Index: stable/4/lib/libc/sys/minherit.2 =================================================================== --- stable/4/lib/libc/sys/minherit.2 (revision 82316) +++ stable/4/lib/libc/sys/minherit.2 (revision 82317) @@ -1,93 +1,128 @@ .\" $FreeBSD$ .\" .\" Copyright (c) 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)minherit.2 8.1 (Berkeley) 6/9/93 .\" .Dd February 17, 1996 .Dt MINHERIT 2 .Os .Sh NAME .Nm minherit .Nd control the inheritance of pages .Sh LIBRARY .Lb libc .Sh SYNOPSIS .Fd #include .Fd #include .Ft int .Fn minherit "void *addr" "size_t len" "int inherit" .Sh DESCRIPTION The .Fn minherit system call changes the specified pages to have the inheritance characteristic .Fa inherit . Not all implementations will guarantee that the inheritance characteristic can be set on a page basis; the granularity of changes may be as large as an entire region. +.Fx +is capable of adjusting inheritance characteristics on a page basis. +Inheritance only effects children created by +.Fn fork . +It has no effect on +.Fn exec . +exec'd processes replace their address space entirely. This function also +has no effect on the parent's address space (other then to potentially +share the address space with its children). +.Pp +Inheritance is a rather esoteric feature largely superceeded by the +MAP_SHARED feature of +.Fn mmap . +However, it is possible to use +.Fn minherit +to share a block of memory between parent and child that has been mapped +MAP_PRIVATE. That is, modifications made by parent or child are shared but +the original underlying file is left untouched. +.Bl -tag -width MAP_HASSEMAPHORE +.It Dv INHERIT_SHARE +This option causes the address space in question to be shared between +parent and child. It has no effect on how the original underlying backing +store was mapped. +.It Dv INHERIT_NONE +This option prevents the address space in question from being inherited +at all. The address space will be unmapped in the child. +.It Dv INHERIT_COPY +This option causes the child to inherit the address space as copy-on-write. +This option also has an unfortunate side effect of causing the parent +address space to become copy-on-write when the parent forks. If the +original mapping was MAP_SHARED, it will no longer be shared in the parent +after the parent forks and there is no way to get the previous +shared-backing-store mapping without unmapping and remapping the address +space in the parent. +.El .Sh RETURN VALUES .Rv -std minherit .Sh ERRORS The .Fn minherit function will fail if: .Bl -tag -width Er .It Bq Er EINVAL The virtual address range specified by the .Fa addr and .Fa len arguments is not valid. .It Bq Er EACCES The flags specified by the .Fa inherit argument were not valid for the pages specified by the .Fa addr and .Fa len arguments. .El .Sh SEE ALSO .Xr fork 2 , .Xr madvise 2 , .Xr mincore 2 , .Xr mprotect 2 , .Xr msync 2 , .Xr munmap 2 , .Xr rfork 2 .Sh HISTORY The .Fn minherit function first appeared in .Ox . Index: stable/4/sys/sys/mman.h =================================================================== --- stable/4/sys/sys/mman.h (revision 82316) +++ stable/4/sys/sys/mman.h (revision 82317) @@ -1,155 +1,162 @@ /*- * Copyright (c) 1982, 1986, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)mman.h 8.2 (Berkeley) 1/9/95 * $FreeBSD$ */ #ifndef _SYS_MMAN_H_ #define _SYS_MMAN_H_ #include /* + * Inheritance for minherit() + */ +#define INHERIT_SHARE 0 +#define INHERIT_COPY 1 +#define INHERIT_NONE 2 + +/* * Protections are chosen from these bits, or-ed together */ #define PROT_NONE 0x00 /* no permissions */ #define PROT_READ 0x01 /* pages can be read */ #define PROT_WRITE 0x02 /* pages can be written */ #define PROT_EXEC 0x04 /* pages can be executed */ /* * Flags contain sharing type and options. * Sharing types; choose one. */ #define MAP_SHARED 0x0001 /* share changes */ #define MAP_PRIVATE 0x0002 /* changes are private */ #define MAP_COPY MAP_PRIVATE /* Obsolete */ /* * Other flags */ #define MAP_FIXED 0x0010 /* map addr must be exactly as requested */ #define MAP_RENAME 0x0020 /* Sun: rename private pages to file */ #define MAP_NORESERVE 0x0040 /* Sun: don't reserve needed swap area */ #define MAP_INHERIT 0x0080 /* region is retained after exec */ #define MAP_NOEXTEND 0x0100 /* for MAP_FILE, don't change file size */ #define MAP_HASSEMAPHORE 0x0200 /* region may contain semaphores */ #define MAP_STACK 0x0400 /* region grows down, like a stack */ #define MAP_NOSYNC 0x0800 /* page to but do not sync underlying file */ /* * Extended flags */ #define MAP_NOCORE 0x00020000 /* dont include these pages in a coredump */ #ifdef _P1003_1B_VISIBLE /* * Process memory locking */ #define MCL_CURRENT 0x0001 /* Lock only current memory */ #define MCL_FUTURE 0x0002 /* Lock all future memory as well */ #endif /* _P1003_1B_VISIBLE */ /* * Error return from mmap() */ #define MAP_FAILED ((void *)-1) /* * msync() flags */ #define MS_SYNC 0x0000 /* msync synchronously */ #define MS_ASYNC 0x0001 /* return immediately */ #define MS_INVALIDATE 0x0002 /* invalidate all cached data */ /* * Mapping type */ #define MAP_FILE 0x0000 /* map from file (default) */ #define MAP_ANON 0x1000 /* allocated from memory, swap space */ /* * Advice to madvise */ #define MADV_NORMAL 0 /* no further special treatment */ #define MADV_RANDOM 1 /* expect random page references */ #define MADV_SEQUENTIAL 2 /* expect sequential page references */ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_DONTNEED 4 /* dont need these pages */ #define MADV_FREE 5 /* dont need these pages, and junk contents */ #define MADV_NOSYNC 6 /* try to avoid flushes to physical media */ #define MADV_AUTOSYNC 7 /* revert to default flushing strategy */ #define MADV_NOCORE 8 /* do not include these pages in a core file */ #define MADV_CORE 9 /* revert to including pages in a core file */ /* * Return bits from mincore */ #define MINCORE_INCORE 0x1 /* Page is incore */ #define MINCORE_REFERENCED 0x2 /* Page has been referenced by us */ #define MINCORE_MODIFIED 0x4 /* Page has been modified by us */ #define MINCORE_REFERENCED_OTHER 0x8 /* Page has been referenced */ #define MINCORE_MODIFIED_OTHER 0x10 /* Page has been modified */ #ifndef _KERNEL #include __BEGIN_DECLS #ifdef _P1003_1B_VISIBLE int mlockall __P((int)); int munlockall __P((void)); int shm_open __P((const char *, int, mode_t)); int shm_unlink __P((const char *)); #endif /* _P1003_1B_VISIBLE */ int mlock __P((const void *, size_t)); #ifndef _MMAP_DECLARED #define _MMAP_DECLARED void * mmap __P((void *, size_t, int, int, int, off_t)); #endif int mprotect __P((const void *, size_t, int)); int msync __P((void *, size_t, int)); int munlock __P((const void *, size_t)); int munmap __P((void *, size_t)); #ifndef _POSIX_SOURCE int madvise __P((void *, size_t, int)); int mincore __P((const void *, size_t, char *)); int minherit __P((void *, size_t, int)); #endif __END_DECLS #endif /* !_KERNEL */ #endif