1 files changed, 94 insertions, 63 deletions

diff --git a/toys/posix/date.c b/toys/posix/date.c
index 09a548f5..43b558a5 100644
--- a/toys/posix/date.c
+++ b/toys/posix/date.c
@@ -29,6 +29,9 @@ config DATE
     YYYY-MM-DD [hh:mm[:ss]]   ISO 8601
     hh:mm[:ss]                24-hour time today
 
+    All input formats can be preceded by TZ="id" to set the input time zone
+    separately from the output time zone. Otherwise $TZ sets both.
+
     +FORMAT specifies display format string using strftime(3) syntax:
 
     %% literal %             %n newline              %t tab
@@ -41,7 +44,7 @@ config DATE
     %N nanosec (output only)
 
     %U Week of year (0-53 start sunday)   %W Week of year (0-53 start monday)
-    %V Week of year (1-53 start monday, week < 4 days not part of this year) 
+    %V Week of year (1-53 start monday, week < 4 days not part of this year)
 
     %D = "%m/%d/%y"    %r = "%I : %M : %S %p"   %T = "%H:%M:%S"   %h = "%b"
     %x locale date     %X locale time           %c locale date/time
@@ -56,10 +59,25 @@ GLOBALS(
   unsigned nano;
 )
 
-// Handle default posix date format (mmddhhmm[[cc]yy]) or @UNIX[.FRAC]
-// returns 0 success, nonzero for error
-static int parse_default(char *str, struct tm *tm)
+static void check_range(int a, int low, int high)
+{
+  if (a<low) error_exit("%d<%d", a, low);
+  if (a>high) error_exit("%d>%d", a, high);
+}
+
+static void check_tm(struct tm *tm)
 {
+  check_range(tm->tm_sec, 0, 60);
+  check_range(tm->tm_min, 0, 59);
+  check_range(tm->tm_hour, 0, 23);
+  check_range(tm->tm_mday, 1, 31);
+  check_range(tm->tm_mon, 0, 11);
+}
+
+// Returns 0 success, nonzero for error.
+static int parse_formats(char *str, time_t *t)
+{
+  struct tm tm;
   time_t now;
   int len = 0, i;
   char *formats[] = {
@@ -71,12 +89,9 @@ static int parse_default(char *str, struct tm *tm)
   // Parse @UNIXTIME[.FRACTION]
   if (*str == '@') {
     long long ll;
-    time_t tt;
 
-    // Collect seconds and nanoseconds
-    // Note: struct tm hasn't got a fractional seconds field, thus strptime()
-    // doesn't support it, so store nanoseconds out of band (in globals).
-    // tt and ll are separate because we can't guarantee time_t is 64 bit (yet).
+    // Collect seconds and nanoseconds.
+    // &ll is not just t because we can't guarantee time_t is 64 bit (yet).
     sscanf(str, "@%lld%n", &ll, &len);
     if (str[len]=='.') {
       str += len+1;
@@ -86,9 +101,7 @@ static int parse_default(char *str, struct tm *tm)
       }
     }
     if (str[len]) return 1;
-    tt = ll;
-    localtime_r(&tt, tm);
-
+    *t = ll;
     return 0;
   }
 
@@ -97,25 +110,28 @@ static int parse_default(char *str, struct tm *tm)
     char *p;
 
     now = time(0);
-    localtime_r(&now, tm);
-    tm->tm_hour = tm->tm_min = tm->tm_sec = 0;
-    if ((p = strptime(str, formats[i], tm)) && !*p) return 0;
+    localtime_r(&now, &tm);
+    tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
+    tm.tm_isdst = -1;
+    if ((p = strptime(str,formats[i],&tm)) && !*p) {
+      if ((*t = mktime(&tm)) != -1) return 0;
+    }
   }
 
   // Posix format?
-  sscanf(str, "%2u%2u%2u%2u%n", &tm->tm_mon, &tm->tm_mday, &tm->tm_hour,
-    &tm->tm_min, &len);
+  sscanf(str, "%2u%2u%2u%2u%n", &tm.tm_mon, &tm.tm_mday, &tm.tm_hour,
+    &tm.tm_min, &len);
   if (len != 8) return 1;
   str += len;
-  tm->tm_mon--;
+  tm.tm_mon--;
 
-  // If year specified, overwrite one we fetched earlier
+  // If year specified, overwrite one we fetched earlier.
   if (*str && *str != '.') {
     unsigned year;
 
     len = 0;
     sscanf(str, "%u%n", &year, &len);
-    if (len == 4) tm->tm_year = year - 1900;
+    if (len == 4) tm.tm_year = year - 1900;
     else if (len != 2) return 1;
     str += len;
 
