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 #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);