/** @file
Implementation of internal file buffer allocation functions.
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distribution. The full text of the license may be found at
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
Copyright (c) 1990, 1993
The Regents of the University of California. All rights reserved.
This code is derived from software contributed to Berkeley by
Chris Torek.
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- Redistributions of source code must retain the above copyright
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NetBSD: makebuf.c,v 1.14 2003/08/07 16:43:28 agc Exp
makebuf.c 8.1 (Berkeley) 6/4/93
**/
#include <LibConfig.h>
#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "reentrant.h"
#include "local.h"
#include <MainData.h>
/*
* Allocate a file buffer, or switch to unbuffered I/O.
* Per the ANSI C standard, ALL tty devices default to line buffered.
*
* As a side effect, we set __SOPT or __SNPT (en/dis-able fseek
* optimisation) right after the fstat() that finds the buffer size.
*/
void
__smakebuf(FILE *fp)
{
void *p;
int flags;
size_t size;
int couldbetty;
_DIAGASSERT(fp != NULL);
if (fp != NULL) {
if (fp->_flags & __SNBF) {
fp->_bf._base = fp->_p = fp->_nbuf;
fp->_bf._size = 1;
return;
}
flags = __swhatbuf(fp, &size, &couldbetty);
if ((p = malloc(size)) == NULL) {
fp->_flags |= __SNBF;
fp->_bf._base = fp->_p = fp->_nbuf;
fp->_bf._size = 1;
return;
}
gMD->cleanup = _cleanup;
flags |= __SMBF;
fp->_bf._base = fp->_p = p;
fp->_bf._size = (int)size;
if (couldbetty || isatty(fp->_file))
flags |= __SLBF;
fp->_flags |= flags;
}
}
/*
* Internal routine to determine `proper' buffering for a file.
*/
int
__swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty)
{
struct stat st;
_DIAGASSERT(fp != NULL);
_DIAGASSERT(bufsize != NULL);
_DIAGASSERT(couldbetty != NULL);
if(fp == NULL) {
return (__SNPT);
}
if (fp->_file < 0 || fstat(fp->_file, &st) < 0) {
*couldbetty = 0;
*bufsize = BUFSIZ;
return (__SNPT);
}
/* could be a tty iff it is a character device */
*couldbetty = S_ISCHR(st.st_mode);
if (st.st_blksize == 0) {
*bufsize = BUFSIZ;
return (__SNPT);
}
/*
* Optimise fseek() only if it is a regular file. (The test for
* __sseek is mainly paranoia.) It is safe to set _blksize
* unconditionally; it will only be used if __SOPT is also set.
*/
*bufsize = st.st_blksize;
fp->_blksize = st.st_blksize;
return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ?
__SOPT : __SNPT);
}