1 files changed, 70 insertions, 0 deletions
diff --git a/checklinks.awk b/checklinks.awk
new file mode 100644
index 0000000..82a5fea
--- /dev/null
+++ b/checklinks.awk
@@ -0,0 +1,70 @@
+# Check links in tz tables.
+
+# Contributed by Paul Eggert.  This file is in the public domain.
+
+BEGIN {
+    # Special marker indicating that the name is defined as a Zone.
+    # It is a newline so that it cannot match a valid name.
+    # It is not null so that its slot does not appear unset.
+    Zone = "\n"
+}
+
+/^Z/ {
+    if (defined[$2]) {
+	if (defined[$2] == Zone) {
+	    printf "%s: Zone has duplicate definition\n", $2
+	} else {
+	    printf "%s: Link with same name as Zone\n", $2
+	}
+	status = 1
+    }
+    defined[$2] = Zone
+}
+
+/^L/ {
+    if (defined[$3]) {
+	if (defined[$3] == Zone) {
+	    printf "%s: Link with same name as Zone\n", $3
+	} else if (defined[$3] == $2) {
+	    printf "%s: Link has duplicate definition\n", $3
+	} else {
+	    printf "%s: Link to both %s and %s\n", $3, defined[$3], $2
+	}
+	status = 1
+    }
+    if (backcheck && FILENAME != backcheck && $3 != "GMT") {
+      printf "%s: Link should be in '%s'\n", $3, backcheck
+      status = 1
+    }
+    if ($4 == "#=") {
+      shortcut[$5] = $3
+    }
+    used[$2] = 1
+    defined[$3] = $2
+}
+
+END {
+    for (tz in used) {
+	if (defined[tz] != Zone) {
+	  if (!defined[tz]) {
+	    printf "%s: Link to nowhere\n", tz
+	    status = 1
+	  } else if (DATAFORM != "vanguard") {
+	    printf "%s: Link to link\n", tz
+	    status = 1
+	  }
+	}
+    }
+    for (tz in shortcut) {
+      if (defined[shortcut[tz]] != defined[tz]) {
+	target = (!defined[tz] ? "absence" \
+		  : defined[tz] == "\n" ? "zone" \
+		  : defined[tz])
+	printf "%s: target %s disagrees with %s's target %s\n", \
+	  tz, target, shortcut[tz], defined[shortcut[tz]]
+	status = 1
+      }
+    }
+
+    exit status
+}