Merge branch 'main' into testing

Makefile

@@ -16,9 +16,12 @@
 DESTDIR ?= dist
 PREFIX ?= /usr/local
 
-MANDIR != [ $(PREFIX) = / ] && printf '/usr/share/man\n' \
+# normalized prefix
+PREFIX_N != (test -d $(PREFIX) && [ '-' != $(PREFIX) ] \
+	&& CDPATH= cd -P -- $(PREFIX) && pwd -P)
+MANDIR != [ $(PREFIX_N) = / ] && printf '/usr/share/man\n' \
 	|| printf '/share/man\n'
-SYSEXITS != printf '\043include <sysexits.h>\n' | cpp -M - | sed 's/ /\n/g' \
+SYSEXITS != printf '\043include <sysexits.h>\n' | cpp -M - | tr ' ' '\n' \
 	| sed -n 's/sysexits\.h//p' || printf 'include\n'
 
 CC ?= cc
@@ -29,7 +32,7 @@ RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
 CFLAGS += -I$(SYSEXITS)
 
 .PHONY: all
-all: docs dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
+all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
 
 # keep build/include until bindgen(1) has stdin support
 # https://github.com/rust-lang/rust-bindgen/issues/2703
@@ -40,8 +43,8 @@ build:
 clean:
 	rm -rf build dist
 
-dist: all
+dist: all docs
-	mkdir -p $(DESTDIR)/$(PREFIX)/bin $(DESTDIR)/$(PREFIX)/share/man/man1
+	mkdir -p $(DESTDIR)/$(PREFIX)/bin $(DESTDIR)/$(PREFIX)/$(MANDIR)/man1
 	cp build/bin/* $(DESTDIR)/$(PREFIX)/bin
 	cp build/docs/*.1 $(DESTDIR)/$(PREFIX)/$(MANDIR)/man1
 

docs/dj.1

@@ -4,32 +4,24 @@
 .\" 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 DJ 1 2024-06-17 "Harakit X.X.X"
+.TH DJ 1 2024-07-03 "Harakit X.X.X"
 .SH NAME
 dj \(en disk jockey
 .\"
 .SH SYNOPSIS
 
 dj
-.RB ( -AdHnq )
+.RB [ -Hn ]
-.RB ( -a
+.RB [ -a\ byte ]
-.RB [ byte ])
+.RB [ -c\ count ]
-.RB ( -c
-.RB [ count ])
 
-.RB ( -i
+.RB [ -i\ file ]
-[\fBinput file\fP])
+.RB [ -b\ block_size ]
-.RB ( -b
+.RB [ -s\ offset ]
-[\fBinput block size\fP])
-.RB ( -s
-[\fBinput offset\fP])
 
-.RB ( -o
+.RB [ -o\ file ]
-[\fBoutput file\fP])
+.RB [ -B\ block_size ]
-.RB ( -B
+.RB [ -S\ offset ]
-[\fBoutput block size\fP])
-.RB ( -S
-[\fBoutput offset\fP])
 .\"
 .SH DESCRIPTION
 
@@ -42,68 +34,109 @@ respectively. This language is inherited from the
 .BR dd (1p)
 utility and used here to decrease ambiguity.
 
-When seeking or skipping to a byte, writing or reading starts at the byte
+The offset used when skipping or seeking refers to how many bytes are skipped
-immediately subsequent to the specified byte.
+or sought. Running
+.BR dj (1)
+with a skip offset of 1 skips one byte into the input and reads from the second
+byte onwards. A programmer may think of a file as a zero-indexed array of
+bytes; in this analogy, the offset given is the index of the byte at which to
+start reading or writing.
 .\"
 .SH OPTIONS
 
-.IP \fB-i\fP
+.IP \fB-i\fP\ \fIfile\fP
 Takes a file path as an argument and opens it for use as an input.
-.IP \fB-b\fP
+.IP \fB-b\fP\ \fIblock_size\fP
 Takes a numeric argument as the size in bytes of the input buffer, the default
 being 1024.
 .IP \fB-s\fP
-Takes a numeric argument as the number of bytes to skip into the input
+Takes a numeric argument as the index of the byte at which reading will
-before starting to read. If the standard input is used, bytes read to this point
+commence; \(lqskips\(rq that number of bytes. If the standard input is used,
-are discarded.
+bytes read to this point are discarded.
 .IP \fB-o\fP
 Takes a file path as an argument and opens it for use as an output.
-.IP \fB-B\fP
+.IP \fB-B\fP\ \fIblock_size\fP
 Does the same as
 .B -b
 but for the output buffer.
 .IP \fB-S\fP
-Seeks a number of bytes through the output before starting to write from
+Takes a numeric argument as the index of the byte at which writing will
-the input. If the output is a stream, null characters are printed.
+commence; \(lqseeks\(rq that number of bytes. If the standard output is used,
+null characters are printed.
 .IP \fB-a\fP
 Accepts a single literal byte with which the input buffer is padded in the event
-of an incomplete read from the input file.
+of an incomplete read from the input file. If the option argument is empty, the
-.IP \fB-A\fP
+null byte is used.
-Specifying this option pads the input buffer with null bytes in the event of an
-incomplete read. This is equivalent to specifying
-.B -a
-with a null byte instead of a character.
 .IP \fB-c\fP
 Specifies a number of reads to make. The default is 0, in which case the
 input is read until a partial or empty read is made.
-.IP \fB-d\fP
-Prints invocation information before program execution as described in the
-DIAGNOSTICS section. Each invocation increments the debug level of the
-program.
 .IP \fB-H\fP
-Prints diagnostics messages in a human-readable manner as described in the
+Prints diagnostic messages in a human-readable manner as described in the
 DIAGNOSTICS section.
 .IP \fB-n\fP
 Retries failed reads once before exiting.
-.IP \fB-q\fP
-Suppresses error messages which print when a read or write is partial or
-empty. Each invocation decrements the debug level of the program.
 .\"
 .SH STANDARD INPUT
 
