MPROTECT(2) System Calls Manual MPROTECT(2)
mprotect -- control the protection of pages
Standard C Library (libc, -lc)
mprotect(void *addr, size_t len, int prot);
The mprotect() system call changes the specified pages to have protection
prot. Not all implementations will guarantee protection on a page basis;
the granularity of protection changes may be as large as an entire
The protections (region accessibility) are specified in the prot argument
by OR'ing the following values:
PROT_EXEC Pages may be executed.
PROT_READ Pages may be read.
PROT_WRITE Pages may be written.
PROT_NONE No permissions.
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate the error.
[EACCES] A memory protection violation occurred, or the
PROT_EXEC flag was attempted on pages which belong to
a filesystem mounted with the NOEXEC flag.
[EINVAL] An invalid memory range, or invalid parameters were
[ENOMEM] A resource shortage occurred while internally calling
madvise(2), mincore(2), msync(2), munmap(2)
The mprotect() function first appeared in 4.4BSD.
NetBSD 6.1.5 April 3, 2011 NetBSD 6.1.5