fop(1): literal record separator

Makefile

@@ -1,6 +1,7 @@
 # Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
 # Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 # Copyright (c) 2023 Sasha Koshka <sashakoshka@tebibyte.media>
+# Copyright (c) 2024 Aaditya Aryal <aryalaadi123@gmail.com>
 # SPDX-License-Identifier: FSFAP
 #
 # Copying and distribution of this file, with or without modification, are
@@ -13,21 +14,23 @@
 .PRAGMA: posix_202x # future POSIX standard support à la pdpmake(1)
 .PRAGMA: command_comment # breaks without this?
 
-DESTDIR=./dist
+DESTDIR ?= dist
-PREFIX=/usr/local
+PREFIX ?= /usr/local
 
-SYSEXITS!=printf '\043include <sysexits.h>\n' | cpp -M - | sed 's/ /\n/g' \
+MANDIR != [ $(PREFIX) = / ] && printf '/usr/share/man\n' \
-	| sed -n 's/sysexits\.h//p' || printf 'include/\n'
+	|| printf '/share/man\n'
+SYSEXITS != printf '\043include <sysexits.h>\n' | cpp -M - | sed 's/ /\n/g' \
+	| sed -n 's/sysexits\.h//p' || printf 'include\n'
 
-CC?=cc
+CC ?= cc
-RUSTC?=rustc
+RUSTC ?= rustc
-RUSTLIBS=--extern getopt=build/o/libgetopt.rlib \
+RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
 	--extern sysexits=build/o/libsysexits.rlib \
 	--extern strerror=build/o/libstrerror.rlib
-CFLAGS+=-I$(SYSEXITS)
+CFLAGS += -I$(SYSEXITS)
 
 .PHONY: all
-all: dj false fop hru intcmp rpn scrut str strcmp true
+all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
 
 build:
 	# keep build/include until bindgen(1) has stdin support
@@ -36,12 +39,12 @@ build:
 
 .PHONY: clean
 clean:
-	rm -rf build/ dist/
+	rm -rf build dist
 
 dist: all
-	mkdir -p $(DESTDIR)$(PREFIX)/bin $(DESTDIR)$(PREFIX)/share/man/man1
+	mkdir -p $(DESTDIR)/$(PREFIX)/bin $(DESTDIR)/$(PREFIX)/share/man/man1
-	cp build/bin/* $(DESTDIR)$(PREFIX)/bin/
+	cp build/bin/* $(DESTDIR)/$(PREFIX)/bin
-	cp docs/*.1 $(DESTDIR)$(PREFIX)/share/man/man1/
+	cp docs/*.1 $(DESTDIR)/$(PREFIX)/$(MANDIR)/man1
 
 .PHONY: install
 install: dist
@@ -96,6 +99,16 @@ intcmp: build/bin/intcmp
 build/bin/intcmp: src/intcmp.c build
 	$(CC) $(CFLAGS) -o $@ src/intcmp.c
 
+.PHONY: mm
+mm: build/bin/mm
+build/bin/mm: src/mm.c build
+	$(CC) $(CFLAGS) -o $@ src/mm.c
+
+.PHONY: npc
+npc: build/bin/npc
+build/bin/npc: src/npc.c build
+	$(CC) $(CFLAGAS) -o $@ src/npc.c
+
 .PHONY: rpn
 rpn: build/bin/rpn
 build/bin/rpn: src/rpn.rs build rustlibs
@@ -116,6 +129,13 @@ strcmp: build/bin/strcmp
 build/bin/strcmp: src/strcmp.c build
 	$(CC) $(CFLAGS) -o $@ src/strcmp.c
 
+.PHONY: swab
+swab: build/bin/swab
+build/bin/swab: src/swab.rs build build/o/libsysexits.rlib
+	$(RUSTC) $(RUSTFLAGS) --extern getopt=build/o/libgetopt.rlib \
+		--extern sysexits=build/o/libsysexits.rlib \
+		-o $@ src/swab.rs
+
 .PHONY: true
 true: build/bin/true
 build/bin/true: src/true.c build

