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 <sys/param.h>
  40 #include <machine/atomic.h>
  41 #include <unistd.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45
  46 #include <spinlock.h>
  47
  48 #include "libc_private.h"
  49 #include "local.h"
  50 #include "glue.h"
  51
  52 int     __sdidinit;
  53
  54 #define NDYNAMIC 10             /* add ten more whenever necessary */
  55
  56 #define std(flags, file) {              \
  57         ._flags = (flags),              \
  58         ._file = (file),                \
  59         ._cookie = __sF + (file),       \
  60         ._close = __sclose,             \
  61         ._read = __sread,               \
  62         ._seek = __sseek,               \
  63         ._write = __swrite,             \
  64 }
  65                                 /* the usual - (stdin + stdout + stderr) */
  66 static FILE usual[FOPEN_MAX - 3];
  67 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  68
  69 static FILE __sF[3] = {
  70         std(__SRD, STDIN_FILENO),
  71         std(__SWR, STDOUT_FILENO),
  72         std(__SWR|__SNBF, STDERR_FILENO)
  73 };
  74
  75 FILE *__stdinp = &__sF[0];
  76 FILE *__stdoutp = &__sF[1];
  77 FILE *__stderrp = &__sF[2];
  78
  79 struct glue __sglue = { &uglue, 3, __sF };
  80 static struct glue *lastglue = &uglue;
  81
  82 static struct glue *    moreglue(int);
  83
  84 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
  85 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
  86 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
  87
  88 #if NOT_YET
  89 #define SET_GLUE_PTR(ptr, val)  atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
  90 #else
  91 #define SET_GLUE_PTR(ptr, val)  ptr = val
  92 #endif
  93
  94 static struct glue *
  95 moreglue(n)
  96         int n;
  97 {
  98         struct glue *g;
  99         static FILE empty;
 100         FILE *p;
 101
 102         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE));
 103         if (g == NULL)
 104                 return (NULL);
 105         p = (FILE *)ALIGN(g + 1);
 106         g->next = NULL;
 107         g->niobs = n;
 108         g->iobs = p;
 109         while (--n >= 0)
 110                 *p++ = empty;
 111         return (g);
 112 }
 113
 114 /*
 115  * Find a free FILE for fopen et al.
 116  */
 117 FILE *
 118 __sfp()
 119 {
 120         FILE    *fp;
 121         int     n;
 122         struct glue *g;
 123
 124         if (!__sdidinit)
 125                 __sinit();
 126         /*
 127          * The list must be locked because a FILE may be updated.
 128          */
 129         THREAD_LOCK();
 130         for (g = &__sglue; g != NULL; g = g->next) {
 131                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 132                         if (fp->_flags == 0)
 133                                 goto found;
 134         }
 135         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 136         if ((g = moreglue(NDYNAMIC)) == NULL)
 137                 return (NULL);
 138         THREAD_LOCK();          /* reacquire the lock */
 139         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 140         lastglue = g;           /* not atomic; only accessed when locked */
 141         fp = g->iobs;
 142 found:
 143         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 144         THREAD_UNLOCK();
 145         fp->_p = NULL;          /* no current pointer */
 146         fp->_w = 0;             /* nothing to read or write */
 147         fp->_r = 0;
 148         fp->_bf._base = NULL;   /* no buffer */
 149         fp->_bf._size = 0;
 150         fp->_lbfsize = 0;       /* not line buffered */
 151         fp->_file = -1;         /* no file */
 152 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 153         fp->_ub._base = NULL;   /* no ungetc buffer */
 154         fp->_ub._size = 0;
 155         fp->_lb._base = NULL;   /* no line buffer */
 156         fp->_lb._size = 0;
 157 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 158         fp->_orientation = 0;
 159         memset(&fp->_mbstate, 0, sizeof(mbstate_t));
 160         return (fp);
 161 }
 162
 163 /*
 164  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 165  * but documented historically for certain applications.  Bad applications.
 166  */
 167 __warn_references(f_prealloc,
 168         "warning: this program uses f_prealloc(), which is not recommended.");
 169
 170 void
 171 f_prealloc(void)
 172 {
 173         struct glue *g;
 174         int n;
 175
 176         n = getdtablesize() - FOPEN_MAX + 20;           /* 20 for slop. */
 177         /*
 178          * It should be safe to walk the list without locking it;
 179          * new nodes are only added to the end and none are ever
 180          * removed.
 181          */
 182         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 183                 /* void */;
 184         if ((n > 0) && ((g = moreglue(n)) != NULL)) {
 185                 THREAD_LOCK();
 186                 SET_GLUE_PTR(lastglue->next, g);
 187                 lastglue = g;
 188                 THREAD_UNLOCK();
 189         }
 190 }
 191
 192 /*
 193  * exit() calls _cleanup() through *__cleanup, set whenever we
 194  * open or buffer a file.  This chicanery is done so that programs
 195  * that do not use stdio need not link it all in.
 196  *
 197  * The name `_cleanup' is, alas, fairly well known outside stdio.
 198  */
 199 void
 200 _cleanup()
 201 {
 202         /* (void) _fwalk(fclose); */
 203         (void) _fwalk(__sflush);                /* `cheating' */
 204 }
 205
 206 /*
 207  * __sinit() is called whenever stdio's internal variables must be set up.
 208  */
 209 void
 210 __sinit()
 211 {
 212
 213         /* Make sure we clean up on exit. */
 214         __cleanup = _cleanup;           /* conservative */
 215         __sdidinit = 1;
 216 }