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MPROTECT(2) FreeBSD System Calls Manual MPROTECT(2)
NAME
mprotect - control the protection of pages
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/mman.h>
int
mprotect(void *addr, size_t len, int prot);
DESCRIPTION
The mprotect() system call changes the specified pages to have protection
prot.
The prot argument shall be PROT_NONE (no permissions at all) or the
bitwise or of one or more of the following values:
PROT_READ The pages can be read.
PROT_WRITE The pages can be written.
PROT_EXEC The pages can be executed.
In addition to these standard protection flags, the FreeBSD
implementation of mprotect() provides the ability to set the maximum
protection of a region (which prevents mprotect from adding to the
permissions later). This is accomplished by bitwise or'ing one or more
PROT_ values wrapped in the PROT_MAX() macro into the prot argument.
RETURN VALUES
The mprotect() function returns the value 0 if successful; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
ERRORS
The mprotect() system call will fail if:
[EACCES] The calling process was not allowed to change the
protection to the value specified by the prot
argument.
[EINVAL] The virtual address range specified by the addr and
len arguments is not valid.
[EINVAL] The prot argument contains unhandled bits.
[ENOTSUP] The prot argument contains permissions which are not a
subset of the specified maximum permissions.
SEE ALSO
madvise(2), mincore(2), msync(2), munmap(2)
HISTORY
The mprotect() system call was first documented in 4.2BSD and first
appeared in 4.4BSD.
The PROT_MAX functionality was introduced in FreeBSD 13.