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32 .\" @(#)memset.3 8.1 (Berkeley) 6/4/93
40 .Nd write a byte to byte string
46 .Fn memset "void *dest" "int c" "size_t len"
47 .Fd #define __STDC_WANT_LIB_EXT1__ 1
49 .Fn memset_s "void *dest" "rsize_t destsz" "int c" "rsize_t len"
62 Undefined behaviour from
64 resulting from storage overflow, will occur if
66 is greater than the the length of buffer
68 The behaviour is also undefined if
70 is an invalid pointer.
74 function behaves the same as
76 except that an error is returned and the currently registered
77 runtime-constraint handler is called if
89 (buffer overflow would occur).
90 The runtime-constraint handler is called first and may not return.
91 If it does return, an error is returned to the caller.
93 .Xr explicit_bzero 3 ,
95 is not removed through Dead Store Elimination (DSE), making it useful for
96 clearing sensitive data.
100 may be optimized away if the object modified by the function is not accessed
102 To clear memory that will not subsequently be accessed it is advised to use
106 For instance, a buffer containing a password should be cleared with
113 function returns its first argument.
116 function returns zero on success, non-zero on error.
119 .Xr explicit_bzero 3 ,
120 .Xr set_constraint_handler_s 3 ,