huwcampbell.com
Reactos
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
45extern "C"
46#endif
47#ifdef __USE_CONTEXT
48void* __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
57void* __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