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MPROTECT(2) BSD System Calls Manual MPROTECT(2) NAME mprotect -- control the protection of pages LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <sys/mman.h> int mprotect(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 re- gion. 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. In addition to these protection flags, FreeBSD provides the ability to set the maximum protection of a region (which prevents mprotect from up- grading the permissions). This is accomplished by or'ing one or more PROT_ values wrapped in the PROT_MAX() macro into the prot argument. 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 indicate the error. ERRORS The mprotect() system call will fail if: [EACCES] The calling process was not allowed to change the pro- tection to the value specified by the prot argument. [EINVAL] The virtual address range specified by the addr and len arguments is not valid. [EINVAL] The prot argument contains unhandled bits. [ENOTSUP] The prot argument contains permissions which are not a subset of the specified maximum permissions. SEE ALSO madvise(2), mincore(2), msync(2), munmap(2) HISTORY The mprotect() system call was first documented in 4.2BSD and first ap- peared in 4.4BSD. The PROT_MAX functionality was introduced in FreeBSD 13. BSD February 26, 2020 BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY
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