stdio/FreeBSD/findfp.c

   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. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)findfp.c    8.2 (Berkeley) 1/4/94";
  39 #endif /* LIBC_SCCS and not lint */
  40 #include <sys/cdefs.h>
  41 __FBSDID("$FreeBSD: src/lib/libc/stdio/findfp.c,v 1.29 2004/05/22 15:19:41 tjr Exp $");
  42
  43 #include <sys/param.h>
  44 #include <machine/atomic.h>
  45 #include <unistd.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49
  50 #include <spinlock.h>
  51
  52 #include "libc_private.h"
  53 #include "local.h"
  54 #include "glue.h"
  55
  56 int     __sdidinit;
  57
  58 #define NDYNAMIC 10             /* add ten more whenever necessary */
  59
  60 #define std(flags, file) \
  61         {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
  62          {0}, __sFX + file}
  63   /*     p r w flags file _bf z  cookie      close    read    seek    write */
  64   /*     _ub _extra */
  65                                 /* the usual - (stdin + stdout + stderr) */
  66 static FILE usual[FOPEN_MAX - 3];
  67 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
  68 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  69
  70 static struct __sFILEX __sFX[3];
  71
  72 /*
  73  * We can't make this 'static' until 6.0-current due to binary
  74  * compatibility concerns.  This also means we cannot change the
  75  * sizeof(FILE) until that time either and must continue to use the
  76  * __sFILEX stuff to add to FILE.
  77  */
  78 FILE __sF[3] = {
  79         std(__SRD, STDIN_FILENO),
  80         std(__SWR, STDOUT_FILENO),
  81         std(__SWR|__SNBF, STDERR_FILENO)
  82 };
  83
  84 /*
  85  * The following kludge is done to ensure enough binary compatibility
  86  * with future versions of libc.  Or rather it allows us to work with
  87  * libraries that have been built with a newer libc that defines these
  88  * symbols and expects libc to provide them.  We only have need to support
  89  * i386 and alpha because they are the only "old" systems we have deployed.
  90  */
  91 FILE *__stdinp = &__sF[0];
  92 FILE *__stdoutp = &__sF[1];
  93 FILE *__stderrp = &__sF[2];
  94
  95 struct glue __sglue = { &uglue, 3, __sF };
  96 static struct glue *lastglue = &uglue;
  97
  98 static struct glue *    moreglue(int);
  99
 100 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
 101 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
 102 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
 103
 104 #if NOT_YET
 105 #define SET_GLUE_PTR(ptr, val)  atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
 106 #else
 107 #define SET_GLUE_PTR(ptr, val)  ptr = val
 108 #endif
 109
 110 static struct glue *
 111 moreglue(n)
 112         int n;
 113 {
 114         struct glue *g;
 115         static FILE empty;
 116         static struct __sFILEX emptyx;
 117         FILE *p;
 118         struct __sFILEX *fx;
 119
 120         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
 121             n * sizeof(struct __sFILEX));
 122         if (g == NULL)
 123                 return (NULL);
 124         p = (FILE *)ALIGN(g + 1);
 125         fx = (struct __sFILEX *)&p[n];
 126         g->next = NULL;
 127         g->niobs = n;
 128         g->iobs = p;
 129         while (--n >= 0) {
 130                 *p = empty;
 131                 p->_extra = fx;
 132                 *p->_extra = emptyx;
 133                 p++, fx++;
 134         }
 135         return (g);
 136 }
 137
 138 /*
 139  * Find a free FILE for fopen et al.
 140  */
 141 FILE *
 142 __sfp()
 143 {
 144         FILE    *fp;
 145         int     n;
 146         struct glue *g;
 147
 148         if (!__sdidinit)
 149                 __sinit();
 150         /*
 151          * The list must be locked because a FILE may be updated.
 152          */
 153         THREAD_LOCK();
 154         for (g = &__sglue; g != NULL; g = g->next) {
 155                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 156                         if (fp->_flags == 0)
 157                                 goto found;
 158         }
 159         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 160         if ((g = moreglue(NDYNAMIC)) == NULL)
 161                 return (NULL);
 162         THREAD_LOCK();          /* reacquire the lock */
 163         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 164         lastglue = g;           /* not atomic; only accessed when locked */
 165         fp = g->iobs;
 166 found:
 167         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 168         THREAD_UNLOCK();
 169         fp->_p = NULL;          /* no current pointer */
 170         fp->_w = 0;             /* nothing to read or write */
 171         fp->_r = 0;
 172         fp->_bf._base = NULL;   /* no buffer */
 173         fp->_bf._size = 0;
 174         fp->_lbfsize = 0;       /* not line buffered */
 175         fp->_file = -1;         /* no file */
 176 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 177         fp->_ub._base = NULL;   /* no ungetc buffer */
 178         fp->_ub._size = 0;
 179         fp->_lb._base = NULL;   /* no line buffer */
 180         fp->_lb._size = 0;
 181 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 182         fp->_extra->orientation = 0;
 183         memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
 184         return (fp);
 185 }
 186
 187 /*
 188  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 189  * but documented historically for certain applications.  Bad applications.
 190  */
 191 __warn_references(f_prealloc,
 192         "warning: this program uses f_prealloc(), which is not recommended.");
 193
 194 void
 195 f_prealloc()
 196 {
 197         struct glue *g;
 198         int n;
 199
 200         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 201         /*
 202          * It should be safe to walk the list without locking it;
 203          * new nodes are only added to the end and none are ever
 204          * removed.
 205          */
 206         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 207                 /* void */;
 208         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 209                 THREAD_LOCK();
 210                 SET_GLUE_PTR(lastglue->next, g);
 211                 lastglue = g;
 212                 THREAD_UNLOCK();
 213         }
 214 }
 215
 216 /*
 217  * exit() calls _cleanup() through *__cleanup, set whenever we
 218  * open or buffer a file.  This chicanery is done so that programs
 219  * that do not use stdio need not link it all in.
 220  *
 221  * The name `_cleanup' is, alas, fairly well known outside stdio.
 222  */
 223 void
 224 _cleanup()
 225 {
 226         /* (void) _fwalk(fclose); */
 227         (void) _fwalk(__sflush);                /* `cheating' */
 228 }
 229
 230 /*
 231  * __sinit() is called whenever stdio's internal variables must be set up.
 232  */
 233 void
 234 __sinit()
 235 {
 236         int     i;
 237
 238         THREAD_LOCK();
 239         if (__sdidinit == 0) {
 240                 /* Set _extra for the usual suspects. */
 241                 for (i = 0; i < FOPEN_MAX - 3; i++)
 242                         usual[i]._extra = &usual_extra[i];
 243
 244                 /* Make sure we clean up on exit. */
 245                 __cleanup = _cleanup;           /* conservative */
 246                 __sdidinit = 1;
 247         }
 248         THREAD_UNLOCK();
 249 }