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| Code Block |
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/* Legacy function defined elsewhere - cannot be modified */
void audit_log(char *errstr) {
fprintf(stderr, "Error: %s.\n", errstr);
}
/* ... */
const char INVFNAME[] = "Invalid file name.";
audit_log((char *)INVFNAME); /* EXP05-EX1 */
/* ... */
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EXP05-EX2: Because "const" means read-only and not constant, it is sometimes useful to declare struct members as (pointer to) const objects to obtain diagnostics when the user tries to change them in some way other than via the functions that are specifically designed to maintain that data type. Within those functions, however, it may be necessary to strip off the const qualification to update those members.
Risk Assessment
If the object is constant, the compiler may allocate storage in ROM or write-protected memory. Attempting to modify such an object may lead to a program crash or denial-of-service attack.
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