 The standard input shall be used as an input if no inputs are specified or if
-one or more of the input files is \(lq-\(rq.
+input file is \(lq-\(rq.
 .\"
 .SH STANDARD OUTPUT
 The standard output shall be used as an output if no inputs are specified or if
-one or more of the input files is \(lq-\(rq.
+the output file is \(lq-\(rq.
+.\"
+.SH EXAMPLES
+
+The following
+.BR sh (1p)
+line:
+
+.RS
+printf 'Hello, world!\(rsn' | dj -c 1 -b 7 -s 7 2>/dev/null
+.RE
+
+Produces the following output:
+
+.RS
+world!
+.RE
+
+The following
+.BR sh (1p)
+lines run sequentially:
+
+.RS
+tr '\(rs0' 0    </dev/zero | dj -c 1 -b 6 -o hello.txt
+
+tr '\(rs0' H    </dev/zero | dj -c 1 -b 1 -o hello.txt
+
+tr '\(rs0' e    </dev/zero | dj -c 1 -b 1 -o hello.txt -S 1
+
+tr '\(rs0' l    </dev/zero | dj -c 1 -b 2 -o hello.txt -S 2
+
+tr '\(rs0' o    </dev/zero | dj -c 1 -b 1 -o hello.txt -S 4
+
+tr '\(rs0' '\(rsn' </dev/zero | dj -c 1 -b 1 -o hello.txt -S 5
+
+dj -i hello.txt
+.RE
+
+Produce the following output:
+
+.RS
+Hello
+.RE
+
+It may be particularly illuminating to print the contents of the example
+.B hello.txt
+after each
+.BR dj (1)
+invocation.
 .\"
 .SH DIAGNOSTICS
 
-On a partial or empty read, unless the
+On a partial or empty read, a diagnostic message is printed. Then, the program
-.B -q
+exits unless the
-option is specified, a diagnostic message is printed. Then, the program exits
-unless the
 .B -n
 option is specified.
 
@@ -128,20 +161,6 @@ option may be specified. In this event, the following format is used instead:
 {ASCII line feed}
 .RE
 
-If the
-.B -d
-option is specified, debug information will be printed at the beginning of
-execution. This output contains information regarding how the program was
-invoked. The following example is the result of running the program with
-.B -d
-as the only argument:
-
-.RS
-argv0=dj
-in=<stdin>      ibs=1024        skip=0  align=ff       count=0
-out=<stdout>    obs=1024        seek=0  debug= 3       noerror=0
-.RE
-
 In non-recoverable errors that don\(cqt pertain to the read-write cycle, a
 diagnostic message is printed and the program exits with the appropriate
 .BR sysexits.h (3)
@@ -156,17 +175,26 @@ is specified along with the
 option and a count, actual byte output is the product of the count and the input
 block size and therefore may be lower than expected. If the
 .B -a
-or
+option is specified, this could make written data nonsensical.
-.B -A
-options are specified, this could make written data nonsensical.
 .\"
 .SH CAVEATS
 
 Existing files are not truncated on ouput and are instead overwritten.
 
-Many lowercase options have capitalized variants and vice-versa which can be
+The options
-confusing. Capitalized options tend to affect output or are more intense
+.B -b
-versions of lowercase options.
+and
+.B -B
+could be confused for each other, and so could
+.B -s
+and
+.BR -S .
+The lowercase option affects input and the capitalized option affects output.
+
+The skipped or sought bytes while processing irregular files, such as streams,
+are reported in the diagnostic output, because they were actually read or
+written. This is as opposed to bytes skipped while processing regular files,
+which are not reported.
 .\"
 .SH RATIONALE
 
@@ -187,3 +215,4 @@ Copyright \(co 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
 .\"
 .SH SEE ALSO
 .BR dd (1p)
+.BR lseek (3p)

docs/fop.1

@@ -22,7 +22,7 @@ Performs operations on specified fields in data read from the standard input.
 .\"
 .SH OPTIONS
 
-.IP \fB-d\fP
+.IP \fB-d\fP\ \fIdelimiter\fP
 Sets a delimiter by which the input data will be split into fields. The default
 is an ASCII record separator.
 .\"

docs/intcmp.1

@@ -11,9 +11,7 @@ intcmp \(en compare integers
 .SH SYNOPSIS
 
 intcmp
-.RB ( -egl )
+.RB [ -egl ]\ integer\ integer...
-.RB [ integer ]
-.RB [ integer... ]
 .SH DESCRIPTION
 Compare integers to each other.
 .\"

docs/mm.1

@@ -10,11 +10,9 @@ mm \(en middleman
 .SH SYNOPSIS
 
 mm
-.RB ( -aenu )
+.RB [ -aenu ]
-.RB ( -i
+.RB [ -i\ input ]
-.RB [ input ])
+.RB [ -o\ output ]
-.RB ( -o
-.RB [ output ])
 .\"
 .SH DESCRIPTION
 
@@ -26,10 +24,10 @@ Catenate input files and write them to the start of each output file or stream.
 Opens subsequent outputs for appending rather than updating.
 .IP \fB-e\fP
 Use the standard error as an output.
-.IP \fB-i\fP
+.IP \fB-i\fP\ \fIinput\fP
 Opens a path as an input. If one or more of the input files is \(lq-\(rq or if
 no inputs are specified, the standard input shall be used.
-.IP \fB-o\fP
+.IP \fB-o\fP\ \fIoutput\fP
 Opens a path as an output. If one or more of the output files is \(lq-\(rq or if
 no outputs are specified, the standard output shall be used.
 .IP \fB-u\fP

docs/npc.1

@@ -11,7 +11,7 @@ npc \(en show non-printing characters
 .SH SYNOPSIS
 
 npc
-.RB ( -et )
+.RB [ -et ]
 .\"
 .SH DESCRIPTION
 

docs/scrut.1

@@ -10,8 +10,8 @@ scrut \(en scrutinize file properties
 .SH SYNOPSIS
 
 scrut
-.RB ( -LSbcdefgkprsuwx )
+.RB [ -LSbcdefgkprsuwx ]
-.RB [ file... ]
+.B file...
 .\"
 .SH DESCRIPTION
 

docs/str.1

@@ -11,8 +11,7 @@ str \(en test string arguments
 .SH SYNOPSIS
 
 str
-.RB [ type ]
+.B type string...
-.RB [ string... ]
 .\"
 .SH DESCRIPTION
 

docs/strcmp.1

@@ -11,8 +11,7 @@ strcmp \(en compare strings
 .SH SYNOPSIS
 
 strcmp
-.RM [ string ]
+.B string string...
-.RB [ strings... ]
 .\"
 .SH DESCRIPTION
 

docs/swab.1

@@ -11,11 +11,8 @@ swab \(en swap bytes
 .SH SYNOPSIS
 
 swab
-.RB ( -f )
+.RB [ -f ]
-.RB ( -w
+.RB [ -w\ word_size ]
-.R [
-.B word size
-.R ])
 .\"
 .SH DESCRIPTION
 
@@ -25,11 +22,10 @@ Swap the latter and former halves of a block of bytes.
 
 .IP \fB-f\fP
 Ignore SIGINT signal.
-.IP \fB-w\fP
+.IP \fB-w\fP\ \fIword_size\fP
-Configures the word size; that is, the size in bytes of the block size
+Configures the word size; that is, the size in bytes of the block size on which
-on which to operate. The default word size is 2. The word size must be
+to operate. The default word size is 2. The word size must be cleanly divisible
-cleanly divisible by 2, otherwise the block of bytes being processed can\(cqt be
+by 2, otherwise the block of bytes being processed can\(cqt be halved.
-halved.
 .\"
 .SH EXAMPLES
 

src/dj.c

@@ -16,282 +16,113 @@
  * along with this program. If not, see https://www.gnu.org/licenses/.
  */
 
-#include <ctype.h> /* isupper(3), tolower(3) */
+#include <assert.h> /* assert(3) */
 #include <errno.h> /* errno */
 #include <fcntl.h> /* open(2) */
 #include <stdio.h> /* fprintf(3), stderr */
-#include <stdlib.h> /* free(3), malloc(3), strtol(3), size_t */
+#include <stdlib.h> /* malloc(3), strtol(3), size_t */
 #include <string.h> /* memcpy(3), memmove(3), memset(3) */
-#include <sysexits.h> /* EX_OK, EX_USAGE */
+#if !defined EX_OK || !defined EX_OSERR || !defined EX_USAGE
+#	include <sysexits.h>
+#endif
 #include <unistd.h> /* close(2), getopt(3), lseek(2), read(2), write(2),
                      * optarg, optind, STDIN_FILENO, STDOUT_FILENO */
+#include <sys/stat.h> /* S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH,
+                         S_IWUSR */
 extern int errno;
 
+char *program_name = "dj";
+
 /* dj uses two structures that respectively correspond to the reading and
  * writing ends of its jockeyed "pipe". User-configurable members are noted
  * with their relevant options. */
 struct Io{
-	int bs;			/* buffer size (-bB) */
+	char *buf;	  	/* buffer */
+	char *fn;	  	/* file name (-io) */
+	size_t bs;    	/* buffer size (-bB) */
 	size_t bufuse;	/* buffer usage */
-	char *buf;		/* buffer */
+	size_t bytes; 	/* bytes processed */
-	int bytes;		/* bytes processed */
+	size_t prec;  	/* partial records processed */
-	int fd;			/* file descriptor */
+	size_t rec;   	/* records processed */
-	int fl;			/* file opening flags */
+	long seek;  	/* remaining bytes to seek/skip (-sS) */
-	char *fn;		/* file name (may be stdin_name or stdout_name) (-io) */
+	int error;  	/* errno */
-	int prec;		/* partial records processed */
+	int fd;		  	/* file descriptor */
-	int rec;		/* records processed */
+	int fl;		  	/* file opening flags */
-	long seek;		/* bytes to seek/skip (will be 0 after skippage) (-sS) */
+};
-} ep[2]; /* "engineered pipe"; also "extended play", for the deejay */
 
