From 6df5b8a703c57364fd9c6f302ad495810418f612 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Sun, 30 Oct 2022 10:08:52 +0100
Subject: [PATCH] Make backspace work

---
 README.md              |  1 -
 apps/src/session.c     | 23 ++++++++++++++++++-----
 libs/libc/src/file.cpp | 15 +++++++++++++--
 3 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 473cae46..c7879e0f 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,6 @@ A simple kernel and userspace for the x86_64 platform, written mostly in C++ and
 
 ## Notes
 - The default user is named 'selene' and you can log into it with the password 'moon'.
-- Beware of backspace, as it looks like it works but it doesn't work except when entering shell commands. So if you make a mistake while entering a username or password, you'll have to try again.
 
 ## Setup
 To build and run Luna, you will need to build a [GCC Cross-Compiler](https://wiki.osdev.org/Why_do_I_need_a_Cross_Compiler%3F) and cross-binutils for `x86_64-luna`. (Yes, Luna is advanced enough that it can use its own [OS-Specific Toolchain](https://wiki.osdev.org/OS_Specific_Toolchain), instead of a bare metal target like `x86_64-elf`. It is the first of my OS projects to be able to do so. The patches for Binutils and GCC are [binutils.patch](tools/binutils.patch) and [gcc.patch](tools/gcc.patch)).
diff --git a/apps/src/session.c b/apps/src/session.c
index 58ea1afb..90704812 100644
--- a/apps/src/session.c
+++ b/apps/src/session.c
@@ -10,6 +10,7 @@ static char* echoing_fgets(char* buf, size_t size, FILE* stream)
 {
     char* s = buf;
     memset(buf, 0, size);
+    size_t oldsize = size;
     while (size)
     {
         int c = fgetc(stream);
@@ -23,12 +24,24 @@ static char* echoing_fgets(char* buf, size_t size, FILE* stream)
                     return NULL;
             };
         }
-        size--;
-        *buf = (char)c;
-        buf++;
+        if ((char)c == '\b')
+        {
+            if (size != oldsize)
+            {
+                buf--;
+                size++;
+                putchar('\b');
+            }
+        }
+        else
+        {
+            size--;
+            *buf = (char)c;
+            buf++;
+            putchar((char)c);
+            if ((char)c == '\n') return s;
+        }
         *buf = 0;
-        putchar((char)c);
-        if ((char)c == '\n') return s;
     }
     return s;
 }
diff --git a/libs/libc/src/file.cpp b/libs/libc/src/file.cpp
index 77b5c9c6..147a82e0 100644
--- a/libs/libc/src/file.cpp
+++ b/libs/libc/src/file.cpp
@@ -154,8 +154,19 @@ extern "C"
                     buf++;
                     break;
                 }
-                buf++;
-                size--;
+                if (*buf == '\b')
+                {
+                    if (size != original_size)
+                    {
+                        buf--;
+                        size++;
+                    }
+                }
+                else
+                {
+                    buf++;
+                    size--;
+                }
             }
             else
             {