1 /* Target memory searching 2 3 Copyright (C) 2020-2023 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 #include "gdbsupport/common-defs.h" 21 22 #include "gdbsupport/search.h" 23 #include "gdbsupport/byte-vector.h" 24 25 /* This implements a basic search of memory, reading target memory and 26 performing the search here (as opposed to performing the search in on the 27 target side with, for example, gdbserver). */ 28 29 int 30 simple_search_memory 31 (gdb::function_view<target_read_memory_ftype> read_memory, 32 CORE_ADDR start_addr, ULONGEST search_space_len, 33 const gdb_byte *pattern, ULONGEST pattern_len, 34 CORE_ADDR *found_addrp) 35 { 36 const unsigned chunk_size = SEARCH_CHUNK_SIZE; 37 /* Buffer to hold memory contents for searching. */ 38 unsigned search_buf_size; 39 40 search_buf_size = chunk_size + pattern_len - 1; 41 42 /* No point in trying to allocate a buffer larger than the search space. */ 43 if (search_space_len < search_buf_size) 44 search_buf_size = search_space_len; 45 46 gdb::byte_vector search_buf (search_buf_size); 47 48 /* Prime the search buffer. */ 49 50 if (!read_memory (start_addr, search_buf.data (), search_buf_size)) 51 { 52 warning (_("Unable to access %s bytes of target " 53 "memory at %s, halting search."), 54 pulongest (search_buf_size), hex_string (start_addr)); 55 return -1; 56 } 57 58 /* Perform the search. 59 60 The loop is kept simple by allocating [N + pattern-length - 1] bytes. 61 When we've scanned N bytes we copy the trailing bytes to the start and 62 read in another N bytes. */ 63 64 while (search_space_len >= pattern_len) 65 { 66 gdb_byte *found_ptr; 67 unsigned nr_search_bytes 68 = std::min (search_space_len, (ULONGEST) search_buf_size); 69 70 found_ptr = (gdb_byte *) memmem (search_buf.data (), nr_search_bytes, 71 pattern, pattern_len); 72 73 if (found_ptr != NULL) 74 { 75 CORE_ADDR found_addr = start_addr + (found_ptr - search_buf.data ()); 76 77 *found_addrp = found_addr; 78 return 1; 79 } 80 81 /* Not found in this chunk, skip to next chunk. */ 82 83 /* Don't let search_space_len wrap here, it's unsigned. */ 84 if (search_space_len >= chunk_size) 85 search_space_len -= chunk_size; 86 else 87 search_space_len = 0; 88 89 if (search_space_len >= pattern_len) 90 { 91 unsigned keep_len = search_buf_size - chunk_size; 92 CORE_ADDR read_addr = start_addr + chunk_size + keep_len; 93 int nr_to_read; 94 95 /* Copy the trailing part of the previous iteration to the front 96 of the buffer for the next iteration. */ 97 gdb_assert (keep_len == pattern_len - 1); 98 if (keep_len > 0) 99 memcpy (&search_buf[0], &search_buf[chunk_size], keep_len); 100 101 nr_to_read = std::min (search_space_len - keep_len, 102 (ULONGEST) chunk_size); 103 104 if (!read_memory (read_addr, &search_buf[keep_len], nr_to_read)) 105 { 106 warning (_("Unable to access %s bytes of target " 107 "memory at %s, halting search."), 108 plongest (nr_to_read), 109 hex_string (read_addr)); 110 return -1; 111 } 112 113 start_addr += chunk_size; 114 } 115 } 116 117 /* Not found. */ 118 119 return 0; 120 } 121