hautils

commit 9d66bb8b11c00654db0abfa08997f71525d941aa
parent 61d21ca3316cfb7902f0572de6aa93b083426b99
Author: Drew DeVault <sir@cmpwn.com>
Date:   Thu,  8 Jul 2021 15:00:53 -0400

head: new command

Diffstat:
M
.gitignore
 | 
1
+
M
Makefile
 | 
2
++
A
head.ha
 | 
57
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
main/main.ha
 | 
2
+-

4 files changed, 61 insertions(+), 1 deletion(-)
diff --git a/.gitignore b/.gitignore
@@ -3,3 +3,4 @@ false
 true
 tee
 uname
+head
diff --git a/Makefile b/Makefile
@@ -5,6 +5,7 @@ HARE=hare
 utils=\
 	cat \
 	false \
+	head \
 	tee \
 	true \
 	uname
@@ -22,6 +23,7 @@ clean:
 
 cat: cat.ha main/main.ha
 false: false.ha
+head: head.ha
 tee: tee.ha
 true: true.ha
 uname: uname.ha
diff --git a/head.ha b/head.ha
@@ -0,0 +1,57 @@
+use bufio;
+use errors;
+use fmt;
+use fs;
+use getopt;
+use io;
+use main;
+use os;
+use strconv;
+
+export fn utilmain() (void | main::error) = {
+	const cmd = getopt::parse(os::args, "print the first lines of files",
+		('n', "lines", "set the number of lines to print"));
+	defer getopt::finish(&cmd);
+
+	let n = 10u;
+	for (let i = 0z; i < len(cmd.opts); i += 1) {
+		const opt = cmd.opts[i];
+		// Only opt is -n
+		n = match (strconv::stou(opt.1)) {
+			(strconv::invalid | strconv::overflow) =>
+				fmt::fatal("Invalid number given for -n"),
+			n: uint => n,
+		};
+	};
+
+	if (len(cmd.args) == 0) {
+		head(os::stdin, n)?;
+	};
+
+	for (let i = 0z; i < len(cmd.args); i += 1) {
+		const file = match (os::open(cmd.args[i])) {
+			err: fs::error => fmt::fatal("Error opening '{}': {}",
+				cmd.args[i], fs::strerror(err)),
+			file: *io::stream => file,
+		};
+		defer io::close(file);
+		head(file, n)?;
+	};
+};
+
+fn head(in: *io::stream, n: uint) (void | main::error) = {
+	static let buf: [os::BUFSIZ]u8 = [0...];
+	const in = bufio::buffered(in, buf, []);
+	defer io::close(in);
+
+	for (n > 0; n -= 1) {
+		let line = match (bufio::scanline(in)) {
+			err: io::error => return err,
+			io::EOF => break,
+			line: []u8 => line,
+		};
+		defer free(line);
+		io::write(os::stdout, line)?;
+		fmt::println()?;
+	};
+};
diff --git a/main/main.ha b/main/main.ha
@@ -2,7 +2,7 @@ use fmt;
 use fs;
 use io;
 
-export type error = (io::error | fs::error);
+export type error = !(io::error | fs::error);
 
 @symbol("utilmain") fn utilmain() (main::error | void);