1MPROTECT(P) POSIX Programmer's Manual MPROTECT(P)
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6 mprotect - set protection of memory mapping
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9 #include <sys/mman.h>
10 int mprotect(void *addr, size_t len, int prot);
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15 The mprotect() function shall change the access protections to be that
16 specified by prot for those whole pages containing any part of the
17 address space of the process starting at address addr and continuing
18 for len bytes. The parameter prot determines whether read, write, exe‐
19 cute, or some combination of accesses are permitted to the data being
20 mapped. The prot argument should be either PROT_NONE or the bitwise-
21 inclusive OR of one or more of PROT_READ, PROT_WRITE, and PROT_EXEC.
22 If an implementation cannot support the combination of access types
24 specified by prot, the call to mprotect() shall fail.
25 An implementation may permit accesses other than those specified by
27 prot; however, no implementation shall permit a write to succeed where
28 PROT_WRITE has not been set or shall permit any access where PROT_NONE
29 alone has been set. Implementations shall support at least the follow‐
30 ing values of prot: PROT_NONE, PROT_READ, PROT_WRITE, and the bitwise-
31 inclusive OR of PROT_READ and PROT_WRITE. If PROT_WRITE is specified,
32 the application shall ensure that it has opened the mapped objects in
33 the specified address range with write permission, unless MAP_PRIVATE
34 was specified in the original mapping, regardless of whether the file
35 descriptors used to map the objects have since been closed.
36 The implementation shall require that addr be a multiple of the page
38 size as returned by sysconf().
39 The behavior of this function is unspecified if the mapping was not
41 established by a call to mmap().
42 When mprotect() fails for reasons other than [EINVAL], the protections
44 on some of the pages in the range [addr,addr+len) may have been
45 changed.
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48 Upon successful completion, mprotect() shall return 0; otherwise, it
49 shall return -1 and set errno to indicate the error.
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52 The mprotect() function shall fail if:
53 EACCES The prot argument specifies a protection that violates the
55 access permission the process has to the underlying memory
56 object.
57 EAGAIN The prot argument specifies PROT_WRITE over a MAP_PRIVATE map‐
59 ping and there are insufficient memory resources to reserve for
60 locking the private page.
61 EINVAL The addr argument is not a multiple of the page size as returned
63 by sysconf().
64 ENOMEM Addresses in the range [addr,addr+len) are invalid for the
66 address space of a process, or specify one or more pages which
67 are not mapped.
68 ENOMEM The prot argument specifies PROT_WRITE on a MAP_PRIVATE mapping,
70 and it would require more space than the system is able to sup‐
71 ply for locking the private pages, if required.
72 ENOTSUP
74 The implementation does not support the combination of accesses
75 requested in the prot argument.
76 The following sections are informative.
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81 None.
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84 The [EINVAL] error above is marked EX because it is defined as an
85 optional error in the POSIX Realtime Extension.
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88 None.
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91 None.
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94 mmap() , sysconf() , the Base Definitions volume of
95 IEEE Std 1003.1-2001, <sys/mman.h>
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98 Portions of this text are reprinted and reproduced in electronic form
99 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
100 -- Portable Operating System Interface (POSIX), The Open Group Base
101 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
102 Electrical and Electronics Engineers, Inc and The Open Group. In the
103 event of any discrepancy between this version and the original IEEE and
104 The Open Group Standard, the original IEEE and The Open Group Standard
105 is the referee document. The original Standard can be obtained online
106 at http://www.opengroup.org/unix/online.html .
107IEEE/The Open Group 2003 MPROTECT(P)