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 #include <libkern/OSAtomic.h>
  50 #include <errno.h>
  51
  52 #include <pthread.h>
  53 #include <spinlock.h>
  54
  55 #include "libc_private.h"
  56 #include "local.h"
  57 #include "glue.h"
  58
  59 int     __sdidinit;
  60
  61 #define NDYNAMIC 10             /* add ten more whenever necessary */
  62
  63 #define std(flags, file) \
  64         {0,0,0,flags,file,{0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
  65          {0}, __sFX + file}
  66   /*     p r w flags file _bf z  cookie      close    read    seek    write */
  67   /*     _ub _extra */
  68 #define __sFXInit       {0, PTHREAD_MUTEX_INITIALIZER}
  69   /* set counted */
  70 #define __sFXInit3      {0, PTHREAD_MUTEX_INITIALIZER, 0, 0, 0, 1}
  71                                 /* the usual - (stdin + stdout + stderr) */
  72
  73 static int __scounted;          /* streams counted against STREAM_MAX */
  74 static int __stream_max;
  75
  76 static FILE usual[FOPEN_MAX - 3];
  77 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
  78 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  79
  80 static struct __sFILEX __sFX[3] = {__sFXInit3, __sFXInit3, __sFXInit3};
  81
  82 /*
  83  * We can't make this 'static' until 6.0-current due to binary
  84  * compatibility concerns.  This also means we cannot change the
  85  * sizeof(FILE) until that time either and must continue to use the
  86  * __sFILEX stuff to add to FILE.
  87  */
  88 FILE __sF[3] = {
  89         std(__SRD, STDIN_FILENO),
  90         std(__SWR, STDOUT_FILENO),
  91         std(__SWR|__SNBF, STDERR_FILENO)
  92 };
  93
  94 /*
  95  * The following kludge is done to ensure enough binary compatibility
  96  * with future versions of libc.  Or rather it allows us to work with
  97  * libraries that have been built with a newer libc that defines these
  98  * symbols and expects libc to provide them.  We only have need to support
  99  * i386 and alpha because they are the only "old" systems we have deployed.
 100  */
 101 FILE *__stdinp = &__sF[0];
 102 FILE *__stdoutp = &__sF[1];
 103 FILE *__stderrp = &__sF[2];
 104
 105 struct glue __sglue = { &uglue, 3, __sF };
 106 static struct glue *lastglue = &uglue;
 107
 108 static struct glue *    moreglue(int);
 109
 110 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
 111 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
 112 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
 113
 114 #if NOT_YET
 115 #define SET_GLUE_PTR(ptr, val)  atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
 116 #else
 117 #define SET_GLUE_PTR(ptr, val)  ptr = val
 118 #endif
 119
 120 static struct glue *
 121 moreglue(n)
 122         int n;
 123 {
 124         struct glue *g;
 125         static FILE empty;
 126         static struct __sFILEX emptyx = __sFXInit;
 127         FILE *p;
 128         struct __sFILEX *fx;
 129
 130         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
 131             n * sizeof(struct __sFILEX));
 132         if (g == NULL)
 133                 return (NULL);
 134         p = (FILE *)ALIGN(g + 1);
 135         fx = (struct __sFILEX *)&p[n];
 136         g->next = NULL;
 137         g->niobs = n;
 138         g->iobs = p;
 139         while (--n >= 0) {
 140                 *p = empty;
 141                 p->_extra = fx;
 142                 *p->_extra = emptyx;
 143                 p++, fx++;
 144         }
 145         return (g);
 146 }
 147
 148 /*
 149  * Find a free FILE for fopen et al.
 150  */
 151 FILE *
 152 __sfp(int count)
 153 {
 154         FILE    *fp;
 155         int     n;
 156         struct glue *g;
 157
 158         if (!__sdidinit)
 159                 __sinit();
 160
 161         if (count) {
 162                 if (__scounted >= __stream_max) {
 163                         THREAD_UNLOCK();
 164                         errno = EMFILE;
 165                         return NULL;
 166                 }
 167                 OSAtomicIncrement32(&__scounted);
 168         }
 169         /*
 170          * The list must be locked because a FILE may be updated.