-/* Additionally, the following global variables are used to store user options.
+/* To be assigned to main:fmt and used with printio(). */
- */
+static char *fmt_asv   = "%d\037%d\036%d\037%d\035%d\036%d\034";
+static char *fmt_human = "%d+%d > %d+%d; %d > %d\n";
 
-/* (-a)  */ static int align; /* Only the lower 8b are used but align is
-                               * negative if no alignment is being done. */
-
-/* (-c)  */ static int count; /* 0 if dj(1) runs until no more reads are
-                               * possible. */
-
-/* ASCII field separator delimited statistics */
-            static char *fmt_asv   = "%d\037%d\036%d\037%d\035%d\036%d\034";
-/* human-readable statistics */
-            static char *fmt_human = "%d+%d > %d+%d; %d > %d\n";
-/* pointer to chosen formatting */
-/* (-H)  */ static char *fmt_output; /* fmt_asv (default) or fmt_human (-H) */
-
-/* (-dq) */ static char debug;       /*
- *  -d  increments             dj -qq | 0 - no diagnostic output whatsoever
- *   -q decrements             dj -q  | 1 - typical output without
- *                                    |     notifications on partial reads or
- *                                    |     writes
- *                             dj     | 2 - typical output (default)
- *                             dj -d  | 3 - verbose status messages */
-
-/* (-n)  */ static char noerror;     /* 0 - exits on partial reads or writes
-                                      *     (default)
-                                      * 1 - retries on partial reads/writes
-                                      *     (-n) */
-
-/* Non-configurable defaults. */
-#define bs_default 1024 /* GNU dd(1) default; twice POSIX but a neat 2^10 */
-static char *program_name = "<no argv[0]>";
 static char *stdin_name = "<stdin>";
 static char *stdout_name = "<stdout>";
-static int read_flags = O_RDONLY; /* These flags are consistent with Busybox */
-static int write_flags = O_WRONLY | O_CREAT; /* dd(1). */
 
-/* Macro to set defaults for user-configurable options. */
+static int creat_mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH
-#define setdefaults do{ \
+	| S_IWOTH; /* Consistent with touch(1p). */
-	align = -1; \
+static int read_flags = O_RDONLY; /* Consistent with Busybox dd(1). */
-	count = 0; \
+static int write_flags = O_WRONLY | O_CREAT;
-	debug = 2; \
-	fmt_output = fmt_asv; \
-	noerror = 0; \
-	ep[0].fl = read_flags; \
-	Io_setdefaults(&ep[0]); \
-	ep[1].fl = write_flags; \
-	Io_setdefaults(&ep[1]); }while(0)
 
 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
 
-/* Macro to check if fd is a std* file, e.g. stdin. */
+/* Macro to check if fd is stdin or stdout */
-#define fdisstd(fd) \
+#define fdisstd(fd) ((fd) == STDIN_FILENO || (fd) == STDOUT_FILENO)
-		((fd) == STDIN_FILENO \
-		|| (fd) == STDOUT_FILENO \
-		|| (fd) == STDERR_FILENO)
 
