From 79dc2434cb8d39213b24b89f6c618174d8e9cbd4 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Sun, 24 Mar 2019 18:05:34 -0500
Subject: Factor out xparsedate() and xvali_date() into lib.

---
 toys/posix/date.c | 133 ++++--------------------------------------------------
 1 file changed, 10 insertions(+), 123 deletions(-)

(limited to 'toys/posix')

diff --git a/toys/posix/date.c b/toys/posix/date.c
index 43b558a5..685ac8bf 100644
--- a/toys/posix/date.c
+++ b/toys/posix/date.c
@@ -59,135 +59,29 @@ GLOBALS(
   unsigned nano;
 )
 
-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[] = {
-    // Formats with years must come first.
-    "%Y-%m-%d %H:%M:%S", "%Y-%m-%d %H:%M", "%Y-%m-%d",
-    "%H:%M:%S", "%H:%M"
-  };
-
-  // Parse @UNIXTIME[.FRACTION]
-  if (*str == '@') {
-    long long ll;
-
-    // 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;
-      for (len = 0; len<9; len++) {
-        TT.nano *= 10;
-        if (isdigit(str[len])) TT.nano += str[len]-'0';
-      }
-    }
-    if (str[len]) return 1;
-    *t = ll;
-    return 0;
-  }
-
-  // Is it one of the fancy formats?
-  for (i = 0; i<ARRAY_LEN(formats); i++) {
-    char *p;
-
-    now = time(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);
-  if (len != 8) return 1;
-  str += len;
-  tm.tm_mon--;
-
-  // 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;
-    else if (len != 2) return 1;
-    str += len;
-
-    // 2 digit years, next 50 years are "future", last 50 years are "past".
-    // 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;
-
-      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;
-    }
-  }
-  // Fractional part?
-  if (*str == '.') {
-    len = 0;
-    sscanf(str, ".%u%n", &tm.tm_sec, &len);
-    str += len;
-  } else tm.tm_sec = 0;
-
-  // Does that look like a valid date?
-  check_tm(&tm);
-  if ((*t = mktime(&tm)) == -1) return 1;
-
-  // Shouldn't be any trailing garbage.
-  return *str;
-}
-
 // Handles any leading `TZ="blah" ` in the input string.
-static int parse_date(char *str, time_t *t)
+static void parse_date(char *str, time_t *t)
 {
-  char *new_tz = NULL, *old_tz;
-  int result;
+  char *new_tz = NULL, *old_tz, *s = str;
 
   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;
+    if (!(str = strchr(new_tz, '"'))) xvali_date(0, s);
+    *str++ = 0;
+    while (isspace(*str)) str++;
 
     // Switch $TZ.
     old_tz = getenv("TZ");
     setenv("TZ", new_tz, 1);
     tzset();
   }
-  result = parse_formats(str, t);
+  time(t);
+  xparsedate(str, t, &TT.nano);
   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
@@ -236,10 +130,8 @@ void date_main(void)
       struct tm tm = {};
       char *s = strptime(TT.d, TT.D+(*TT.D=='+'), &tm);
 
-      if (!s || *s) goto bad_showdate;
-      check_tm(&tm);
-      if ((t = mktime(&tm)) == -1) goto bad_showdate;
-    } else if (parse_date(TT.d, &t)) goto bad_showdate;
+      t = (s && *s) ? xvali_date(&tm, s) : xvali_date(0, TT.d);
+    } else parse_date(TT.d, &t);
   } else {
     struct timespec ts;
     struct stat st;
@@ -264,7 +156,7 @@ void date_main(void)
   } else if (setdate) {
     struct timeval tv;
 
-    if (parse_date(setdate, &t)) goto bad_setdate;
+    parse_date(setdate, &t);
     tv.tv_sec = t;
     tv.tv_usec = TT.nano/1000;
     if (settimeofday(&tv, NULL) < 0) perror_msg("cannot set date");
@@ -279,9 +171,4 @@ void date_main(void)
   }
 
   return;
-
-bad_showdate:
-  setdate = TT.d;
-bad_setdate:
-  error_exit("bad date '%s'", setdate);
 }
-- 
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