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This noncompliant code example is based on the managed string library developed by CERT \[[Burch 2006|AA. Bibliography#Seacord 06]\]. In this example, the managed string type, and functions that operate on this type, are defined in the {{string_m.h}} header file as follows: |
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struct string_mx {
size_t size;
size_t maxsize;
unsigned char strtype;
char *cstr;
};
typedef struct string_mx string_mx;
/* Function declarations */
extern errno_t strcpy_m(string_mx *s1, const string_mx *s2);
extern errno_t strcat_m(string_mx *s1, const string_mx *s2);
/* etc. */
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In the external string_m.h file, the string_mx type is defined to be an instance of struct string_mx, which, in turn, is declared as an incomplete type.
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struct string_mx;
typedef struct string_mx string_mx;
/* Function declarations */
extern errno_t strcpy_m(string_mx *s1, const string_mx *s2);
extern errno_t strcat_m(string_mx *s1, const string_mx *s2) ;
/* etc. */
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In the internal header file, struct string_mx is fully defined but not visible to a user of the data abstraction.
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struct string_mx {
size_t size;
size_t maxsize;
unsigned char strtype;
char *cstr;
};
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