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mprotect(2) [freebsd man page]

MPROTECT(2)						      BSD System Calls Manual						       MPROTECT(2)

mprotect -- control the protection of pages LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/mman.h> int mprotect(const 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 indi- cate the error. ERRORS
The mprotect() system call will fail if: [EINVAL] The virtual address range specified by the addr and len arguments is not valid. [EACCES] The calling process was not allowed to change the protection to the value specified by the prot argument. SEE ALSO
madvise(2), mincore(2), msync(2), munmap(2) HISTORY
The mprotect() system call first appeared in 4.4BSD. BSD
June 9, 1993 BSD

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mprotect(2)							   System Calls 						       mprotect(2)

mprotect - set 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(3C), to be that specified by prot. Legitimate values for prot are the same as those permitted for mmap(2) and are defined in <sys/mman.h> as: PROT_READ /* page can be read */ PROT_WRITE /* page can be written */ PROT_EXEC /* page can be executed */ PROT_NONE /* page can not be accessed */ 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. If the error occurs on some page at addr2, then the protections of all whole pages in the range [addr, addr2] will have been modi- fied. RETURN VALUES
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 the access permission the process has to the underlying memory object. EINVAL The len argument has a value equal to 0, or addr is not a multiple of the page size as returned by sysconf(3C). 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 address range [addr, addr + len) includes one or more pages that have been locked in memory and that were mapped MAP_PRIVATE; prot includes PROT_WRITE; and the system has insufficient resources to reserve memory for the private pages that may be created. These private pages may be created by store operations in the now-writable address range. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
mmap(2), plock(3C), mlock(3C), mlockall(3C), sysconf(3C), attributes(5), standards(5) SunOS 5.10 12 Jan 1998 mprotect(2)
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