-/* Macro to call the cleanup functions that operate on struct io on the
- * particular io[2] used in main. Error conditions are not checked because this
- * is only used when the program is about to terminate (hence its name). */
-#define terminate(io) do{ \
-	Io_buffree(&(io)[0]); \
-	Io_buffree(&(io)[1]); \
-	Io_fdclose(&(io)[0]); \
-	Io_fdclose(&(io)[1]); }while(0)
-
-/* Allocates *io's buffer. Returns NULL if unsuccessful. */
-static void *
-Io_bufalloc(struct Io *io){
-
-	return (io->buf = malloc(io->bs * (sizeof *io->buf)));
-}
-
-/* Frees *io's buffer. Returns io. */
-static struct Io *
-Io_buffree(struct Io *io){
-
-	free(io->buf);
-
-	return io;
-}
-
-/* Fills the unused portion of io's buffer with padding, updating io->bufuse.
- * Returns io. */
-static struct Io *
-Io_bufrpad(struct Io *io, int padding){
-	
-	memset(io->buf + io->bufuse, padding, io->bs - io->bufuse);
-	io->bufuse = io->bs;
-
-	return io;
-}
-
-/* Copies from the buffer in src as much as possible to the free space in the
- * dest buffer, removing the copied units from src and permuting the remaining
- * units in the src buffer to the start of the buffer, modifying both the src
- * and dest bufuse and returning dest. */
-static struct Io*
-Io_bufxapp(struct Io *dest, struct Io *src){
-	int n;
-
-	n = MIN(src->bufuse, dest->bs - dest->bufuse);
-	memcpy(dest->buf + dest->bufuse, src->buf, n);
-	dest->bufuse += n;
-	memmove(src->buf, src->buf + n, src->bs - n);
-	src->bufuse -= n;
-
-	return dest;
-}
-
-/* Copies from the buffer in src to the buffer in dest no more than n units,
- * removing the copied units from src and permuting the remaining units in the
- * src buffer to the start of the buffer, modifying both the src and dest
- * bufuse and returning dest. */
-static struct Io*
-Io_bufxfer(struct Io *dest, struct Io *src, int n){
-
-	memcpy(dest->buf, src->buf, (dest->bufuse = n));
-	memmove(src->buf, src->buf + n, (src->bufuse -= n));
-
-	return dest;
-}
-
-/* Closes io->fn and returns -1 on error, otherwise io->fd. */
-static int
-Io_fdclose(struct Io *io){
-
-	return fdisstd(io->fd)
-		? 0
-		: close(io->fd);
-}
-
-/* Opens io->fn and saves the file descriptor into io->fd. Returns io->fd,
- * which will be -1 if an error occured. */
-static int
-Io_fdopen(struct Io *io, char *fn){
-	int fd;
-	
-	if((fd = open(fn, io->fl,
-					/* these are the flags used by touch(1p) */
-					S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH))
-				!= -1
-			&& Io_fdclose(io) == 0){
-		io->fd = fd;
-		io->fn = fn;
-	}
-
-	return fd;
-}
-
-/* Seeks io->seek bytes through *io's file descriptor, (counter-intuitively)
- * returning -1 if successful and a sysexits.h exit code if an unrecoverable
- * error occurred. io->buf will be cleared of useful bytes and io->seek will
- * be set to zero to indicate the seek occurred. */
-static int
-Io_fdseek(struct Io *io){
-	int (*op)(int, void *, size_t);
-	
-	if(!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1)
-		return -1;
-
-	/* repeated code to get the condition out of the loop */
-	if(io->fl == write_flags){
-		memset(io->buf, '\0', io->bs);
-		/* We're going to cheat and use bufuse as the retval for write(2),
-		 * which is fine because it'll be zeroed as this function returns
-		 * 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;
-
-	return -1;
-}
-
-/* Reads io->bs bytes from *io's file descriptor into io->buf, storing the
- * number of read bytes in io->bufuse and updating io->bytes. If io->bufuse is
- * 0, errno will probably be set. Returns io. */
 static struct Io *
 Io_read(struct Io *io){
+	int t;
 
-	io->bytes += (io->bufuse = read(io->fd, io->buf, io->bs));
+	assert(io->bs > 0);
+	assert(io->bufuse < io->bs);
+
+	if((t = read(io->fd, &(io->buf)[io->bufuse], io->bs - io->bufuse)) < 0){
+		io->error = errno;
+		t = 0;
+	}
+
+	io->bufuse += t;
+	io->bytes  += t;
+	io->prec   += (0 < io->bufuse && io->bufuse < io->bs);
+	io->rec    += (io->bufuse == io->bs);
+
+	assert(io->bufuse <= io->bs);
 
 	return io;
 }
 
-/* Sets the variables in a struct *io to the defaults. Identifies the read/
- * write ends of the "pipe" by checking io->fl. Returns io. */
-static struct Io *
-Io_setdefaults(struct Io *io){
-
-	io->bs = bs_default;
-	io->buf = NULL;
-	io->bytes = 0;
-	io->fd = (io->fl == read_flags) ? STDIN_FILENO : STDOUT_FILENO;
-	io->fn = (io->fl == read_flags) ? stdin_name   : stdout_name;
-	io->prec = 0;
-	io->rec = 0;
-	io->seek = 0;
-
-	return io;
-}
-
-/* Writes io->bufuse units from io->buf to io->fd, permuting any unwritten
- * bytes to the start of io->buf and updating io->bufuse. If io->bufuse doesn't
- * change, errno will probably be set. Returns io. */
 static struct Io *
 Io_write(struct Io *io){
 	int t;
 
-	if((t = write(io->fd, io->buf, io->bufuse)) > 0)
+	assert(io->bufuse > 0);
-		memmove(io->buf, io->buf + t, (io->bufuse -= t));
+	assert(io->bufuse <= io->bs);
+
+	if((t = write(io->fd, io->buf, io->bufuse)) < 0){
+		io->error = errno;
+		t = 0;
+	}else if(t > 0)
+		memmove(io->buf, &(io->buf)[t], (io->bufuse -= t));
+
 	io->bytes += t;
+	io->prec  += (t > 0 && io->bufuse > 0);
+	io->rec   += (t > 0 && io->bufuse == 0);
 
 	return io;
 }
 
-/* Prints an error message suitable for the event of an operating system error,
- * with the error itself to be described in the string s. */
 static int
-oserr(char *s){
+oserr(char *e, int n){
-
+	fprintf(stderr, "%s: %s: %s\n", program_name, e, strerror(n));
-	fprintf(stderr, "%s: %s: %s\n", program_name, s, strerror(errno));
-
 	return EX_OSERR;
 }
 
 /* Prints statistics regarding the use of dj, particularly partially and
- * completely read and written records, accessing debug, ep, and fmt_output. */
+ * completely read and written records. */
 static void
-output(void){
+fprintio(FILE *stream, char *fmt, struct Io io[2]){
 
