Fix stack buffer overflow in Vgetname/Vgetclass/Vinquire - #901
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Fixes HDFGroup#872 - Adds buf_size parameter to prevent unbounded strcpy into caller buffers - These functions now double as getting the length of the vgroup name or class, replacing Vgetnamelen/Vgetclassnamelen - Adds internal vgetvgname/vgetvgclass utilities in vg_priv.h for use throughout the library and tools - Updates Java API - Updates Fortran API
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Vgetname, Vgetclass, and Vinquire performed unbounded strcpy into caller-supplied buffers with no length parameter, allowing stack buffer overflows on names/classes longer than the caller anticipated.
Each function now takes a buf_size parameter and returns the actual name/class length on success or FAIL on error, using ptrdiff_t (instead of ssize_t) as the return type for Windows portability without a POSIX-type workaround. This makes Vgetnamelen and Vgetclassnamelen redundant, so they're removed.
Two utility functions were added, vgetvgname/vgetvgclass. They return the name/class of a vgroup, allocating the buffer internally so the caller does not need to know the length of the name/class in advance. Strictly intended for use within the library and tools only by including the private header file vg_priv.h; the caller is responsible for freeing the returned buffer.
BREAKING: callers must update call sites to pass buf_size to any of these three functions and replace the calls to Vgetnamelen/Vgetclassnamelen by the appropriate Vgetname/Vgetclass calls, passing in 0 and NULL for buffer size and buffer.
Fixes #872