1 /* 2 * Copyright (c) Christos Zoulas 2017. 3 * All Rights Reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR 19 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 #include "file.h" 28 29 #ifndef lint 30 FILE_RCSID("@(#)$File: buffer.c,v 1.8 2020/02/16 15:52:49 christos Exp $") 31 #endif /* lint */ 32 33 #include "magic.h" 34 #include <unistd.h> 35 #include <string.h> 36 #include <stdlib.h> 37 #include <sys/stat.h> 38 39 void 40 buffer_init(struct buffer *b, int fd, const struct stat *st, const void *data, 41 size_t len) 42 { 43 b->fd = fd; 44 if (st) 45 memcpy(&b->st, st, sizeof(b->st)); 46 else if (b->fd == -1 || fstat(b->fd, &b->st) == -1) 47 memset(&b->st, 0, sizeof(b->st)); 48 b->fbuf = data; 49 b->flen = len; 50 b->eoff = 0; 51 b->ebuf = NULL; 52 b->elen = 0; 53 } 54 55 void 56 buffer_fini(struct buffer *b) 57 { 58 free(b->ebuf); 59 } 60 61 int 62 buffer_fill(const struct buffer *bb) 63 { 64 struct buffer *b = CCAST(struct buffer *, bb); 65 66 if (b->elen != 0) 67 return b->elen == FILE_BADSIZE ? -1 : 0; 68 69 if (!S_ISREG(b->st.st_mode)) 70 goto out; 71 72 b->elen = CAST(size_t, b->st.st_size) < b->flen ? 73 CAST(size_t, b->st.st_size) : b->flen; 74 if ((b->ebuf = malloc(b->elen)) == NULL) 75 goto out; 76 77 b->eoff = b->st.st_size - b->elen; 78 if (pread(b->fd, b->ebuf, b->elen, b->eoff) == -1) { 79 free(b->ebuf); 80 b->ebuf = NULL; 81 goto out; 82 } 83 84 return 0; 85 out: 86 b->elen = FILE_BADSIZE; 87 return -1; 88 } 89