dj(1): add a ton of assertions, fix if statement, fix io[i] mixups

src/dj.c

@@ -16,10 +16,11 @@
  * along with this program. If not, see https://www.gnu.org/licenses/.
  */
 
+#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 */
 #include <unistd.h> /* close(2), getopt(3), lseek(2), read(2), write(2),
@@ -64,27 +65,22 @@ static int write_flags = O_WRONLY | O_CREAT;
 		|| (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{ \
-	free((io[0]).buf); \
-	free((io[1]).buf); \
-	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)));
+	return io != NULL
+		? (io->buf = malloc(io->bs * (sizeof *io->buf)))
+		: NULL;
 }
 
 /* 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){
-	
+
+	assert(io != NULL);
+
 	memset(io->buf + io->bufuse, padding, io->bs - io->bufuse);
 	io->bufuse = io->bs;
 
@@ -99,6 +95,8 @@ static struct Io*
 Io_bufxapp(struct Io *dest, struct Io *src){
 	int n;
 
+	assert(dest != NULL && src != NULL);
+
 	n = MIN(src->bufuse, dest->bs - dest->bufuse);
 	memcpy(dest->buf + dest->bufuse, src->buf, n);
 	dest->bufuse += n;
@@ -115,32 +113,27 @@ Io_bufxapp(struct Io *dest, struct Io *src){
 static struct Io*
 Io_bufxfer(struct Io *dest, struct Io *src, int n){
 
+	assert(dest != NULL && src != NULL);
+
 	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;
-	
+
+	assert(io != NULL);
+
 	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){
+			&& (fdisstd(io->fd) || close(io->fd) == 0)){
 		io->fd = fd;
 		io->fn = fn;
 	}
@@ -152,8 +145,15 @@ Io_fdopen(struct Io *io, char *fn){
  * of sought bytes from io->seek. This procedure leaves garbage in io->buf. */
 static void
 Io_fdseek(struct Io *io){
-	
+
-	if(io->seek != 0
+	assert(io != NULL);
+	assert(io->fd != STDIN_FILENO  || io->fl == read_flags);
+	assert(io->fd != STDOUT_FILENO || io->fl == write_flags);
+	assert(io->fd != STDERR_FILENO || io->fl == write_flags);
+
+	printf("%s\n", io->fn);
+
+	if(io->seek == 0
 			|| (!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1))
 		return;
 
@@ -178,7 +178,8 @@ Io_fdseek(struct Io *io){
 				/* second chance */
 				io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek));
 		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
-	}
+	}else
+		assert(0); /* UNREACHABLE */
 
 	io->bufuse = 0;
 
@@ -273,9 +274,9 @@ int main(int argc, char *argv[]){
 	for(i = 0; i < 2; ++i){
 		io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
 		io[i].bytes = 0;
-		io[i].fd = i ? STDIN_FILENO : STDOUT_FILENO;
+		io[i].fd = i == 0 ? STDIN_FILENO : STDOUT_FILENO;
-		io[i].fn = i ? stdin_name   : stdout_name;
+		io[i].fn = i == 0 ? stdin_name   : stdout_name;
-		io[i].fl = i ? read_flags   : write_flags;
+		io[i].fl = i == 0 ? read_flags   : write_flags;
 		io[i].prec = 0;
 		io[i].rec = 0;
 		io[i].seek = 0;
@@ -289,12 +290,11 @@ int main(int argc, char *argv[]){
 			switch(c){
 			case 'i': case 'o': i = (c == 'o');
 				if(optarg[0] == '-' && optarg[1] == '\0'){ /* optarg == "-" */
-					io[i].fd = i ? STDIN_FILENO : STDOUT_FILENO;
+					io[i].fd = i == 0 ? STDIN_FILENO : STDOUT_FILENO;
-					io[i].fn = i ? stdin_name   : stdout_name;
+					io[i].fn = i == 0 ? stdin_name   : stdout_name;
 					break;
 				}else if(Io_fdopen(&io[i], optarg) != -1)
 					break;
-				terminate(io);
 				return oserr(optarg);
 			case 'n': noerror = 1; break;
 			case 'H': fmt_output = fmt_human; break;
@@ -308,19 +308,18 @@ int main(int argc, char *argv[]){
 				if(c == 'c' && (count = parse(optarg)) >= 0)
 					break;
 				i = (c >= 'A' && c <= 'Z'); /* uppercase changes output */
-				c &= 0x20 /* 0b 0010 0000 */; /* (ASCII) make lowercase */
+				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(program_name);
 			}
 	}
 
+
 	if(argc > optind){
-		terminate(io);
 		return usage(program_name);
 	}
 
@@ -328,14 +327,13 @@ int main(int argc, char *argv[]){
 		if(Io_bufalloc(&io[i]) == NULL){
 			fprintf(stderr, "%s: Failed to allocate %d bytes\n",
 				program_name, io[i].bs);
-			terminate(io);
 			return EX_OSERR;
-		}else if(io[i].seek > 0)
+		}else if(io[i].seek > 0){
 			Io_fdseek(&io[i]);
 			if(io[i].seek > 0){
-				terminate(io);
 				return oserr(io[i].fn);
 			}
+		}
 	}
 
 	do{	/* read */
@@ -387,7 +385,6 @@ int main(int argc, char *argv[]){
 	}while(count == 0 || --count > 0);
 
 	output(io, fmt_output);
-	terminate(io);
 
 	return EX_OK;
 }