cat(1p): fix unbuffered output

src/cat.c

@@ -28,9 +28,9 @@
 #include <unistd.h>
 
 int main(int argc, char *argv[]) {
-	int i = 1;
 	bool u = false;
-
+	int opt;
+	FILE *file;
 	char *usage_text = "(-u) [file...]";
 	int buf_size = strlen(argv[0]) + strlen("Usage: ") + strlen(usage_text) + 3;
 	char *usage = calloc(buf_size, buf_size);
@@ -39,8 +39,7 @@ int main(int argc, char *argv[]) {
 		snprintf(usage, buf_size, "Usage: %s (-u) [file...]\n", argv[0])
 	) < 0 ) {}
 
-	int opt;
-
+	extern int optind;
 	while ((opt = getopt(argc, argv, "u")) != -1) {
 		switch(opt) {
 			/*
@@ -50,17 +49,17 @@ int main(int argc, char *argv[]) {
 			 *           without delay as each is read.
 			 */
 			case 'u':
-				i = 2;
 				u = true;
 				break;
 			default:
 				break;
 		}
 	}
+	argv += optind;
+	argc -= optind;
 
-	FILE *file;
-
-	for (; i <= (argc - 1); i++) {
+	for (int i = 0; i < argc; i++) {
+		int byte = 0;
 	  /*
 		 * From cat(1p):
 		 *
@@ -72,33 +71,24 @@ int main(int argc, char *argv[]) {
 		 *           but shall accept multiple occurrences of '-' as a file
 		 *           operand.
 		 */
-		printf("argv[%d]: %s\n", i, argv[i]);
-		if (argv[i] == "-" || u && (argc - 1) == 1 || !u && argc == 1) {
-			file = fdopen(0, "r");
+		if (argv[i] == "-" || argc == 0) {
+			file = stdin;
 		} else if ((file = fopen(argv[i], "r")) == NULL) {
 			// TODO: Add error handling
 			fputs(usage, stderr);
 			return EX_NOINPUT;
 		}
 
-		int byte = 0;
-
-		if (u) {
-			while (byte != EOF) {
-				byte = fgetc(file);
+		for (char *buf = calloc(4096, 1); byte != EOF; fputs(buf, stdout)) {
+			byte = fgetc(file);
+			if (u) {
 				putchar(byte);
-			}
-		} else {
-			char *buf = calloc(1, 4096);
-			while (byte != EOF) {
-				byte = fgetc(file);
-				fputc(byte, fdopen(1, "r"));
+			} else {
+				snprintf(buf, 4096, "%c", byte);
 			}
 		}
-		if (fclose(file) == -1) {
-			fprintf(stderr, "%s: %s: Error closing file.\n", argv[0], argv[i]);
-			return EX_OSERR;
-		}
+
+		if (file != stdin) { fclose(file); }
 	}
 
 	return EX_OK;

trincat.c

@@ -0,0 +1,78 @@
+#include <errno.h> /* maybe */
+#include <fcntl.h> /* no */
+#include <sysexits.h> /* sure */
+#include <stdbool.h> /* no */
+#include <stdio.h> /* yes */
+#include <stdlib.h> /* yes */
+#include <string.h> /* maybe */
+#include <unistd.h> /* yes */
+#define BUF_SIZE 4096
+
+unsigned char u = 0; /* unbuffered */
+unsigned char buf[BUF_SIZE];
+
+void usage(char *argv0){
+	fprintf(stderr, "Usage: %s (-u) (file...)\n", argv0);
+	exit(EX_USAGE);
+}
+
+int main(int argc, char *argv[]) {
+	char *argv0;
+	extern int optind;
+	int c;
+	FILE *in;
+	argv0 = argv[0];
+
+	while ((c = getopt(argc, argv, "u")) != -1) {
+			switch(c) {
+					/*
+					 * From cat(1p):
+					 *
+					 * -u        Write bytes from the input file to the standard output
+					 *           without delay as each is read.
+					 */
+					case 'u':
+						u = 1;
+						break;
+					default:
+						usage(argv[0]);
+			}
+	}
+
+	while(++argv != NULL) /* increments over argv[0] */
+		/*
+			 * From cat(1p):
+			 *
+			 * file      A pathname of an input file. If no file operands are
+			 *           specified, the standard input shall be used. If a file is
+			 *           '-', the cat utility shall read from the standard input at
+			 *           that point in the sequence. The cat utility shall not close
+			 *           and reopen standard input when it is referenced in this way,
+			 *           but shall accept multiple occurrences of '-' as a file
+			 *           operand.
+			 */
+	if(argv[0][0] == '-' && argv[0][1] == '\0') in = stdin;
+					else if ((in = fopen(argv[0], "r")) == NULL) {
+							// TODO: Add error handling
+							usage(argv0);
+							return EX_NOINPUT;
+					}
+
+					int byte = 0;
+					char *buf = calloc(4096, 1);
+
+					while ((c = fgetc(in) != EOF)) {
+							if (u) {
+									putchar(c);
+							} else {
+									/* fucky wucky buffering */
+							}
+					}
+
+					if(!u) fputs(buf, stdout);
+
+	        if(in != stdin) fclose(file); /* who cares if it cant close */
+			}
+
+			return EX_OK;
+	}