@@ -123,33 +139,55 @@ static int parse_default(char *str, struct tm *tm)
     // A "future" date in past is a century ahead.
     // A non-future date in the future is a century behind.
     if (len == 2) {
-      unsigned r1 = tm->tm_year % 100, r2 = (tm->tm_year + 50) % 100,
-        century = tm->tm_year - r1;
+      unsigned r1 = tm.tm_year % 100, r2 = (tm.tm_year + 50) % 100,
+        century = tm.tm_year - r1;
 
       if ((r1 < r2) ? (r1 < year && year < r2) : (year < r1 || year > r2)) {
         if (year < r1) year += 100;
       } else if (year > r1) year -= 100;
-      tm->tm_year = year + century;
+      tm.tm_year = year + century;
     }
   }
+  // Fractional part?
   if (*str == '.') {
     len = 0;
-    sscanf(str, ".%u%n", &tm->tm_sec, &len);
+    sscanf(str, ".%u%n", &tm.tm_sec, &len);
     str += len;
-  } else tm->tm_sec = 0;
+  } else tm.tm_sec = 0;
 
-  // Fix up weekday
-  now = mktime(tm);
-  localtime_r(&now, tm);
+  // Does that look like a valid date?
+  check_tm(&tm);
+  if ((*t = mktime(&tm)) == -1) return 1;
 
-  // shouldn't be any trailing garbage
+  // Shouldn't be any trailing garbage.
   return *str;
 }
 
-static void check_range(int a, int low, int high)
+// Handles any leading `TZ="blah" ` in the input string.
+static int parse_date(char *str, time_t *t)
 {
-  if (a<low) error_exit("%d<%d", a, low);
-  if (a>high) error_exit("%d>%d", a, high);
+  char *new_tz = NULL, *old_tz;
+  int result;
+
+  if (!strncmp(str, "TZ=\"", 4)) {
+    // Extract the time zone and skip any whitespace.
+    new_tz = str+4;
+    str = strchr(new_tz, '"');
+    if (!str) return 1;
+    *str++ = '\0';
+    while (isspace(*str)) ++str;
+
+    // Switch $TZ.
+    old_tz = getenv("TZ");
+    setenv("TZ", new_tz, 1);
+    tzset();
+  }
+  result = parse_formats(str, t);
+  if (new_tz) {
+    if (old_tz) setenv("TZ", old_tz, 1);
+    else unsetenv("TZ");
+  }
+  return result;
 }
 
 // Print strftime plus %N escape(s). note: modifies fmt for %N
@@ -183,17 +221,25 @@ static void puts_time(char *fmt, struct tm *tm)
 
 void date_main(void)
 {
-  char *setdate = *toys.optargs, *format_string = "%a %b %e %H:%M:%S %Z %Y";
-  struct tm tm;
-
-  memset(&tm, 0, sizeof(struct tm));
+  char *setdate = *toys.optargs, *format_string = "%a %b %e %H:%M:%S %Z %Y",
+    *tz = NULL;
+  time_t t;
+
+  if (FLAG(u)) {
+    tz = getenv("TZ");
+    setenv("TZ", "UTC", 1);
+    tzset();
+  }
 
   if (TT.d) {
     if (TT.D) {
+      struct tm tm = {};
       char *s = strptime(TT.d, TT.D+(*TT.D=='+'), &tm);
 
       if (!s || *s) goto bad_showdate;
-    } else if (parse_default(TT.d, &tm)) goto bad_showdate;
+      check_tm(&tm);
+      if ((t = mktime(&tm)) == -1) goto bad_showdate;
+    } else if (parse_date(TT.d, &t)) goto bad_showdate;
   } else {
     struct timespec ts;
     struct stat st;
@@ -203,7 +249,7 @@ void date_main(void)
       ts = st.st_mtim;
     } else clock_gettime(CLOCK_REALTIME, &ts);
 
-    ((toys.optflags & FLAG_u) ? gmtime_r : localtime_r)(&ts.tv_sec, &tm);
+    t = ts.tv_sec;
     TT.nano = ts.tv_nsec;
   }
 
@@ -216,37 +262,22 @@ void date_main(void)
 
   // Set the date
   } else if (setdate) {
-    char *tz;
     struct timeval tv;
-    int u = toys.optflags & FLAG_u;
-
-    if (parse_default(setdate, &tm)) goto bad_setdate;
-
-    check_range(tm.tm_sec, 0, 60);
-    check_range(tm.tm_min, 0, 59);
-    check_range(tm.tm_hour, 0, 23);
-    check_range(tm.tm_mday, 1, 31);
-    check_range(tm.tm_mon, 0, 11);
-
-    if (u) {
-      tz = getenv("TZ");
-      setenv("TZ", "UTC", 1);
-      tzset();
-    }
-    errno = 0;
-    tv.tv_sec = mktime(&tm);
-    if (errno) goto bad_setdate;
-    if (u) {
-      if (tz) setenv("TZ", tz, 1);
-      else unsetenv("TZ");
-      tzset();
-    }
 
+    if (parse_date(setdate, &t)) goto bad_setdate;
+    tv.tv_sec = t;
     tv.tv_usec = TT.nano/1000;
     if (settimeofday(&tv, NULL) < 0) perror_msg("cannot set date");
   }
 
-  puts_time(format_string, &tm);
+  puts_time(format_string, localtime(&t));
+
+  if (FLAG(u)) {
+    if (tz) setenv("TZ", tz, 1);
+    else unsetenv("TZ");
+    tzset();
+  }
+
   return;
 
 bad_showdate: