pkgs/profpatsch/e: fix by rewriting in rust and execing into block

calling `execlineb -c` has unfortunate quoting issues, cause for
cornercases like arguments that contain spaces or `"` the result would
be a completely broken command line.

Instead, let’s do our own block construction in a small rust
program (for speed). I tried implementing it in bash first but even
prepending spaces to a string is a complete waste of time in that
language.

1 files changed, 33 insertions, 0 deletions

diff --git a/pkgs/profpatsch/execline/run-cmd-line-block.rs b/pkgs/profpatsch/execline/run-cmd-line-block.rs
new file mode 100644
index 00000000..324ce858
--- /dev/null
+++ b/pkgs/profpatsch/execline/run-cmd-line-block.rs
@@ -0,0 +1,33 @@
+use std::ffi::{OsString, OsStr};
+use std::process::{Command};
+use std::os::unix::process::CommandExt;
+
+fn main() -> std::io::Result<()> {
+  let args = std::env::args_os();
+  let mut cmd : Vec<OsString> = vec![];
+  let mut depth = 0;
+  for arg in args.skip(1) {
+    if arg == OsString::from("[") {
+        depth = depth + 1;
+    } else if arg == OsString::from("]") {
+        depth = depth - 1;
+        cmd.push(prepend_block_depth(depth, &OsString::from("")));
+    } else {
+        cmd.push(prepend_block_depth(depth, &arg));
+    }
+  }
+
+  Err(match cmd.len() {
+      0 => std::process::exit(0),
+      1 => Command::new(&cmd[0]).exec(),
+      _ => Command::new(&cmd[0])
+             .args(&cmd[1..])
+             .exec()
+  })
+}
+
+fn prepend_block_depth(depth: usize, arg: &OsStr) -> OsString {
+    let mut s = OsString::from(" ".repeat(depth));
+    s.push(arg);
+    s
+}