 171          */
 172         THREAD_LOCK();
 173         for (g = &__sglue; g != NULL; g = g->next) {
 174                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 175                         if (fp->_flags == 0)
 176                                 goto found;
 177         }
 178         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 179         if ((g = moreglue(NDYNAMIC)) == NULL)
 180                 return (NULL);
 181         THREAD_LOCK();          /* reacquire the lock */
 182         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 183         lastglue = g;           /* not atomic; only accessed when locked */
 184         fp = g->iobs;
 185 found:
 186         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 187         THREAD_UNLOCK();
 188         fp->_p = NULL;          /* no current pointer */
 189         fp->_w = 0;             /* nothing to read or write */
 190         fp->_r = 0;
 191         fp->_bf._base = NULL;   /* no buffer */
 192         fp->_bf._size = 0;
 193         fp->_lbfsize = 0;       /* not line buffered */
 194         fp->_file = -1;         /* no file */
 195 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 196         fp->_ub._base = NULL;   /* no ungetc buffer */
 197         fp->_ub._size = 0;
 198         fp->_lb._base = NULL;   /* no line buffer */
 199         fp->_lb._size = 0;
 200 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 201         fp->_extra->fl_mutex = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;
 202         fp->_extra->orientation = 0;
 203         fp->_extra->counted = count ? 1 : 0;
 204         memset(&fp->_extra->mbstate, 0, sizeof(mbstate_t));
 205         return (fp);
 206 }
 207
 208 /*
 209  * Mark as free and update count as needed
 210  */
 211 __private_extern__ void
 212 __sfprelease(FILE *fp)
 213 {
 214         if (fp->_extra->counted) {
 215                 OSAtomicDecrement32(&__scounted);
 216                 fp->_extra->counted = 0;
 217         }
 218         fp->_flags = 0;
 219 }
 220
 221 /*
 222  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 223  * but documented historically for certain applications.  Bad applications.
 224  */
 225 __warn_references(f_prealloc,
 226         "warning: this program uses f_prealloc(), which is not recommended.");
 227
 228 void
 229 f_prealloc()
 230 {
 231         struct glue *g;
 232         int n;
 233
 234         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 235         /*
 236          * It should be safe to walk the list without locking it;
 237          * new nodes are only added to the end and none are ever
 238          * removed.
 239          */
 240         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 241                 /* void */;
 242         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 243                 THREAD_LOCK();
 244                 SET_GLUE_PTR(lastglue->next, g);
 245                 lastglue = g;
 246                 THREAD_UNLOCK();
 247         }
 248 }
 249
 250 /*
 251  * exit() calls _cleanup() through *__cleanup, set whenever we
 252  * open or buffer a file.  This chicanery is done so that programs
 253  * that do not use stdio need not link it all in.
 254  *
 255  * The name `_cleanup' is, alas, fairly well known outside stdio.
 256  */
 257 void
 258 _cleanup()
 259 {
 260         /* (void) _fwalk(fclose); */
 261         (void) _fwalk(__sflush);                /* `cheating' */
 262 }
 263
 264 /*
 265  * __sinit() is called whenever stdio's internal variables must be set up.
 266  */
 267 void
 268 __sinit()
 269 {
 270         int     i;
 271
 272         THREAD_LOCK();
 273         if (__sdidinit == 0) {
 274                 /* Set _extra for the usual suspects. */
 275                 for (i = 0; i < FOPEN_MAX - 3; i++)
 276                         usual[i]._extra = &usual_extra[i];
 277
 278                 /* Make sure we clean up on exit. */
 279                 __cleanup = _cleanup;           /* conservative */
 280                 __sdidinit = 1;
 281                 __stream_max = sysconf(_SC_STREAM_MAX);
 282                 __scounted = 3;                 /* std{in,out,err} already exists */
 283         }
 284         THREAD_UNLOCK();
 285 }