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  * 4. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 static char sccsid[] = "@(#)findfp.c    8.2 (Berkeley) 1/4/94";
  35 #endif /* LIBC_SCCS and not lint */
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD: src/lib/libc/stdio/findfp.c,v 1.34 2009/12/05 19:31:38 ed Exp $");
  38
  39 #include <TargetConditionals.h>
  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 #include <libkern/OSAtomic.h>
  48 #include <errno.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 pthread_once_t  __sdidinit;
  58
  59 #if !TARGET_OS_EMBEDDED
  60 #define NDYNAMIC 10             /* add ten more whenever necessary */
  61 #else
  62 #define NDYNAMIC 1              /* add one at a time on embedded */
  63 #endif
  64
  65 #define std(flags, file) {              \
  66         ._flags = (flags),              \
  67         ._file = (file),                \
  68         ._cookie = __sF + (file),       \
  69         ._close = __sclose,             \
  70         ._read = __sread,               \
  71         ._seek = __sseek,               \
  72         ._write = __swrite,             \
  73         ._extra = __sFX + file,         \
  74 }
  75   /* set counted */
  76 #define __sFXInit3      {.fl_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER, .counted = 1}
  77
  78 static int __scounted;          /* streams counted against STREAM_MAX */
  79 static int __stream_max;
  80
  81 #if !TARGET_OS_EMBEDDED
  82 /* usual and usual_extra are data pigs. See 7929728. For embedded we should
  83  * always allocate dynamically, and probably should for desktop too. */
  84                                 /* the usual - (stdin + stdout + stderr) */
  85 static FILE usual[FOPEN_MAX - 3];
  86 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
  87 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  88 #endif /* !TARGET_OS_EMBEDDED */
  89
  90 static struct __sFILEX __sFX[3] = {__sFXInit3, __sFXInit3, __sFXInit3};
  91
  92 /*
  93  * We can't make this 'static' due to binary compatibility concerns.
  94  * This also means we cannot change the sizeof(FILE) and must continue to
  95  * use the __sFILEX stuff to add to FILE.
  96  */
  97 FILE __sF[3] = {
  98         std(__SRD, STDIN_FILENO),
  99         std(__SWR, STDOUT_FILENO),
 100         std(__SWR|__SNBF, STDERR_FILENO)
 101 };
 102
 103 FILE *__stdinp = &__sF[0];
 104 FILE *__stdoutp = &__sF[1];
 105 FILE *__stderrp = &__sF[2];
 106
 107 #if !TARGET_OS_EMBEDDED
 108 struct glue __sglue = { &uglue, 3, __sF };
 109 static struct glue *lastglue = &uglue;
 110 #else
 111 struct glue __sglue = { NULL, 3, __sF };
 112 static struct glue *lastglue = &__sglue;
 113 #endif
 114
 115 static struct glue *    moreglue(int);
 116
 117 static pthread_mutex_t filelist_lock = PTHREAD_MUTEX_INITIALIZER;
 118 #define FILELIST_LOCK() do { pthread_mutex_lock(&filelist_lock); } while(0)
 119 #define FILELIST_UNLOCK()       do { pthread_mutex_unlock(&filelist_lock); } while(0)
 120
 121 static struct glue *
 122 moreglue(n)
 123         int n;
 124 {
 125         struct glue *g;
 126         FILE *p;
 127         struct __sFILEX *fx;
 128
 129         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
 130             n * sizeof(struct __sFILEX));
 131         if (g == NULL)
 132                 return (NULL);
 133         p = (FILE *)ALIGN(g + 1);
 134         fx = (struct __sFILEX *)&p[n];
 135         g->next = NULL;
 136         g->niobs = n;
 137         g->iobs = p;
 138
 139         while (--n >= 0) {
 140                 bzero(p, sizeof(*p));
 141                 p->_extra = fx;
 142                 INITEXTRA(p);
 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         pthread_once(&__sdidinit, __sinit);
 159
 160         if (count) {
 161                 if (__scounted >= __stream_max) {
 162                         errno = EMFILE;
 163                         return NULL;
 164                 }
 165                 OSAtomicIncrement32(&__scounted);
 166         }
 167         /*
 168          * The list must be locked because a FILE may be updated.
