HP-UX Reference (11i v1 00/12) - 2 System Calls (vol 5)

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STANDARD Printed by: Nora Chuang [nchuang] STANDARD

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mprotect(2) mprotect(2)

NAME

mprotect - set or check protection of memory mapping

SYNOPSIS

#include <sys/mman.h>

int mprotect(void *addr, size_t len, int prot);

DESCRIPTION

The mprotect() function changes the access protections on the mappings speciﬁed by the range [addr,

addr+len], rounding len up to the next multiple of the page size as returned by sysconf(), to be that

speciﬁed by prot. Legitimate values for prot are the same as those permitted for mmap() and are deﬁned

in <sys/mman.h> :

PROT_READ Page can be read.

PROT_WRITE Page can be written.

PROT_EXEC Page can be executed.

PROT_NONE Page cannot be accessed.

PROT_CHECK Check page effective permissions

If PROT_CHECK ﬂag is speciﬁed, mprotect() checks the access protections on the mappings speciﬁed

with the rest of prot value to see if the requested permissions are set.

When mprotect() fails for reasons other than EINVAL, the protections on some of the pages in the

range [addr, addr+len] may have been changed.

RETURN VALUE

Upon successful completion, mprotect() returns 0. Otherwise, it returns -1 and sets errno to indicate

the error.

ERRORS

The mprotect() function will fail if:

[EACCES] The prot argument speciﬁes a protection that violates, or is different than (in the case

where ﬂag PROT_CHECK is present), the access permission the process has to the

underlying memory object.

[EINVAL] The addr argument is not a multiple of the page size as returned by

sysconf().

[ENOMEM] Addresses in the range [addr, addr+len] are invalid for the address space of a process,

or specify one or more pages which are not mapped.

The

mprotect() function may fail if:

[EAGAIN] The prot argument speciﬁes PROT_WRITE over a MAP_PRIVATE mapping and

there are insufﬁcient memory resources to reserve for locking the private page.