dj(1): refactor (remove Io_setdefaults and other stuff)

src/dj.c

@@ -16,7 +16,6 @@
  * along with this program. If not, see https://www.gnu.org/licenses/.
  */
 
-#include <ctype.h> /* isupper(3), tolower(3) */
 #include <errno.h> /* errno */
 #include <fcntl.h> /* open(2) */
 #include <stdio.h> /* fprintf(3), stderr */
@@ -29,6 +28,8 @@
                          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. */
@@ -49,9 +50,9 @@ struct Io{
 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";
 
-static char *program_name = "<no argv[0]>";
 static char *stdin_name = "<stdin>";
 static char *stdout_name = "<stdout>";
+
 static int read_flags = O_RDONLY; /* Consistent with Busybox dd(1). */
 static int write_flags = O_WRONLY | O_CREAT;
 
@@ -195,23 +196,6 @@ Io_read(struct Io *io){
 	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 = 1024 /* bytes; 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
-	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. */
@@ -263,12 +247,12 @@ parse(char *s){
 }
 
 static int
-usage(void){
+usage(char *s){
 
 	fprintf(stderr, "Usage: %s (-Hn) (-a [byte]) (-c [count])\n"
 		"\t(-i [input file]) (-b [input block size]) (-s [input offset])\n"
 		"\t(-o [output file]) (-B [output block size]) (-S [output offset])\n",
-		program_name);
+		s);
 
 	return EX_USAGE;
 }
@@ -276,31 +260,37 @@ usage(void){
 int main(int argc, char *argv[]){
 	int align; /* low 8b used, negative if no alignment is being done */
 	int count; /* 0 if dj(1) runs until no more reads are possible */
+	char *fmt_output; /* == fmt_asv (default) or fmt_human (-H) */
+	size_t i; /* side of io being modified */
 	struct Io io[2];
-	char *fmt_output; /* fmt_asv (default) or fmt_human (-H) */
 	char noerror; /* 0=exits (default) 1=retries on partial reads or writes */
-	int c;
-	int i;
 
 	/* Set defaults. */
 	align = -1;
 	count = 0;
 	fmt_output = fmt_asv;
 	noerror = 0;
-	io[0].fl = read_flags;
+	for(i = 0; i < 2; ++i){
-	Io_setdefaults(&io[0]);
+		io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
-	io[1].fl = write_flags;
+		io[i].bytes = 0;
-	Io_setdefaults(&io[1]);
+		io[i].fd = i ? STDIN_FILENO : STDOUT_FILENO;
+		io[i].fn = i ? stdin_name   : stdout_name;
+		io[i].fl = i ? read_flags   : write_flags;
+		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: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 == "-" */
-					io[i].fd = (i == 0) ? STDIN_FILENO : STDOUT_FILENO;
+					io[i].fd = i ? STDIN_FILENO : STDOUT_FILENO;
-					io[i].fn = (i == 0) ? stdin_name   : stdout_name;
+					io[i].fn = i ? stdin_name   : stdout_name;
 					break;
 				}else if(Io_fdopen(&io[i], optarg) != -1)
 					break;
@@ -314,24 +304,24 @@ int main(int argc, char *argv[]){
 					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'); /* uppercase changes output */
-				c = tolower(c);
+				c &= 0x20 /* 0b 0010 0000 */; /* (ASCII) make lowercase */
 				if((c == 'b' && (io[i].bs = parse(optarg)) > 0)
 						|| (c == 's' && (io[i].seek = parse(optarg)) >= 0))
 					break;
 				/* FALLTHROUGH */
 			default:
 				terminate(io);
-				return usage();
+				return usage(program_name);
 			}
 	}
 
 	if(argc > optind){
 		terminate(io);
-		return usage();
+		return usage(program_name);
 	}
 
 	for(i = 0; i < 2; ++i){
@@ -366,7 +356,7 @@ int main(int argc, char *argv[]){
 			++io[0].rec;
 
 		/* write */
-		do{	if(io[1].bs > io[0].bs){ /* io[1].bs > io[0].bs */
+		do{	if(io[1].bs > io[0].bs){
 				Io_bufxapp(&io[1], &io[0]);
 				if(io[0].bs + io[1].bufuse <= io[1].bs && count != 1)
 					continue; /* we could write more */