Merge pull request 'Handling redirects/pipes and no stdin' (#4) from emma/breed:arg-parsing into main

Reviewed-on: #4

Cargo.lock

@@ -62,6 +62,7 @@ version = "0.1.0"
 dependencies = [
  "arg",
  "crossterm",
+ "libc",
  "ropey",
  "yacexits",
 ]

Cargo.toml

@@ -7,5 +7,6 @@ license = "AGPL-3.0-or-later"
 [dependencies]
 arg = "0.4.1"
 crossterm = "0.26"
+libc = "0.2.141"
 ropey = "1.6"
 yacexits = "0.1.5"

src/main.rs

@@ -451,7 +451,12 @@ fn main() -> Result<()> {
     let mut buf = Vec::new();
 
     match argv.get(1).map(|s| s.as_str()) {
-        Some("-") | None => unsafe { File::from_raw_fd(0) }, // stdin as a file
+        Some("-") | None => {
+            let stdin = 0; // get stdin as a file descriptor
+            if unsafe { libc::isatty(stdin) } == 0 {
+                unsafe { File::from_raw_fd(stdin) }
+            } else { File::open("/dev/null").unwrap() }
+        },
         Some(path) => {
             std::fs::File::open(path).unwrap_or_else(|_| {
                 eprintln!(