Remove dc_open() from the Rust API

This means the Context becomes a struct following the normal Rust
conventions where when it is created it is usable.  This will over
time allow removing a lot of runtime checks and simplify code.  Many
members will no longer need to be Options or similar.

The C API needs to remain compatible so hides the implementation of
this behind another struct which can be opened and closed.

examples/repl/cmdline.rs

@@ -396,8 +396,6 @@ pub unsafe fn dc_cmdline(context: &Context, line: &str) -> Result<(), failure::E
             _ => println!(
                 "==========================Database commands==\n\
                  info\n\
-                 open <file to open or create>\n\
-                 close\n\
                  set <configuration-key> [<value>]\n\
                  get <configuration-key>\n\
                  oauth2\n\
@@ -474,14 +472,6 @@ pub unsafe fn dc_cmdline(context: &Context, line: &str) -> Result<(), failure::E
                 println!("Already authorized.");
             }
         }
-        "open" => {
-            ensure!(!arg1.is_empty(), "Argument <file> missing");
-            dc_close(context);
-            ensure!(dc_open(context, arg1, None), "Open failed");
-        }
-        "close" => {
-            dc_close(context);
-        }
         "initiate-key-transfer" => {
             let setup_code = dc_initiate_key_transfer(context);
             if !setup_code.is_null() {

examples/repl/main.rs

@@ -14,6 +14,7 @@ extern crate lazy_static;
 extern crate rusqlite;
 
 use std::borrow::Cow::{self, Borrowed, Owned};
+use std::path::Path;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex, RwLock};
 
@@ -41,7 +42,7 @@ use self::cmdline::*;
 
 // Event Handler
 
-unsafe extern "C" fn receive_event(
+fn receive_event(
     _context: &Context,
     event: Event,
     data1: uintptr_t,
@@ -384,21 +385,16 @@ impl Highlighter for DcHelper {
 impl Helper for DcHelper {}
 
 fn main_0(args: Vec<String>) -> Result<(), failure::Error> {
-    let mut context = dc_context_new(
-        Some(receive_event),
-        0 as *mut libc::c_void,
-        Some("CLI".into()),
-    );
-
     unsafe { dc_cmdline_skip_auth() };
-
-    if args.len() == 2 {
-        if unsafe { !dc_open(&mut context, &args[1], None) } {
-            println!("Error: Cannot open {}.", args[0],);
-        }
-    } else if args.len() != 1 {
+    if args.len() != 2 {
         println!("Error: Bad arguments, expected [db-name].");
+        return Err(format_err!("No db-name specified"));
     }
+    let context = Context::new(
+        Box::new(receive_event),
+        "CLI".into(),
+        Path::new(&args[1]).to_path_buf(),
+    )?;
 
     println!("Delta Chat Core is awaiting your commands.");
 

examples/simple.rs

@@ -16,9 +16,8 @@ use deltachat::job::{
     perform_imap_fetch, perform_imap_idle, perform_imap_jobs, perform_smtp_idle, perform_smtp_jobs,
 };
 
-extern "C" fn cb(_ctx: &Context, event: Event, data1: usize, data2: usize) -> usize {
+fn cb(_ctx: &Context, event: Event, data1: usize, data2: usize) -> usize {
     println!("[{:?}]", event);
-
     match event {
         Event::CONFIGURE_PROGRESS => {
             println!("  progress: {}", data1);
@@ -39,7 +38,11 @@ extern "C" fn cb(_ctx: &Context, event: Event, data1: usize, data2: usize) -> us
 
 fn main() {
     unsafe {
-        let ctx = dc_context_new(Some(cb), std::ptr::null_mut(), None);
+        let dir = tempdir().unwrap();
+        let dbfile = dir.path().join("db.sqlite");
+        println!("creating database {:?}", dbfile);
+        let ctx =
+            Context::new(Box::new(cb), "FakeOs".into(), dbfile).expect("Failed to create context");
         let running = Arc::new(RwLock::new(true));
         let info = dc_get_info(&ctx);
         let info_s = CStr::from_ptr(info);
@@ -73,13 +76,6 @@ fn main() {
             }
         });
 
-        let dir = tempdir().unwrap();
-        let dbfile = dir.path().join("db.sqlite");
-
-        println!("opening database {:?}", dbfile);
-
-        assert!(dc_open(&ctx, dbfile.to_str().unwrap(), None));
-
         println!("configuring");
         let args = std::env::args().collect::<Vec<String>>();
         assert_eq!(args.len(), 2, "missing password");