From 8fe903a9ff94d423d3dd836afbd7528bcaaa0d84 Mon Sep 17 00:00:00 2001
From: jn <jn@ccc.ac>
Date: Mon, 30 Jan 2023 21:28:33 +0100
Subject: [PATCH] kernel/vfs: Don't ignore buffer length in read(stream)

---
 applications/sh/main.asm         |  2 +-
 applications/terminal/main.asm   |  4 +++-
 applications/terminal/stream.asm |  2 ++
 kernel/vfs.asm                   | 28 ++++++++++++++++++++++++----
 4 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/applications/sh/main.asm b/applications/sh/main.asm
index 67f58a5..c743c33 100644
--- a/applications/sh/main.asm
+++ b/applications/sh/main.asm
@@ -8,6 +8,7 @@ shell_task_return:
     call shell_clear_buffer
     call shell_print_prompt
 shell_task_loop:
+    mov r0, 1
     mov r1, [shell_terminal_stream_struct_ptr]
     mov r2, shell_char_buffer
     call read
@@ -16,7 +17,6 @@ shell_task_loop:
     cmp.8 r0, 0
     ifnz call shell_task_parse_key
 
-    call yield_task
     rjmp shell_task_loop
 
 shell_task_parse_key:
diff --git a/applications/terminal/main.asm b/applications/terminal/main.asm
index bac675e..8fd4276 100644
--- a/applications/terminal/main.asm
+++ b/applications/terminal/main.asm
@@ -40,7 +40,9 @@ event_loop_end:
     call is_task_id_used
     ifz jmp close_window
     call yield_task
-    mov.8 [read_buffer], 0
+    cmp.8 [read_buffer_ack], 1
+    ifz mov.8 [read_buffer], 0
+    ifz mov.8 [read_buffer_ack], 0
     rjmp event_loop
 
 mouse_down:
diff --git a/applications/terminal/stream.asm b/applications/terminal/stream.asm
index afcd796..5cca348 100644
--- a/applications/terminal/stream.asm
+++ b/applications/terminal/stream.asm
@@ -9,6 +9,8 @@ stream_write_to_terminal:
 
 stream_get_input:
     mov r0, [read_buffer]
+    mov [read_buffer_ack], 1
     ret
 
 read_buffer: data.32 0
+read_buffer_ack: data.32 0
diff --git a/kernel/vfs.asm b/kernel/vfs.asm
index 4d45785..531cbac 100644
--- a/kernel/vfs.asm
+++ b/kernel/vfs.asm
@@ -53,11 +53,11 @@ tell:
 
 ; read specified number of bytes into the specified buffer
 ; inputs:
-; r0: number of bytes to read (ignored if file struct is a stream)
+; r0: number of bytes to read
 ; r1: pointer to file struct
-; r2: pointer to destination buffer (always 4 bytes if file struct is a stream)
+; r2: pointer to destination buffer
 ; outputs:
-; none
+; r0: number of bytes left to read (streams can read short)
 read:
     push r3
     push r1
@@ -73,6 +73,26 @@ read:
     pop r3
     ret
 stream_read:
+    push r1
+    push r2
+
+stream_read_loop:
+    call stream_read_char
+    call yield_task
+
+    cmp.8 [r2], 0
+    ifz jmp stream_read_out
+
+    inc r2
+    dec r0
+    ifnz jmp stream_read_loop
+
+stream_read_out:
+    pop r2
+    pop r1
+    ret
+
+stream_read_char:
     push r0
     push r1
     push r2
@@ -83,7 +103,7 @@ stream_read:
 
     ; put the result into [r2]
     pop r2
-    mov [r2], r0
+    mov.8 [r2], r0
 
     pop r1
     pop r0