src/stdio/__fdopen.c

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