http.c: Force POSIX locale on append_expire

Otherwise, strftime(3) could return different strings depending on the
system configuration, and therefore return 0 if the resulting string
does not fit into buf.

1 files changed, 15 insertions, 3 deletions

diff --git a/http.c b/http.c
index 098912b..0fcae07 100644
--- a/http.c
+++ b/http.c
@@ -6,6 +6,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <inttypes.h>
+#include <locale.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdlib.h>
@@ -2750,11 +2751,18 @@ failure:
 
 static int append_expire(struct dynstr *const d, const struct tm *const exp)
 {
+    int ret = -1;
     char s[sizeof "Thu, 01 Jan 1970 00:00:00 GMT"];
+    const locale_t l = newlocale(LC_TIME_MASK, "POSIX", (locale_t)0);
 
-    if (!strftime(s, sizeof s, "%a, %d %b %Y %H:%M:%S GMT", exp))
+    if (l == (locale_t)0)
     {
-        fprintf(stderr, "%s: strftime(3) failed\n", __func__);
+        fprintf(stderr, "%s: newlocale(3): %s\n", __func__, strerror(errno));
+        goto end;
+    }
+    else if (!strftime_l(s, sizeof s, "%a, %d %b %Y %H:%M:%S GMT", exp, l))
+    {
+        fprintf(stderr, "%s: strftime_l(3) failed\n", __func__);
         return -1;
     }
     else if (dynstr_append(d, "; Expires=%s", s))
@@ -2763,7 +2771,11 @@ static int append_expire(struct dynstr *const d, const struct tm *const exp)
         return -1;
     }
 
-    return 0;
+    ret = 0;
+
+end:
+    freelocale(l);
+    return ret;
 }
 
 char *http_cookie_create(const char *const key, const char *const value,