-	if(debug >= 1)
+	fprintf(stream, fmt,
-		fprintf(stderr, fmt_output,
+		io[0].rec, io[0].prec, io[1].rec, io[1].prec,
-			ep[0].rec, ep[0].prec, ep[1].rec, ep[1].prec,
+		io[0].bytes, io[1].bytes);
-			ep[0].bytes, ep[1].bytes);
 
 	return;
 }
@@ -311,142 +142,211 @@ parse(char *s){
 }
 
 static int
-usage(void){
+usage(char *s){
 
-	fprintf(stderr, "Usage: %s (-AdfHqQ) (-a [byte]) (-c [count])\n"
+	fprintf(stderr, "Usage: %s [-Hn] [-a byte] [-c count]\n"
-		"\t(-i [input file]) (-b [input block size]) (-s [input offset])\n"
+		"\t[-i file] [-b block_size] [-s offset]\n"
-		"\t(-o [output file]) (-B [output block size]) (-S [output offset])\n",
+		"\t[-o file] [-B block_size] [-S offset]\n",
 		program_name);
 
 	return EX_USAGE;
 }
 
 int main(int argc, char *argv[]){
-	int c;
+ 	int align;    /* low 8b used, negative if no alignment is being done */
-	int i;
+	int count;    /* 0 if dj(1) runs until no more reads are possible */
+	char *fmt;    /* == fmt_asv (default) or fmt_human (-H) */
+	size_t i;     /* side of io being modified */
+	char noerror; /* 0=exits (default) 1=retries on partial reads or writes */
+	struct Io io[2 /* { in, out } */];
 
-	setdefaults;
+	/* Set defaults. */
+	align = -1;
+	count = 0;
+	fmt = fmt_asv;
+	noerror = 0;
+	for(i = 0; i < (sizeof io) / (sizeof *io); ++i){
+		io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
+		io[i].bufuse = 0;
+		io[i].bytes = 0;
+		io[i].fd = i == 0 ? STDIN_FILENO : STDOUT_FILENO;
+		io[i].fn = i == 0 ? stdin_name   : stdout_name;
+		io[i].fl = i == 0 ? read_flags   : write_flags;
+		io[i].error = 0;
+		io[i].prec = 0;
+		io[i].rec = 0;
+		io[i].seek = 0;
+	}
 
 	if(argc > 0){
+		int c;
+
 		program_name = argv[0];
-		while((c = getopt(argc, argv, "a:Ab:B:c:di:hHnqs:S:o:")) != -1)
+		while((c = getopt(argc, argv, ":a:b:B:c:i:hHns:S:o:")) != -1)
 			switch(c){
-			case 'i': case 'o':
+			case 'i': case 'o': i = (c == 'o');
-				i = (c == 'o');
 				if(optarg[0] == '-' && optarg[1] == '\0'){ /* optarg == "-" */
-					ep[i].fd = (i == 0) ? STDIN_FILENO : STDOUT_FILENO;
+					io[i].fd = i == 0 ? STDIN_FILENO : STDOUT_FILENO;
-					ep[i].fn = (i == 0) ? stdin_name   : stdout_name;
+					io[i].fn = i == 0 ? stdin_name   : stdout_name;
 					break;
-				}else if(Io_fdopen(&ep[i], optarg) != -1)
+				}else{
-					break;
+					int fd;
-				terminate(ep);
+
-				return oserr(optarg);
+					if((fd = open(optarg, io[i].fl, creat_mode)) != -1
-			case 'A': align = '\0'; break;
+							&& (fdisstd(io[i].fd) || close(io[i].fd) == 0)){
-			case 'd': ++debug; break;
+						io[i].fd = fd;
-			case 'n': noerror = 1; break;
+						io[i].fn = optarg;
-			case 'H': fmt_output = fmt_human; break;
+						break;
-			case 'q': --debug; break;
+					}
+				}
+				return oserr(optarg, errno);
+			case 'n': noerror = 1;     break;
+			case 'H': fmt = fmt_human; break;
 			case 'a':
-				if(optarg[0] != '\0' && optarg[1] == '\0'){
+				if(optarg[0] == '\0' || optarg[1] == '\0'){
 					align = optarg[0];
 					break;
 				}
 				/* FALLTHROUGH */
-			case 'c': case 'b': case 's': case 'B': case 'S':
+			case 'c': case 'b': case 's': case 'B': case 'S': /* numbers */
 				if(c == 'c' && (count = parse(optarg)) >= 0)
 					break;
-				i = isupper(c);
+				i = (c >= 'A' && c <= 'Z');
-				c = tolower(c);
+				c |= 0x20 /* 0b 0010 0000 */; /* (ASCII) make lowercase */
-				if((c == 'b' && (ep[i].bs = parse(optarg)) > 0)
+				if((c == 'b' && (io[i].bs = parse(optarg)) > 0)
-						|| (c == 's' && (ep[i].seek = parse(optarg)) >= 0))
+						|| (c == 's' && (io[i].seek = parse(optarg)) >= 0))
 					break;
 				/* FALLTHROUGH */
 			default:
-				terminate(ep);
+				return usage(program_name);
-				return usage();
 			}
 	}
 
-	if(debug >= 3)
+	assert(io->fd != STDIN_FILENO  || io->fl == read_flags);
-		fprintf(stderr,
+	assert(io->fd != STDOUT_FILENO || io->fl == write_flags);
-			"argv0=%s\n"
-			"in=%s\tibs=%d\tskip=%ld\talign=%hhx\tcount=%d\n"
-			"out=%s\tobs=%d\tseek=%ld\tdebug=%2d\tnoerror=%d\n",
-			program_name,
-			ep[0].fn, ep[0].bs, ep[0].seek, align, count,
-			ep[1].fn, ep[1].bs, ep[1].seek, debug, noerror);
 
