extra .text section created

crates/linker/src/pe.rs

@@ -916,4 +916,163 @@ mod test {
 
         assert_eq!("Hello, 42!\n", output);
     }
+
+    fn foobar_help(dir: &Path) {
+        use object::ObjectSection;
+
+        let host_zig = indoc!(
+            r#"
+            const std = @import("std");
+
+            extern fn magic() callconv(.C) u64;
+
+            pub fn main() !void {
+                const stdout = std.io.getStdOut().writer();
+                try stdout.print("Hello, {}!\n", .{magic()});
+            }
+            "#
+        );
+
+        let app_zig = indoc!(
+            r#"
+            export fn magic() u64 {
+                return 42;
+            }
+            "#
+        );
+
+        let zig = std::env::var("ROC_ZIG").unwrap_or_else(|_| "zig".into());
+
+        std::fs::write(dir.join("host.zig"), host_zig.as_bytes()).unwrap();
+        std::fs::write(dir.join("app.zig"), app_zig.as_bytes()).unwrap();
+
+        let dylib_bytes = crate::generate_dylib::synthetic_dll(&["magic".into()]);
+        std::fs::write(dir.join("libapp.obj"), dylib_bytes).unwrap();
+
+        let output = std::process::Command::new(&zig)
+            .current_dir(dir)
+            .args(&[
+                "build-exe",
+                "libapp.obj",
+                "host.zig",
+                "-lc",
+                "-target",
+                "x86_64-windows-gnu",
+                "--strip",
+                "-OReleaseFast",
+            ])
+            .output()
+            .unwrap();
+
+        if !output.status.success() {
+            use std::io::Write;
+
+            std::io::stdout().write_all(&output.stdout).unwrap();
+            std::io::stderr().write_all(&output.stderr).unwrap();
+
+            panic!("zig build-exe failed");
+        }
+
+        let data = std::fs::read(dir.join("host.exe")).unwrap();
+        let new_sections = [*b".text\0\0\0"];
+        increase_number_of_sections_help(&data, &new_sections, &dir.join("dynhost.exe"));
+
+        let output = std::process::Command::new(&zig)
+            .current_dir(dir)
+            .args(&[
+                "build-obj",
+                "app.zig",
+                "-target",
+                "x86_64-windows-gnu",
+                "--strip",
+                "-OReleaseFast",
+            ])
+            .output()
+            .unwrap();
+
+        if !output.status.success() {
+            use std::io::Write;
+
+            std::io::stdout().write_all(&output.stdout).unwrap();
+            std::io::stderr().write_all(&output.stderr).unwrap();
+
+            panic!("zig build-obj failed");
+        }
+
+        let mut app = std::fs::read(dir.join("dynhost.exe")).unwrap();
+        let dynamic_relocations = DynamicRelocationsPe::new(&app);
+
+        // Here we manually add the app.obj assembly to the host's .text section
+        // We can "just" do this because the space reserved for this section is bigger
+        // than what is actually used (because PE rounds up sections to a big alignment,
+        // here 0x200)
+        //
+        // So, we append the bytes at the end of the current .text section, redirect the call
+        // to `magic` to the virtual address of the .text section (so right before the new
+        // assembly bytes that we added) and then update the length of the .text section
+
+        let file = PeFile64::parse(app.as_slice()).unwrap();
+        let text_section = file.sections().next().unwrap();
+
+        // end of the code section as an offset into the file
+        let code_section_end =
+            (text_section.file_range().unwrap().0 + text_section.size()) as usize;
+
+        // the virtual address of the end of the text section
+        let code_section_end_virtual = text_section.address() + text_section.size();
+
+        // this is cheating a little bit: these bytes are copied from the `app.obj`
+        // we could get them out programatically of course.
+        let app_bytes: &[u8] = &[0xb8, 0x2a, 0, 0, 0, 0xc3];
+
+        // put our new code into the existing .text section
+        app[code_section_end..][..app_bytes.len()].copy_from_slice(app_bytes);
+
+        redirect_dummy_dll_functions(&mut app, &dynamic_relocations, &[code_section_end_virtual]);
+
+        remove_dummy_dll_import_table(
+            &mut app,
+            dynamic_relocations.data_directories_offset_in_file,
+            dynamic_relocations.imports_offset_in_file,
+            dynamic_relocations.dummy_import_index,
+        );
+
+        // again, a constant that we could get programatically
+        let section_table_offset = 384;
+
+        // update the size of the .text section (which is the first section header)
+        let p = load_struct_inplace_mut::<ImageSectionHeader>(&mut app, section_table_offset);
+        p.virtual_size
+            .set(LE, p.virtual_size.get(LE) + app_bytes.len() as u32);
+
+        std::fs::write(dir.join("hostapp.exe"), app).unwrap()
+    }
+
+    #[test]
+    fn foobar() {
+        // let dir = tempfile::tempdir().unwrap();
+        // let dir = dir.path();
+        let dir = Path::new("/tmp/wlink");
+
+        foobar_help(dir);
+
+        let output = std::process::Command::new("wine")
+            .current_dir(dir)
+            .args(&["hostapp.exe"])
+            .output()
+            .unwrap();
+
+        if !output.status.success() {
+            use std::io::Write;
+
+            std::io::stdout().write_all(&output.stdout).unwrap();
+            std::io::stderr().write_all(&output.stderr).unwrap();
+
+            panic!("wine failed");
+        }
+
+        let output = String::from_utf8_lossy(&output.stdout);
+
+        assert_eq!("Hello, 42!\n", output);
+    }
 }