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. 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  * @(#)findfp.c 8.2 (Berkeley) 1/4/94
  33  * $FreeBSD: src/lib/libc/stdio/findfp.c,v 1.33 2009/03/01 19:25:40 das Exp $
  34  */
  35
  36 #include <sys/param.h>
  37 #include <machine/atomic.h>
  38 #include <unistd.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include <spinlock.h>
  44
  45 #include "libc_private.h"
  46 #include "local.h"
  47
  48 int     __sdidinit;
  49
  50 #define NDYNAMIC 10             /* add ten more whenever necessary */
  51
  52 #define std(flags, file) {              \
  53         .pub = {                        \
  54                 ._flags = (flags),      \
  55                 ._fileno = (file),      \
  56         },                              \
  57         ._cookie = __sF + (file),       \
  58         ._close = __sclose,             \
  59         ._read = __sread,               \
  60         ._seek = __sseek,               \
  61         ._write = __swrite,             \
  62 }
  63                                 /* the usual - (stdin + stdout + stderr) */
  64 static FILE usual[FOPEN_MAX - 3];
  65 static struct glue uglue = { NULL, FOPEN_MAX - 3, usual };
  66
  67 static FILE __sF[3] = {
  68         std(__SRD, STDIN_FILENO),
  69         std(__SWR, STDOUT_FILENO),
  70         std(__SWR|__SNBF, STDERR_FILENO)
  71 };
  72
  73 FILE *__stdinp = &__sF[0];
  74 FILE *__stdoutp = &__sF[1];
  75 FILE *__stderrp = &__sF[2];
  76
  77 struct glue __sglue = { &uglue, 3, __sF };
  78 static struct glue *lastglue = &uglue;
  79
  80 static struct glue *    moreglue(int);
  81
  82 static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
  83 #define THREAD_LOCK()   if (__isthreaded) _SPINLOCK(&thread_lock)
  84 #define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock)
  85
  86 #if 0 /* not yet */
  87 #define SET_GLUE_PTR(ptr, val)  atomic_set_rel_ptr(&(ptr), (uintptr_t)(val))
  88 #else
  89 #define SET_GLUE_PTR(ptr, val)  ptr = val
  90 #endif
  91
  92 static struct glue *
  93 moreglue(int n)
  94 {
  95         struct glue *g;
  96         static FILE empty;
  97         FILE *p;
  98
  99         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE));
 100         if (g == NULL)
 101                 return (NULL);
 102         p = (FILE *)ALIGN(g + 1);
 103         g->next = NULL;
 104         g->niobs = n;
 105         g->iobs = p;
 106         while (--n >= 0)
 107                 *p++ = empty;
 108         return (g);
 109 }
 110
 111 /*
 112  * Find a free FILE for fopen et al.
 113  */
 114 FILE *
 115 __sfp(void)
 116 {
 117         FILE    *fp;
 118         int     n;
 119         struct glue *g;
 120
 121         if (!__sdidinit)
 122                 __sinit();
 123         /*
 124          * The list must be locked because a FILE may be updated.
 125          */
 126         THREAD_LOCK();
 127         for (g = &__sglue; g != NULL; g = g->next) {
 128                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 129                         if (fp->pub._flags == 0)
 130                                 goto found;
 131         }
 132         THREAD_UNLOCK();        /* don't hold lock while malloc()ing. */
 133         if ((g = moreglue(NDYNAMIC)) == NULL)
 134                 return (NULL);
 135         THREAD_LOCK();          /* reacquire the lock */
 136         SET_GLUE_PTR(lastglue->next, g); /* atomically append glue to list */
 137         lastglue = g;           /* not atomic; only accessed when locked */
 138         fp = g->iobs;
 139 found:
 140         fp->pub._flags = 1;     /* reserve this slot; caller sets real flags */
 141         THREAD_UNLOCK();
 142         fp->pub._p = NULL;      /* no current pointer */
 143         fp->pub._w = 0;         /* nothing to read or write */
 144         fp->pub._r = 0;
 145         fp->_bf._base = NULL;   /* no buffer */
 146         fp->_bf._size = 0;
 147         fp->pub._lbfsize = 0;   /* not line buffered */
 148         fp->pub._fileno = -1;   /* no file */
 149 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 150         fp->_ub._base = NULL;   /* no ungetc buffer */
 151         fp->_ub._size = 0;
 152         fp->_lb._base = NULL;   /* no line buffer */
 153         fp->_lb._size = 0;
 154 /*      fp->_lock = NULL; */    /* once set always set (reused) */
 155         memset(WCIO_GET(fp), 0, sizeof(struct wchar_io_data));
 156         return (fp);
 157 }
 158
 159 /*
 160  * exit() calls _cleanup() through *__cleanup, set whenever we
 161  * open or buffer a file.  This chicanery is done so that programs
 162  * that do not use stdio need not link it all in.
 163  *
 164  * The name `_cleanup' is, alas, fairly well known outside stdio.
 165  */
 166 void
 167 _cleanup(void)
 168 {
 169         /* _fwalk(fclose); */
 170         _fwalk(__sflush);               /* `cheating' */
 171 }
 172
 173 /*
 174  * __sinit() is called whenever stdio's internal variables must be set up.
 175  */
 176 void
 177 __sinit(void)
 178 {
 179
 180         /* Make sure we clean up on exit. */
 181         __cleanup = _cleanup;           /* conservative */
 182         __sdidinit = 1;
 183 }