explicit checks of return value in format

Author: eddelbuettel

inst/NEWS.Rd

@@ -4,6 +4,7 @@
 \newcommand{\ghit}{\href{https://github.com/RcppCore/Rcpp/issues/#1}{##1}}
 
 \section{Changes in Rcpp version 0.12.9 (2017-01-xx)}{
+  \itemize{
     \item Changes in Rcpp API:
     \itemize{
       \item The exception stack message is now correctly demangled on all
@@ -19,8 +20,9 @@
     \item Changes in Rcpp Documentation:
     \itemize{
       \item Exposed pointers macros were included in the Rcpp Extending vignette
-       (MathurinD; James Balamuta in \ghpr{592} addressing \ghit{418}).
+      (MathurinD; James Balamuta in \ghpr{592} addressing \ghit{418}).
     }
+  }
 }
 
 \section{Changes in Rcpp version 0.12.8 (2016-11-16)}{

inst/include/Rcpp/date_datetime/Date.h

@@ -106,8 +106,12 @@ namespace Rcpp {
             char txt[32];
             struct tm temp = m_tm;
             temp.tm_year -= baseYear();    // adjust for fact that system has year rel. to 1900
-            ::strftime(txt, 31, fmt, &temp);
-            return std::string(txt);
+            int res = ::strftime(txt, 31, fmt, &temp);
+            if (res == 0) {
+                return std::string("");
+            } else {
+                return std::string(txt);
+            }
         }
 
         friend inline std::ostream &operator<<(std::ostream & os, const Date d);

inst/include/Rcpp/date_datetime/Datetime.h

@@ -72,9 +72,17 @@ namespace Rcpp {
             char txtiso[64], txtsec[64];
             time_t t = static_cast<time_t>(std::floor(m_dt));
             struct tm temp = *localtime(&t); // localtime, not gmtime
-            ::strftime(txtiso, 63, fmt, &temp);
-            ::snprintf(txtsec, 63, "%s.%06d", txtiso, m_us);
-            return std::string(txtsec);
+            int res = ::strftime(txtiso, 63, fmt, &temp);
+            if (res == 0) {
+                return std::string("");
+            } else {
+                res = ::snprintf(txtsec, 63, "%s.%06d", txtiso, m_us);
+                if (res <= 0) {
+                    return std::string("");
+                } else {
+                    return std::string(txtsec);
+                }
+            }
         }
 
         friend inline std::ostream &operator<<(std::ostream & s, const Datetime d);