open_memstream.c revision 1.1
1 /* $NetBSD: open_memstream.c,v 1.1 2014/10/13 00:40:36 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2013 Advanced Computing Technologies LLC 5 * Written by: John H. Baldwin <jhb (at) FreeBSD.org> 6 * All rights reserved. 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 #if 0 32 __FBSDID("$FreeBSD: head/lib/libc/stdio/open_memstream.c 247411 2013-02-27 19:50:46Z jhb $"); 33 #endif 34 __RCSID("$NetBSD: open_memstream.c,v 1.1 2014/10/13 00:40:36 christos Exp $"); 35 36 #include "namespace.h" 37 #include <assert.h> 38 #include <errno.h> 39 #include <limits.h> 40 #include <stdio.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <wchar.h> 44 45 #define OFF_MAX LLONG_MAX 46 47 struct memstream { 48 char **bufp; 49 size_t *sizep; 50 size_t len; 51 size_t offset; 52 }; 53 54 static int 55 memstream_grow(struct memstream *ms, off_t newoff) 56 { 57 char *buf; 58 size_t newsize; 59 60 if (newoff < 0 || newoff >= SSIZE_MAX) 61 newsize = SSIZE_MAX - 1; 62 else 63 newsize = newoff; 64 if (newsize > ms->len) { 65 buf = realloc(*ms->bufp, newsize + 1); 66 if (buf != NULL) { 67 #ifdef DEBUG 68 fprintf(stderr, "MS: %p growing from %zd to %zd\n", 69 ms, ms->len, newsize); 70 #endif 71 memset(buf + ms->len + 1, 0, newsize - ms->len); 72 *ms->bufp = buf; 73 ms->len = newsize; 74 return (1); 75 } 76 return (0); 77 } 78 return (1); 79 } 80 81 static void 82 memstream_update(struct memstream *ms) 83 { 84 85 *ms->sizep = ms->len < ms->offset ? ms->len : ms->offset; 86 } 87 88 static ssize_t 89 memstream_write(void *cookie, const void *buf, size_t len) 90 { 91 struct memstream *ms; 92 size_t tocopy; 93 off_t more; 94 95 ms = cookie; 96 more = ms->offset; 97 more += len; 98 if (!memstream_grow(ms, more)) 99 return (-1); 100 tocopy = ms->len - ms->offset; 101 if (len < tocopy) 102 tocopy = len; 103 memcpy(*ms->bufp + ms->offset, buf, tocopy); 104 ms->offset += tocopy; 105 memstream_update(ms); 106 #ifdef DEBUG 107 fprintf(stderr, "MS: write(%p, %zu) = %zu\n", ms, len, tocopy); 108 #endif 109 return (ssize_t)tocopy; 110 } 111 112 static off_t 113 memstream_seek(void *cookie, off_t pos, int whence) 114 { 115 struct memstream *ms; 116 #ifdef DEBUG 117 size_t old; 118 #endif 119 120 ms = cookie; 121 #ifdef DEBUG 122 old = ms->offset; 123 #endif 124 switch (whence) { 125 case SEEK_SET: 126 /* _fseeko() checks for negative offsets. */ 127 assert(pos >= 0); 128 ms->offset = pos; 129 break; 130 case SEEK_CUR: 131 /* This is only called by _ftello(). */ 132 assert(pos == 0); 133 break; 134 case SEEK_END: 135 if (pos < 0) { 136 if (pos + (ssize_t)ms->len < 0) { 137 #ifdef DEBUG 138 fprintf(stderr, 139 "MS: bad SEEK_END: pos %jd, len %zu\n", 140 (intmax_t)pos, ms->len); 141 #endif 142 errno = EINVAL; 143 return (-1); 144 } 145 } else { 146 if (OFF_MAX - (ssize_t)ms->len < pos) { 147 #ifdef DEBUG 148 fprintf(stderr, 149 "MS: bad SEEK_END: pos %jd, len %zu\n", 150 (intmax_t)pos, ms->len); 151 #endif 152 errno = EOVERFLOW; 153 return (-1); 154 } 155 } 156 ms->offset = ms->len + pos; 157 break; 158 } 159 memstream_update(ms); 160 #ifdef DEBUG 161 fprintf(stderr, "MS: seek(%p, %jd, %d) %zu -> %zu\n", ms, 162 (intmax_t)pos, whence, old, ms->offset); 163 #endif 164 return (ms->offset); 165 } 166 167 static int 168 memstream_close(void *cookie) 169 { 170 171 free(cookie); 172 return (0); 173 } 174 175 FILE * 176 open_memstream(char **bufp, size_t *sizep) 177 { 178 struct memstream *ms; 179 int save_errno; 180 FILE *fp; 181 182 if (bufp == NULL || sizep == NULL) { 183 errno = EINVAL; 184 return (NULL); 185 } 186 *bufp = calloc(1, 1); 187 if (*bufp == NULL) 188 return (NULL); 189 ms = malloc(sizeof(*ms)); 190 if (ms == NULL) { 191 save_errno = errno; 192 free(*bufp); 193 *bufp = NULL; 194 errno = save_errno; 195 return (NULL); 196 } 197 ms->bufp = bufp; 198 ms->sizep = sizep; 199 ms->len = 0; 200 ms->offset = 0; 201 memstream_update(ms); 202 fp = funopen2(ms, NULL, memstream_write, memstream_seek, 203 NULL, memstream_close); 204 if (fp == NULL) { 205 save_errno = errno; 206 free(ms); 207 free(*bufp); 208 *bufp = NULL; 209 errno = save_errno; 210 return (NULL); 211 } 212 fwide(fp, -1); 213 return (fp); 214 } 215
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