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#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include "stdio.h"
#define PERMS 0666
FILE _iob[OPN_MAX] = {
{0, NULL, NULL, _READ, 0},
{0, NULL, NULL, _WRITE, 1},
{0, NULL, NULL, _WRITE | _UNBUF, 2}
};
FILE *fopen(char *name, char *mode)
{
FILE *fp;
if (*mode != 'r' && *mode != 'w' && *mode != 'a')
return NULL;
for(fp = _iob; fp < _iob + OPN_MAX; ++fp)
if (!(fp->flag & (_READ | _WRITE)))
break;
if (fp == _iob + OPN_MAX)
return NULL;
if (*mode == 'w') {
fp->fd = open(name, O_WRONLY);
} else if (*mode == 'a') {
if ((fp->fd = open(name, O_WRONLY)) == -1)
fp->fd = creat(name, PERMS);
lseek(fp->fd, 0L, 2);
} else {
fp->fd = open(name, O_RDONLY);
}
if (fp->fd == -1) {
fp->fd = 0;
return NULL;
}
fp->base = fp->ptr = NULL;
fp->flag = (*mode == 'r') ? _READ : _WRITE;
fp->cnt = 0;
return fp;
}
int _fillbuf(FILE *fp)
{
int bufsize;
if ((fp->flag & (_READ | _EOF | _ERR)) != _READ)
return EOF;
bufsize = (fp->flag & _UNBUF) ? 1 : BUFSIZ;
if (fp->base == NULL)
if ((fp->base = malloc(bufsize)) == NULL)
return EOF;
fp->ptr = fp->base;
fp->cnt = read(fp->fd, fp->base, bufsize);
if (--fp->cnt < 0) {
if (fp->cnt == -1)
fp->flag = _EOF;
else // fp->cnt == -2
fp->flag = _ERR;
fp->cnt = 0;
return EOF;
}
return (unsigned char) *fp->ptr++;
}
int _flushbuf(int c, FILE *fp)
{
int bufsize, nc;
if ((fp->flag & (_WRITE | _ERR)) != _WRITE)
return EOF;
bufsize = (fp->flag & _UNBUF) ? 1 : BUFSIZ;
if (fp->base == NULL) {
if ((fp->base = malloc(bufsize)) == NULL)
return EOF;
} else {
nc = fp->ptr - fp->base;
if (write(fp->fd, fp->base, nc) != nc) {
fp->flag = _ERR;
return EOF;
}
}
fp->ptr = fp->base;
fp->cnt = bufsize - 1;
*fp->ptr++ = c;
return (unsigned char) c;
}
int fflush(FILE *fp)
{
int rc = 0;
if (fp < _iob && fp >= _iob + OPN_MAX)
return EOF;
if (fp->flag & _WRITE)
rc = _flushbuf(0, fp);
fp->ptr = fp->base;
fp->cnt = (fp->flag & _UNBUF) ? 1 : BUFSIZ;
return rc;
}
int fclose(FILE *fp)
{
int rc;
if ((rc = fflush(fp)) != EOF) {
free(fp->base);
fp->base = fp->ptr = NULL;
fp->flag &= ~(_READ | _WRITE);
fp->cnt = 0;
close(fp->fd);
}
return rc;
}
int fseek(FILE *fp, ssize_t os, int origin)
{
int rc = 0;
if (fp < _iob && fp >= _iob + OPN_MAX)
return EOF;
if (fp->flag & _READ) {
if (os == SEEK_CUR)
os -= fp->cnt;
rc = lseek(fp->fd, os, origin);
fp->cnt = 0;
} else if (fp->flag & _WRITE) {
if ((rc = fflush(fp)) != EOF)
rc = lseek(fp->fd, os, origin);
}
return (rc == -1) ? -1 : 0;
}
int puts(const char *s)
{
while (*s)
if (putchar(*s++) == EOF)
return EOF;
fflush(stdout);
return 1;
}
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