/*- * SPDX-License-Identifier: BSD-3-Clause * * 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. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #if defined(LIBC_SCCS) && !defined(lint) static char sccsid[] = "@(#)makebuf.c 8.1 (Berkeley) 6/4/93"; #endif /* LIBC_SCCS and not lint */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include "namespace.h" #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include "un-namespace.h" #include "libc_private.h" #include "local.h" #include <xlocale/_stdio.h> #include <xlocale/_stdlib.h> #include <os/once_private.h> #ifdef FEATURE_SMALL_STDIOBUF # define MAXBUFSIZE (1 << 12) #else # define MAXBUFSIZE (1 << 16) #endif #define TTYBUFSIZE 4096 #define MAXEVPSIZE 16 static char __fallback_evp[MAXEVPSIZE]; static char __stdout_evp[MAXEVPSIZE]; static void __loadevp(const char* key, char destination[MAXEVPSIZE]) { char* evp = getenv(key); if (evp != NULL) { strlcpy(destination, evp, MAXEVPSIZE); } else { destination[0] = '\0'; } } static void __evpinit(void* __unused unused) { __loadevp("STDBUF", __fallback_evp); __loadevp("STDBUF1", __stdout_evp); } static char* __getevp(int fd) { static os_once_t predicate; os_once(&predicate, NULL, __evpinit); if (fd == STDOUT_FILENO && __stdout_evp[0] != '\0') { return __stdout_evp; } else if (__fallback_evp[0] != '\0') { return __fallback_evp; } else { return NULL; } } /* * Internal routine to determine environment override buffering for a file. * * Sections of the below taken from NetBSD's version of this file under the same license. */ static int __senvbuf(FILE *fp, size_t *bufsize, int *couldbetty) { char* evp; char* end; int flags; long size; flags = 0; // Default to fully buffered if ((evp = __getevp(fp->_file)) == NULL) { return flags; } // Look at the first character only to determine buffering mode switch (*evp) { case 'u': case 'U': flags |= __SNBF; break; case 'l': case 'L': flags |= __SLBF; break; case 'f': case 'F': // Default flags is fully buffered break; default: // Unexpected buffering mode, use default fully buffered return flags; } // User specified envrionment defaults have higher priority than tty defaults *couldbetty = 0; // Advance the envrionment variable pointer, so we can attempt to parse the number evp++; if (!isdigit(*evp)) { return flags; // No number found, this protects us from negative size values } size = strtol_l(evp, &end, 10, LC_C_LOCALE); if (*end != '\0') { return flags; } if (size <= 0) { return __SNBF; // Override with unbuffered if the buffer size is 0 } // We had a non zero buffer, cap it and return the flags; *bufsize = size > MAXBUFSIZE ? MAXBUFSIZE : size; return flags; } /* * 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; if (fp->_flags & __SNBF) { fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; return; } flags = __swhatbuf(fp, &size, &couldbetty); if (fp->_file >= 0) { flags |= __senvbuf(fp, &size, &couldbetty); if (flags & __SNBF) { fp->_flags |= __SNBF; fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; return; } } if (couldbetty && isatty(fp->_file)) { flags |= __SLBF; /* st_blksize for ttys is 128K, so make it more reasonable */ if (size > TTYBUFSIZE) fp->_blksize = size = TTYBUFSIZE; } if ((p = malloc(size)) == NULL) { fp->_flags |= __SNBF; fp->_bf._base = fp->_p = fp->_nbuf; fp->_bf._size = 1; return; } __cleanup = _cleanup; flags |= __SMBF; fp->_bf._base = fp->_p = p; fp->_bf._size = size; fp->_flags |= flags; } /* * Internal routine to determine `proper' buffering for a file. */ int __swhatbuf(FILE *fp, size_t *bufsize, int *couldbetty) { struct stat st; 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 = (st.st_mode & S_IFMT) == S_IFCHR; 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. */ fp->_blksize = *bufsize = st.st_blksize > MAXBUFSIZE ? MAXBUFSIZE : st.st_blksize; return ((st.st_mode & S_IFMT) == S_IFREG && fp->_seek == __sseek ? __SOPT : __SNPT); }