improved stdin handling (#156)

src/tail/cmd_line.v → src/tail/parse_args.v

@@ -1,5 +1,7 @@
 import common
 import flag
+import os
+import time
 
 struct Args {
 	bytes          i64
@@ -15,7 +17,7 @@ struct Args {
 	files          []string
 }
 
-fn get_args(args []string) Args {
+fn parse_args(args []string) Args {
 	mut fp := flag.new_flag_parser(args)
 
 	fp.application(app_name)
@@ -65,9 +67,10 @@ fn get_args(args []string) Args {
 		descriptors are not supported'.trim_indent())
 
 	fp.footer(common.coreutils_footer())
-	file_args := fp.finalize() or { exit_error(err.msg()) }
+	files_arg := fp.finalize() or { exit_error(err.msg()) }
 	from_start := bytes_arg.starts_with('+') || lines_arg.starts_with('+')
 	delimiter := if zero_terminated_arg { `\0` } else { `\n` }
+	files := scan_files_arg(files_arg)
 
 	return Args{
 		bytes: string_to_i64(bytes_arg) or { exit_error(err.msg()) }
@@ -80,10 +83,46 @@ fn get_args(args []string) Args {
 		sleep_interval: sleep_interval_arg
 		from_start: from_start
 		delimiter: delimiter
-		files: file_args
+		files: files
 	}
 }
 
+fn scan_files_arg(files_arg []string) []string {
+	mut files := []string{}
+
+	for file in files_arg {
+		if file == '-' {
+			files << stdin_to_tmp()
+			continue
+		}
+		files << file
+	}
+
+	if files.len == 0 {
+		files << stdin_to_tmp()
+	}
+
+	return files
+}
+
+const tmp_pattern = '/${app_name}-tmp-'
+
+fn stdin_to_tmp() string {
+	tmp := '${os.temp_dir()}/${tmp_pattern}${time.ticks()}'
+	os.create(tmp) or { exit_error(err.msg()) }
+	mut f := os.open_append(tmp) or { exit_error(err.msg()) }
+	defer { f.close() }
+
+	for {
+		s := os.get_raw_line()
+		if s.len == 0 {
+			break
+		}
+		f.write_string(s) or { exit_error(err.msg()) }
+	}
+	return tmp
+}
+
 @[noreturn]
 fn exit_success(msg string) {
 	println(msg)

src/tail/tail.v

@@ -13,7 +13,7 @@ pub mut:
 }
 
 fn main() {
-	args := get_args(os.args)
+	args := parse_args(os.args)
 	tail(args, fn (s string) {
 		print(s)
 		flush_stdout()
@@ -22,16 +22,7 @@ fn main() {
 
 fn tail(args Args, out_fn fn (string)) {
 	mut tail_forever := false
-	mut files := args.files.map(FileInfo{ name: it })
-
-	// Perhaps there is a better way to handle stdin?
-	if args.files.len == 0 || args.files[0] == '-' {
-		tmp := tmp_from_stdin()
-		files = [FileInfo{
-			name: tmp
-			stdin: true
-		}]
-	}
+	mut files := args.files.map(FileInfo{ name: it, stdin: it.contains(tmp_pattern) })
 
 	for {
 		for i, mut file in files {