cde/programs/dtksh/ksh93/src/lib/libast/sfio/sfsetbuf.c

   1 /* $XConsortium: sfsetbuf.c /main/3 1995/11/01 18:35:58 rswiston $ */
   2 /***************************************************************
   3 *                                                              *
   4 *                      AT&T - PROPRIETARY                      *
   5 *                                                              *
   6 *         THIS IS PROPRIETARY SOURCE CODE LICENSED BY          *
   7 *                          AT&T CORP.                          *
   8 *                                                              *
   9 *                Copyright (c) 1995 AT&T Corp.                 *
  10 *                     All Rights Reserved                      *
  11 *                                                              *
  12 *           This software is licensed by AT&T Corp.            *
  13 *       under the terms and conditions of the license in       *
  14 *       http://www.research.att.com/orgs/ssr/book/reuse        *
  15 *                                                              *
  16 *               This software was created by the               *
  17 *           Software Engineering Research Department           *
  18 *                    AT&T Bell Laboratories                    *
  19 *                                                              *
  20 *               For further information contact                *
  21 *                     gsf@research.att.com                     *
  22 *                                                              *
  23 ***************************************************************/
  24 #include        "sfhdr.h"
  25
  26 /*      Set a (new) buffer for a stream.
  27 **      If size < 0, it is assigned a suitable value depending on the
  28 **      kind of stream. The actual buffer size allocated is dependent
  29 **      on how much memory is available.
  30 **
  31 **      Written by Kiem-Phong Vo (06/27/90)
  32 */
  33
  34 #if __STD_C
  35 Void_t* sfsetbuf(reg Sfio_t* f, reg Void_t* buf, reg int size)
  36 #else
  37 Void_t* sfsetbuf(f,buf,size)
  38 reg Sfio_t*     f;      /* stream to be buffered */
  39 reg Void_t*     buf;    /* new buffer */
  40 reg int         size;   /* buffer size, -1 for default size */
  41 #endif
  42 {
  43         reg int         sf_malloc;
  44         struct stat     st;
  45         reg uchar*      obuf;
  46         reg Sfdisc_t*   disc;
  47         reg int         osize, oflags, blksize;
  48         reg int         justopen, init, okmmap, local;
  49
  50         GETLOCAL(f,local);
  51
  52         if(size == 0 && buf)
  53         {       /* special case to get buffer info */
  54                 _Sfi = (f->flags&SF_MMAP) ? (f->endb-f->data) : f->size;
  55                 return (Void_t*)f->data;
  56         }
  57
  58         /* cleanup actions already done, don't allow write buffering any more */
  59         if(_Sfexiting && !(f->flags&SF_STRING) && (f->mode&SF_WRITE))
  60                 return NIL(Void_t*);
  61
  62         if((init = f->mode&SF_INIT) )
  63         {       if(!f->pool && _sfsetpool(f) < 0)
  64                         return NIL(Void_t*);
  65         }
  66         else if((f->mode&SF_RDWR) != SFMODE(f,local) && _sfmode(f,0,local) < 0)
  67                 return NIL(Void_t*);
  68
  69         justopen = f->mode&SF_OPEN;
  70         f->mode &= ~SF_OPEN;
  71         if(init)
  72                 f->mode = (f->mode&SF_RDWR)|SF_LOCK;
  73         else
  74         {       int     rv;
  75
  76                 /* make sure there is no hidden read data */
  77                 if((f->flags&(SF_PROCESS|SF_READ)) == (SF_PROCESS|SF_READ) &&
  78                    (f->mode&SF_WRITE) && _sfmode(f,SF_READ,local) < 0)
  79                         return NIL(Void_t*);
  80
  81                 /* synchronize first */
  82                 SFLOCK(f,local); rv = SFSYNC(f); SFOPEN(f,local);
  83                 if(rv < 0)
  84                         return NIL(Void_t*);
  85
  86                 /* turn off the SF_SYNCED bit because buffer is changing */
  87                 f->mode &= ~SF_SYNCED;
  88         }
  89
  90         SFLOCK(f,local);
  91
  92         blksize = 0;
  93         oflags = f->flags;
  94
  95         /* see if memory mapping is possible (see sfwrite for SF_BOTH) */
