mm(1): fixes creating files

src/mm.rs

@@ -36,12 +36,12 @@ fn main() -> ExitCode {
 	let argv = args().collect::<Vec<_>>();
 	let usage = format!("Usage: {} [-aetu] [-i input] [-o output]", argv[0]);
 
-	let mut a = false; /* append rather than update */
+	let mut a = false; /* append to the file */
 	let mut e = false; /* use stderr as an output */
-	let mut t = true;
+	let mut t = true; /* do not truncate the file before writing */
 	let mut u = false; /* unbuffer i/o */
-	let mut ins = Vec::new(); /* initial inputs vector */
-	let mut outs = Vec::new(); /* initial outputs vector */
+	let mut ins = Vec::new(); /* initial input file path vector */
+	let mut outs = Vec::new(); /* initial output file path vector */
 
 	while let Some(opt) = argv.getopt("aei:o:tu") {
 		match opt.opt() {
@@ -74,29 +74,43 @@ fn main() -> ExitCode {
 	let inputs = ins.iter().map(|file| {
 		/* if a file is “-”, it is stdin */
 		if *file == "-" {
-			return unsafe { File::from_raw_fd(stdin().as_raw_fd()) }; /* fd0 = stdin */
+			/* portable way to access stdin as a file */
+			return unsafe { File::from_raw_fd(stdin().as_raw_fd()) };
 		}
 
-		match File::options().open(file) {
+		match File::open(file) {
 			Ok(f) => f,
 			Err(e) => {
-				eprintln!("{}: {}", argv[0], e.strerror());
+				eprintln!("{}: {}: {}", argv[0], file, e.strerror());
 				exit(EX_IOERR);
 			},
 		}
 	}).collect::<Vec<_>>();
 
+	println!("{:?}", outs);
+
 	/* map all path strings to files */
 	let mut outputs = outs.iter().map(|file| {
 		/* of a file is “-”, it is stdout */
 		if *file == "-" {
-			return unsafe { File::from_raw_fd(stdout().as_raw_fd()) }; /* fd1 = stdout */
+			/* portable way to access stdout as a file */
+			return unsafe { File::from_raw_fd(stdout().as_raw_fd()) }; 
 		}
 
-		match File::options().truncate(t).append(a).open(file) {
+		let options = File::options()
+			/* truncate if -t is specified and append if -a is specified */
+			.truncate(t)
+			.append(a)
+			/* enable the ability to create and write to files */
+			.create(true)
+			.write(true)
+			/* finally, open the file! */
+			.open(file);
+
+		match options {
 			Ok(f) => return f,
 			Err(e) => {
-				eprintln!("{}: {}", argv[0], e.strerror());
+				eprintln!("{}: {}: {}", argv[0], file, e.strerror());
 				exit(EX_IOERR);
 			},
 		};
@@ -104,13 +118,16 @@ fn main() -> ExitCode {
 
 	/* if -e is specified, use stderr */
 	if e {
-		outputs.push(unsafe { File::from_raw_fd(stderr().as_raw_fd()) }); /* fd2 = stderr */
+		/* portable way to access stderr as a file */
+		outputs.push(unsafe { File::from_raw_fd(stderr().as_raw_fd()) });
 	}
 
 	let mut outputs = outputs.iter().map(|o| {
 		if u {
+			/* unbuffered writing through a buffer of capacity 0 */
 			BufWriter::with_capacity(0, o)
 		} else {
+			/* theoretically buffered writing */
 			BufWriter::new(o)
 		}
 	}).collect::<Vec<_>>();
@@ -127,6 +144,7 @@ fn main() -> ExitCode {
 					eprintln!("{}: {}", argv[0], e.strerror());
 					return ExitCode::from(EX_IOERR as u8);
 				}
+				/* immediately flush the output for -u */
 				if let Err(e) = out.flush() { 
 					eprintln!("{}: {}", argv[0], e.strerror());
 					return ExitCode::from(EX_IOERR as u8);