sunday work

wip/peek/peek.c

@@ -1,11 +1,13 @@
 /* #include <errno.h> /* errno */
 #include <stdio.h> /* fprintf(3), getc(3), putc(3), EOF */
 #include <stdlib.h> /* size_t */
-#if !defined EX_OK || !defined EX_USAGE
+#include <string.h> /* strerror(3) */
+#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), write(2), STDERR_FILENO, STDIN_FILENO */
+#include <unistd.h> /* fork(2), getopt(3), pipe(2), write(2), STDERR_FILENO,
+                     * STDOUT_FILENO */
 
 static char *program_name = "peek";
 
@@ -14,43 +16,68 @@ int main(int argc, char *argv[]){
 	int eof;
 	size_t i;
 	char include_eof;
-	size_t j;
+	int outputs[] = {0 /* stdout */, 0 /* stderr */, 0 /* -p */};
-	int outputs[] = {0 /* stdout */, 0 /* stderr */, 0 /* -p */, 0};
+	int p[2] = {0, 0};
 	struct termios t;
 
-	/* disable terminal echo */
+	/* terminal echo */
 	tcgetattr(STDIN_FILENO, &t);
 	t.c_lflag ^= ECHO;
 	tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
 
+	if(argc < 1)
+		argv[0] = program_name;
+
 	eof = EOF;
 	include_eof = 0;
-	to_stderr = 0;
-	to_stdout = 0;
 	while((c = getopt(argc, argv, "1enop:")) != -1)
 		switch(c){
 		case '1': eof = '\n';                 break;
 		case 'n': include_eof = 1;            break;
-		case 'o': outputs[0] = STDIN_FILENO;  break;
+		case 'o': outputs[0] = STDOUT_FILENO; break;
 		case 'e': outputs[1] = STDERR_FILENO; break;
-		case 'p': printf("not yet implemented\n");
+		case 'p':
+			printf("not implemented\n"); return;
+			if(pipe(p) != 0){
+				fprintf(stderr, "%s: %s\n",
+					argv[0] == NULL
+						? program_name
+						: argv[0],
+					strerror(errno));
+				return EX_OSERR;
+			}else
+				outputs[2] = p[1];
+			break;
 		default:
 			fprintf(stderr, "Usage: %s (-1eno) (-p [program])\n",
 				argv[0] == NULL ? program_name : argv[0]);
 			return EX_USAGE;
 		}
 
-	/* permute non-zero outputs to front */
+	if(outputs[2] != 0){
-	for(i = 0; i < (sizeof outputs) / (sizeof *outputs) - 1; ++i)
+		switch(fork()){
-		if(outputs[i] == 0)
+		case -1:
-			for(j = 1; j < (sizeof outputs) / (sizeof *outputs);
+			fprintf(stderr, "%s: %s\n", argv[0], strerror(errno));
-					++j)
+			return EX_OSERR;
-				outputs[j - 1] = outputs[j];
+		case 0:
+			if(dup2(p[0], STDIN_FILENO) != STDIN_FILENO){
+				fprintf(stderr, "%s: %s\n",
+					argv[0] == NULL
+						? program_name
+						: argv[0],
+					strerror(errno));
+				return EX_OSERR;
+			}
+			/* exec */
+		}
+	}
 
 	do{	if((c = getc(stdin)) != eof || include_eof)
-			for(i = 0; outputs[i] != 0; ++i);
+			for(i = 0; i < (sizeof outputs)/(sizeof *outputs); ++i)
-				if(write(outputs[i], &c, 1) != 1)
+				if(outputs[i] != 0
-					{/* errro */}
+						&& write(outputs[i], &c, 1)
+							!= 1)
+					{/* errno */}
 	}while(c != eof);
 
 	tcgetattr(STDIN_FILENO, &t);