c - strftime() からの出力結果に困惑

Question

time.h を何度か注意深く見た後、次の func を書きました。

void output_date ( int day, int month, int year ) {
    char buffer[64] = "";
    struct tm *e_time = calloc( (size_t) 1, sizeof(struct tm) );

    e_time->tm_year = year - 1900;
    e_time->tm_mon = month - 1;
    e_time->tm_mday = day;
    e_time->tm_hour = 0;
    e_time->tm_min = 0;
    e_time->tm_sec = 0;
    e_time->tm_isdst = -1;

    /* strftime ( buffer, 64, (char *)0, e_time ); */
    strftime ( buffer, 64, "%a %b %e %H:%M:%S %Z (%z) %Y", e_time );

    printf ( "%s\n", buffer );

    free(e_time);
    e_time = NULL;

}

次に、可能な入力の範囲でこの関数を呼び出したところ、次のような奇妙な出力しか見られませんでした。

Sun Jul  8 00:00:00  () 2013
Sun Jul  9 00:00:00  () 2013
Sun Jul 10 00:00:00  () 2013
Sun Jul 11 00:00:00  () 2013
Sun Jul 12 00:00:00  () 2013

フォーマット文字列を strftime にテストすると、次のように良好な結果が得られます。

$ date -u "+%a %b %e %H:%M:%S %Z (%z) %Y"
Sat Oct 12 00:40:05 GMT (+0000) 2013

デバッガーを介してシングルステップまで行ったところ、同じ奇妙な結果が表示されました。

stopped in main at line 27 in file "flight.c"
   27                       output_date ( day+1, month+1, year );
(dbx) print day+1, month+1, year
day+1 = 1
month+1 = 1
year = 1977

(dbx) step                      
stopped in output_date at line 43 in file "flight.c"
   43       char buffer[64] = "";
(dbx) step
stopped in output_date at line 44 in file "flight.c"
   44       struct tm *e_time = calloc( (size_t) 1, sizeof(struct tm) );
(dbx) step
stopped in output_date at line 46 in file "flight.c"
   46       e_time->tm_year = year - 1900;
(dbx) print e_time
e_time = 0x100101640
(dbx) step        
stopped in output_date at line 47 in file "flight.c"
   47       e_time->tm_mon = month - 1;
(dbx) step
stopped in output_date at line 48 in file "flight.c"
   48       e_time->tm_mday = day;
(dbx) step
stopped in output_date at line 49 in file "flight.c"
   49       e_time->tm_hour = 0;
(dbx) step
stopped in output_date at line 50 in file "flight.c"
   50       e_time->tm_min = 0;
(dbx) step
stopped in output_date at line 51 in file "flight.c"
   51       e_time->tm_sec = 0;
(dbx) step
stopped in output_date at line 52 in file "flight.c"
   52       e_time->tm_isdst = -1;
(dbx) step
stopped in output_date at line 55 in file "flight.c"
   55       strftime ( buffer, 64, "%a %b %e %H:%M:%S %Z (%z) %Y", e_time );
(dbx) print *e_time
*e_time = {
    tm_sec   = 0
    tm_min   = 0
    tm_hour  = 0
    tm_mday  = 1
    tm_mon   = 0
    tm_year  = 77
    tm_wday  = 0
    tm_yday  = 0
    tm_isdst = -1
}
(dbx) step        
stopped in output_date at line 57 in file "flight.c"
   57       printf ( "%s\n", buffer );
(dbx) print buffer
buffer = "Sun Jan  1 00:00:00  () 1977"
(dbx) quit    

実際、私が得たのは、曜日が日曜日で、正しい月と正しい日と年だけです。他に正しいと思われるものはほとんどありません。

明らかな何かが欠けていますか？