From: Javier Sagredo <javier.sagredo@iohk.io>
Date: Fri, 29 May 2026 00:16:35 +0000 (+0200)
Subject: copy_stream/2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=0c9d76c8ab95ab33390532601bbccc7b7b5af04c;p=scryer-prolog.git

copy_stream/2
---

diff --git a/build/instructions_template.rs b/build/instructions_template.rs
index 7b8be1f8..1a0f6cce 100644
--- a/build/instructions_template.rs
+++ b/build/instructions_template.rs
@@ -467,6 +467,8 @@ enum SystemClauseType {
     SocketServerAccept,
     #[strum_discriminants(strum(props(Arity = "1", Name = "$socket_server_close")))]
     SocketServerClose,
+    #[strum_discriminants(strum(props(Arity = "2", Name = "$copy_stream")))]
+    CopyStream,
     #[strum_discriminants(strum(props(Arity = "4", Name = "$tls_accept_client")))]
     TLSAcceptClient,
     #[strum_discriminants(strum(props(Arity = "3", Name = "$tls_client_connect")))]
diff --git a/src/instructions.rs b/src/instructions.rs
index f029e463..7d9ace8f 100644
--- a/src/instructions.rs
+++ b/src/instructions.rs
@@ -835,6 +835,7 @@ impl Instruction {
             | &Instruction::CallSocketServerOpen
             | &Instruction::CallSocketServerAccept
             | &Instruction::CallSocketServerClose
+            | &Instruction::CallCopyStream
             | &Instruction::CallTLSAcceptClient
             | &Instruction::CallTLSClientConnect
             | &Instruction::CallSucceed
@@ -1094,6 +1095,7 @@ impl Instruction {
             | &Instruction::ExecuteSocketServerOpen
             | &Instruction::ExecuteSocketServerAccept
             | &Instruction::ExecuteSocketServerClose
+            | &Instruction::ExecuteCopyStream
             | &Instruction::ExecuteTLSAcceptClient
             | &Instruction::ExecuteTLSClientConnect
             | &Instruction::ExecuteSucceed
diff --git a/src/lib/sockets.pl b/src/lib/sockets.pl
index f6689161..4d2579d5 100644
--- a/src/lib/sockets.pl
+++ b/src/lib/sockets.pl
@@ -8,6 +8,7 @@ In both cases, with a stream, you can use the usual predicates to read and write
                     socket_server_open/2,
                     socket_server_accept/4,
                     socket_server_close/1,
+                    copy_stream/2,
                     current_hostname/1]).
 
 :- use_module(library(error)).
@@ -92,3 +93,11 @@ socket_server_close(ServerSocket) :-
 % Returns the current hostname of the computer in which Scryer Prolog is executing right now
 current_hostname(HostName) :-
     '$current_hostname'(HostName).
+
+%% copy_stream(+InputStream, +OutputStream).
+%
+% Copies all remaining bytes from InputStream to OutputStream in a single
+% native call, without materialising the contents on the Prolog heap.
+% Intended for streaming binary content (e.g. file -> TLS socket).
+copy_stream(In, Out) :-
+    '$copy_stream'(In, Out).
diff --git a/src/machine/dispatch.rs b/src/machine/dispatch.rs
index 90a65cb1..267b9651 100644
--- a/src/machine/dispatch.rs
+++ b/src/machine/dispatch.rs
@@ -4938,6 +4938,14 @@ impl Machine {
                         try_or_throw!(self.machine_st, self.socket_server_close(), continue);
                         self.machine_st.p = self.machine_st.cp;
                     }
+                    &Instruction::CallCopyStream => {
+                        try_or_throw!(self.machine_st, self.copy_stream(), continue);
+                        step_or_fail!(self.machine_st, self.machine_st.p += 1);
+                    }
+                    &Instruction::ExecuteCopyStream => {
+                        try_or_throw!(self.machine_st, self.copy_stream(), continue);
+                        step_or_fail!(self.machine_st, self.machine_st.p = self.machine_st.cp);
+                    }
                     &Instruction::CallTLSAcceptClient => {
                         #[cfg(feature = "tls")]
                         try_or_throw!(self.machine_st, self.tls_accept_client(), continue);
diff --git a/src/machine/system_calls.rs b/src/machine/system_calls.rs
index df15aeb5..f66d7c32 100644
--- a/src/machine/system_calls.rs
+++ b/src/machine/system_calls.rs
@@ -7267,6 +7267,47 @@ impl Machine {
         Ok(())
     }
 
+    #[inline(always)]
+    pub(crate) fn copy_stream(&mut self) -> CallResult {
+        let mut input = self.machine_st.get_stream_or_alias(
+            self.machine_st.registers[1],
+            &self.indices,
+            atom!("$copy_stream"),
+            2,
+        )?;
+        let mut output = self.machine_st.get_stream_or_alias(
+            self.machine_st.registers[2],
+            &self.indices,
+            atom!("$copy_stream"),
+            2,
+        )?;
+
+        let stub_gen = || functor_stub(atom!("$copy_stream"), 2);
+        let mut buf = [0u8; 65536];
+
+        loop {
+            let n = match input.read(&mut buf) {
+                Ok(0) => break,
+                Ok(n) => n,
+                Err(ref e) if e.kind() == ErrorKind::Interrupted => continue,
+                Err(_) => {
+                    let err = self
+                        .machine_st
+                        .existence_error(ExistenceError::Stream(input.into()));
+                    return Err(self.machine_st.error_form(err, stub_gen()));
+                }
+            };
+            if output.write_all(&buf[..n]).is_err() {
+                let err = self
+                    .machine_st
+                    .existence_error(ExistenceError::Stream(output.into()));
+                return Err(self.machine_st.error_form(err, stub_gen()));
+            }
+        }
+
+        Ok(())
+    }
+
     #[inline(always)]
     pub(crate) fn socket_server_close(&mut self) -> CallResult {
         let culprit = self.deref_register(1);