Add [-DWMY] flags for date adjustment.

Discussed with: freebsd-hackers

1 files changed, 337 insertions, 0 deletions

diff --git a/bin/date/vary.c b/bin/date/vary.c
new file mode 100644
index 0000000..5df3a0c
--- /dev/null
+++ b/bin/date/vary.c
@@ -0,0 +1,337 @@
+#include <time.h>
+#include <string.h>
+#include <stdlib.h>
+#include "vary.h"
+
+struct trans {
+  int val;
+  char *str;
+};
+
+static struct trans trans_mon[] = {
+  { 1, "jan" }, { 2, "feb" }, { 3, "mar" }, { 4, "apr" }, { 5, "may" },
+  { 6, "jun" }, { 7, "jul" }, { 8, "aug" }, { 9, "sep" }, { 10, "oct" },
+  { 11, "nov" }, { 12, "dec" },
+  { 1, "january" }, { 2, "february" }, { 3, "march" }, { 4, "april" },
+  { 6, "june" }, { 7, "july" }, { 8, "august" }, { 9, "september" },
+  { 10, "october" }, { 11, "november" }, { 12, "december" },
+  { -1, NULL }
+};
+
+static struct trans trans_wday[] = {
+  { 0, "sun" }, { 1, "mon" }, { 2, "tue" }, { 3, "wed" }, { 4, "thr" },
+  { 4, "thu" }, { 5, "fri" }, { 6, "sat" },
+  { 0, "sunday" }, { 1, "monday" }, { 2, "tuesday" }, { 3, "wednesday" },
+  { 4, "thursday" }, { 5, "friday" }, { 6, "saturday" },
+  { -1, NULL }
+};
+
+static char digits[] = "0123456789";
+
+static int
+trans(const struct trans t[], const char *arg)
+{
+  int f;
+
+  if (strspn(arg, digits) == strlen(arg))
+    return atoi(arg);
+
+  for (f = 0; t[f].val != -1; f++)
+    if (!strcasecmp(t[f].str, arg))
+      return t[f].val;
+
+  return -1;
+}
+
+struct vary *
+vary_append(struct vary *v, char flag, char *arg)
+{
+  struct vary *result, **nextp;
+
+  if (!strchr("DWMY", flag))
+    return 0;
+
+  if (v) {
+    result = v;
+    while (v->next)
+      v = v->next;
+    nextp = &v->next;
+  } else
+    nextp = &result;
+
+  *nextp = (struct vary *)malloc(sizeof(struct vary));
+  (*nextp)->flag = flag;
+  (*nextp)->arg = arg;
+  (*nextp)->next = NULL;
+  return result;
+}
+
+static int mdays[12] = { 31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
+
+static int
+daysinmonth(const struct tm *t)
+{
+  int year;
+
+  year = t->tm_year + 1900;
+
+  if (t->tm_mon == 1)
+    if (!(year % 400))
+      return 29;
+    else if (!(year % 100))
+      return 28;
+    else if (!(year % 4))
+      return 29;
+    else
+      return 28;
+  else if (t->tm_mon >= 0 && t->tm_mon < 12)
+    return mdays[t->tm_mon];
+
+  return 0;
+}
+
+
+static int
+adjyear(struct tm *t, char type, int val)
+{
+  switch (type) {
+    case '+':
+      t->tm_year += val;
+      break;
+    case '-':
+      t->tm_year -= val;
+      break;
+    default:
+      t->tm_year = val;
+      if (t->tm_year < 69)
+      	t->tm_year += 100;		/* as per date.c */
+      else if (t->tm_year > 1900)
+        t->tm_year -= 1900;             /* struct tm holds years since 1900 */
+      break;
+  }
+  return mktime(t) != -1;
+}
+
+static int
+sadjyear(struct tm *t, char *arg)
+{
+  switch (*arg) {
+    case '+':
+    case '-':
+      return adjyear(t, *arg, atoi(arg+1));
+    default:
+      return adjyear(t, '\0', atoi(arg));
+  }
+}
+
+static int
+adjmon(struct tm *t, char type, int val, int istext)
+{
+  if (val < 0)
+    return 0;
+
+  switch (type) {
+    case '+':
+      if (istext)
+        if (val <= t->tm_mon)
+          val += 11 - t->tm_mon;	/* early next year */
+        else
+          val -= t->tm_mon + 1;		/* later this year */
+      if (!adjyear(t, '+', (t->tm_mon + val) / 12))
+        return 0;
+      val %= 12;
+      t->tm_mon += val;
+      if (t->tm_mon > 11)
+        t->tm_mon -= 12;
+      break;
+
+    case '-':
+      if (istext)
+        if (val-1 > t->tm_mon)
+          val = 13 - val + t->tm_mon;	/* later last year */
+        else
+          val = t->tm_mon - val + 1;	/* early this year */
+      if (!adjyear(t, '-', val / 12))
+        return 0;
+      val %= 12;
