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 int     __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 #define __sFXInit       {.fl_mutex = PTHREAD_MUTEX_INITIALIZER}
  76   /* set counted */
  77 #define __sFXInit3      {.fl_mutex = PTHREAD_MUTEX_INITIALIZER, .counted = 1}
  78
  79 static int __scounted;          /* streams counted against STREAM_MAX */
  80 static int __stream_max;
  81
  82 #if !TARGET_OS_EMBEDDED
  83 /* usual and usual_extra are data pigs. See 7929728. For embedded we should
  84  * always allocate dynamically, and probably should for desktop too. */
  85                                 /* the usual - (stdin + stdout + stderr) */
  86 static FILE usual[FOPEN_MAX - 3];
  87 static struct __sFILEX usual_extra[FOPEN_MAX - 3];
  88 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  89 #endif /* !TARGET_OS_EMBEDDED */
  90
  91 static struct __sFILEX __sFX[3] = {__sFXInit3, __sFXInit3, __sFXInit3};
  92
  93 /*
  94  * We can't make this 'static' due to binary compatibility concerns.
  95  * This also means we cannot change the sizeof(FILE) and must continue to
  96  * use the __sFILEX stuff to add to FILE.
  97  */
  98 FILE __sF[3] = {
  99         std(__SRD, STDIN_FILENO),
 100         std(__SWR, STDOUT_FILENO),
 101         std(__SWR|__SNBF, STDERR_FILENO)
 102 };
 103
 104 FILE *__stdinp = &__sF[0];
 105 FILE *__stdoutp = &__sF[1];
 106 FILE *__stderrp = &__sF[2];
 107
 108 #if !TARGET_OS_EMBEDDED
 109 struct glue __sglue = { &uglue, 3, __sF };
 110 static struct glue *lastglue = &uglue;
 111 #else
 112 struct glue __sglue = { NULL, 3, __sF };
 113 static struct glue *lastglue = &__sglue;
 114 #endif
 115
 116 static struct glue *    moreglue(int);
 117
 118 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
 119 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
 120 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
 121
 122 #if NOT_YET
 123 #define SET_GLUE_PTR(ptr, val)  atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
 124 #else
 125 #define SET_GLUE_PTR(ptr, val)  ptr = val
 126 #endif
 127
 128 static struct glue *
 129 moreglue(n)
 130         int n;
 131 {
 132         struct glue *g;
 133         static const FILE empty;
 134         FILE *p;
 135         static const struct __sFILEX emptyx = __sFXInit;
 136         struct __sFILEX *fx;
 137
 138         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE) +
 139             n * sizeof(struct __sFILEX));
 140         if (g == NULL)
 141                 return (NULL);
 142         p = (FILE *)ALIGN(g + 1);
 143         fx = (struct __sFILEX *)&p[n];
 144         g->next = NULL;
 145         g->niobs = n;
 146         g->iobs = p;
 147
 148         while (--n >= 0) {
 149                 *p = empty;
 150                 p->_extra = fx;
 151                 *p->_extra = emptyx;
 152                 p++, fx++;
 153         }
 154         return (g);
 155 }
 156
 157 /*
 158  * Find a free FILE for fopen et al.
 159  */
 160 FILE *
 161 __sfp(int count)
 162 {
 163         FILE    *fp;
 164         int     n;
 165         struct glue *g;
 166
 167         if (!__sdidinit)
 168                 __sinit();
 169
 170         if (count) {
 171                 if (__scounted >= __stream_max) {
 172                         THREAD_UNLOCK();
 173                         errno = EMFILE;
 174                         return NULL;
 175                 }
 176                 OSAtomicIncrement32(&__scounted);
 177         }
 178         /*
 179          * The list must be locked because a FILE may be updated.
 180          */
 181         THREAD_LOCK();
 182         for (g = &__sglue; g != NULL; g = g->next) {
 183                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 184                         if (fp->_flags == 0)
 185                                 goto found;
 186         }
 187         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 188         if ((g = moreglue(NDYNAMIC)) == NULL)
 189                 return (NULL);
 190         THREAD_LOCK();          /* reacquire the lock */
 191         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 192         lastglue = g;           /* not atomic; only accessed when locked */
 193         fp = g->iobs;
 194 found:
 195         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 196         THREAD_UNLOCK();
 197         fp->_p = NULL;          /* no current pointer */
 198         fp->_w = 0;             /* nothing to read or write */
 199         fp->_r = 0;
 200         fp->_bf._base = NULL;   /* no buffer */
 201         fp->_bf._size = 0;
 202         fp->_lbfsize = 0;       /* not line buffered */
 203         fp->_file = -1;         /* no file */
 204 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 205         fp->_ub._base = NULL;   /* no ungetc buffer */
 206         fp->_ub._size = 0;
 207         fp->_lb._base = NULL;   /* no line buffer */
 208         fp->_lb._size = 0;
 209 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 210         INITEXTRA(fp);
 211         fp->_extra->counted = count ? 1 : 0;
 212         return (fp);
 213 }
 214
 215 /*
 216  * Mark as free and update count as needed
 217  */
 218 __private_extern__ void
 219 __sfprelease(FILE *fp)
 220 {
 221         if (fp->_counted) {
 222                 OSAtomicDecrement32(&__scounted);
 223                 fp->_counted = 0;
 224         }
 225         fp->_flags = 0;
 226 }
 227
 228 /*
 229  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 230  * but documented historically for certain applications.  Bad applications.
 231  */
 232 __warn_references(f_prealloc,
 233         "warning: this program uses f_prealloc(), which is not recommended.");
 234
 235 void
 236 f_prealloc(void)
 237 {
 238         struct glue *g;
 239         int n;
 240
 241         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 242         /*
 243          * It should be safe to walk the list without locking it;
 244          * new nodes are only added to the end and none are ever
 245          * removed.
 246          */
 247         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 248                 /* void */;
 249         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 250                 THREAD_LOCK();
 251                 SET_GLUE_PTR(lastglue->next, g);
 252                 lastglue = g;
 253                 THREAD_UNLOCK();
 254         }
 255 }
 256
 257 /*
 258  * exit() calls _cleanup() through *__cleanup, set whenever we
 259  * open or buffer a file.  This chicanery is done so that programs
 260  * that do not use stdio need not link it all in.
 261  *
 262  * The name `_cleanup' is, alas, fairly well known outside stdio.
 263  */
 264 void
 265 _cleanup()
 266 {
 267         /* (void) _fwalk(fclose); */
 268         (void) _fwalk(__sflush);                /* `cheating' */
 269 }
 270
 271 /*
 272  * __sinit() is called whenever stdio's internal variables must be set up.
 273  */
 274 void
 275 __sinit()
 276 {
 277         THREAD_LOCK();
 278         if (__sdidinit == 0) {
 279 #if !TARGET_OS_EMBEDDED
 280                 int i;
 281 #endif
 282                 /* Make sure we clean up on exit. */
 283                 __cleanup = _cleanup;           /* conservative */
 284                 __stream_max = sysconf(_SC_STREAM_MAX);
 285                 __scounted = 3;                 /* std{in,out,err} already exists */
 286
 287 #if !TARGET_OS_EMBEDDED
 288                 /* Set _extra for the usual suspects. */
 289                 for (i = 0; i < FOPEN_MAX - 3; i++) {
 290                         usual[i]._extra = &usual_extra[i];
 291                         INITEXTRA(&usual[i]);
 292                 }
 293 #endif
 294
 295                 __sdidinit = 1;
 296         }
 297         THREAD_UNLOCK();
 298 }