1 // 2 // lsearch.cpp 3 // 4 // Copyright (c) Microsoft Corporation. All rights reserved. 5 // 6 // Defines _lsearch(), which performs a linear search over an array, appending 7 // the key to the end of the array if it is not found. 8 // 9 #include <corecrt_internal.h> 10 #include <memory.h> 11 #include <search.h> 12 13 #ifdef _M_CEE 14 #define __fileDECL __clrcall 15 #else 16 #define __fileDECL __cdecl 17 #endif 18 19 20 21 #ifdef __USE_CONTEXT 22 #define __COMPARE(context, p1, p2) (*compare)(context, p1, p2) 23 #else 24 #define __COMPARE(context, p1, p2) (*compare)(p1, p2) 25 #endif 26 27 28 // Performs a linear search over the array, looking for the value 'key' in an 29 // array of 'num' elements of 'width' bytes in size. Returns a pointer to the 30 // matching element if found. Otherwise, adds a new element to the end of the 31 // array, copied from 'key'. 32 // 33 // Parameters: 34 // * key: The key for which to search 35 // * base: A pointer to the initial element of the array to be searched 36 // * num: A pointer to an integer containing the number of elements in the 37 // array. If a new element is appended, this function increments the 38 // pointed-to value. 39 // * width: The size of each element, in bytes. 40 // * comp: Pointer to a function returning analog of strcmp for strings, but 41 // supplied by the caller for comparing the array elements. It 42 // accepts two pointers to elements; returns negative if 1 < 2; 43 // zero if 1 == 2, and positive if 1 > 2. 44 #ifndef _M_CEE 45 extern "C" 46 #endif 47 #ifdef __USE_CONTEXT 48 void* __fileDECL _lsearch_s( 49 void const* const key, 50 void* const base, 51 unsigned int* const num, 52 size_t const width, 53 int (__fileDECL* compare)(void*, void const*, void const*), 54 void* const context 55 ) 56 #else // __USE_CONTEXT 57 void* __fileDECL _lsearch( 58 const void* const key, 59 void* const base, 60 unsigned int* const num, 61 unsigned int const width, 62 int (__fileDECL* compare)(void const*, void const*) 63 ) 64 #endif // __USE_CONTEXT 65 { 66 _VALIDATE_RETURN(key != nullptr, EINVAL, nullptr); 67 _VALIDATE_RETURN(num != nullptr, EINVAL, nullptr); 68 _VALIDATE_RETURN(base != nullptr, EINVAL, nullptr); 69 _VALIDATE_RETURN(width > 0, EINVAL, nullptr); 70 _VALIDATE_RETURN(compare != nullptr, EINVAL, nullptr); 71 72 char* const first = static_cast<char*>(base); 73 char* const last = first + *num * width; 74 75 // Reentrancy diligence: Save (and unset) global-state mode to the stack before making callout to 'compare' 76 __crt_state_management::scoped_global_state_reset saved_state; 77 78 for (char* p = first; p != last; p += width) 79 { 80 if (__COMPARE(context, key, p) == 0) 81 { 82 return p; 83 } 84 } 85 86 memcpy(last, key, width); 87 ++(*num); 88 return last; 89 } 90 91 #undef __COMPARE 92