add experimental gdb debug lib

.gdbinit

@@ -5,3 +5,38 @@ break core::option::expect_failed::h4927e1fef06c4878
 break core::panicking::panic
 break libcore/panicking.rs:58
 break libcore/result.rs:945
+set auto-load python-scripts
+break melib/src/mailbox/thread.rs:1010
+set print thread-events off
+
+#python
+#import os
+#import sys
+#
+#sys.path.insert(0, os.getcwd() + '/scripts/gdb_meli/')
+#import gdb
+#import gdb_meli
+#
+#print(gdb_meli.__file__)
+#
+#help(gdb_meli)
+##from gdb_meli import build_pretty_printer
+##print(gdb.objfiles()[0].filename)
+##gdb_meli.register_pretty_printer(gdb)
+##gdb.printing.register_pretty_printer(
+##    gdb.current_objfile(),
+##    gdb_meli.build_pretty_printer())
+#end
+python
+
+import sys, os
+
+sys.path.insert(0, os.getcwd() + '/scripts/gdb_meli/')
+
+
+import gdb_meli, gdb
+#gdb_meli.register_meli_printers(gdb)
+#gdb.printing.register_pretty_printer(
+#	 gdb.current_objfile(),
+#	 gdb_meli.build_meli_printer())
+end

Cargo.toml

@@ -21,4 +21,4 @@ lto = true
 debug = true
 
 [workspace]
-members = ["melib", "ui"]
+members = ["melib", "ui", "debug_printer"]

debug_printer/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "debug_printer"
+version = "0.0.1"  #:version
+authors = []
+workspace = ".."
+
+[lib]
+name = "debugprinter"
+crate-type = ["dylib"]
+path = "src/lib.rs"
+
+
+[dependencies]
+libc = {version = "0.2.55", features = ["extra_traits",] }
+melib = { path = "../melib", version = "*" }
+ui = { path = "../ui", version = "*" }

debug_printer/src/lib.rs

@@ -0,0 +1,44 @@
+extern crate libc;
+extern crate melib;
+
+use melib::Envelope;
+use std::ffi::CString;
+use std::os::raw::c_char;
+
+#[no_mangle]
+pub extern "C" fn print_envelope(ptr: *const Envelope) -> *const c_char {
+    unsafe {
+        assert!(!ptr.is_null(), "Null pointer in print_envelope");
+        //println!("got addr {}", p as u64);
+        //unsafe { CString::new("blah".to_string()).unwrap().as_ptr() }
+        let s = CString::new(format!("{:?}", *ptr)).unwrap();
+        drop(ptr);
+        let p = s.as_ptr();
+        std::mem::forget(s);
+        p
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn get_empty_envelope() -> *mut Envelope {
+    let mut ret = Envelope::default();
+    let ptr = std::ptr::NonNull::new(&mut ret as *mut Envelope)
+        .expect("Envelope::default() has a NULL pointer?");
+
+    let ptr = ptr.as_ptr();
+    std::mem::forget(ret);
+    ptr
+}
+
+#[no_mangle]
+pub extern "C" fn destroy_cstring(ptr: *mut c_char) {
+    unsafe {
+        let slice = CString::from_raw(ptr);
+        drop(slice);
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn envelope_size() -> libc::size_t {
+    std::mem::size_of::<Envelope>()
+}