docs/mm.1

@@ -0,0 +1,76 @@
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH mm 1
+
+.SH NAME
+
+mm \(en middleman
+
+.SH SYNOPSIS
+
+mm
+.RB ( -aenu )
+.RB ( -i
+.RB [ input ])
+.RB ( -o
+.RB [ output ])
+
+.SH DESCRIPTION
+
+Mm catenates input files and writes them to the start of each output file.
+
+.SH OPTIONS
+
+Mm, upon receiving the
+.B -a
+option, will open subsequent outputs for appending rather than updating.
+.PP
+The
+.B -i
+option opens a path as an input. Without any inputs specified mm will use
+standard input. Standard input itself can be specified by giving the path '-'.
+.PP
+The
+.B -o
+option opens a path as an output. Without any outputs specified mm will use
+standard output. Standard output itself can be specified by giving the
+path '-'. Standard error itself can be specified with the
+.B -e
+option.
+.PP
+The
+.B -u
+option ensures neither input or output will be buffered.
+.PP
+The
+.B -n
+option tells mm to ignore SIGINT signals.
+
+.SH DIAGNOSTICS
+
+If an output can no longer be written mm prints a diagnostic message, ceases
+writing to that particular output, and if there are more outputs specified,
+continues, eventually exiting unsuccessfully.
+.PP
+On error mm prints a diagnostic message and exits with the appropriate
+sysexits.h(3) status.
+
+.SH BUGS
+
+Mm does not truncate existing files, which may lead to unexpected results.
+
+.SH RATIONALE
+
+Mm was modeled after the cat and tee utilities specified in POSIX.
+
+.SH COPYRIGHT
+
+Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+cat(1p), dd(1), dj(1), tee(1p)

docs/swab.1

@@ -0,0 +1,71 @@
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH swab 1
+
+.SH NAME
+
+swab \(en swap bytes
+
+.SH SYNOPSIS
+
+swab
+.RB ( -f )
+.RB ( -w
+.R [
+.B word size
+.R ])
+
+.SH USAGE
+
+Swab swaps the latter and former halves of a block of bytes.
+
+.SH EXAMPLES
+
+The following sh(1p) line:
+
+.R printf 'hello world!\n' | swab
+
+Produces the following output:
+
+.R ehll oowlr!d
+
+.SH OPTIONS
+
+The
+.B -f
+option ignores system call interruptions.
+.PP
+The
+.B -w
+option configures the word size; that is, the size in bytes of the block size
+on which to operate. By default the word size is 2. The word size must be
+cleanly divisible by 2, otherwise the block of bytes being processed can't be
+halved.
+
+.SH DIAGNOSTICS
+
+If an error is encountered in input, output, or invocation, a diagnostic
+message will be written to standard error and swab will exit with the
+appropriate status from sysexits.h(3).
+
+.SH RATIONALE
+
+Swab was modeled after the
+.R conv=swab
+functionality specified in the POSIX dd utility but additionally allows the
+word size to be configured.
+.PP
+Swab is useful for fixing the endianness of binary files produced on other
+machines.
+
+.SH COPYRIGHT
+
+Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+dd(1p)

src/dj.c

@@ -203,28 +203,28 @@ Io_fdseek(struct Io *io){
 	
 	if(!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1)
 		return -1;
-	else if(io->fl == write_flags){
-		memset(io->buf, '\0', io->bs);
-		/* This is a dirty trick; rather than testing conditions and operating
-		 * likewise, because the parameters to read or write are going to be
-		 * the same either way, just use a function pointer to keep track of
-		 * the intended operation. */
-		op = (int (*)(int, void *, size_t))&write;
-		/* Function pointer casts are risky; this works because the difference
-		 * is in the second parameter and only that write(2) makes the buffer
-		 * const whereas read(2) does not. To avoid even the slightest
-		 * undefined behavior comment out the cast, just be ready for a
-		 * -Wincompatible-function-pointer-types if your compiler notices it.
-		 */
-	}else
-		op = &read;
 
-	/* We're going to cheat and use bufuse as the retval for write(2), which is
+	/* repeated code to get the condition out of the loop */
-	 * fine because it'll be zeroed as this function returns anyway. */
+	if(io->fl == write_flags){
-	do{	if(	(io->bufuse = (*op)(io->fd, io->buf, MIN(io->bs, io->seek))) == 0)
+		memset(io->buf, '\0', io->bs);
-			/* second chance */
+		/* We're going to cheat and use bufuse as the retval for write(2),
-			io->bufuse = (*op)(io->fd, io->buf, MIN(io->bs, io->seek));
+		 * which is fine because it'll be zeroed as this function returns
-	}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+		 * anyway. */
+		do{
+			if((io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek)))
+					== 0)
+				/* second chance */
+				io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek));
+		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	}else if(io->fl == read_flags){
+		do{
+			if((io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek)))
+					== 0)
+				/* second chance */
+				io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek));
+		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	}else
+		return EX_SOFTWARE;
 
 	io->bufuse = 0;
 

src/fop.rs

@@ -32,18 +32,12 @@ use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
 
 fn main() {
 	let argv = args().collect::<Vec<String>>();
-	let mut d = '␞';
+	let mut d = 0x1E.to_string();
 	let mut arg_parser = Parser::new(&argv, "d:");
 
 	while let Some(opt) = arg_parser.next() {
 		match opt {
-			Ok(Opt('d', Some(arg))) => {
+			Ok(Opt('d', Some(arg))) => d = arg,
-				let arg_char = arg.chars().collect::<Vec<char>>();
-				if arg_char.len() > 1 {
-					eprintln!("{}: {}: Not a character.", argv[0], arg);
-					exit(EX_USAGE);
-				} else { d = arg_char[0]; }
-			},
 			_ => {},
 		};
 	}
@@ -63,7 +57,7 @@ fn main() {
 
 	let mut buf = String::new();
 	let _ = stdin().read_to_string(&mut buf);
-	let mut fields = buf.split(d).collect::<Vec<&str>>();
+	let mut fields = buf.split(&d).collect::<Vec<&str>>();
 
 	let opts = argv
 		.iter()

src/mm.c

@@ -0,0 +1,236 @@
+/*
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+#include <errno.h> /* errno */
+#include <signal.h> /* signal(2), SIG_ERR, SIG_IGN, SIGINT */
+#include <stdio.h> /* fclose(3), fopen(3), fprintf(3), getc(3), putc(3),
+                    * setvbuf(3), size_t, _IONBF, NULL */
+#include <stdlib.h> /* free(3), realloc(3) */
+#include <string.h> /* strcmp(3), strerror(3) */
+#include <unistd.h> /* getopt(3) */
+#if !defined EX_IOERR || !defined EX_OK || !defined EX_OSERR \
+		|| !defined EX_USAGE
+#	include <sysexits.h>
+#endif
+extern int errno;
+
+/* This structure is how open files are tracked. */
+struct Files{
+	size_t a;	/* allocation */
+	size_t s;	/* used size */
+	char *mode;	/* file opening mode */
+	char **names;	/* file names */
+	FILE **files;	/* file pointers */
+};
+
+/* How much to grow the allocation when it's saturated. */
+#ifndef ALLOC_INCREMENT
+#	define ALLOC_INCREMENT 1
+#endif
+
+/* How much to grow the allocation at program start. */
+#ifndef ALLOC_INITIAL
+#	define ALLOC_INITIAL 10
+#endif
+
+/* pre-allocated strings */
+static char *program_name = "<no argv[0]>";
+static char *stdin_name = "<stdin>";
+static char *stdout_name = "<stdout>";
+static char *stderr_name = "<stderr>";
+static char *(fmode[]) = { (char []){"rb"}, (char []){"rb+"} };
+static char *wharsh = "wb";
+
+/* Adds the open FILE pointer for the file at the path s to the files struct,
+ * returning the FILE if successful and NULL if not, allocating more memory in
+ * the files buffers as needed. */
+static FILE *
+Files_append(struct Files *files, FILE *file, char *name){
+
+	if(file == NULL || (files->s == files->a
+			&& ((files->files = realloc(files->files,
+					(files->a += (files->a == 0)
+						? ALLOC_INITIAL
+						: ALLOC_INCREMENT)
+					* sizeof *(files->files))) == NULL
+				|| (files->names = realloc(files->names,
+					files->a * sizeof *(files->names))) == NULL)))
+		return NULL;
+
+	files->names[files->s] = name;
+	return files->files[files->s++] = file;
+}
+
+/* Opens the file at the path p and puts it in the files struct, returning NULL
+ * if either the opening or the placement of the open FILE pointer fail. */
+#define Files_open(files, p) \
+	Files_append((files), fopen((p), (files)->mode), (p))
+
+/* Prints a diagnostic message based on errno and returns an exit status
+ * appropriate for an OS error. */
+static int
+oserr(char *s, char *r){
+
+	fprintf(stderr, "%s: %s: %s\n", s, r, strerror(errno));
+
+	return EX_OSERR;
+}
+
+/* Hijacks i and j from main and destructs the files[2] struct used by main by
+ * closing its files and freeing its files and names arrays, returning retval
+ * from main. */
+#define terminate \
+	for(i = 0; i < 2; ++i){ \
+		for(j = 0; j < files[i].s; ++j) \
+			if(files[i].files[j] != stdin \
+					&& files[i].files[j] != stdout \
+					&& files[i].files[j] != stderr) \
+				fclose(files[i].files[j]); \
+		free(files[i].files); \
+		free(files[i].names); \
+	} \
