October 7, 2006 MPROTECT 2

### NAME

mprotect - control the protection of pages

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```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.

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.

### RETURN VALUES

Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

### ERRORS

[```EACCES`]
  A memory protection violation occurred, or the ```PROT_EXECUTE` flag was attempted on pages which belong to a filesystem mounted with the ```NOEXEC` `flag.`

[```EINVAL`]
  An invalid memory range, or invalid parameters were provided.

[```ENOMEM`]
  A resource shortage occurred while internally calling uvm_map_protect(``).

### SEE ALSO

madvise(2), mincore(2), msync(2), munmap(2)

### HISTORY

The mprotect(``) function first appeared in 4.4BSD.