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 #pragma clang diagnostic push
  34 #pragma clang diagnostic ignored "-Wcomma"
  35
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 static char sccsid[] = "@(#)findfp.c    8.2 (Berkeley) 1/4/94";
  38 #endif /* LIBC_SCCS and not lint */
  39 #include <sys/cdefs.h>
  40 __FBSDID("$FreeBSD: src/lib/libc/stdio/findfp.c,v 1.34 2009/12/05 19:31:38 ed Exp $");
  41
  42 #include <TargetConditionals.h>
  43
  44 #include <sys/param.h>
  45 #include <machine/atomic.h>
  46 #include <unistd.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <libkern/OSAtomic.h>
  51 #include <errno.h>
  52
  53 #include <pthread.h>
  54 #include <spinlock.h>
  55
  56 #include "libc_private.h"
  57 #include "local.h"
  58 #include "glue.h"
  59
  60 pthread_once_t  __sdidinit;
  61
  62 #if !TARGET_OS_IPHONE
  63 #define NDYNAMIC 10             /* add ten more whenever necessary */
  64 #else
  65 #define NDYNAMIC 1              /* add one at a time on embedded */
  66 #endif
  67
  68 #define std(flags, file) {              \
  69         ._flags = (flags),              \
  70         ._file = (file),                \
  71         ._cookie = __sF + (file),       \
  72         ._close = __sclose,             \
  73         ._read = __sread,               \
  74         ._seek = __sseek,               \
  75         ._write = __swrite,             \
  76         ._extra = __sFX + file,         \
  77 }
  78   /* set counted */
  79 #define __sFXInit3      {.fl_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER, .counted = 1}
  80
  81 static int64_t __scounted;              /* streams counted against STREAM_MAX */
  82 static int64_t __stream_max;
  83
  84 #if !(TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR)
  85 /* usual and usual_extra are data pigs. See 7929728. For embedded we should
  86  * always allocate dynamically, and probably should for desktop too. */
  87                                 /* the usual - (stdin + stdout + stderr) */
  88 static FILE usual[FOPEN_MAX - 3];
  89 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
  90 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  91 #endif /* !(TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR) */
  92
  93 static struct __sFILEX __sFX[3] = {__sFXInit3, __sFXInit3, __sFXInit3};
  94
  95 /*
  96  * We can't make this 'static' due to binary compatibility concerns.
  97  * This also means we cannot change the sizeof(FILE) and must continue to
  98  * use the __sFILEX stuff to add to FILE.
  99  */
 100 FILE __sF[3] = {
 101         std(__SRD, STDIN_FILENO),
 102         std(__SWR, STDOUT_FILENO),
 103         std(__SWR|__SNBF, STDERR_FILENO)
 104 };
 105
 106 FILE *__stdinp = &__sF[0];
 107 FILE *__stdoutp = &__sF[1];
 108 FILE *__stderrp = &__sF[2];
 109
 110 #if !(TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR)
 111 struct glue __sglue = { &uglue, 3, __sF };
 112 static struct glue *lastglue = &uglue;
 113 #else
 114 struct glue __sglue = { NULL, 3, __sF };
 115 static struct glue *lastglue = &__sglue;
 116 #endif
 117
 118 static struct glue *    moreglue(int);
 119
 120 static pthread_mutex_t filelist_lock = PTHREAD_MUTEX_INITIALIZER;
 121 #define FILELIST_LOCK() do { pthread_mutex_lock(&filelist_lock); } while(0)
 122 #define FILELIST_UNLOCK()       do { pthread_mutex_unlock(&filelist_lock); } while(0)
 123
 124 static struct glue *
 125 moreglue(int n)
 126 {
 127         struct glue *g;
 128         FILE *p;
 129         struct __sFILEX *fx;
 130         size_t align;
 131
 132         align = __alignof__( (struct { FILE f; struct __sFILEX s; }){} );
 133         g = (struct glue *)malloc(sizeof(*g) + align + n * sizeof(FILE) +
 134             n * sizeof(struct __sFILEX));
 135         if (g == NULL)
 136                 return (NULL);
 137         p = (FILE *)roundup((uintptr_t)(g + 1), align);
 138         fx = (struct __sFILEX *)&p[n];
 139         g->next = NULL;
 140         g->niobs = n;
 141         g->iobs = p;
 142
 143         while (--n >= 0) {
 144                 bzero(p, sizeof(*p));
 145                 p->_extra = fx;
 146                 INITEXTRA(p);
 147                 p++, fx++;
 148         }
 149         return (g);
 150 }
 151
 152 /*
 153  * Find a free FILE for fopen et al.
