Linux下的C库函数源代码

/*** *sbheap.c - Small-block heap code * * Copyright (c) Microsoft Corporation. All rights reserved. * *Purpose: * Core code for small-block heap. * *******************************************************************************/ #include <stddef.h> #include <stdlib.h> #include <string.h> #include <winheap.h> #include <windows.h> #include <internal.h> #include <malloc.h> #include <limits.h> #ifndef _WIN64 /* Current (VC++ 6.0) small-block heap code and data */ size_t __sbh_threshold; int __sbh_initialized; PHEADER __sbh_pHeaderList; // pointer to list start PHEADER __sbh_pHeaderScan; // pointer to list rover int __sbh_sizeHeaderList; // allocated size of list int __sbh_cntHeaderList; // count of entries defined PHEADER __sbh_pHeaderDefer=NULL; int __sbh_indGroupDefer; /* Prototypes for user functions */ size_t __cdecl _get_sbh_threshold(void); int __cdecl _set_sbh_threshold(size_t); void DumpEntry(char *, int *); #endif /* _WIN64 */ /*** *size_t _get_sbh_threshold() - return small-block threshold * *Purpose: * Return the current value of __sbh_threshold * *Entry: * None. * *Exit: * See above. * *Exceptions: * *******************************************************************************/ size_t __cdecl _get_sbh_threshold (void) { /* Ensure already initialised */ _ASSERTE(_crtheap); if(!_crtheap) { return 0; } #ifndef _WIN64 if ( __active_heap == __V6_HEAP ) { return __sbh_threshold; } #ifdef CRTDLL if ( __active_heap == __V5_HEAP ) { return __old_sbh_threshold; } #endif /* CRTDLL */ #endif /* _WIN64 */ return 0; } /*** *int _set_sbh_threshold(threshold) - set small-block heap threshold * *Purpose: * Set the upper limit for the size of an allocation which will be * supported from the small-block heap. * *Entry: * size_t threshold - proposed new value for __sbh_theshold * *Exit: * Returns 1 if successful. Returns 0 if threshold was invalid. * *Exceptions: * Input parameters are validated. Refer to the validation section of the function. * *******************************************************************************/ int __cdecl _set_sbh_threshold (size_t threshold) { _ASSERTE(_crtheap); if(!_crtheap) { return 0; } #ifndef _WIN64 if ( __active_heap == __V6_HEAP ) { // test against maximum value - if too large, return error _VALIDATE_RETURN(threshold <= MAX_ALLOC_DATA_SIZE, EINVAL, 0); __sbh_threshold = threshold; return 1; } #ifdef CRTDLL if ( __active_heap == __V5_HEAP ) { // Round up the proposed new value to the nearest paragraph threshold = (threshold + _OLD_PARASIZE - 1) & ~(_OLD_PARASIZE - 1); // Require that at least two allocations be can be made within a // page. _VALIDATE_RETURN( threshold <= (_OLD_PARASIZE * (_OLD_PARAS_PER_PAGE / 2)), EINVAL, 0); __old_sbh_threshold = threshold; return 1; } // if threshold is 0, we just return if (threshold == 0) { return 1; } // if necessary, initialize a small-block heap if (__active_heap == __SYSTEM_HEAP) { LinkerVersion lv; _GetLinkerVersion(&lv); if (lv.bverMajor >= 6) { // Initialize the VC++ 6.0 small-block heap _VALIDATE_RETURN( (threshold <= MAX_ALLOC_DATA_SIZE) && __sbh_heap_init(threshold), EINVAL, 0); __sbh_threshold = threshold; __active_heap = __V6_HEAP; return 1; } else { // Initialize the old (VC++ 5.0) small-block heap threshold = (threshold + _OLD_PARASIZE - 1) & ~(_OLD_PARASIZE - 1); _VALIDATE_RETURN( (threshold <= (_OLD_PARASIZE * (_OLD_PARAS_PER_PAGE / 2))) && (__old_sbh_new_region() != NULL), EINVAL, 0); __old_sbh_threshold = threshold; __active_heap = __V5_HEAP; return 1; } } #else /* CRTDLL */ // if threshold is 0, we just return if (threshold == 0) { return 1; } // if necessary, initialize a small-block heap if (__active_heap == __SYSTEM_HEAP) { // Initialize the VC++ 6.0 small-block heap _VALIDATE_RETURN( (threshold <= MAX_ALLOC_DATA_SIZE) && __sbh_heap_init(threshold), EINVAL, 0); __sbh_threshold = threshold; __active_heap = __V6_HEAP; return 1; } #endif /* CRTDLL */ #endif /* _WIN64 */ errno = EINVAL; return 0; } /*** *_set_amblksiz(size) - Set the value of _amblksiz * *Purpose: * Set the value of _amblksiz * *Entry: * size_t size, needs to be > 0 *Exit: * Returns 0 if everything is ok, else return the errno_t * *Exceptions: * Input parameters are validated. Refer to the validation section of the function. * *******************************************************************************/ errno_t __cdecl _set_amblksiz(size_t size) { /* validation section */ _VALIDATE_RETURN_ERRCODE(0 < size && size <= UINT_MAX, EINVAL); _VALIDATE_RETURN_ERRCODE(_crtheap, EINVAL); _BEGIN_SECURE_CRT_DEPRECATION_DISABLE _amblksiz = (unsigned int)size; _END_SECURE_CRT_DEPRECATION_DISABLE return 0; } /*** *_get_amblksiz(pSize) - Get the value of _amblksiz * *Purpose: * Get the value of _amblksiz * *Entry: * size_t *pSize *Exit: * Returns 0 if everything is ok, else return the errno_t * *Exceptions: * Input parameters are validated. Refer to the validation section of the function. * *******************************************************************************/ errno_t __cdecl _get_amblksiz(size_t *pSize) { /* validation section */ _VALIDATE_RETURN_ERRCODE(pSize != NULL, EINVAL); _VALIDATE_RETURN_ERRCODE(_crtheap, EINVAL); _BEGIN_SECURE_CRT_DEPRECATION_DISABLE *pSize = _amblksiz; _END_SECURE_CRT_DEPRECATION_DISABLE return 0; } #ifndef _WIN64 /*** *int __sbh_heap_init() - set small-block heap threshold * *Purpose: * Allocate space for initial header list and init variables. * *Entry: * None. * *Exit: * Returns 1 if successful. Returns 0 if initialization failed. * *Exceptions: * *******************************************************************************/ int __cdecl __sbh_heap_init (size_t threshold) { if (!(__sbh_pHeaderList = HeapAlloc(_crtheap, 0, 16 * sizeof(HEADER)))) return FALSE; __sbh_threshold = threshold; __sbh_pHeaderScan = __sbh_pHeaderList; __sbh_pHeaderDefer = NULL; __sbh_cntHeaderList = 0; __sbh_sizeHeaderList = 16; return TRUE; } /*** *PHEADER *__sbh_find_block(pvAlloc) - find block in small-block heap * *Purpose: * Determine if the specified allocation block lies in the small-block * heap and, if so, return the header to be used for the block. * *Entry: * void * pvBlock - pointer to block to be freed * *Exit: * If successful, a pointer to the header