  96         okmmap = (buf || (f->flags&SF_STRING) || (f->flags&SF_RDWR) == SF_RDWR) ? 0 : 1;
  97
  98         /* save old buffer info */
  99 #ifdef MAP_TYPE
 100         if(f->flags&SF_MMAP)
 101         {       if(f->data)
 102                 {       (void)munmap((caddr_t)f->data,f->endb-f->data);
 103                         f->data = NIL(uchar*);
 104                 }
 105         } else
 106 #endif
 107         if(f->data == f->tiny)
 108         {       f->data = NIL(uchar*);
 109                 f->size = 0;
 110         }
 111         obuf  = f->data;
 112         osize = f->size;
 113
 114         f->flags &= ~(SF_MMAP|SF_MALLOC);
 115
 116         /* pure read/string streams must have a valid string */
 117         if((f->flags&(SF_RDWR|SF_STRING)) == SF_RDSTR && (size < 0 || !buf))
 118                 size = 0;
 119
 120         /* set disc to the first discipline with a seekf */
 121         for(disc = f->disc; disc; disc = disc->disc)
 122                 if(disc->seekf)
 123                         break;
 124
 125         if((init || local) && !(f->flags&SF_STRING))
 126         {       /* ASSERT(f->file >= 0) */
 127                 st.st_mode = 0;
 128
 129                 /* if has discipline, set size by discipline if possible */
 130                 if(disc)
 131                 {       if((f->here = SFSK(f,0L,1,disc)) < 0)
 132                                 goto unseekable;
 133                         else
 134                         {       f->extent = SFSK(f,0L,2,disc);
 135                                 (void)SFSK(f,f->here,0,disc);
 136                                 goto setbuf;
 137                         }
 138                 }
 139
 140                 /* get file descriptor status */
 141                 if(fstat(f->file,&st) < 0)
 142                         goto unseekable;
 143
 144 #if _stat_blksize       /* preferred io block size */
 145                 if((blksize = (int)st.st_blksize) > 0)
 146                         while((blksize + (int)st.st_blksize) <= SF_PAGE)
 147                                 blksize += (int)st.st_blksize;
 148 #endif
 149                 if(S_ISREG(st.st_mode) || S_ISDIR(st.st_mode))
 150                         f->here = justopen ? 0L : SFSK(f,0L,1,f->disc);
 151                 else    f->here = -1;
 152                 if(f->here >= 0)
 153                 {       /* normal file, set file extent */
 154                         f->extent = (long)st.st_size;
 155
 156                         /* don't MMAP directories */
 157                         if(S_ISDIR(st.st_mode) )
 158                                 okmmap = 0;
 159
 160                         /* seekable std-devices are share-public by default */
 161                         if(f == sfstdin || f == sfstdout || f == sfstderr)
 162                                 f->flags |= SF_SHARE|SF_PUBLIC;
 163                 }
 164                 else
 165                 {
 166                 unseekable:
 167                         f->extent = -1L;
 168                         f->here = 0L;
 169
 170                         if(init)
 171                         {       /* pipe std-devices are automatically shared */
 172                                 if(S_ISFIFO(st.st_mode) )
 173                                 {       if(f == sfstdin || f == sfstdout || f == sfstderr)                                              f->flags |= SF_SHARE;
 174                                 }
 175                                 else if(S_ISCHR(st.st_mode) )
 176                                 {       /* set line mode for terminals */
 177                                         if(!(f->flags&SF_LINE) && isatty(f->file))
 178                                                 f->flags |= SF_LINE;
 179
 180                                         /* special case /dev/null for efficiency */
 181                                         else
 182                                         {       reg int dev, ino;
 183                                                 dev = (int)st.st_dev;
 184                                                 ino = (int)st.st_ino;
 185                                                 if(stat(DEVNULL,&st) >= 0 &&
 186                                                    dev == st.st_dev && ino == st.st_ino)
 187                                                 {       SFSETNULL(f);
 188                                                         blksize = 1024;
