eina_tmpstr: add eina_tmpstr_strftime

Summary:

@feature

Test Plan:
eina_tmpstr_strftime API can be used to create a temporary string
which is updated with strftime output

eina_tmpstr_steal can be used to get actual string set in eina_tmpstr

Reviewers: cedric

Subscribers: rajeshps, cedric, govi

Differential Revision: https://phab.enlightenment.org/D3048

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>

AUTHORS

@@ -53,6 +53,7 @@ ChunEon Park (Hermet) <hermet@hermet.pe.kr>
 Rajeev Ranjan (Rajeev) <rajeev.r@samsung.com> <rajeev.jnnce@gmail.com>
 Subodh Kumar <s7158.kumar@samsung.com>
 Michelle Legrand <legrand.michelle@outlook.com>
+Shilpa Singh <shilpa.singh@samsung.com> <shilpasingh.o@gmail.com>
 
 Eet
 ---

src/lib/eina/eina_tmpstr.c

@@ -133,13 +133,48 @@ eina_tmpstr_len(Eina_Tmpstr *tmpstr)
    for (s = strs; s; s = s->next)
      {
         if (s->str == tmpstr)
-	  {
+          {
              size_t ret = s->length;
              eina_lock_release(&_mutex);
              return ret;
-	  }
+          }
      }
    eina_lock_release(&_mutex);
 
    return strlen(tmpstr);
 }
+
+EAPI Eina_Tmpstr *
+eina_tmpstr_strftime(const char *format, const struct tm *tm)
+{
+   const size_t flen = strlen(format);
+   size_t buflen = 16; // An arbitrary starting size
+   char *buf = NULL;
+
+   do {
+      char *tmp;
+      size_t len;
+
+      tmp = realloc(buf, buflen * sizeof(char));
+      if (!tmp) goto on_error;
+      buf = tmp;
+
+      len = strftime(buf, buflen, format, tm);
+      // Check if we have the expected result and return it.
+      if ((len > 0 && len < buflen) || (len == 0 && flen == 0))
+        {
+           Eina_Tmpstr *r;
+
+           r = eina_tmpstr_add_length(buf, len + 1);
+           free(buf);
+           return r;
+        }
+
+      /* Possibly buf overflowed - try again with a bigger buffer */
+      buflen <<= 1; // multiply buffer size by 2
+   } while (buflen < 128 * flen);
+
+ on_error:
+   free(buf);
+   return NULL;
+}

src/lib/eina/eina_tmpstr.h

@@ -237,6 +237,31 @@ EAPI size_t eina_tmpstr_len(Eina_Tmpstr *tmpstr);
  */
 EAPI void eina_tmpstr_del(Eina_Tmpstr *tmpstr) EINA_ARG_NONNULL(1);
 
+/**
+ * @brief Add a new temporary string based on strftime output.
+ *
+ * @param tm Pointer to a tm structure needed by strftime.
+ * @param format String containing format specifiers needed by strftime.
+ *
+ * This will add a new temporary string by updating the string value by output
+ * of strftime.
+ *
+ * Example usage:
+ *
+ * @code
+ * time_t curr_time;
+ * struct tm * info;
+ * Eina_Tmpstr *buf;
+ *
+ * curr_time = time(NULL);
+ * info = localtime(&curr_time);
+ * buf = eina_tmpstr_strftime("%I:%M%p", info);
+ * @endcode
+ *
+ * @since 1.16.0
+ */
+EAPI Eina_Tmpstr *eina_tmpstr_strftime(const char *format, const struct tm *tm) EINA_ARG_NONNULL(2);
+
 /**
  * @}
  */