 169          */
 170         FILELIST_LOCK();
 171         for (g = &__sglue; g != NULL; g = g->next) {
 172                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 173                         if (fp->_flags == 0)
 174                                 goto found;
 175         }
 176         FILELIST_UNLOCK();      /* don't hold lock while malloc()ing. */
 177         if ((g = moreglue(NDYNAMIC)) == NULL)
 178                 return (NULL);
 179         FILELIST_LOCK();                /* reacquire the lock */
 180         lastglue->next = g; /* atomically append glue to list */
 181         lastglue = g;           /* not atomic; only accessed when locked */
 182         fp = g->iobs;
 183 found:
 184         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 185         FILELIST_UNLOCK();
 186
 187         /* _flags = 1 means the FILE* is in use, and this thread owns the object while it is being initialized */
 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         INITEXTRA(fp);
 202         fp->_extra->counted = count ? 1 : 0;
 203         return (fp);
 204 }
 205
 206 /*
 207  * Mark as free and update count as needed
 208  */
 209 __private_extern__ void
 210 __sfprelease(FILE *fp)
 211 {
 212         if (fp->_counted) {
 213                 OSAtomicDecrement32(&__scounted);
 214                 fp->_counted = 0;
 215         }
 216
 217         pthread_mutex_destroy(&fp->_extra->fl_mutex);
 218
 219         /* Make sure nobody else is enumerating the list while we clear the "in use" _flags field. */
 220         FILELIST_LOCK();
 221         fp->_flags = 0;
 222         FILELIST_UNLOCK();
 223 }
 224
 225 /*
 226  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 227  * but documented historically for certain applications.  Bad applications.
 228  */
 229 __warn_references(f_prealloc,
 230         "warning: this program uses f_prealloc(), which is not recommended.");
 231
 232 void
 233 f_prealloc(void)
 234 {
 235         struct glue *g;
 236         int n;
 237
 238         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 239         /*
 240          * It should be safe to walk the list without locking it;
 241          * new nodes are only added to the end and none are ever
 242          * removed.
 243          */
 244         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 245                 /* void */;
 246         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 247                 FILELIST_LOCK();
 248                 lastglue->next = g;
 249                 lastglue = g;
 250                 FILELIST_UNLOCK();
 251         }
 252 }
 253
 254 /*
 255  * exit() calls _cleanup() through *__cleanup, set whenever we
 256  * open or buffer a file.  This chicanery is done so that programs
 257  * that do not use stdio need not link it all in.
 258  *
 259  * The name `_cleanup' is, alas, fairly well known outside stdio.
 260  */
 261 void
 262 _cleanup()
 263 {
 264         /* (void) _fwalk(fclose); */
 265         (void) _fwalk(__sflush);                /* `cheating' */
 266 }
 267
 268 /*
 269  * __sinit() is called whenever stdio's internal variables must be set up.
 270  */
 271 void
 272 __sinit()
 273 {
 274 #if !TARGET_OS_EMBEDDED
 275         int i;
 276 #endif
 277
 278         /* Make sure we clean up on exit. */
 279         __cleanup = _cleanup;           /* conservative */
 280         __stream_max = sysconf(_SC_STREAM_MAX);
 281         __scounted = 3;                 /* std{in,out,err} already exists */
 282
 283 #if !TARGET_OS_EMBEDDED
 284         /* Set _extra for the usual suspects. */
 285         for (i = 0; i < FOPEN_MAX - 3; i++) {
 286                 usual[i]._extra = &usual_extra[i];
 287                 INITEXTRA(&usual[i]);
 288         }
 289 #endif
 290 }