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@(#)mprotect.2 8.1 (Berkeley) 6/9/93
.Dd September 8, 2019 .Dt MPROTECT 2 .Os .Sh NAME .Nm mprotect .Nd control the protection of pages .Sh LIBRARY .Lb libc .Sh SYNOPSIS n sys/mman.h .Ft int .Fn mprotect "void *addr" "size_t len" "int prot" .Sh DESCRIPTION The .Nm system call changes the specified pages to have protection .Fa prot . Not all implementations will guarantee protection on a page basis; the granularity of protection changes may be as large as an entire region.
p The protections (region accessibility) are specified in the .Fa prot argument by .Tn OR Ns 'ing the following values: l -tag -width "Dv MAP_WRITE" -offset indent t Dv PROT_EXEC Pages may be executed. t Dv PROT_READ Pages may be read. t Dv PROT_WRITE Pages may be written. t Dv PROT_NONE Placeholder when requesting no access permission. .El .Sh RETURN VALUES Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and .Va errno is set to indicate the error. .Sh ERRORS l -tag -width Er t Bq Er EACCES A memory protection violation occurred.
p The .Dv PROT_EXEC flag was attempted on pages which belong to a file system mounted with the .Dv NOEXEC flag.
p The new protection is less restrictive than the protection originally set with .Xr mmap 2 .
p PaX mprotect restrictions prohibit the requested protection. t Bq Er EINVAL An invalid memory range, or invalid parameters were provided. t Bq Er ENOMEM A resource shortage occurred while internally calling .Xr uvm_map_protect 9 . .El .Sh SEE ALSO .Xr madvise 2 , .Xr mincore 2 , .Xr msync 2 , .Xr munmap 2 .Sh HISTORY The .Nm function first appeared in SunOS 4.0 and subsequently x 4.4 .
Indexes created Mon Sep 22 13:09:51 GMT 2025