-	if(argc > optind){
+	if(argc > optind)
-		terminate(ep);
+		return usage(program_name);
-		return usage();
-	}
 
-	for(i = 0; i <= 1; ++i){
+	for(i = 0; i < (sizeof io) / (sizeof *io); ++i){
-		if(Io_bufalloc(&ep[i]) == NULL){
+		/* buffer allocation */
-			fprintf(stderr, "%s: Failed to allocate %d bytes\n",
+		if((io[i].buf = malloc(io[i].bs * (sizeof *(io[i].buf)))) == NULL){
-				program_name, ep[i].bs);
+			fprintf(stderr, "%s: Failed to allocate %zd bytes\n",
-			terminate(ep);
+				program_name, io[i].bs);
 			return EX_OSERR;
-		}else if(ep[i].seek > 0)
+		}
-			switch(Io_fdseek(&ep[i])){
+		/* easy seeking */
-			case EX_OK:
+		if(!fdisstd(io[i].fd) && lseek(io[i].fd, io[i].seek, SEEK_SET) != -1)
-				output();
+			io[i].seek = 0;
-				terminate(ep);
-				return EX_OK;
-			}
 	}
 
-	do{	/* read */
+	/* hard seeking */
-		Io_read(&ep[0]);
+	if(io[1].seek > 0){
-		if(!noerror && ep[0].bufuse == 0)
+		size_t t;
-			Io_read(&ep[0]); /* second chance */
+		do{
-		if(ep[0].bufuse == 0) /* that's all she wrote */
+			memset(io[1].buf, '\0',
-			break;
+				(t = io[1].bufuse = MIN(io[1].bs, io[1].seek)));
-		else if(ep[0].bufuse < ep[0].bs){
+			if(Io_write(&io[1])->bufuse == t && !noerror && io[1].error == 0)
-			++ep[0].prec;
+				Io_write(&io[1]); /* second chance */
-			if(debug >= 2){
+			if(io[1].error != 0)
-				fprintf(stderr, "%s: Partial read:\n\t", program_name);
+				return oserr(io[1].fn, io[1].error);
-				output();
+		}while((io[1].seek -= (t - io[1].bufuse)) > 0 && io[1].bufuse != t);
-			}
+		io[1].bufuse = 0;
-			if(!noerror)
+	}
-				count = 1;
-			if(align >= 0)
-				Io_bufrpad(&ep[0], align);
-		}else
-			++ep[0].rec;
 
-		/* write */
+	if(io[1].seek > 0){
-		do{	if(ep[1].bs > ep[0].bs){ /* io[1].bs > io[0].bs */
+		fprintio(stderr, fmt, io);
-				Io_bufxapp(&ep[1], &ep[0]);
+		return oserr(io[1].fn, errno);
-				if(ep[0].bs + ep[1].bufuse <= ep[1].bs && count != 1)
+	}
-					continue; /* we could write more */
-			}else
-				Io_bufxfer(&ep[1], &ep[0], MIN(ep[0].bufuse, ep[1].bs));
 
-			c = ep[1].bufuse;
+	do{
-			Io_write(&ep[1]);
+		assert(io[0].bufuse == 0);
-			if(!noerror && ep[1].bufuse == c)
+
-				Io_write(&ep[1]); /* second chance */
+		{ /* read */
-			if(c == ep[1].bufuse){ /* no more love */
+			char skipping;
-				count = 1;
+			size_t t;
+
+			/* hack to intentionally get a partial read from Io_read */
+			if((skipping = (io[0].seek > 0)) && io[0].seek < io[0].bs)
+				io[0].bufuse = io[0].bs - io[0].seek;
+
+			t = io[0].bufuse;
+			if(Io_read(&io[0])->bufuse == t && !noerror && io[0].error == 0)
+				Io_read(&io[0]); /* second chance */
+			assert(io[0].bufuse >= t);
+			if(io[0].bufuse == t) /* that's all she wrote */
 				break;
-			}else if(c > ep[1].bufuse && ep[1].bufuse > 0){
+
-				ep[1].prec += 1;
+			if(/* t < io[0].bufuse && */ io[0].bufuse < io[0].bs){
-				if(debug >= 2){
+				fprintf(stderr, "%s: Partial read:\n\t", program_name);
-					fprintf(stderr, "%s: Partial write:\n\t", program_name);
+				fprintio(stderr, fmt, io);
-					output();
-				}
 				if(!noerror)
 					count = 1;
-			}else if(ep[1].bufuse == 0 && c < ep[1].bs)
+				if(align >= 0){
-				++ep[1].prec;
+					/* fill the rest of the ibuf with padding */
-			else
+					memset(&(io[0].buf)[io[0].bufuse], align,
-				++ep[1].rec;
+						io[0].bs - io[0].bufuse);
-		}while(ep[0].bufuse > 0);
+					io->bufuse = io->bs;
+				}
+			}
+
+			if(skipping){
+				io[0].bufuse = 0;
+				count += (count != 0);
+				continue;
+			}
+		}
+
+		/* write */
+		do{
+			int t;
+
+			if(io[0].bs <= io[1].bs){
+				int n;
+
+				/* saturate obuf */
+				memcpy(io[1].buf, io[0].buf,
+				       (io[1].bufuse = (n = MIN(io[0].bufuse, io[1].bs))));
+				/* permute the copied units out of ibuf */
+				memmove(io[0].buf, &(io[0].buf)[n], (io[0].bufuse -= n));
+			}else /* if(io[0].bs < io[1].bs) */ {
+				int n;
+
+				/* drain what we can from ibuf */
+				memcpy(&(io[1].buf)[io[1].bufuse], io[0].buf,
+				       (n = MIN(io[0].bufuse, io[1].bs - io[1].bufuse)));
+				io[1].bufuse += n;
+				/* permute out the copied units */
+				memmove(io[0].buf, &(io[0].buf)[n], io[0].bs - n);
+				io[0].bufuse -= n;
+
+				if(io[0].bs + io[1].bufuse <= io[1].bs && count != 1)
+					continue; /* obuf not saturated - we could write more */
+			}
+
+			t = io[1].bufuse;
+			if(Io_write(&io[1])->bufuse == t && !noerror && io[1].error == 0)
+				Io_write(&io[1]); /* second chance */
+			assert(io[1].bufuse <= t);
+			if(io[1].bufuse == t){ /* no more love */
+				count = 1;
+				break;
+			}
+
+			if(0 < io[1].bufuse /* && io[1].bufuse < t */){
+				fprintf(stderr, "%s: Partial write:\n\t", program_name);
+				fprintio(stderr, fmt, io);
+				if(!noerror)
+					count = 1;
+			}
+		}while(io[0].bufuse > 0);
 	}while(count == 0 || --count > 0);
 