 154  */
 155 FILE *
 156 __sfp(int count)
 157 {
 158         FILE    *fp;
 159         int     n;
 160         struct glue *g;
 161
 162         pthread_once(&__sdidinit, __sinit);
 163
 164         if (count) {
 165                 int64_t new = OSAtomicIncrement64(&__scounted);
 166                 if (new > __stream_max) {
 167                         /* Greater than the saved limit, check again with getrlimit. */
 168                         if (new > (__stream_max = sysconf(_SC_STREAM_MAX))){
 169                                 OSAtomicDecrement64(&__scounted);
 170                                 errno = EMFILE;
 171                                 return NULL;
 172                         }
 173                 }
 174                 /* Overflowing #streams beyond RLIMIT_INFINITY */
 175                 if (new < 0) {
 176                         errno = EOVERFLOW;
 177                         return NULL;
 178                 }
 179         }
 180         /*
 181          * The list must be locked because a FILE may be updated.
 182          */
 183         FILELIST_LOCK();
 184         for (g = &__sglue; g != NULL; g = g->next) {
 185                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 186                         if (fp->_flags == 0)
 187                                 goto found;
 188         }
 189         FILELIST_UNLOCK();      /* don't hold lock while malloc()ing. */
 190         if ((g = moreglue(NDYNAMIC)) == NULL)
 191                 return (NULL);
 192         FILELIST_LOCK();                /* reacquire the lock */
 193         lastglue->next = g; /* atomically append glue to list */
 194         lastglue = g;           /* not atomic; only accessed when locked */
 195         fp = g->iobs;
 196 found:
 197         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 198         FILELIST_UNLOCK();
 199
 200         /* _flags = 1 means the FILE* is in use, and this thread owns the object while it is being initialized */
 201         fp->_p = NULL;          /* no current pointer */
 202         fp->_w = 0;             /* nothing to read or write */
 203         fp->_r = 0;
 204         fp->_bf._base = NULL;   /* no buffer */
 205         fp->_bf._size = 0;
 206         fp->_lbfsize = 0;       /* not line buffered */
 207         fp->_file = -1;         /* no file */
 208 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 209         fp->_ub._base = NULL;   /* no ungetc buffer */
 210         fp->_ub._size = 0;
 211         fp->_lb._base = NULL;   /* no line buffer */
 212         fp->_lb._size = 0;
 213 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 214         INITEXTRA(fp);
 215         fp->_extra->counted = count ? 1 : 0;
 216         return (fp);
 217 }
 218
 219 /*
 220  * Mark as free and update count as needed
 221  */
 222 __private_extern__ void
 223 __sfprelease(FILE *fp)
 224 {
 225         if (fp->_counted) {
 226                 OSAtomicDecrement64(&__scounted);
 227                 fp->_counted = 0;
 228         }
 229
 230         pthread_mutex_destroy(&fp->_extra->fl_mutex);
 231
 232         /* Make sure nobody else is enumerating the list while we clear the "in use" _flags field. */
 233         FILELIST_LOCK();
 234         fp->_flags = 0;
 235         FILELIST_UNLOCK();
 236 }
 237
 238 /*
 239  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 240  * but documented historically for certain applications.  Bad applications.
 241  */
 242 __warn_references(f_prealloc,
 243         "warning: this program uses f_prealloc(), which is not recommended.");
 244
 245 void
 246 f_prealloc(void)
 247 {
 248         struct glue *g;
 249         int n;
 250
 251         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 252         /*
 253          * It should be safe to walk the list without locking it;
 254          * new nodes are only added to the end and none are ever
 255          * removed.
 256          */
 257         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 258                 /* void */;
 259         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 260                 FILELIST_LOCK();
 261                 lastglue->next = g;
 262                 lastglue = g;
 263                 FILELIST_UNLOCK();
 264         }
 265 }
 266
 267 /*
 268  * exit() calls _cleanup() through *__cleanup, set whenever we
 269  * open or buffer a file.  This chicanery is done so that programs
 270  * that do not use stdio need not link it all in.
 271  *
 272  * The name `_cleanup' is, alas, fairly well known outside stdio.
 273  */
 274 void
 275 _cleanup(void)
 276 {
 277         /* (void) _fwalk(fclose); */
 278         (void) _fwalk(__sflush);                /* `cheating' */
 279 }
 280
 281 /*
 282  * __sinit() is called whenever stdio's internal variables must be set up.
 283  */
 284 void
 285 __sinit(void)
 286 {
 287 #if !(TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR)
 288         int i;
 289 #endif
 290
 291         /* Make sure we clean up on exit. */
 292         __cleanup = _cleanup;           /* conservative */
 293         __stream_max = sysconf(_SC_STREAM_MAX);
 294         __scounted = 3;                 /* std{in,out,err} already exists */
 295
 296 #if !(TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR)
 297         /* Set _extra for the usual suspects. */
 298         for (i = 0; i < FOPEN_MAX - 3; i++) {
 299                 usual[i]._extra = &usual_extra[i];
 300                 INITEXTRA(&usual[i]);
 301         }
 302 #endif
 303 }
 304 #pragma clang diagnostic pop