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A similar situation arises when realloc() is supplied a pointer to non-dynamically allocated memory. The realloc() function is used to resize a block of dynamic memory. If realloc() is supplied a pointer to memory not allocated by a memory allocation function, such as malloc(), the program may terminate abnormally.
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Noncompliant Code Example
This non-compliant noncompliant code example sets str to reference either dynamically allocated memory or a statically allocated string literal depending on the value of argc. In either case, str is passed as an argument to free(). If anything other than dynamically allocated memory is referenced by str, the call to free(str) is erroneous.
| Code Block | ||
|---|---|---|
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enum { MAX_ALLOCATION = 1000 };
int main(int argc, const char const *argv[]) {
char *str = NULL;
size_t len;
if (argc == 2) {
len = strlen(argv[1])+1;
if (len > MAX_ALLOCATION) {
/* Handle Error */
}
str = (char *)malloc(len);
if (str == NULL) {
/* Handle Allocation Error */
}
strcpy(str, argv[1]);
}
else {
str = "usage: $>a.exe [string]";
printf("%s\n", str);
}
/* ... */
free(str);
return 0;
}
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| Code Block | ||
|---|---|---|
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enum { MAX_ALLOCATION = 1000 };
int main(int argc, const char const *argv[]) {
char *str = NULL;
size_t len;
if (argc == 2) {
len = strlen(argv[1])+1;
if (len > MAX_ALLOCATION) {
/* Handle Error */
}
str = (char *)malloc(len);
if (str == NULL) {
/* Handle Allocation Error */
}
strcpy(str, argv[1]);
}
else {
printf("%s\n", "usage: $>a.exe [string]");
return -1;
}
/* ... */
free(str);
return 0;
}
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