lib/libc/stdio/fmemopen.c

   1 /* $NetBSD: fmemopen.c,v 1.5 2010/09/27 17:08:29 tnozaki Exp $ */
   2
   3 /*-
   4  * Copyright (c)2007, 2010 Takehiko NOZAKI,
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  */
  29
  30 #include <sys/cdefs.h>
  31 #if defined(LIBC_SCCS) && !defined(lint)
  32 __RCSID("$NetBSD: fmemopen.c,v 1.5 2010/09/27 17:08:29 tnozaki Exp $");
  33 #endif /* LIBC_SCCS and not lint */
  34
  35 #include <assert.h>
  36 #include <errno.h>
  37 #include <fcntl.h>
  38 #include <stddef.h>
  39 #include <stdio.h>
  40 #include <stdlib.h>
  41
  42 #include "reentrant.h"
  43 #include "local.h"
  44
  45 struct fmemopen_cookie {
  46         char *head, *tail, *cur, *eob;
  47 };
  48
  49 static int
  50 fmemopen_read(void *cookie, char *buf, int nbytes)
  51 {
  52         struct fmemopen_cookie *p;
  53         char *s;
  54
  55         _DIAGASSERT(cookie != NULL);
  56         _DIAGASSERT(buf != NULL && nbytes > 0);
  57
  58         p = (struct fmemopen_cookie *)cookie;
  59         s = p->cur;
  60         do {
  61                 if (p->cur == p->tail)
  62                         break;
  63                 *buf++ = *p->cur++;
  64         } while (--nbytes > 0);
  65
  66         return (int)(p->cur - s);
  67 }
  68
  69 static int
  70 fmemopen_write(void *cookie, const char *buf, int nbytes)
  71 {
  72         struct fmemopen_cookie *p;
  73         char *s;
  74
  75         _DIAGASSERT(cookie != NULL);
  76         _DIAGASSERT(buf != NULL && nbytes > 0);
  77
  78         p = (struct fmemopen_cookie *)cookie;
  79         if (p->cur >= p->tail)
  80                 return 0;
  81         s = p->cur;
  82         do {
  83                 if (p->cur == p->tail - 1) {
  84                         if (*buf == '\0') {
  85                                 *p->cur++ = '\0';
  86                                 goto ok;
  87                         }
  88                         break;
  89                 }
  90                 *p->cur++ = *buf++;
  91         } while (--nbytes > 0);
  92         *p->cur = '\0';
  93 ok:
  94         if (p->cur > p->eob)
  95                 p->eob = p->cur;
  96
  97         return (int)(p->cur - s);
  98 }
  99
 100 static fpos_t
 101 fmemopen_seek(void *cookie, fpos_t offset, int whence)
 102 {
 103         struct fmemopen_cookie *p;
 104
 105         _DIAGASSERT(cookie != NULL);
 106
 107         p = (struct fmemopen_cookie *)cookie;
 108         switch (whence) {
 109         case SEEK_SET:
 110                 break;
 111         case SEEK_CUR:
 112                 offset += p->cur - p->head;
 113                 break;
 114         case SEEK_END:
 115                 offset += p->eob - p->head;
 116                 break;
 117         default:
 118                 errno = EINVAL;
 119                 goto error;
 120         }
 121         if (offset >= (fpos_t)0 && offset <= p->tail - p->head) {
 122                 p->cur = p->head + (ptrdiff_t)offset;
 123                 return (fpos_t)(p->cur - p->head);
 124         }
 125 error:
 126         return (fpos_t)-1;
 127 }
 128
 129 static int
 130 fmemopen_close0(void *cookie)
 131 {
 132         _DIAGASSERT(cookie != NULL);
 133
 134         free(cookie);
 135
 136         return 0;
 137 }
 138
 139 static int
 140 fmemopen_close1(void *cookie)
 141 {
 142         struct fmemopen_cookie *p;
 143
 144         _DIAGASSERT(cookie != NULL);
 145
 146         p = (struct fmemopen_cookie *)cookie;
 147         free(p->head);
 148         free(p);
 149
 150         return 0;
 151 }
 152
 153
 154 FILE *
 155 fmemopen(void * __restrict buf, size_t size, const char * __restrict mode)
 156 {
 157         int flags, oflags;
 158         FILE *fp;
 159         struct fmemopen_cookie *cookie;
 160
 161         if (size < (size_t)1)
 162                 goto invalid;
 163
 164         flags = __sflags(mode, &oflags);
 165         if (flags == 0)
 166                 return NULL;
 167
 168         if ((oflags & O_RDWR) == 0 && buf == NULL)
 169                 goto invalid;
 170
 171         fp = __sfp();
 172         if (fp == NULL)
 173                 return NULL;
 174         fp->_file = -1;
 175
 176         cookie = malloc(sizeof(*cookie));
 177         if (cookie == NULL)
 178                 goto release;
 179
 180         if (buf == NULL) {
 181                 cookie->head = malloc(size);
 182                 if (cookie->head == NULL) {
 183                         free(cookie);
 184                         goto release;
 185                 }
 186                 *cookie->head = '\0';
 187                 fp->_close = &fmemopen_close1;
 188         } else {
 189                 cookie->head = (char *)buf;
 190                 if (oflags & O_TRUNC)
 191                         *cookie->head = '\0';
 192                 fp->_close = &fmemopen_close0;
 193         }
 194
 195         cookie->tail = cookie->head + size;
 196         cookie->eob  = cookie->head;
 197         do {
 198                 if (*cookie->eob == '\0')
 199                         break;
 200                 ++cookie->eob;
 201         } while (--size > 0);
 202
 203         cookie->cur = (oflags & O_APPEND) ? cookie->eob : cookie->head;
 204
 205         fp->_flags  = flags;
 206         fp->_write  = (flags & __SRD) ? NULL : &fmemopen_write;
 207         fp->_read   = (flags & __SWR) ? NULL : &fmemopen_read;
 208         fp->_seek   = &fmemopen_seek;
 209         fp->_cookie = (void *)cookie;
 210
 211         return fp;
 212
 213 invalid:
 214         errno = EINVAL;
 215         return NULL;
 216
 217 release:
 218         fp->_flags = 0;
 219         return NULL;
 220 }