1 /* $NetBSD: open_memstream.c,v 1.2 2024/01/23 15:32:54 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2013 Advanced Computing Technologies LLC 5 * Written by: John H. Baldwin <jhb@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 1.2 2024/01/23 15:32:54 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 __inline size_t 55 off_t_to_size_t(off_t off) 56 { 57 if (off < 0 || off >= SSIZE_MAX) 58 return SSIZE_MAX - 1; 59 return (size_t)off; 60 } 61 62 static int 63 memstream_grow(struct memstream *ms, off_t newoff) 64 { 65 char *buf; 66 size_t newsize; 67 68 newsize = off_t_to_size_t(newoff); 69 if (newsize > ms->len) { 70 buf = realloc(*ms->bufp, newsize + 1); 71 if (buf != NULL) { 72 #ifdef DEBUG 73 fprintf(stderr, "MS: %p growing from %zd to %zd\n", 74 ms, ms->len, newsize); 75 #endif 76 memset(buf + ms->len + 1, 0, newsize - ms->len); 77 *ms->bufp = buf; 78 ms->len = newsize; 79 return (1); 80 } 81 return (0); 82 } 83 return (1); 84 } 85 86 static void 87 memstream_update(struct memstream *ms) 88 { 89 90 *ms->sizep = ms->len < ms->offset ? ms->len : ms->offset; 91 } 92 93 static ssize_t 94 memstream_write(void *cookie, const void *buf, size_t len) 95 { 96 struct memstream *ms; 97 size_t tocopy; 98 off_t more; 99 100 ms = cookie; 101 more = ms->offset; 102 more += len; 103 if (!memstream_grow(ms, more)) 104 return (-1); 105 tocopy = ms->len - ms->offset; 106 if (len < tocopy) 107 tocopy = len; 108 memcpy(*ms->bufp + ms->offset, buf, tocopy); 109 ms->offset += tocopy; 110 memstream_update(ms); 111 #ifdef DEBUG 112 fprintf(stderr, "MS: write(%p, %zu) = %zu\n", ms, len, tocopy); 113 #endif 114 return (ssize_t)tocopy; 115 } 116 117 static off_t 118 memstream_seek(void *cookie, off_t pos, int whence) 119 { 120 struct memstream *ms; 121 #ifdef DEBUG 122 size_t old; 123 #endif 124 125 ms = cookie; 126 #ifdef DEBUG 127 old = ms->offset; 128 #endif 129 switch (whence) { 130 case SEEK_SET: 131 /* _fseeko() checks for negative offsets. */ 132 assert(pos >= 0); 133 ms->offset = off_t_to_size_t(pos); 134 break; 135 case SEEK_CUR: 136 /* This is only called by _ftello(). */ 137 assert(pos == 0); 138 break; 139 case SEEK_END: 140 if (pos < 0) { 141 if (pos + (ssize_t)ms->len < 0) { 142 #ifdef DEBUG 143 fprintf(stderr, 144 "MS: bad SEEK_END: pos %jd, len %zu\n", 145 (intmax_t)pos, ms->len); 146 #endif 147 errno = EINVAL; 148 return (-1); 149 } 150 } else { 151 if (OFF_MAX - (ssize_t)ms->len < pos) { 152 #ifdef DEBUG 153 fprintf(stderr, 154 "MS: bad SEEK_END: pos %jd, len %zu\n", 155 (intmax_t)pos, ms->len); 156 #endif 157 errno = EOVERFLOW; 158 return (-1); 159 } 160 } 161 ms->offset = off_t_to_size_t(ms->len + pos); 162 break; 163 } 164 memstream_update(ms); 165 #ifdef DEBUG 166 fprintf(stderr, "MS: seek(%p, %jd, %d) %zu -> %zu\n", ms, 167 (intmax_t)pos, whence, old, ms->offset); 168 #endif 169 return (ms->offset); 170 } 171 172 static int 173 memstream_close(void *cookie) 174 { 175 176 free(cookie); 177 return (0); 178 } 179 180 FILE * 181 open_memstream(char **bufp, size_t *sizep) 182 { 183 struct memstream *ms; 184 int save_errno; 185 FILE *fp; 186 187 if (bufp == NULL || sizep == NULL) { 188 errno = EINVAL; 189 return (NULL); 190 } 191 *bufp = calloc(1, 1); 192 if (*bufp == NULL) 193 return (NULL); 194 ms = malloc(sizeof(*ms)); 195 if (ms == NULL) { 196 save_errno = errno; 197 free(*bufp); 198 *bufp = NULL; 199 errno = save_errno; 200 return (NULL); 201 } 202 ms->bufp = bufp; 203 ms->sizep = sizep; 204 ms->len = 0; 205 ms->offset = 0; 206 memstream_update(ms); 207 fp = funopen2(ms, NULL, memstream_write, memstream_seek, 208 NULL, memstream_close); 209 if (fp == NULL) { 210 save_errno = errno; 211 free(ms); 212 free(*bufp); 213 *bufp = NULL; 214 errno = save_errno; 215 return (NULL); 216 } 217 fwide(fp, -1); 218 return (fp); 219 } 220