+      if (val > t->tm_mon) {
+        if (!adjyear(t, '-', 1))
+          return 0;
+        val -= 12;
+      }
+      t->tm_mon -= val;
+      break;
+
+    default:
+      if (val > 12 || val < 1)
+        return 0;
+      t->tm_mon = --val;
+  }
+
+  return mktime(t) != -1;
+}
+
+static int
+sadjmon(struct tm *t, char *arg)
+{
+  int istext;
+  int val;
+
+  switch (*arg) {
+    case '+':
+    case '-':
+      istext = strspn(arg+1, digits) != strlen(arg+1);
+      val = trans(trans_mon, arg+1);
+      return adjmon(t, *arg, val, istext);
+    default:
+      istext = strspn(arg, digits) != strlen(arg);
+      val = trans(trans_mon, arg);
+      return adjmon(t, '\0', val, istext);
+  }
+}
+
+static int
+adjday(struct tm *t, char type, int val)
+{
+  int mdays;
+  switch (type) {
+    case '+':
+      while (val) {
+        mdays = daysinmonth(t);
+        if (val > mdays - t->tm_mday) {
+          val -= mdays - t->tm_mday + 1;
+          t->tm_mday = 1;
+          if (!adjmon(t, '+', 1, 0))
+            return 0;
+        } else {
+          t->tm_mday += val;
+          val = 0;
+        }
+      }
+      break;
+    case '-':
+      while (val)
+        if (val >= t->tm_mday) {
+          val -= t->tm_mday;
+          t->tm_mday = 1;
+          if (!adjmon(t, '-', 1, 0))
+            return 0;
+          t->tm_mday = daysinmonth(t);
+        } else {
+          t->tm_mday -= val;
+          val = 0;
+        }
+      break;
+    default:
+      if (val > 0 && val <= daysinmonth(t))
+        t->tm_mday = val;
+      else
+        return 0;
+      break;
+  }
+
+  return mktime(t) != -1;
+}
+
+static int
+sadjwday(struct tm *t, char *arg)
+{
+  int istext;
+  int val;
+
+  switch (*arg) {
+    case '+':
+    case '-':
+      istext = strspn(arg+1, digits) != strlen(arg+1);
+      val = trans(trans_wday, arg+1);
+      break;
+    default:
+      istext = 0;
+      val = trans(trans_wday, arg);
+      break;
+  }
+
+  if (val < 0)
+    return 0;
+
+  switch (*arg) {
+    case '+':
+      if (istext)
+        if (val < t->tm_wday)
+          val = 7 - t->tm_wday + val;  /* early next week */
+        else
+          val -= t->tm_wday;           /* later this week */
+      else
+        val *= 7;                      /* "-W +5" == "5 weeks in the future" */
+      return adjday(t, '+', val);
+    case '-':
+      if (istext)
+        if (val > t->tm_wday)
+          val = 7 - val + t->tm_wday;  /* later last week */
+        else
+          val = t->tm_wday - val;      /* early this week */
+      else
+        val *= 7;                      /* "-W -5" == "5 weeks ago" */
+      return adjday(t, '-', val);
+    default:
+      if (val < t->tm_wday)
+        return adjday(t, '-', t->tm_wday - val);
+      else if (val > 6)
+        return 0;
+      else if (val > t->tm_wday)
+        return adjday(t, '+', val - t->tm_wday);
+  }
+  return 1;
+}
+
+static int
+sadjday(struct tm *t, char *arg)
+{
+  switch (*arg) {
+    case '+':
+    case '-':
+      return adjday(t, *arg, atoi(arg+1));
+    default:
+      return adjday(t, '\0', atoi(arg));
+  }
+}
+
+const struct vary *
+vary_apply(const struct vary *v, struct tm *t)
+{
+  for (; v; v = v->next) {
+    switch (v->flag) {
+      case 'D':
+        if (!sadjday(t, v->arg))
+          return v;
+        break;
+      case 'W':
+        if (!sadjwday(t, v->arg))
+          return v;
+        break;
+      case 'M':
+        if (!sadjmon(t, v->arg))
+          return v;
+        break;
+      case 'Y':
+        if (!sadjyear(t, v->arg))
+          return v;
+        break;
+      default:
+        return v;
+    }
+  }
+  return 0;
+}
+
+void
+vary_destroy(struct vary *v)
+{
+  struct vary *n;
+
+  while (v) {
+    n = v->next;
+    free(v);
+    v = n;
+  }
+}