+	return retval
+
+/* Prints a usage text, in which s is the program being run (i.e. argv[0]), and
+ * returns an exit status appropriate for a usage error. */
+int usage(char *s){
+
+	fprintf(stderr, "Usage: %s (-aenu) (-i [input])... (-o [output])...\n", s);
+
+	return EX_USAGE;
+}
+
+int main(int argc, char *argv[]){
+	int c;
+	struct Files files[2]; /* {read, write} */
+	size_t i;
+	size_t j;
+	size_t k; /* loop index but also unbuffer status */
+	int retval;
+
+	/* Initializes the files structs with their default values, standard
+	 * input and standard output. If an input or an output is specified
+	 * these initial values will be overwritten, so to, say, use mm(1)
+	 * equivalently to tee(1p), -o - will need to be specified before
+	 * additional files to ensure standard output is still written. */
+	for(i = 0; i < 2; ++i){
+		files[i].a = 0;
+		files[i].s = 0;
+		files[i].mode = fmode[i];
+		files[i].files = NULL;
+		files[i].names = NULL;
+		Files_append(&files[i], i == 0 ? stdin : stdout,
+			i == 0 ? stdin_name : stdout_name);
+		files[i].s = 0;
+	}
+
+	k = 0;
+
+	if(argc > 0)
+		program_name = argv[0];
+
+	if(argc > 1)
+		while((c = getopt(argc, argv, "aehi:no:u")) != -1)
+			switch(c){
+			case 'a': /* "rb+" -> "ab" */
+				files[1].mode[0] = 'a';
+				files[1].mode[2] = '\0';
+				break;
+			case 'e':
+				if(Files_append(&files[1], stderr, stderr_name) != NULL)
+					break;
+				retval = oserr(argv[0], "-e");
+				terminate;
+			case 'i':
+				if((strcmp(optarg, "-") == 0 && Files_append(&files[0],
+							stdin, stdin_name) != NULL)
+						|| Files_open(&files[0], optarg) != NULL)
+					break;
+				retval = oserr(argv[0], optarg);
+				terminate;
+			case 'o':
+				if((strcmp(optarg, "-") == 0 && Files_append(&files[1],
+							stdout, stdout_name) != NULL)
+						|| Files_open(&files[1], optarg) != NULL)
+					break;
+				/* does not exist, so try to create it */
+				if(errno == ENOENT){
+					files[1].mode = wharsh;
+					if(Files_open(&files[1], optarg) != NULL){
+						files[1].mode = fmode[1];
+						break;
+					}
+				}
+				retval = oserr(argv[0], optarg);
+				terminate;
+			case 'n':
+				if(signal(SIGINT, SIG_IGN) != SIG_ERR)
+					break;
+				retval = oserr(argv[0], "-n");
+				terminate;
+			case 'u':
+				k = 1;
+				break;
+			default:
+				retval = usage(argv[0]);
+				terminate;
+			}
+
+	if(optind != argc){
+		retval = usage(argv[0]);
+		terminate;
+	}
+
+	files[0].s += files[0].s == 0;
+	files[1].s += files[1].s == 0;
+	
+	/* Unbuffer files. */
+	if(k){
+		for(i = 0;
+			i < files[0].s;
+			setvbuf(files[0].files[i++], NULL, _IONBF, 0));
+		for(i = 0;
+			i < files[1].s;
+			setvbuf(files[1].files[i++], NULL, _IONBF, 0));
+	}
+
+	retval = EX_OK;
+
+	/* Actual program loop. */
+	for(i = 0; i < files[0].s; ++i) /* iterate ins */
+		while((c = getc(files[0].files[i])) != EOF) /* iterate chars */
+			for(j = 0; j < files[1].s; ++j) /* iterate outs */
+				if(putc(c, files[1].files[j]) == EOF){
+					/* notebook's full */
+					retval = EX_IOERR;
+					fprintf(stderr, "%s: %s: %s\n",
+						program_name, files[1].names[j], strerror(errno));
+					if(fclose(files[1].files[j]) == EOF)
+						fprintf(stderr, "%s: %s: %s\n",
+							program_name, files[1].names[j], strerror(errno));
+					/* massage out the tense muscle */
+					for(k = j--; k < files[1].s - 1; ++k){
+						files[1].files[k] = files[1].files[k+1];
+						files[1].names[k] = files[1].names[k+1];
+					}
+					if(--files[1].s == 0)
+						terminate;
+				}
+
+	terminate;
+}

src/scrut.c

@@ -1,5 +1,6 @@
 /*
- * Copyright (c) 2023 DTB <trinity@trinity.moe>
+ * Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
+ * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
  * SPDX-License-Identifier: AGPL-3.0-or-later
  *
  * This program is free software: you can redistribute it and/or modify it under
@@ -17,13 +18,15 @@
  */
 
