lib/libc/stdio/findfp.c

   1 /*      $NetBSD: findfp.c,v 1.22 2006/10/07 20:46:59 thorpej Exp $      */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)findfp.c    8.2 (Berkeley) 1/4/94";
  39 #else
  40 __RCSID("$NetBSD: findfp.c,v 1.22 2006/10/07 20:46:59 thorpej Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45 #include <sys/param.h>
  46 #include <unistd.h>
  47 #include <stdio.h>
  48 #include <errno.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include "reentrant.h"
  52 #include "local.h"
  53 #include "glue.h"
  54
  55 int     __sdidinit;
  56
  57 #define NDYNAMIC 10             /* add ten more whenever necessary */
  58
  59 #define std(flags, file) \
  60 /*        p     r  w  flags  file  bf     lfbsize  cookie       close */ \
  61         { NULL, 0, 0, flags, file, { NULL, 0 }, 0, __sF + file, __sclose, \
  62 /*        read      seek     write     ext                              up */ \
  63           __sread,  __sseek, __swrite, { (void *)(__sFext + file), 0 }, NULL, \
  64 /*        ur ubuf,                 nbuf      lb     blksize  offset */ \
  65           0, { '\0', '\0', '\0' }, { '\0' }, { NULL, 0 }, 0, (fpos_t)0 }
  66
  67                                 /* the usual - (stdin + stdout + stderr) */
  68 static FILE usual[FOPEN_MAX - 3];
  69 static struct __sfileext usualext[FOPEN_MAX - 3];
  70 static struct glue uglue = { 0, FOPEN_MAX - 3, usual };
  71
  72 #if defined(_REENTRANT) && !defined(__lint__) /* XXX lint is busted */
  73 #define STDEXT { ._lock = MUTEX_INITIALIZER, ._lockcond = COND_INITIALIZER }
  74 struct __sfileext __sFext[3] = { STDEXT,
  75                                  STDEXT,
  76                                  STDEXT};
  77 #else
  78 struct __sfileext __sFext[3];
  79 #endif
  80
  81 FILE __sF[3] = {
  82         std(__SRD, STDIN_FILENO),               /* stdin */
  83         std(__SWR, STDOUT_FILENO),              /* stdout */
  84         std(__SWR|__SNBF, STDERR_FILENO)        /* stderr */
  85 };
  86 struct glue __sglue = { &uglue, 3, __sF };
  87
  88 static struct glue *moreglue __P((int));
  89 void f_prealloc __P((void));
  90
  91 #ifdef _REENTRANT
  92 rwlock_t __sfp_lock = RWLOCK_INITIALIZER;
  93 #endif
  94
  95 static struct glue *
  96 moreglue(n)
  97         int n;
  98 {
  99         struct glue *g;
 100         FILE *p;
 101         struct __sfileext *pext;
 102         static FILE empty;
 103
 104         g = (struct glue *)malloc(sizeof(*g) + ALIGNBYTES + n * sizeof(FILE)
 105                 + n * sizeof(struct __sfileext));
 106         if (g == NULL)
 107                 return (NULL);
 108         p = (FILE *)ALIGN((u_long)(g + 1));
 109         g->next = NULL;
 110         g->niobs = n;
 111         g->iobs = p;
 112         pext = (void *)(p + n);
 113         while (--n >= 0) {
 114                 *p = empty;
 115                 _FILEEXT_SETUP(p, pext);
 116                 p++;
 117                 pext++;
 118         }
 119         return (g);
 120 }
 121
 122 /*
 123  * Find a free FILE for fopen et al.
 124  */
 125 FILE *
 126 __sfp()
 127 {
 128         FILE *fp;
 129         int n;
 130         struct glue *g;
 131
 132         if (!__sdidinit)
 133                 __sinit();
 134
 135         rwlock_wrlock(&__sfp_lock);
 136         for (g = &__sglue;; g = g->next) {
 137                 for (fp = g->iobs, n = g->niobs; --n >= 0; fp++)
 138                         if (fp->_flags == 0)
 139                                 goto found;
 140                 if (g->next == NULL && (g->next = moreglue(NDYNAMIC)) == NULL)
 141                         break;
 142         }
 143         rwlock_unlock(&__sfp_lock);
 144         return (NULL);
 145 found:
 146         fp->_flags = 1;         /* reserve this slot; caller sets real flags */
 147         fp->_p = NULL;          /* no current pointer */
 148         fp->_w = 0;             /* nothing to read or write */
 149         fp->_r = 0;
 150         fp->_bf._base = NULL;   /* no buffer */
 151         fp->_bf._size = 0;
 152         fp->_lbfsize = 0;       /* not line buffered */
 153         fp->_file = -1;         /* no file */
 154 /*      fp->_cookie = <any>; */ /* caller sets cookie, _read/_write etc */
 155         _UB(fp)._base = NULL;   /* no ungetc buffer */
 156         _UB(fp)._size = 0;
 157         fp->_lb._base = NULL;   /* no line buffer */
 158         fp->_lb._size = 0;
 159         memset(WCIO_GET(fp), 0, sizeof(struct wchar_io_data));
 160         rwlock_unlock(&__sfp_lock);
 161         return (fp);
 162 }
 163
 164 /*
 165  * XXX.  Force immediate allocation of internal memory.  Not used by stdio,
 166  * but documented historically for certain applications.  Bad applications.
 167  */
 168 void
 169 f_prealloc()
 170 {
 171         struct glue *g;
 172         int n;
 173
 174         n = (int)sysconf(_SC_OPEN_MAX) - FOPEN_MAX + 20; /* 20 for slop. */
 175         for (g = &__sglue; (n -= g->niobs) > 0 && g->next; g = g->next)
 176                 /* void */;
 177         if (n > 0)
 178                 g->next = moreglue(n);
 179 }
 180
 181 /*
 182  * exit() calls _cleanup() through *__cleanup, set whenever we
 183  * open or buffer a file.  This chicanery is done so that programs
 184  * that do not use stdio need not link it all in.
 185  *
 186  * The name `_cleanup' is, alas, fairly well known outside stdio.
 187  */
 188 void
 189 _cleanup()
 190 {
 191         /* (void) _fwalk(fclose); */
 192         (void) fflush(NULL);                    /* `cheating' */
 193 }
 194
 195 /*
 196  * __sinit() is called whenever stdio's internal variables must be set up.
 197  */
 198 void
 199 __sinit()
 200 {
 201         int i;
 202
 203         for (i = 0; i < FOPEN_MAX - 3; i++)
 204                 _FILEEXT_SETUP(&usual[i], &usualext[i]);
 205
 206         /* make sure we clean up on exit */
 207         __cleanup = _cleanup;           /* conservative */
 208         __sdidinit = 1;
 209 }