...
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <stdio.h>
void func(const char *file_name) {
FILE *file;
if ((file = fopen(file_name, "wb")) == NULL) {
/* Handle error */
}
/* Operate on the file */
fclose(file);
} |
...
Compliant Solution (Windows)
Microsoft documents a list of reserved identifiers that represent devices and have a device namespace to be used specifically by devices [MSDN]. This compliant solution tests the given file name against these constructs:
| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <ctype.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
static bool isReservedName(const char *path) {
/* This list of reserved names comes from MSDN */
static const char *reserved[] = { "nul", "con", "prn", "aux",
"com1", "com2", "com3",
"com4", "com5", "com6",
"com7", "com8", "com9",
"lpt1", "lpt2", "lpt3",
"lpt4", "lpt5", "lpt6",
"lpt7", "lpt8", "lpt9" };
char *lower;
char *temp;
bool ret = false;
/*
* First, check to see if this is a device namespace, which
* always starts with \\.\, since device namespaces are not
* legal file paths.
*/
temp = strstr(path, "\\\\.\\");
if (temp == path) {
return true;
}
/*
* Since Windows uses a case-insensitive file system, operate
* on a lowercase version of the given filename. Note: this
* ignores globalization issues and assumes ASCII
* characters.
*/
lower = (char *)malloc(strlen(path) + 1);
if (!lower) {
return false;
}
temp = lower;
while (*path) {
*lower++ = tolower(*path++);
}
lower = temp;
/* Compare against the list of ancient reserved names */
for (size_t i = 0; !ret &&
i < sizeof(reserved) / sizeof(*reserved); ++i) {
if (0 == strcmp(lower, reserved[i])) {
ret = true;
}
}
free(lower);
return ret;
} |
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