    end
   end
 
   describe "write operations" do
diff --git a/src/io.cr b/src/io.cr
index 4193a823ea76..b1a076eb5e5d 100644
--- a/src/io.cr
+++ b/src/io.cr
@@ -564,7 +564,7 @@ abstract class IO
     count = slice.size
     while slice.size > 0
       read_bytes = read(slice)
-      return slice_total_size &- slice.size if read_bytes == 0
+      return count &- slice.size if read_bytes == 0
       slice += read_bytes
     end
     count
diff --git a/src/io/memory.cr b/src/io/memory.cr
index 9678c241fc47..493db2de3cd7 100644
--- a/src/io/memory.cr
+++ b/src/io/memory.cr
@@ -175,11 +175,6 @@ class IO::Memory < IO
     end
   end
 
-  def read_greedy(slice : Bytes) : Int32
-    # IO::Memory is always greedy
-    read(slice)
-  end
-
   def peek : Bytes
     check_open