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. 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.
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.
SEE ALSO
HISTORY
The mprotect() system call first appeared in 4.4BSD.