LibC: Add ctime_r() and asctime_r() implementations

Need this for a port of FIO (Flexible IO Tester)
https://fio.readthedocs.io/

2 files changed, 16 insertions, 1 deletions

diff --git a/Userland/Libraries/LibC/time.cpp b/Userland/Libraries/LibC/time.cpp
index 9331bbde13..966521d994 100644
--- a/Userland/Libraries/LibC/time.cpp
+++ b/Userland/Libraries/LibC/time.cpp
@@ -84,6 +84,12 @@ char* ctime(const time_t* t)
     return asctime(localtime(t));
 }
 
+char* ctime_r(const time_t* t, char* buf)
+{
+    struct tm tm_buf;
+    return asctime_r(localtime_r(t, &tm_buf), buf);
+}
+
 static const int __seconds_per_day = 60 * 60 * 24;
 
 static void time_to_tm(struct tm* tm, time_t t)
@@ -180,7 +186,14 @@ struct tm* gmtime_r(const time_t* t, struct tm* tm)
 char* asctime(const struct tm* tm)
 {
     static char buffer[69];
-    strftime(buffer, sizeof buffer, "%a %b %e %T %Y", tm);
+    return asctime_r(tm, buffer);
+}
+
+char* asctime_r(const struct tm* tm, char* buffer)
+{
+    // Spec states buffer must be at least 26 bytes.
+    constexpr size_t assumed_len = 26;
+    strftime(buffer, assumed_len, "%a %b %e %T %Y", tm);
     return buffer;
 }
 
diff --git a/Userland/Libraries/LibC/time.h b/Userland/Libraries/LibC/time.h
index 74cf7f8de6..558f28be3b 100644
--- a/Userland/Libraries/LibC/time.h
+++ b/Userland/Libraries/LibC/time.h
@@ -57,8 +57,10 @@ time_t mktime(struct tm*);
 time_t timegm(struct tm*);
 time_t time(time_t*);
 char* ctime(const time_t*);
+char* ctime_r(const time_t* tm, char* buf);
 void tzset();
 char* asctime(const struct tm*);
+char* asctime_r(const struct tm*, char* buf);
 
 #define CLOCKS_PER_SEC 1000
 clock_t clock();