Provided by: freebsd-manpages_12.2-1_all
mprotect — control the protection of pages
Standard C Library (libc, -lc)
#include <sys/mman.h> int 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 region. A region is the virtual address space defined by the start and end addresses of a struct vm_map_entry. Currently these protection bits are known, which can be combined, OR'd together: PROT_NONE No permissions at all. PROT_READ The pages can be read. PROT_WRITE The pages can be written. PROT_EXEC The pages can be executed.
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.
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.
The mprotect() system call first appeared in 4.4BSD.