2024-01-03 work

Wip/dj/dj.c

@@ -15,19 +15,86 @@
 
 /* information that needs to be kept about each file in the "pipe" */
 struct Io{
-	size_t index;	/* index in io[] array */
-	char *fn;		/* file name (may be stdin_name or stdout_name) */
-	int rec;		/* records processed */
-	int prec;		/* partial records processed */
-	int fd;			/* file descriptor */
-	int seek;		/* bytes to seek/skip (will be 0 after skippage) */
 	int bs;			/* buffer size */
 	size_t bufuse;	/* buffer usage */
 	char *buf;		/* buffer */
+	int fd;			/* file descriptor */
+	int fl;			/* file opening flags */
+	char *fn;		/* file name (may be stdin_name or stdout_name) */
+	size_t index;	/* index in io[] array */
+	int prec;		/* partial records processed */
+	int rec;		/* records processed */
+	int seek;		/* bytes to seek/skip (will be 0 after skippage) */
 };
 
-static char stdin_name = "<stdin>";
+static char *stdin_name = "<stdin>";
-static char stdout_name = "<stdout>";
+static char *stdout_name = "<stdout>";
+
+static void *
+Io_bufalloc(struct Io *io){
+
+	return (io->buf = malloc(io->bs * (sizeof io->buf)));
+}
+
+static void
+Io_buffree(struct Io *io){
+
+	free(io->buf);
+
+	return;
+}
+
+static int
+Io_fdclose(struct Io *io){
+
+	return fdisnotstd(io->fd)
+		? close(io->fd)
+		: 0;
+}
+
+static int
+Io_fdopen(struct Io *io, char *fn){
+	int fd;
+	
+	if((fd = open(fn, io->fl)) != -1
+			&& (fdisnotstd(io->fd) || close(io->fd) == 0)){
+		io->fd = fd;
+		io->fn = fn;
+	}
+
+	return fd;
+}
+
+static int _read(int fd, void *b, size_t bs);
+
+/* counter-intuitively, returns negative if successful and a sysexits.h exit
+ * code if an unrecoverable error occurred */
+static int
+Io_seek(struct Io *io){
+	
+	if(fdisnotstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) == -1)
+		return -1;
+	else if(io->fl == O_RDONLY){
+		do	if((io->bufuse = _read(io->fd, io->buf,
+					(io->bs < io->seek) ? io->bs : io->seek)) != 0)								
+				io->seek -= io->bufuse;
+			else /* not enough to skip */
+				return EX_OK;
+		while(io->seek > 0);
+	}else{
+		memset(io->buf, '\0', io->bs);
+		/* cheat and use bufuse as the retval for write
+		 * (the buffer is zeroed, it doesn't matter) */
+		do	if((io->bufuse = write(io->fd, io->buf,
+						(io->bs < io->seek) ? io->bs : io->seek)) != 0)
+				io->seek -= io->bufuse;
+			else
+				return EX_OK;
+		while(io->seek > 0);
+	}
+
+	return -1;
+}
 
 static void
 Io_setdefaults(struct Io io[2]){
@@ -35,11 +102,15 @@ Io_setdefaults(struct Io io[2]){
 	io[0].bs = io[1].bs = 1024;
 	io[0].buf = io[1].buf = NULL;
 	io[0].fd = STDIN_FILENO;
-	io[0].fn = stdin_name;
 	io[1].fd = STDOUT_FILENO;
+	io[0].fl = O_RDONLY;
+	io[1].fl = O_WRONLY | O_CREAT;
+	io[0].fn = stdin_name;
 	io[1].fn = stdout_name;
 	io[0].index = 0;
 	io[1].index = 1;
+	io[0].prec = io[1].prec = 0;
+	io[0].rec = io[1].rec = 0;
 	io[0].seek = io[1].seek = 0;
 
 	return;
@@ -71,42 +142,42 @@ parse(char *s){
 /* s is the component (e.g. filename) that failed */
 static int
 oserr(char *argv0, char *s){
+
 	fprintf(stderr, "%s: %s: %s\n", argv0, s, strerror(errno));
+
 	return EX_OSERR;
 }
 
-/* diagnostic output
+/* diagnostic output */
- * dd(1p) does %d+%d\n%d+%d\n */
 struct Io *
 output(struct Io io[2]){
 
