1 /* $NetBSD: buffer.c,v 1.1.1.5 2023/08/18 18:36:49 christos Exp $ */ 2 3 /* 4 * Copyright (c) Christos Zoulas 2017. 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 immediately at the beginning of the file, without modification, 12 * 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 FOR 21 * 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 #include "file.h" 30 31 #ifndef lint 32 #if 0 33 FILE_RCSID("@(#)$File: buffer.c,v 1.13 2023/07/02 12:48:39 christos Exp $") 34 #else 35 __RCSID("$NetBSD: buffer.c,v 1.1.1.5 2023/08/18 18:36:49 christos Exp $"); 36 #endif 37 #endif /* lint */ 38 39 #include "magic.h" 40 #include <unistd.h> 41 #include <string.h> 42 #include <stdlib.h> 43 #include <sys/stat.h> 44 45 void 46 buffer_init(struct buffer *b, int fd, const struct stat *st, const void *data, 47 size_t len) 48 { 49 b->fd = fd; 50 if (st) 51 memcpy(&b->st, st, sizeof(b->st)); 52 else if (b->fd == -1 || fstat(b->fd, &b->st) == -1) 53 memset(&b->st, 0, sizeof(b->st)); 54 b->fbuf = data; 55 b->flen = len; 56 b->eoff = 0; 57 b->ebuf = NULL; 58 b->elen = 0; 59 } 60 61 void 62 buffer_fini(struct buffer *b) 63 { 64 free(b->ebuf); 65 b->ebuf = NULL; 66 b->elen = 0; 67 } 68 69 int 70 buffer_fill(const struct buffer *bb) 71 { 72 struct buffer *b = CCAST(struct buffer *, bb); 73 74 if (b->elen != 0) 75 return b->elen == FILE_BADSIZE ? -1 : 0; 76 77 if (!S_ISREG(b->st.st_mode)) 78 goto out; 79 80 b->elen = CAST(size_t, b->st.st_size) < b->flen ? 81 CAST(size_t, b->st.st_size) : b->flen; 82 if (b->elen == 0) { 83 free(b->ebuf); 84 b->ebuf = NULL; 85 return 0; 86 } 87 if ((b->ebuf = malloc(b->elen)) == NULL) 88 goto out; 89 90 b->eoff = b->st.st_size - b->elen; 91 if (pread(b->fd, b->ebuf, b->elen, b->eoff) == -1) { 92 free(b->ebuf); 93 b->ebuf = NULL; 94 goto out; 95 } 96 97 return 0; 98 out: 99 b->elen = FILE_BADSIZE; 100 return -1; 101 } 102