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ICU-827 improve default U_MAX_PTR(base) definition to make sure that it never returns a pointer >base+0x7fffffff

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X-SVN-Rev: 4187
This commit is contained in:
Markus Scherer 2001-03-20 00:39:56 +00:00
parent f93f18d9f9
commit 54fdb244d6
1 changed files with 13 additions and 2 deletions
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15
icu4c/source/common/unicode/utypes.h
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@ -188,11 +188,22 @@ typedef uint8_t UVersionInfo[U_MAX_VERSION_LENGTH];
/**
* \def U_MAX_PTR
* Maximum value of a (void*) - use to indicate the limit of an 'infinite' buffer.
* @param ptr The beginning of a buffer to find the maximum offset from
* In fact, buffer sizes must not exceed 2GB so that the difference between
* the buffer limit and the buffer start can be expressed in an int32_t.
*
* The definition of U_MAX_PTR must fulfill the following conditions:
* - return the largest possible pointer greater than base
* - return a valid pointer according to the machine architecture (AS/400, 64-bit, etc.)
* - avoid wrapping around at high addresses
* - make sure that the returned pointer is not farther from base than 0x7fffffff
*
* For some architectures (like AS/400), a custom macro must be defined in platform.h.in or similar.
*
* @param base The beginning of a buffer to find the maximum offset from
* @internal
*/
#ifndef U_MAX_PTR
#define U_MAX_PTR(ptr) ((void*)-1)
# define U_MAX_PTR(base) ((void *)(((char *)(base)+0x7fffffff)>(char *)(base) ? ((char *)(base)+0x7fffffff) : (char *)-1))
#endif
/*===========================================================================*/