stdio/findfp-fbsd.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 <pthread.h>
  51 #include <spinlock.h>
  52
  53 #include "libc_private.h"
  54 #include "local.h"
  55 #include "glue.h"
  56
  57 int     __sdidinit;
  58
  59 #define NDYNAMIC 10             /* add ten more whenever necessary */
  60
  61 #define std(flags, file) \
  62         {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
  63          {0}, __sFX + file}
  64   /*     p r w flags file _bf z  cookie      close    read    seek    write */
  65   /*     _ub _extra */
  66 #define __sFXInit       {0, PTHREAD_MUTEX_INITIALIZER}
  67                                 /* the usual - (stdin + stdout + stderr) */
  68 static FILE usual[FOPEN_MAX - 3];
  69 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
  70 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  71
  72 static struct __sFILEX __sFX[3] = {__sFXInit, __sFXInit, __sFXInit};
  73
  74 /*
  75  * We can't make this 'static' until 6.0-current due to binary
  76  * compatibility concerns.  This also means we cannot change the
  77  * sizeof(FILE) until that time either and must continue to use the
  78  * __sFILEX stuff to add to FILE.
  79  */
  80 FILE __sF[3] = {
  81         std(__SRD, STDIN_FILENO),
  82         std(__SWR, STDOUT_FILENO),
  83         std(__SWR|__SNBF, STDERR_FILENO)
  84 };
  85
  86 /*
  87  * The following kludge is done to ensure enough binary compatibility
  88  * with future versions of libc.  Or rather it allows us to work with
  89  * libraries that have been built with a newer libc that defines these
  90  * symbols and expects libc to provide them.  We only have need to support
  91  * i386 and alpha because they are the only "old" systems we have deployed.
  92  */
  93 FILE *__stdinp = &__sF[0];
  94 FILE *__stdoutp = &__sF[1];
  95 FILE *__stderrp = &__sF[2];
  96
  97 struct glue __sglue = { &uglue, 3, __sF };
  98 static struct glue *lastglue = &uglue;
  99
 100 static struct glue *    moreglue(int);
 101
 102 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
 103 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
 104 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
 105
 106 #if NOT_YET
 107 #define SET_GLUE_PTR(ptr, val)  atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
 108 #else
 109 #define SET_GLUE_PTR(ptr, val)  ptr = val
 110 #endif
 111
 112 static struct glue *
 113 moreglue(n)
 114         int n;
 115 {
 116         struct glue *g;
 117         static FILE empty;
 118         static struct __sFILEX emptyx = __sFXInit;
 119         FILE *p;
 120         struct __sFILEX *fx;
 121
 122         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
 123             n * sizeof(struct __sFILEX));
 124         if (g == NULL)
 125                 return (NULL);
 126         p = (FILE *)ALIGN(g + 1);
 127         fx = (struct __sFILEX *)&p[n];
 128         g->next = NULL;
 129         g->niobs = n;
 130         g->iobs = p;
 131         while (--n >= 0) {
 132                 *p = empty;
 133                 p->_extra = fx;
 134                 *p->_extra = emptyx;
 135                 p++, fx++;
 136         }
 137         return (g);
 138 }
 139
 140 /*
 141  * Find a free FILE for fopen et al.
 142  */
 143 FILE *
 144 __sfp()
 145 {
 146         FILE    *fp;
 147         int     n;
 148         struct glue *g;
 149
 150         if (!__sdidinit)
 151                 __sinit();
 152         /*
 153          * The list must be locked because a FILE may be updated.
 154          */
 155         THREAD_LOCK();
 156         for (g = &__sglue; g != NULL; g = g->next) {
 157                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 158                         if (fp->_flags == 0)
 159                                 goto found;
 160         }
 161         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 162         if ((g = moreglue(NDYNAMIC)) == NULL)
 163                 return (NULL);
 164         THREAD_LOCK();          /* reacquire the lock */
 165         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 166         lastglue = g;           /* not atomic; only accessed when locked */
 167         fp = g->iobs;
 168 found:
 169         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 170         THREAD_UNLOCK();
 171         fp->_p = NULL;          /* no current pointer */
 172         fp->_w = 0;             /* nothing to read or write */
 173         fp->_r = 0;
 174         fp->_bf._base = NULL;   /* no buffer */
 175         fp->_bf._size = 0;
 176         fp->_lbfsize = 0;       /* not line buffered */
 177         fp->_file = -1;         /* no file */
 178 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 179         fp->_ub._base = NULL;   /* no ungetc buffer */
 180         fp->_ub._size = 0;
 181         fp->_lb._base = NULL;   /* no line buffer */
 182         fp->_lb._size = 0;
 183 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 184         fp->_extra->fl_mutex = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 185         fp->_extra->orientation = 0;
 186         memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
 187         return (fp);
 188 }
 189
 190 /*
 191  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 192  * but documented historically for certain applications.  Bad applications.
 193  */
 194 __warn_references(f_prealloc,
 195         "warning: this program uses f_prealloc(), which is not recommended.");
 196
 197 void
 198 f_prealloc()
 199 {
 200         struct glue *g;
 201         int n;
 202
 203         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 204         /*
 205          * It should be safe to walk the list without locking it;
 206          * new nodes are only added to the end and none are ever
 207          * removed.
 208          */
 209         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 210                 /* void */;
 211         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 212                 THREAD_LOCK();
 213                 SET_GLUE_PTR(lastglue->next, g);
 214                 lastglue = g;
 215                 THREAD_UNLOCK();
 216         }
 217 }
 218
 219 /*
 220  * exit() calls _cleanup() through *__cleanup, set whenever we
 221  * open or buffer a file.  This chicanery is done so that programs
 222  * that do not use stdio need not link it all in.
 223  *
 224  * The name `_cleanup' is, alas, fairly well known outside stdio.
 225  */
 226 void
 227 _cleanup()
 228 {
 229         /* (void) _fwalk(fclose); */
 230         (void) _fwalk(__sflush);                /* `cheating' */
 231 }
 232
 233 /*
 234  * __sinit() is called whenever stdio's internal variables must be set up.
 235  */
 236 void
 237 __sinit()
 238 {
 239         int     i;
 240
 241         THREAD_LOCK();
 242         if (__sdidinit == 0) {
 243                 /* Set _extra for the usual suspects. */
 244                 for (i = 0; i < FOPEN_MAX - 3; i++)
 245                         usual[i]._extra = &usual_extra[i];
 246
 247                 /* Make sure we clean up on exit. */
 248                 __cleanup = _cleanup;           /* conservative */
 249                 __sdidinit = 1;
 250         }
 251         THREAD_UNLOCK();
 252 }