2024-01-01 work

Wip/dj/dj.c

@@ -2,9 +2,10 @@
 #include <fcntl.h> /* open(2) */
 #include <stdio.h> /* fprintf(3), stderr */
 #include <stdlib.h> /* free(3), malloc(3), strtol(3), size_t */
+#include <string.h> /* memset(3) */
 #include <sysexits.h> /* EX_OK, EX_USAGE */
-#include <unistd.h> /* close(2), getopt(3), optarg, optind, STDIN_FILENO,
-                       STDOUT_FILENO */
+#include <unistd.h> /* close(2), getopt(3), read(2), write(2), optarg, optind,
+                       STDIN_FILENO, STDOUT_FILENO */
 
 #define ARGV0 (argv[0] == NULL ? "<no argv[0]>" : argv[0])
 
@@ -61,10 +62,10 @@ terminate(struct Io io[2]){
 
 static int
 usage(char *argv0){
-	fprintf(stderr, "Usage: %s (-f) (-c [count]\n"
-		"\t(-i [input file]) (-a) (-b [input block size])"
+	fprintf(stderr, "Usage: %s (-af) (-c [count]\n"
+		"\t(-i [input file]) (-b [input block size])"
 			" (-s [input offset])\n"
-		"\t(-o [output file]) (-A) (-B [output block size])"
+		"\t(-o [output file]) (-B [output block size])"
 			" (-S [output offset])\n", ARGV0);
 	return EX_USAGE;
 }
@@ -75,7 +76,6 @@ static char stdout_name = "<stdout>";
 int main(int argc, char *argv[]){
 	struct Io{
 		size_t index;
-		char align;
 		char *fn;
 		int rec;
 		int prec;
@@ -85,6 +85,7 @@ int main(int argc, char *argv[]){
 		size_t bufuse;
 		char *buf;
 	} io[2]; /* { read, write } same as pipe(2) */
+	char align;
 	int c;
 	int count;
 	size_t i;
@@ -92,10 +93,11 @@ int main(int argc, char *argv[]){
 	char noerror;
 
 	/* defaults */
+	align = 0;
 	count = 0;
 	noerror = 0;
-	io[0].align = io[1].align = 0;
 	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;
@@ -105,7 +107,7 @@ int main(int argc, char *argv[]){
 	io[0].seek = io[1].seek = 0;
 
 	if(argc > 0)
-		while((c = getopt(argc, argv, "aAc:i:b:fs:o:B:S:")) != -1)
+		while((c = getopt(argc, argv, "ac:i:b:fs:o:B:S:")) != -1)
 			if(c == 'i' || c == 'o'){ /* file arguments */
 				int t;
 
@@ -118,23 +120,26 @@ int main(int argc, char *argv[]){
 						|| (io[p].fd != STDIN_FILENO
 							&& io[p].fd != STDOUT_FILENO
 							&& fclose(io[p].f) == EOF){
+					terminate(io);
 					return oserr(argv[0], optarg);
 				}else{
 					io[p].fd = t;
 					io[p].fn = optarg;
 				}
+			/* boolean arguments */
+			}else if(c == 'a')
+				align = 1;
+			else if(c == 'f')
+				noerror = 1;
 			/* numeric arguments */
-			}else if(!((c == 'c' && (count = parse(optarg)) < 0)
+			else if(!((c == 'c' && (count = parse(optarg)) < 0)
 					|| (c == 'b' && (io[0].bs = parse(optarg)) < 0)
 					|| (c == 's' && (io[0].seek = parse(optarg)) < 0)
 					|| (c == 'B' && (io[1].bs = parse(optarg)) < 0)
-					|| (c == 'S' && (io[1].seek = parse(optarg)) < 0)))
+					|| (c == 'S' && (io[1].seek = parse(optarg)) < 0))){
+				terminate(io);
 				return usage(argv[0]);
-			/* boolean arguments */
-			else if(c == 'a' || c == 'A')
-				io[c == 'A'].align = 1;
-			else if(c == 'f')
-				noerror = 1;
+			}
 
 	if(argc > optind)
 		return usage(argv[0]);
@@ -144,20 +149,37 @@ int main(int argc, char *argv[]){
 		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 */
-			if(io[p].fd == STDIN_FILENO){
-				do{	io[p].seek -= (io[p].bufuse
-						= _read(io[p].fd, io[p].buf,
-							io[p].bs < io[p].seek ? io[p].bs : io[p].seek));
-					if(io[p].bufuse == 0)
-						return terminate(output(io));
-				}while(io[p].seek > 0);
-			else if(io[p].f == stdout)
-				for(i = 0; i < io[p].seek; ++i)
-					putc('\0', io[p].f;
-			else if(fseek(io[p].f, io[p].seek, SEEK_SET) == -1)
-				return oserr(argv[0], io[p].fn);
+			if(io[p].fd == STDIN_FILENO
+					|| io[p].fd == STDOUT_FILENO
+					|| lseek(io[p].fd, io[p].seek, SEEK_SET) == -1){
+				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);
+				}
+			}
 		}
 	}
 
@@ -175,11 +197,5 @@ int main(int argc, char *argv[]){
 
 	}while(count == 0 || --count > 0);
 
-	for(i = 0; i <= 1; ++i){
-		free(io[i].buf);
-		if(io[i].fd != STDIN_FILENO && io[i].fd != STDOUT_FILENO)
-			close(io[i].fd);
-	}
-
-	return EX_OK;
+	return terminate(output(io));
 }