From b81f8f69dfcc7b7835e0f16ecb52864fd6972f9d Mon Sep 17 00:00:00 2001
From: 4lDO2 <4lDO2@protonmail.com>
Date: Tue, 19 Jul 2022 11:16:47 +0200
Subject: [PATCH] Adapt clone_grant_using_fmap to fork and deprecate.

---
 Cargo.lock                    |  7 +++++++
 Cargo.toml                    |  3 ++-
 src/clone_grant_using_fmap.rs | 26 ++++++++++++--------------
 3 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 8ee9ef3..f288860 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6,6 +6,7 @@ version = 3
 name = "acid"
 version = "0.1.0"
 dependencies = [
+ "libc",
  "redox_syscall 0.2.12 (git+https://gitlab.redox-os.org/redox-os/syscall.git)",
  "strace",
  "x86",
@@ -23,6 +24,12 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "libc"
+version = "0.2.126"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "349d5a591cd28b49e1d1037471617a32ddcda5731b99419008085f72d5a53836"
+
 [[package]]
 name = "raw-cpuid"
 version = "10.3.0"
diff --git a/Cargo.toml b/Cargo.toml
index 5ff4674..af1c79e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,7 +5,8 @@ authors = ["Jeremy Soller <jackpot51@gmail.com>"]
 edition = "2018"
 
 [dependencies]
-x86 = "0.47.0"
+libc = "0.2"
 redox_syscall = { git = "https://gitlab.redox-os.org/redox-os/syscall.git" }
 strace = { git = "https://gitlab.redox-os.org/redox-os/strace-redox", default-features = false }
+x86 = "0.47.0"
 #strace = { path = "../../strace/source", default-features = false }
diff --git a/src/clone_grant_using_fmap.rs b/src/clone_grant_using_fmap.rs
index 11a411c..7d72e51 100644
--- a/src/clone_grant_using_fmap.rs
+++ b/src/clone_grant_using_fmap.rs
@@ -1,3 +1,5 @@
+// TODO: This is no longer implemented by the kernel. Should it be moved to resist?
+
 use syscall::data::{Map, Packet};
 use syscall::error::{Error, Result, EFAULT, EINVAL};
 use syscall::flag::{CloneFlags, MapFlags, O_CREAT, O_RDONLY, O_RDWR, O_CLOEXEC, WaitFlags};
@@ -28,7 +30,9 @@ impl Daemon {
 
         let [read_pipe, write_pipe] = pipes;
 
-        if unsafe { clone(CloneFlags::empty())? } == 0 {
+        let result = unsafe { libc::fork() };
+
+        if result == 0 {
             let _ = close(read_pipe);
 
             f(Daemon {
@@ -36,7 +40,7 @@ impl Daemon {
             });
             // TODO: Replace Infallible with the never type once it is stabilized.
             unreachable!();
-        } else {
+        } else if result > 0 {
             let _ = close(write_pipe);
 
             let mut data = [0];
@@ -50,6 +54,8 @@ impl Daemon {
             } else {
                 Err(Error::new(EIO))
             }
+        } else {
+            return Err(Error::new(std::io::Error::last_os_error().raw_os_error().unwrap_or(EINVAL)));
         }
     }
 
@@ -132,24 +138,16 @@ fn inner(readonly: bool) -> Result<()> {
 
     let pid;
     unsafe {
-        pid = syscall::clone(CloneFlags::empty())?;
+        pid = libc::fork() as usize;
 
-        // Keep in mind these two constants may disappear in the near future.
-        const PML4_SIZE: usize = 0x0000_0080_0000_0000;
-        const USER_TMP_GRANT_OFFSET: usize = 7 * PML4_SIZE;
-        const USER_GRANT_OFFSET: usize = 2 * PML4_SIZE;
+        assert_ne!(pid, (-1_isize) as usize);
 
-        assert!((ptr as usize) >= USER_GRANT_OFFSET);
-        assert!((ptr as usize) <= USER_TMP_GRANT_OFFSET);
-
-        // Make sure the temporary addresses are not left after the kernel has cloned.
-        assert_eq!(syscall::virttophys((ptr as usize) - USER_GRANT_OFFSET + USER_TMP_GRANT_OFFSET), Err(Error::new(EFAULT)));
-        println!("Old memory was correctly unmapped, for the {} process", if pid == 0 { "child" } else { "parent" });
+        println!("Fork was successful, for the {} process", if pid == 0 { "child" } else { "parent" });
 
         if pid == 0 {
             println!("Child process: checking...");
 
-            // We are the child process. Hopefully the kernel copied the grant properly and without
+            // We are the child process. Hopefully relibc copied the grant properly and without
             // aliasing.
             if readonly {
                 assert_eq!(ptr.read_volatile(), 42);