 189                                                 }
 190                                         }
 191                                 }
 192
 193                                 /* initialize save input buffer for r+w streams */
 194                                 if(!(f->flags&SF_PROCESS) && (f->flags&SF_BOTH) )
 195                                         (void)_sfpopen(f,-1,-1);
 196                         }
 197                 }
 198
 199                 /* set page size, this is also the desired default buffer size */
 200 #if _lib_getpagesize
 201                 if(_Sfpage <= 0)
 202                         _Sfpage = (int)getpagesize();
 203 #endif
 204                 if(_Sfpage <= 0)
 205                         _Sfpage = SF_PAGE;
 206         }
 207
 208 #ifdef MAP_TYPE
 209         if(okmmap && size && (f->mode&SF_READ) && f->extent >= 0 )
 210         {       /* see if we can try memory mapping */
 211                 if(!disc)
 212                         for(disc = f->disc; disc; disc = disc->disc)
 213                                 if(disc->readf)
 214                                         break;
 215                 if(!disc)
 216                 {       f->flags |= SF_MMAP;
 217                         if(size < 0)
 218                         {       size = (blksize > 0 ? blksize : _Sfpage) * SF_NMAP;
 219                                 size = ((size+_Sfpage-1)/_Sfpage)*_Sfpage;
 220                         }
 221                 }
 222         }
 223 #endif
 224
 225         /* get buffer space */
 226 setbuf:
 227         if(size < 0)
 228         {       /* define a default size suitable for block transfer */
 229                 if(init && osize > 0)
 230                         size = osize;
 231                 else if(f == sfstderr && (f->mode&SF_WRITE))
 232                         size = 0;
 233                 else if((f->flags&SF_STRING) || f->extent < 0)
 234                         size = SF_GRAIN;
 235                 else if(blksize > 0)
 236                         size = blksize;
 237                 else if((f->flags&(SF_READ|SF_BOTH)) == SF_READ &&
 238                         f->extent > 0 && f->extent < _Sfpage )
 239                         size = (((int)f->extent + SF_GRAIN-1)/SF_GRAIN)*SF_GRAIN;
 240                 else    size = _Sfpage;
 241
 242                 buf = NIL(Void_t*);
 243         }
 244
 245         sf_malloc = 0;
 246         if(size > 0 && !buf && !(f->flags&SF_MMAP))
 247         {       /* try to allocate a buffer */
 248                 if(obuf && size == osize)
 249                 {       buf = (Void_t*)obuf;
 250                         obuf = NIL(uchar*);
 251                         sf_malloc = (oflags&SF_MALLOC);
 252                 }
 253                 if(!buf)
 254                 {       /* do allocation */
 255                         while(!(buf = (Void_t*) malloc(size)) && size > 0)
 256                                 size /= 2;
 257                         if(size > 0)
 258                                 sf_malloc = SF_MALLOC;
 259                 }
 260         }
 261
 262         if(size == 0 && !(f->flags&(SF_MMAP|SF_STRING)) && (f->mode&SF_READ))
 263         {       /* use the internal buffer */
 264                 size = sizeof(f->tiny);
 265                 buf = (Void_t*)f->tiny;
 266         }
 267
 268         /* set up new buffer */
 269         f->size = size;
 270         f->next = f->data = f->endr = f->endw = (uchar*)buf;
 271         f->endb = (f->mode&SF_READ) ? f->data : f->data+size;
 272         if(f->flags&SF_STRING)
 273         {       /* these fields are used to test actual size - see sfseek() */
 274                 f->extent = (!sf_malloc && (f->flags&(SF_BOTH|SF_READ))) ? size : 0;
 275                 f->here = 0L;
 276
 277                 /* read+string stream should have all data available */
 278                 if((f->mode&SF_READ) && !sf_malloc)
 279                         f->endb = f->data+size;
 280         }
 281
 282         f->flags = (f->flags & ~SF_MALLOC)|sf_malloc;
 283
 284         if(obuf && obuf != f->data && osize > 0 && (oflags&SF_MALLOC))
 285         {       free((Void_t*)obuf);
 286                 obuf = NIL(uchar*);
 287         }
 288
 289         _Sfi = obuf ? osize : 0;
 290
 291         SFOPEN(f,local);
 292
 293         return (Void_t*)obuf;
 294 }