dj(1): refactor to build again and to get rid of globals

src/dj.c

@@ -25,6 +25,8 @@
 #include <sysexits.h> /* EX_OK, EX_USAGE */
 #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;
 
 /* dj uses two structures that respectively correspond to the reading and
@@ -41,47 +43,17 @@ struct Io{
 	int prec;		/* partial records processed */
 	int rec;		/* records processed */
 	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_output and used with output(). */
- */
+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) */
-
-/* (-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 read_flags = O_RDONLY; /* Consistent with Busybox dd(1). */
-static int write_flags = O_WRONLY | O_CREAT; /* dd(1). */
+static int write_flags = O_WRONLY | O_CREAT;
-
-/* Macro to set defaults for user-configurable options. */
-#define setdefaults do{ \
-	align = -1; \
-	count = 0; \
-	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))
 
@@ -238,7 +210,7 @@ Io_read(struct Io *io){
 static struct Io *
 Io_setdefaults(struct Io *io){
 
-	io->bs = bs_default;
+	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;
@@ -275,13 +247,13 @@ oserr(char *s){
 }
 
 /* Prints statistics regarding the use of dj, particularly partially and
- * completely read and written records, accessing ep and fmt_output. */
+ * completely read and written records. */
 static void
-output(void){
+output(struct Io io[2], char *fmt){
 
-	fprintf(stderr, fmt_output,
+	fprintf(stderr, fmt,
-		ep[0].rec, ep[0].prec, ep[1].rec, ep[1].prec,
+		io[0].rec, io[0].prec, io[1].rec, io[1].prec,
-		ep[0].bytes, ep[1].bytes);
+		io[0].bytes, io[1].bytes);
 
 	return;
 }
@@ -312,14 +284,27 @@ 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 */
+	struct Io ep[2]; /* "engineered pipe"; also "extended play", for the DJ */
+	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;
 
-	setdefaults;
+	/* Set defaults. */
+	align = -1;
+	count = 0;
+	fmt_output = fmt_asv;
+	noerror = 0;
+	ep[0].fl = read_flags;
+	Io_setdefaults(&ep[0]);
+	ep[1].fl = write_flags;
+	Io_setdefaults(&ep[1]);
 
 	if(argc > 0){
 		program_name = argv[0];
-		while((c = getopt(argc, argv, "a:Ab:B:c:di:hHnqs:S:o:")) != -1)
+		while((c = getopt(argc, argv, "a:Ab:B:c:i:hHns:S:o:")) != -1)
 			switch(c){
 			case 'i': case 'o':
 				i = (c == 'o');
@@ -369,7 +354,7 @@ int main(int argc, char *argv[]){
 		}else if(ep[i].seek > 0)
 			switch(Io_fdseek(&ep[i])){
 			case EX_OK:
-				output();
+				output(ep, fmt_output);
 				terminate(ep);
 				return EX_OK;
 			}
@@ -384,7 +369,7 @@ int main(int argc, char *argv[]){
 		else if(ep[0].bufuse < ep[0].bs){
 			++ep[0].prec;
 			fprintf(stderr, "%s: Partial read:\n\t", program_name);
-			output();
+			output(ep, fmt_output);
 			if(!noerror)
 				count = 1;
 			if(align >= 0)
@@ -410,7 +395,7 @@ int main(int argc, char *argv[]){
 			}else if(c > ep[1].bufuse && ep[1].bufuse > 0){
 				ep[1].prec += 1;
 				fprintf(stderr, "%s: Partial write:\n\t", program_name);
-				output();
+				output(ep, fmt_output);
 				if(!noerror)
 					count = 1;
 			}else if(ep[1].bufuse == 0 && c < ep[1].bs)
@@ -420,7 +405,7 @@ int main(int argc, char *argv[]){
 		}while(ep[0].bufuse > 0);
 	}while(count == 0 || --count > 0);
 
-	output();
+	output(ep, fmt_output);
 	terminate(ep);
 
 	return EX_OK;