lib/libc/stdio/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  * @(#)findfp.c 8.2 (Berkeley) 1/4/94
  37  * $FreeBSD: src/lib/libc/stdio/findfp.c,v 1.7.2.3 2001/08/17 02:56:31 peter Exp $
  38  * $DragonFly: src/lib/libc/stdio/findfp.c,v 1.11 2006/03/02 18:05:30 joerg Exp $
  39  */
  40
  41 #include <sys/param.h>
  42 #include <machine/atomic.h>
  43 #include <unistd.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47
  48 #include <spinlock.h>
  49
  50 #include <libc_private.h>
  51 #include "local.h"
  52 #include "priv_stdio.h"
  53
  54 int     __sdidinit;
  55
  56 #define NDYNAMIC 10             /* add ten more whenever necessary */
  57
  58 #define std(flags, file) \
  59         {{0,flags,file,0,0,0},{NULL, 0},__sF+file,__sclose,__sread,__sseek,__swrite, \
  60          {NULL,0}, 0, {0,0,0}, {0}, {NULL,0}, 0,0, NULL, PTHREAD_MUTEX_INITIALIZER, NULL, 0 }
  61 /*       p flags file r w _bf  cookie      close    read    seek    write */
  62 /*      _ub */
  63
  64                                 /* the usual - (stdin + stdout + stderr) */
  65 static FILE usual[FOPEN_MAX - 3];
  66 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  67
  68 FILE __sF[3] = {
  69         std(__SRD, STDIN_FILENO),               /* stdin */
  70         std(__SWR, STDOUT_FILENO),              /* stdout */
  71         std(__SWR|__SNBF, STDERR_FILENO)        /* stderr */
  72 };
  73
  74 /*
  75  * note: __sglue starts the walk chain for exit flushing and other things.
  76  */
  77 struct glue __sglue = { &uglue, 3, __sF };      /* GLOBAL, START OF LIST */
  78 static struct glue *lastglue = &uglue;
  79
  80 /*
  81  * The following kludge is done to ensure enough binary compatibility
  82  * with future versions of libc.  Or rather it allows us to work with
  83  * libraries that have been built with a newer libc that defines these
  84  * symbols and expects libc to provide them.  We only have need to support
  85  * i386 and alpha because they are the only "old" systems we have deployed.
  86  */
  87 FILE *__stdinp = &__sF[0];
  88 FILE *__stdoutp = &__sF[1];
  89 FILE *__stderrp = &__sF[2];
  90
  91 static struct glue *    moreglue (int);
  92
  93 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
  94 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
  95 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
  96
  97 #if NOT_YET
  98 #define SET_GLUE_PTR(ptr, val)  atomic_set_ptr(&(ptr), (uintptr_t)(val))
  99 #else
 100 #define SET_GLUE_PTR(ptr, val)  ptr = val
 101 #endif
 102
 103 static
 104 struct glue *
 105 moreglue(int n)
 106 {
 107         struct glue *g;
 108         static FILE empty;
 109         FILE *p;
 110
 111         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE));
 112         if (g == NULL)
 113                 return (NULL);
 114         p = (FILE *)ALIGN(g + 1);
 115         g->next = NULL;
 116         g->niobs = n;
 117         g->iobs = p;
 118         while (--n >= 0) {
 119                 *p = empty;
 120                 p++;
 121         }
 122         return (g);
 123 }
 124
 125 /*
 126  * Find a free FILE for fopen et al.
 127  */
 128 FILE *
 129 __sfp(void)
 130 {
 131         FILE *fp;
 132         int n;
 133         struct glue *g;
 134
 135         if (!__sdidinit)
 136                 __sinit();
 137         /*
 138          * The list must be locked because a FILE may be updated.
 139          */
 140         THREAD_LOCK();
 141         for (g = &__sglue; g != NULL; g = g->next) {
 142                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 143                         if (fp->pub._flags == 0)
 144                                 goto found;
 145         }
 146         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 147         if ((g = moreglue(NDYNAMIC)) == NULL)
 148                 return (NULL);
 149         THREAD_LOCK();          /* reacquire the lock */
 150         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 151         lastglue = g;           /* not atomic; only accessed when locked */
 152         fp = g->iobs;
 153 found:
 154         fp->pub._flags = 1;     /* reserve this slot; caller sets real flags */
 155         THREAD_UNLOCK();
 156         fp->pub._p = NULL;      /* no current pointer */
 157         fp->pub._w = 0;         /* nothing to read or write */
 158         fp->pub._r = 0;
 159         fp->_bf._base = NULL;   /* no buffer */
 160         fp->_bf._size = 0;
 161         fp->pub._lbfsize = 0;   /* not line buffered */
 162         fp->pub._fileno = -1;   /* no file */
 163 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 164         fp->_ub._base = NULL;   /* no ungetc buffer */
 165         fp->_ub._size = 0;
 166         fp->_lb._base = NULL;   /* no line buffer */
 167         fp->_lb._size = 0;
 168         fp->_up = NULL;
 169         fp->fl_mutex = PTHREAD_MUTEX_INITIALIZER;
 170         fp->fl_owner = NULL;
 171         fp->fl_count = 0;
 172         memset(WCIO_GET(fp), 0, sizeof(struct wchar_io_data));
 173         /* fp->_lock = NULL; */
 174         return (fp);
 175 }
 176
 177 /*
 178  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 179  * but documented historically for certain applications.  Bad applications.
 180  */
 181 void    f_prealloc(void);
 182
 183 __warn_references(f_prealloc,
 184         "warning: this program uses f_prealloc(), which is not recommended.");
 185
 186 void
 187 f_prealloc(void)
 188 {
 189         struct glue *g;
 190         int n;
 191
 192         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 193         /*
 194          * It should be safe to walk the list without locking it;
 195          * new nodes are only added to the end and none are ever
 196          * removed.
 197          */
 198         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 199                 /* void */;
 200         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 201                 THREAD_LOCK();
 202                 SET_GLUE_PTR(lastglue->next, g);
 203                 lastglue = g;
 204                 THREAD_UNLOCK();
 205         }
 206 }
 207
 208 /*
 209  * exit() calls _cleanup() through *__cleanup, set whenever we
 210  * open or buffer a file.  This chicanery is done so that programs
 211  * that do not use stdio need not link it all in.
 212  *
 213  * The name `_cleanup' is, alas, fairly well known outside stdio.
 214  */
 215 void
 216 _cleanup(void)
 217 {
 218         /* _fwalk(fclose); */
 219         _fwalk(__sflush);               /* `cheating' */
 220 }
 221
 222 /*
 223  * __sinit() is called whenever stdio's internal variables must be set up.
 224  */
 225 void
 226 __sinit(void)
 227 {
 228         THREAD_LOCK();
 229         if (__sdidinit == 0) {
 230                 /* Make sure we clean up on exit. */
 231                 __cleanup = _cleanup;           /* conservative */
 232                 __sdidinit = 1;
 233         }
 234         THREAD_UNLOCK();
 235 }