-	output();
+	fprintio(stderr, fmt, io);
-	terminate(ep);
+
+	for(i = 0; i < (sizeof io) / (sizeof *io); ++i)
+		if(io[i].error)
+			return oserr(io[i].fn, io[i].error);
 
 	return EX_OK;
 }

src/intcmp.c

@@ -52,7 +52,7 @@ int main(int argc, char *argv[]){
 
 	if(optind + 2 /* ref cmp */ > argc){
 usage:		fprintf(stderr,
-			"Usage: %s (-eghl) [integer] [integer...]\n",
+			"Usage: %s [-egl] integer integer...\n",
 			argv[0] == NULL ? program_name : argv[0]);
 		return EX_USAGE;
 	}

src/mm.c

@@ -110,7 +110,7 @@ oserr(char *s, char *r){
  * returns an exit status appropriate for a usage error. */
 int usage(char *s){
 
-	fprintf(stderr, "Usage: %s (-aenu) (-i [input])... (-o [output])...\n", s);
+	fprintf(stderr, "Usage: %s [-aenu] [-i input]... [-o output]...\n", s);
 
 	return EX_USAGE;
 }

src/npc.c

@@ -39,7 +39,7 @@ int main(int argc, char *argv[]){
 			}
 
 	if(argc > optind){
-usage:		fprintf(stderr, "Usage: %s (-eht)\n", argv[0]);
+usage:		fprintf(stderr, "Usage: %s [-et]\n", argv[0]);
 		return EX_USAGE;
 	}
 

src/scrut.c

@@ -66,7 +66,7 @@ int main(int argc, char *argv[]){
 			if(ops[i] == 'e')
 				continue;
 			else if(ops[i] == 'h'){
-usage:				fprintf(stderr, "Usage: %s (-%s) [file...]\n",
+usage:				fprintf(stderr, "Usage: %s [-%s] file...\n",
 					argv[0] == NULL
 						? program_name
 						: argv[0],

src/str.c

@@ -56,7 +56,7 @@ int main(int argc, char *argv[]){
 				goto pass;
 	}
 
-	fprintf(stderr, "Usage: %s [type] [string...]\n",
+	fprintf(stderr, "Usage: %s type string...\n",
 		argv[0] == NULL ? program_name : argv[0]);
 
 	return EX_USAGE;

src/strcmp.c

@@ -8,7 +8,7 @@ int main(int argc, char *argv[]){
 	int i;
 
 	if(argc < 3){
-		fprintf(stderr, "Usage: %s [string] [string...]\n",
+		fprintf(stderr, "Usage: %s string string...\n",
 			argv[0] == NULL ? program_name : argv[0]);
 		return EX_USAGE;
 	}

src/swab.rs

@@ -29,13 +29,16 @@ use getopt::GetOpt;
 extern crate sysexits;
 use sysexits::{ EX_OK, EX_OSERR, EX_USAGE };
 
+extern crate strerror;
+use strerror::StrError;
+
 fn oserr(s: &str, e: Error) -> ExitCode {
-	eprintln!("{}: {}", s, e);
+	eprintln!("{}: {}", s, e.strerror());
 	ExitCode::from(EX_OSERR as u8)
 }
 
 fn usage(s: &str) -> ExitCode {
-	eprintln!("Usage: {} (-f) (-w [wordsize])", s);
+	eprintln!("Usage: {} [-f] [-w word_size]", s);
 	ExitCode::from(EX_USAGE as u8)
 }