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This noncompliant code example compares the value of the TMP and TEMP environment variables to determine if they are the same.
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char *tmpvar;
char *tempvar;
tmpvar = getenv("TMP");
if (!tmpvar) return -1;
tempvar = getenv("TEMP");
if (!tempvar) return -1;
if (strcmp(tmpvar, tempvar) == 0) {
if (puts("TMP and TEMP are the same.\n") == EOF) {
/* Handle error */
}
}
else {
if (puts("TMP and TEMP are NOT the same.\n") == EOF) {
/* Handle error */
}
}
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Windows provides the [{{getenv_s()}} and {{\_wgetenv_s()}}|http://msdn.microsoft.com/en-us/library/tb2sfw2z(VS.80).aspx] functions for getting a value from the current environment \[[MSDN|AA. Bibliography#MSDN]\]. |
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char *tmpvar;
char *tempvar;
size_t requiredSize;
getenv_s(&requiredSize, NULL, 0, "TMP");
tmpvar = (char *)malloc(requiredSize * sizeof(char));
if (!tmpvar) {
/* Handle error */
}
getenv_s(&requiredSize, tmpvar, requiredSize, "TMP" );
getenv_s(&requiredSize, NULL, 0, "TEMP");
tempvar = (char *)malloc(requiredSize * sizeof(char));
if (!tempvar) {
free(tmpvar);
tmpvar = NULL;
/* Handle error */
}
getenv_s(&requiredSize, tempvar, requiredSize, "TEMP" );
if (strcmp(tmpvar, tempvar) == 0) {
if (puts("TMP and TEMP are the same.\n") == EOF) {
/* Handle error */
}
}
else {
if (puts("TMP and TEMP are NOT the same.\n") == EOF) {
/* Handle Error */
}
}
free(tmpvar);
tmpvar = NULL;
free(tempvar);
tempvar = NULL;
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It is the calling program's responsibility to free any allocated buffers returned by these functions.
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char *tmpvar;
char *tempvar;
size_t len;
errno_t err = _dupenv_s(&tmpvar, &len, "TMP");
if (err) return -1;
err = _dupenv_s(&tempvar, &len, "TEMP");
if (err) {
free(tmpvar);
tmpvar = NULL;
return -1;
}
if (strcmp(tmpvar, tempvar) == 0) {
if (puts("TMP and TEMP are the same.\n") == EOF) {
/* Handle error */
}
}
else {
if (puts("TMP and TEMP are NOT the same.\n") == EOF) {
/* Handle error */
}
}
free(tmpvar);
tmpvar = NULL;
free(tempvar);
tempvar = NULL;
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| Wiki Markup |
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POSIX provides the [{{strdup()}}|http://www.opengroup.org/onlinepubs/009695399/functions/strdup.html] function, which can make a copy of the environment variable string \[[Open Group 2004|AA. Bibliography#Open Group 04]\]. The {{strdup()}} function is also included in ISO/IEC PDTR 24731-2 \[[ISO/IEC PDTR 24731-2|AA. Bibliography#ISO/IEC ISO/IEC PDTR 24731-2]\]. |
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char *tmpvar;
char *tempvar;
const char *temp = getenv("TMP");
if (temp != NULL) {
tmpvar = strdup(temp);
if (tmpvar == NULL) {
/* Handle error */
}
}
else {
return -1;
}
temp = getenv("TEMP");
if (temp != NULL) {
tempvar = strdup(temp);
if (tempvar == NULL) {
free(tmpvar);
tmpvar = NULL;
/* Handle error */
}
}
else {
free(tmpvar);
tmpvar = NULL;
return -1;
}
if (strcmp(tmpvar, tempvar) == 0) {
if (puts("TMP and TEMP are the same.\n") == EOF) {
/* Handle error */
}
}
else {
if (puts("TMP and TEMP are NOT the same.\n") == EOF) {
/* Handle error */
}
}
free(tmpvar);
tmpvar = NULL;
free(tempvar);
tempvar = NULL;
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This compliant solution uses only the C99 malloc() and strcpy() functions to copy the string returned by getenv() into a dynamically allocated buffer.
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char *tmpvar;
char *tempvar;
const char *temp = getenv("TMP");
if (temp != NULL) {
tmpvar = (char *)malloc(strlen(temp)+1);
if (tmpvar != NULL) {
strcpy(tmpvar, temp);
}
else {
/* Handle error */
}
}
else {
return -1;
}
temp = getenv("TEMP");
if (temp != NULL) {
tempvar = (char *)malloc(strlen(temp)+1);
if (tempvar != NULL) {
strcpy(tempvar, temp);
}
else {
free(tmpvar);
tmpvar = NULL;
/* Handle error */
}
}
else {
free(tmpvar);
tmpvar = NULL;
return -1;
}
if (strcmp(tmpvar, tempvar) == 0) {
if (puts("TMP and TEMP are the same.\n") == EOF) {
/* Handle error */
}
}
else {
if (puts("TMP and TEMP are NOT the same.\n") == EOF) {
/* Handle error */
}
}
free(tmpvar);
tmpvar = NULL;
free(tempvar);
tempvar = NULL;
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