__fdopen.c raw

   1  #include "stdio_impl.h"
   2  #include <stdlib.h>
   3  #include <sys/ioctl.h>
   4  #include <fcntl.h>
   5  #include <errno.h>
   6  #include <string.h>
   7  #include "libc.h"
   8  
   9  FILE *__fdopen(int fd, const char *mode)
  10  {
  11  	FILE *f;
  12  	struct winsize wsz;
  13  
  14  	/* Check for valid initial mode character */
  15  	if (!strchr("rwa", *mode)) {
  16  		errno = EINVAL;
  17  		return 0;
  18  	}
  19  
  20  	/* Allocate FILE+buffer or fail */
  21  	if (!(f=malloc(sizeof *f + UNGET + BUFSIZ))) return 0;
  22  
  23  	/* Zero-fill only the struct, not the buffer */
  24  	memset(f, 0, sizeof *f);
  25  
  26  	/* Impose mode restrictions */
  27  	if (!strchr(mode, '+')) f->flags = (*mode == 'r') ? F_NOWR : F_NORD;
  28  
  29  	/* Apply close-on-exec flag */
  30  	if (strchr(mode, 'e')) __syscall(SYS_fcntl, fd, F_SETFD, FD_CLOEXEC);
  31  
  32  	/* Set append mode on fd if opened for append */
  33  	if (*mode == 'a') {
  34  		int flags = __syscall(SYS_fcntl, fd, F_GETFL);
  35  		if (!(flags & O_APPEND))
  36  			__syscall(SYS_fcntl, fd, F_SETFL, flags | O_APPEND);
  37  		f->flags |= F_APP;
  38  	}
  39  
  40  	f->fd = fd;
  41  	f->buf = (unsigned char *)f + sizeof *f + UNGET;
  42  	f->buf_size = BUFSIZ;
  43  
  44  	/* Activate line buffered mode for terminals */
  45  	f->lbf = EOF;
  46  	if (!(f->flags & F_NOWR) && !__syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz))
  47  		f->lbf = '\n';
  48  
  49  	/* Initialize op ptrs. No problem if some are unneeded. */
  50  	f->read = __stdio_read;
  51  	f->write = __stdio_write;
  52  	f->seek = __stdio_seek;
  53  	f->close = __stdio_close;
  54  
  55  	if (!libc.threaded) f->lock = -1;
  56  
  57  	/* Add new FILE to open file list */
  58  	return __ofl_add(f);
  59  }
  60  
  61  weak_alias(__fdopen, fdopen);
  62