-	fprintf(stderr, "%d:%d / %d:%d\n",
+	fprintf(stderr, "%d:%d / %d:%d\n", /* dd(1p) does %d+%d\n%d+%d\n */
 		io[0].rec, io[0].prec, io[1].rec, io[1].prec);;
+
 	return io;
 }
 
 static int
 terminate(struct Io io[2]){
 
-	for(;; ++io){
+	Io_buffree(&io[0]);
-		if(fdisnotstd(io->fd))
+	Io_buffree(&io[1]);
-			close(io->fd);
+	Io_fdclose(&io[0]);
-		free(io->buf);
+	Io_fdclose(&io[1]);
-		if(io->index == 1)
-			break;
-	}
 
 	return EX_OK;
 }
 
 static int
-usage(char *argv0){
+usage(char **argv){
 
 	fprintf(stderr, "Usage: %s (-af) (-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", ARGV0);
+
 	return EX_USAGE;
 }
 
@@ -127,23 +198,10 @@ int main(int argc, char *argv[]){
 
 	if(argc > 0)
 		while((c = getopt(argc, argv, "ac:i:b:fs:o:B:S:")) != -1)
-			if(c == 'i' || c == 'o'){ /* file arguments */
+			if((c == 'i' || c == 'o')
-				int t;
+					&& Io_fdopen(&io[c == 'o'], optarg) != 0){ /* file args */
-
-				p = (c == 'o');
-				if(		((t = open(optarg,
-								c == 'i'
-								? O_RDONLY
-								: O_WRONLY | O_CREAT))
-							== -1)
-						|| (fdisnotstd(io[p].fd)
-							&& close(io[p].fd) != 0)){
 				terminate(io);
 				return oserr(argv[0], optarg);
-				}else{
-					io[p].fd = t;
-					io[p].fn = optarg;
-				}
 			/* boolean arguments */
 			}else if(c == 'a')
 				align = 1;
@@ -156,51 +214,23 @@ int main(int argc, char *argv[]){
 					|| (c == 'B' && (io[1].bs = parse(optarg)) < 0)
 					|| (c == 'S' && (io[1].seek = parse(optarg)) < 0))){
 				terminate(io);
-				return usage(argv[0]);
+				return usage(argv);
 			}
 
 	if(argc > optind)
-		return usage(argv[0]);
+		return usage(argv);
 
 	for(p = 0; p <= 1; ++p){
-		/* buffer alloc */
+		if(Io_bufalloc(&io[p]) == NULL){
-		if((io[p].buf = malloc(io[p].bs * (sizeof io[p].buf))) == NULL){
 			fprintf(stderr, "%s: Failed to allocate %d bytes\n", ARGV0,
 				io[p].bs);
 			terminate(io);
 			return EX_OSERR;
-		}else if(io[p].seek > 0){ /* seek */
+		}else if(io[p].seek > 0) /* seek */
-			if(!fdisnotstd(io[p].fd)
+			switch(Io_seek(&io[p])){
-					|| lseek(io[p].fd, io[p].seek, SEEK_SET) == -1){					
+			case EX_OK:	return terminate(output(io));
-				if(p == 0){
-					do	if((io[p].bufuse = _read(io[p].fd, io[p].buf,
-									io[p].bs < io[p].seek
-										? io[p].bs
-										: io[p].seek))
-								!= 0)
-							io[p].seek -= io[p].bufuse;
-						else /* not enough to skip */
-							return terminate(output(io));
-					while(io[p].seek > 0);
-				}else{
-					memset(io[p].buf, '\0', io[p].bs);
-					/* cheat and use bufuse as the retval for write
-					 * (the buffer is zeroed, it doesn't matter) */
-					do	if((io[p].bufuse = write(io[p].fd, io[p].buf,
-									io[p].bs < io[p].seek
-										? io[p].bs
-										: io[p].seek))
-								!= 0)
-							io[p].seek -= io[p].bufuse;
-						else
-							return terminate(output(io));
-					while(io[p].seek > 0);
 			}
 	}
-		}
-	}
-
-	io[0].prec = io[0].rec = io[1].prec = io[1].rec = 0;
 
 	do{	/* read */ if((io[0].bufuse
 				= read(io[0].fd, io[0].buf, io[0].bs))