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-rw-r--r--ch8/8-02_fopen-and-fillbuf.c82
1 files changed, 12 insertions, 70 deletions
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.");
}