peek(1): strip down to bare essentials, rewrite man page to match

src/peek.c

@@ -17,75 +17,66 @@
  */
 
 #include <signal.h> /* sigaction(2), signal(2), struct sigaction, SIGINT */
-#include <stdio.h> /* fclose(3), fdopen(3), fprintf(3), getc(3), perror(3),
-                    * putc(3), stderr, stdin, stdout, EOF, NULL */
-#include <stdlib.h> /* exit(3), size_t, EXIT_FAILURE */
-#include <string.h> /* strerror(3) */
+#include <stdio.h> /* fprintf(3), fgetc(3), perror(3), fputc(3), stderr, stdin,
+                    * stdout, EOF, NULL */
+#include <stdlib.h> /* exit(3), EXIT_FAILURE */
 #if !defined EX_OK || !defined EX_OSERR || !defined EX_USAGE
 #	include <sysexits.h>
 #endif
 #include <termios.h> /* tcgetattr(3), tcsetattr(3), struct termios, ECHO */
 #include <unistd.h> /* getopt(3), isatty(3), STDIN_FILENO */
 
-static int oserr(char *s){ perror(s); return EX_OSERR; }
-
 static char *program_name = "peek";
 
-static int usage(char *s){
-	fprintf(stderr, "Usage: %s (-1enot) (-p [program [arguments...]])\n",
-		s == NULL ? program_name : s);
-	return EX_USAGE;
-}
-
 /* Restores terminal echo; otherwise when a user ^Cs the terminal would
  * continue to not display typed text. If sig isn't zero, this will terminate
  * the program. */
-void restore_echo(int sig){
+static void restore_echo(int sig){
 	static struct termios t;
 
 	tcgetattr(STDIN_FILENO, &t);
 	t.c_lflag |= ECHO;
 	tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
 
+	/* If, for whatever ungodly reason, exit(3) returns, the user will notice
+	 * their typed characters on the screen. */
 	if(sig != 0)
 		exit(EXIT_FAILURE);
-	else
-		return;
+
+	return;
+}
+
+static int oserr(char *s){ perror(s); return EX_OSERR; }
+static int ioerr(char *s){ perror(s); restore_echo(0); return EX_IOERR; }
+static int usage(char *s){
+	fprintf(stderr, "Usage: %s (-1enot) (-p [program [arguments...]])\n", s);
+	return EX_USAGE;
 }
 
 int main(int argc, char *argv[]){
-	int eof;
-	char include_eof;
-	FILE *outputs[] = {
-		NULL /* stdout */,
-		NULL /* stderr */
-	};
 
 	if(argc < 1)
-		return usage(argv[0]);
+		return usage(program_name);
 
-	eof = EOF;
-	include_eof = 0;
 	{ /* options parsing */
+		char allow_nonterminals;
 		int c;
 
-		while((c = getopt(argc, argv, "1enot")) != -1)
+		allow_nonterminals = 0;
+		while((c = getopt(argc, argv, "i")) != -1)
 			switch(c){
-			case '1':	eof = '\n';          break;
-			case 'n':	include_eof = 1;     break;
-			case 'o':	outputs[0] = stdout; break;
-			case 'e':	outputs[1] = stderr; break;
-			case 't':
-				if(isatty(STDIN_FILENO) != 1){
-					fprintf(stderr, "%s: Must be run in a terminal"
-						" (option -t specified)\n", argv[0]);
-					return EX_USAGE;
-				}
+			case 'i':	allow_nonterminals = 1; break;
 			default:	return usage(argv[0]);
 			}
 
 		if(argc > optind)
 			return usage(argv[0]);
+
+		if(!allow_nonterminals && isatty(STDIN_FILENO) != 1){
+			fprintf(stderr, "%s: Must be run in a terminal"
+			    " (option -i skips this check)\n", argv[0]);
+			return EX_USAGE;
+		}
 	}
 
 	{ /* install signal handler */
@@ -116,15 +107,10 @@ int main(int argc, char *argv[]){
 
 	{ /* actual input loop */
 		int c;
-		size_t i;
 
-		do{	if((c = getc(stdin)) != eof || include_eof)
-				for(i = 0; i < (sizeof outputs)/(sizeof *outputs); ++i)
-					if(outputs[i] != NULL && putc(c, outputs[i]) == EOF){
-						perror(argv[0]);
-						outputs[i] = NULL;
-					}
-		}while(c != eof);
+		while((c = getc(stdin)) != EOF)
+			if(putc(c, stdout) == EOF)
+				return ioerr(argv[0]);
 	}
 
 	restore_echo(0);