From 2b68c3d06fb2961ae3797d1ef461cff655f328b2 Mon Sep 17 00:00:00 2001
From: zlg <zlg@zlg.space>
Date: Sun, 9 Jan 2022 16:41:26 -0800
Subject: Refactor syscalls.h for ch8 exercises

The refactor includes implementations for fflush and fclose as well,
needed in 8-03.
---
 ch8/8-02_fopen-and-fillbuf.c | 82 +++++++-------------------------------------
 1 file changed, 12 insertions(+), 70 deletions(-)

(limited to 'ch8/8-02_fopen-and-fillbuf.c')

diff --git a/ch8/8-02_fopen-and-fillbuf.c b/ch8/8-02_fopen-and-fillbuf.c
index e533da8..66d7336 100644
--- a/ch8/8-02_fopen-and-fillbuf.c
+++ b/ch8/8-02_fopen-and-fillbuf.c
@@ -1,8 +1,9 @@
+#include <errno.h>
+#include <string.h>
 #include <fcntl.h>
-#include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include "8-02_syscalls.h"
+#include "syscalls.h"
 
 /* The C Programming Language: 2nd Edition
  *
@@ -14,76 +15,14 @@
  *
  * The resulting binary of this file (plus the custom header) runs through this
  * source file in about 0.001s. However, the binary is 1KB larger.
+ *
+ * Some subsequent exercises use the same syscalls.h file created for this
+ * exercise. For this reason, the file only refers to its chapter and not
+ * specific exercises.
  */
 
-#define PERMS 0666
-
-int getc(FILE *);
-
-int my__fillbuf(my_FILE *fp) {
-	int bufsize;
-	if (fp->flags._READ == 0) {
-		return EOF;
-	}
-	bufsize = (fp->flags._UNBUF != 0) ? 1 : BUFSIZ;
-	if (fp->base == NULL) {
-		if ((fp->base = (char *) calloc(bufsize, sizeof (char))) == NULL) {
-			return EOF;
-		}
-	}
-	fp->ptr = fp->base;
-	fp->cnt = read(fp->fd, fp->ptr, bufsize);
-	if (--fp->cnt < 0) {
-		if (fp->cnt == -1) {
-			fp->flags._EOF = 1;
-		} else {
-			fp->flags._ERR = 1;
-		}
-		fp->cnt = 0;
-		return EOF;
-	}
-	return (unsigned char) *fp->ptr++;
-}
-
-my_FILE * my_fopen(char *name, char *mode) {
-	int fd;
-	my_FILE *fp;
-	if (*mode != 'r' && *mode != 'w' && *mode != 'a') {
-		return NULL;
-	}
-	for (fp = _iob; fp < _iob + FOPEN_MAX; fp++) {
-		if (fp->flags._READ == 0 && fp->flags._WRITE == 0) {
-			break;
-		}
-	}
-	if (fp >= _iob + FOPEN_MAX) {
-		return NULL;
-	}
-	if (*mode == 'w') {
-		fd = creat(name, PERMS);
-	} else if (*mode == 'a') {
-		if ((fd = open(name, O_WRONLY, 0)) == -1) {
-			fd = creat(name, PERMS);
-		}
-		lseek(fd, 0L, 2);
-	} else {
-		fd = open(name, O_RDONLY, 0);
-	}
-	if (fd == -1) {
-		return NULL;
-	}
-	fp->fd = fd;
-	fp->cnt = 0;
-	if (*mode == 'r') {
-		fp->flags._READ = 1;
-	} else {
-		fp->flags._WRITE = 1;
-	}
-	return fp;
-}
-
 int main() {
-	my_FILE *fp = my_fopen("8-02_fopen-and-fillbuf.c", "r");
+	FILE *fp = fopen("8-02_fopen-and-fillbuf.c", "r");
 	if (fp != NULL) {
 		puts("We could read the file.\n");
 		/* pro tip: don't declare this as 'unsigned' or you'll create an
@@ -91,9 +30,12 @@ int main() {
 		 * half an hour on a newbie mistake like I did. :)
 		 */
 		char c;
-		while ((c = my_getc(fp)) != EOF) {
+		while ((c = getc(fp)) != EOF) {
 			putchar(c);
 		}
+		/* fclose calls fflush */
+		fclose(fp);
+		fclose(stdout);
 	} else {
 		puts("Could not open file for reading.");
 	}
-- 
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