snprintf/fvwrite.c

   1 /*      $OpenBSD: fvwrite.c,v 1.16 2009/10/22 01:23:16 guenther Exp $ */
   2 /*-
   3  * Copyright (c) 1990, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * This code is derived from software contributed to Berkeley by
   7  * Chris Torek.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <errno.h>
  38 #include "local.h"
  39 #include "fvwrite.h"
  40 #include "various.h"
  41
  42 /*
  43  * Write some memory regions.  Return zero on success, EOF on error.
  44  *
  45  * This routine is large and unsightly, but most of the ugliness due
  46  * to the three different kinds of output buffering is handled here.
  47  */
  48 int
  49 __sfvwrite(LTTNG_UST_LFILE *fp, struct __lttng_ust_suio *uio)
  50 {
  51         size_t len;
  52         char *p;
  53         struct __lttng_ust_siov *iov;
  54         int w, s;
  55         char *nl;
  56         int nlknown, nldist;
  57
  58         if ((len = uio->uio_resid) == 0)
  59                 return (0);
  60         /* make sure we can write */
  61         if (cantwrite(fp)) {
  62                 errno = EBADF;
  63                 return (EOF);
  64         }
  65
  66 #define MIN(a, b) ((a) < (b) ? (a) : (b))
  67 #define COPY(n)   (void)memcpy((void *)fp->_p, (void *)p, (size_t)(n))
  68
  69         iov = uio->uio_iov;
  70         p = iov->iov_base;
  71         len = iov->iov_len;
  72         iov++;
  73 #define GETIOV(extra_work) \
  74         while (len == 0) { \
  75                 extra_work; \
  76                 p = iov->iov_base; \
  77                 len = iov->iov_len; \
  78                 iov++; \
  79         }
  80         if (fp->_flags & __SNBF) {
  81                 /*
  82                  * Unbuffered: write up to BUFSIZ bytes at a time.
  83                  */
  84                 do {
  85                         GETIOV(;);
  86                         w = (*fp->_write)(fp->_cookie, p, MIN(len, BUFSIZ));
  87                         if (w <= 0)
  88                                 goto err;
  89                         p += w;
  90                         len -= w;
  91                 } while ((uio->uio_resid -= w) != 0);
  92         } else if ((fp->_flags & __SLBF) == 0) {
  93                 /*
  94                  * Fully buffered: fill partially full buffer, if any,
  95                  * and then flush.  If there is no partial buffer, write
  96                  * one _bf._size byte chunk directly (without copying).
  97                  *
  98                  * String output is a special case: write as many bytes
  99                  * as fit, but pretend we wrote everything.  This makes
 100                  * snprintf() return the number of bytes needed, rather
 101                  * than the number used, and avoids its write function
 102                  * (so that the write function can be invalid).
 103                  */
 104                 do {
 105                         GETIOV(;);
 106                         if ((fp->_flags & (__SALC | __SSTR)) ==
 107                             (__SALC | __SSTR) && fp->_w < len) {
 108                                 size_t blen = fp->_p - fp->_bf._base;
 109                                 unsigned char *_base;
 110                                 int _size;
 111
 112                                 /* Allocate space exponentially. */
 113                                 _size = fp->_bf._size;
 114                                 do {
 115                                         _size = (_size << 1) + 1;
 116                                 } while (_size < blen + len);
 117                                 _base = realloc(fp->_bf._base, _size + 1);
 118                                 if (_base == NULL)
 119                                         goto err;
 120                                 fp->_w += _size - fp->_bf._size;
 121                                 fp->_bf._base = _base;
 122                                 fp->_bf._size = _size;
 123                                 fp->_p = _base + blen;
 124                         }
 125                         w = fp->_w;
 126                         if (fp->_flags & __SSTR) {
 127                                 if (len < w)
 128                                         w = len;
 129                                 COPY(w);        /* copy MIN(fp->_w,len), */
 130                                 fp->_w -= w;
 131                                 fp->_p += w;
 132                                 w = len;        /* but pretend copied all */
 133                         } else if (fp->_p > fp->_bf._base && len > w) {
 134                                 /* fill and flush */
 135                                 COPY(w);
 136                                 /* fp->_w -= w; */ /* unneeded */
 137                                 fp->_p += w;
 138                                 if (ust_safe_fflush(fp))
 139                                         goto err;
 140                         } else if (len >= (w = fp->_bf._size)) {
 141                                 /* write directly */
 142                                 w = (*fp->_write)(fp->_cookie, p, w);
 143                                 if (w <= 0)
 144                                         goto err;
 145                         } else {
 146                                 /* fill and done */
 147                                 w = len;
 148                                 COPY(w);
 149                                 fp->_w -= w;
 150                                 fp->_p += w;
 151                         }
 152                         p += w;
 153                         len -= w;
 154                 } while ((uio->uio_resid -= w) != 0);
 155         } else {
 156                 /*
 157                  * Line buffered: like fully buffered, but we
 158                  * must check for newlines.  Compute the distance
 159                  * to the first newline (including the newline),
 160                  * or `infinity' if there is none, then pretend
 161                  * that the amount to write is MIN(len,nldist).
 162                  */
 163                 nlknown = 0;
 164                 nldist = 0;     /* XXX just to keep gcc happy */
 165                 do {
 166                         GETIOV(nlknown = 0);
 167                         if (!nlknown) {
 168                                 nl = memchr((void *)p, '\n', len);
 169                                 nldist = nl ? nl + 1 - p : len + 1;
 170                                 nlknown = 1;
 171                         }
 172                         s = MIN(len, nldist);
 173                         w = fp->_w + fp->_bf._size;
 174                         if (fp->_p > fp->_bf._base && s > w) {
 175                                 COPY(w);
 176                                 /* fp->_w -= w; */
 177                                 fp->_p += w;
 178                                 if (ust_safe_fflush(fp))
 179                                         goto err;
 180                         } else if (s >= (w = fp->_bf._size)) {
 181                                 w = (*fp->_write)(fp->_cookie, p, w);
 182                                 if (w <= 0)
 183                                         goto err;
 184                         } else {
 185                                 w = s;
 186                                 COPY(w);
 187                                 fp->_w -= w;
 188                                 fp->_p += w;
 189                         }
 190                         if ((nldist -= w) == 0) {
 191                                 /* copied the newline: flush and forget */
 192                                 if (ust_safe_fflush(fp))
 193                                         goto err;
 194                                 nlknown = 0;
 195                         }
 196                         p += w;
 197                         len -= w;
 198                 } while ((uio->uio_resid -= w) != 0);
 199         }
 200         return (0);
 201
 202 err:
 203         fp->_flags |= __SERR;
 204         return (EOF);
 205 }