 #include <stdio.h> /* fprintf(3), stderr, NULL */
-#include <stdlib.h> /* EXIT_FAILURE */
+#include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
 #include <string.h> /* memset(3), strchr(3) */
+#ifndef EX_USAGE
+#	include <sysexits.h>
+#endif
 #include <unistd.h> /* access(3), getopt(3), F_OK, R_OK, W_OK, X_OK */
 #include <sys/stat.h> /* lstat(3), stat struct, S_ISBLK, S_ISCHR, S_ISDIR,
                        * S_ISFIFO, S_ISGID, S_ISREG, S_ISLNK, S_ISSOCK,
                        * S_ISUID, S_ISVTX */
-#include <sysexits.h>
 
 static char args[] = "bcdefghkprsuwxLS";
 static char ops[(sizeof args) / (sizeof *args)];
@@ -57,7 +60,7 @@ int main(int argc, char *argv[]){
 
 	argv += optind;
 	do{	if(access(*argv, F_OK) != 0 || lstat(*argv, &buf) == -1)
-			return 1; /* doesn't exist or isn't stattable */
+			return EXIT_FAILURE; /* doesn't exist or isn't stattable */
 
 		for(i = 0; ops[i] != '\0'; ++i)
 			if(ops[i] == 'e')
@@ -97,8 +100,8 @@ usage:				fprintf(stderr, "Usage: %s (-%s) [file...]\n",
 						&& !S_ISLNK(buf.st_mode))
 					|| (ops[i] == 'S'
 						&& !S_ISSOCK(buf.st_mode)))
-				return 1;
+				return EXIT_FAILURE;
 	}while(*++argv != NULL);
 
-	return 0;
+	return EXIT_SUCCESS;
 }

src/swab.rs

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	env::args,
+	io::{ stdin, stdout, Error, ErrorKind, Read, Write },
+	process::ExitCode,
+	vec::Vec
+};
+
+extern crate getopt;
+use getopt::{ Opt, Parser };
+
+extern crate sysexits;
+use sysexits::{ EX_OK, EX_OSERR, EX_USAGE };
+
+fn oserr(s: &str, e: Error) -> ExitCode {
+	eprintln!("{}: {}", s, e);
+	ExitCode::from(EX_OSERR as u8)
+}
+
+fn usage(s: &str) -> ExitCode {
+	eprintln!("Usage: {} (-f) (-w [wordsize])", s);
+	ExitCode::from(EX_USAGE as u8)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut buf: Vec<u8> = Vec::new();
+	let mut input = stdin();
+	let mut output = stdout().lock();
+
+	let mut opts = Parser::new(&argv, "fw:");
+	let mut force = false;
+	let mut wordsize: usize = 2;
+
+	loop {
+		match opts.next() {
+			None => break,
+			Some(opt) =>
+				match opt {
+					Ok(Opt('f', None)) => force = true,
+					Ok(Opt('w', Some(arg))) => {
+						match arg.parse::<usize>() {
+							Ok(w) if w % 2 == 0 => { wordsize = w; () },
+							_ => { return usage(&argv[0]); },
+						}
+					},
+					_ => { return usage(&argv[0]); }
+				}
+		}
+	}
+
+	buf.resize(wordsize, 0);
+
+	loop {
+		match input.read(&mut buf) {
+			Ok(0) => break ExitCode::from(EX_OK as u8),
+			Ok(v) if v == wordsize => {
+				let (left, right) = buf.split_at(v/2);
+				if let Err(e) = output.write(&right)
+						.and_then(|_| output.write(&left)) {
+					break oserr(&argv[0], e)
+				}
+			},
+			Ok(v) => {
+				if let Err(e) = output.write(&buf[..v]) {
+					break oserr(&argv[0], e)
+				}
+			},
+			Err(e) if e.kind() == ErrorKind::Interrupted && force => continue,
+			Err(e) => break oserr(&argv[0], e)
+		}
+	}
+}