fix empty exe dir crash

Author: MrPicklePinosaur

README.md

@@ -165,6 +165,19 @@ To build from source, you need to have a [rust toolchain](https://www.rust-lang.
 p8tool addcart <path to cart> --name <name of cart> --author <author of cart>
 ```
 
+## Adding custom external apps
+
+**picolauncher** now supports launcher arbritrary external applications. Simply create `drive/exe` directory, and place a cart file with the following contents:
+```p8
+pico-8 cartridge // http://www.pico-8.com
+version 42
+__meta:picolauncher__
+name="curse of the lich king"
+author="johanpeitz"
+path="cotlk/cotlk"
+```
+Where `path` points to the location of the executable you wish to launch (relative to `drive/exe` directory).
+
 ## Contributing
 
 Please see [CONTRIBUTING.md](CONTRIBUTING.md) for more details! Don't hesitate to report bugs and post feature requests!

drive/carts/serial.p8

@@ -80,6 +80,9 @@ end
 function serial_ls_exe()
   serial_writeline('ls_exe:')
   local exes=serial_readline()
+  if #exes == 0 then
+    return {}
+  end
   local split_exes=split(exes, ',', false)
   for k, v in pairs(split_exes) do
     split_exes[k]=table_from_string(v)

drive/config.txt

@@ -30,7 +30,7 @@ foreground_sleep_ms 2 // number of milliseconds to sleep each frame. Try 10 to c
 
 background_sleep_ms 10 // number of milliseconds to sleep each frame when running in the background
 
-sessions 295 // number of times program has been run
+sessions 302 // number of times program has been run
 
 // (scancode) hold this key down and left-click to simulate right-click
 rmb_key 0 // 0 for none  226 for LALT

src/main.rs

@@ -207,17 +207,19 @@ fn main() {
                 // fetch all carts in directory
                 let dir = (&*CART_DIR).join(data); // TODO watch out for path traversal
                 let mut carts = vec![];
-                for entry in read_dir(dir).unwrap() {
-                    let entry = entry.unwrap().path();
-                    if entry.is_file() {
-                        // for each file read metadata and pack into table string
-                        let filename = entry.file_name().unwrap();
-                        let mut metapath = PathBuf::from(filename);
-                        metapath.set_extension("json");
-                        let metapath = METADATA_DIR.join(metapath);
-                        match parse_metadata(&metapath) {
-                            Ok(serialized) => carts.push(serialized),
-                            Err(e) => warn!("failed parsing metadata file: {e:?}"),
+                if let Ok(read_dir) = read_dir(dir) {
+                    for entry in read_dir {
+                        let entry = entry.unwrap().path();
+                        if entry.is_file() {
+                            // for each file read metadata and pack into table string
+                            let filename = entry.file_name().unwrap();
+                            let mut metapath = PathBuf::from(filename);
+                            metapath.set_extension("json");
+                            let metapath = METADATA_DIR.join(metapath);
+                            match parse_metadata(&metapath) {
+                                Ok(serialized) => carts.push(serialized),
+                                Err(e) => warn!("failed parsing metadata file: {e:?}"),
+                            }
                         }
                     }
                 }
@@ -241,35 +243,37 @@ fn main() {
                 // path=picocad/picocad
                 // ```
                 let mut exes = vec![];
-                for entry in read_dir(EXE_DIR.as_path()).unwrap() {
-                    let entry = entry.unwrap().path();
-                    if !entry.is_file() {
-                        continue;
-                    }
-                    // TODO can this fail?
-                    if entry.extension().unwrap() != "p8" {
-                        continue;
-                    }
-                    let Ok(mut cart) = Cart::from_file(&entry) else {
-                        warn!("failed to read exe meta file {entry:?}");
-                        continue;
-                    };
-                    let meta = cart
-                        .get_section(SectionName::Meta("picolauncher".into()))
-                        .join("\n");
+                if let Ok(read_dir) = read_dir(EXE_DIR.as_path()) {
+                    for entry in read_dir {
+                        let entry = entry.unwrap().path();
+                        if !entry.is_file() {
+                            continue;
+                        }
+                        // TODO can this fail?
+                        if entry.extension().unwrap() != "p8" {
+                            continue;
+                        }
+                        let Ok(mut cart) = Cart::from_file(&entry) else {
+                            warn!("failed to read exe meta file {entry:?}");
+                            continue;
+                        };
+                        let meta = cart
+                            .get_section(SectionName::Meta("picolauncher".into()))
+                            .join("\n");
 
-                    let Ok(meta_parsed) = toml::from_str::<ExeMeta>(&meta) else {
-                        warn!("failed to parse metadata section of file {entry:?}");
-                        continue;
-                    };
+                        let Ok(meta_parsed) = toml::from_str::<ExeMeta>(&meta) else {
+                            warn!("failed to parse metadata section of file {entry:?}");
+                            continue;
+                        };
 
-                    println!("{meta_parsed:?}");
-                    let Ok(meta_string) = meta_parsed.to_lua_table() else {
-                        warn!("failed to serialize to lua table for meta file {entry:?}");
-                        continue;
-                    };
+                        println!("{meta_parsed:?}");
+                        let Ok(meta_string) = meta_parsed.to_lua_table() else {
+                            warn!("failed to serialize to lua table for meta file {entry:?}");
+                            continue;
+                        };
 
-                    exes.push(meta_string);
+                        exes.push(meta_string);
+                    }
                 }
                 let mut in_pipe = open_in_pipe().expect("failed to open pipe");
                 let exes_joined = exes.join(",");