[#BloombergLP-bdls-MemoryUtil-protect]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdls.adoc[bdls]::xref:BloombergLP/bdls/MemoryUtil.adoc[MemoryUtil]::protect
:relfileprefix: ../../../
:mrdocs:

Change the access protection on a region of memory starting at the specified `address` and `numBytes` long, according to specified `mode`, making memory readable if `(mode & ACCESS_READ)` is nonzero and writable if `(mode & ACCESS_WRITE)` is nonzero. Return 0 on success, and a nonzero value otherwise. The behavior is undefined if `addr` is not aligned on a page boundary, if `numBytes` is not a multiple of `pageSize()`, or if `numBytes` is 0. Note that some platforms do not support certain protection modes, e.g., on some platforms the memory cannot be made writable but unreadable, or readable but non‐executable. On these platforms the actual access protection set on the region might be more permissive than the specified one. Also note that most memory allocators do not expect memory protection on allocated memory to be changed, so you must reset protection back to ACCESS_READ_WRITE before releasing the memory.

== Synopsis

Declared in `<bdls_memoryutil.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
static
int
protect(
    void* address,
    int numBytes,
    int mode);
----


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