Annotation of prex/usr/lib/libc/stdio/makebuf.c, Revision 1.1
1.1 ! nbrk 1: /*-
! 2: * Copyright (c) 1990, 1993
! 3: * The Regents of the University of California. All rights reserved.
! 4: *
! 5: * This code is derived from software contributed to Berkeley by
! 6: * Chris Torek.
! 7: *
! 8: * Redistribution and use in source and binary forms, with or without
! 9: * modification, are permitted provided that the following conditions
! 10: * are met:
! 11: * 1. Redistributions of source code must retain the above copyright
! 12: * notice, this list of conditions and the following disclaimer.
! 13: * 2. Redistributions in binary form must reproduce the above copyright
! 14: * notice, this list of conditions and the following disclaimer in the
! 15: * documentation and/or other materials provided with the distribution.
! 16: * 3. Neither the name of the University nor the names of its contributors
! 17: * may be used to endorse or promote products derived from this software
! 18: * without specific prior written permission.
! 19: *
! 20: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 21: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 22: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 23: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 24: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 25: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 26: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 27: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 28: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 29: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 30: * SUCH DAMAGE.
! 31: */
! 32:
! 33: #include <sys/types.h>
! 34: #include <sys/stat.h>
! 35: #include <unistd.h>
! 36: #include <stdio.h>
! 37: #include <stdlib.h>
! 38: #include "local.h"
! 39:
! 40: /*
! 41: * Internal routine to determine `proper' buffering for a file.
! 42: */
! 43: static int
! 44: __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
! 45: {
! 46: struct stat st;
! 47:
! 48: *bufsize = BUFSIZ;
! 49: *couldbetty = 0;
! 50: if (fp->_file < 0 || fstat(fp->_file, &st) < 0)
! 51: return 0;
! 52:
! 53: /* could be a tty iff it is a character device */
! 54: *couldbetty = S_ISCHR(st.st_mode);
! 55: return 0;
! 56: }
! 57:
! 58: /*
! 59: * Allocate a file buffer, or switch to unbuffered I/O.
! 60: * Per the ANSI C standard, ALL tty devices default to line buffered.
! 61: *
! 62: * As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
! 63: * optimisation) right after the fstat() that finds the buffer size.
! 64: */
! 65: void
! 66: __smakebuf(fp)
! 67: FILE *fp;
! 68: {
! 69: void *p;
! 70: int flags;
! 71: size_t size;
! 72: int couldbetty;
! 73:
! 74: if (fp->_flags & __SNBF) {
! 75: fp->_bf._base = fp->_p = fp->_nbuf;
! 76: fp->_bf._size = 1;
! 77: return;
! 78: }
! 79: flags = __swhatbuf(fp, &size, &couldbetty);
! 80: if ((p = malloc(size)) == NULL) {
! 81: fp->_flags |= __SNBF;
! 82: fp->_bf._base = fp->_p = fp->_nbuf;
! 83: fp->_bf._size = 1;
! 84: return;
! 85: }
! 86: __cleanup = _cleanup;
! 87: flags |= __SMBF;
! 88: fp->_bf._base = fp->_p = p;
! 89: fp->_bf._size = size;
! 90: if (couldbetty && isatty(fp->_file))
! 91: flags |= __SLBF;
! 92:
! 93: fp->_flags |= flags;
! 94: }
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