github.com/afumu/libc@v0.0.6/musl/src/stdio/__fdopen.c (about)

     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);