From e7c86f7d79f641ab8a0e542d32e857494e943389 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Wed, 13 Jan 2021 06:21:53 -0600
Subject: Fix "date -I" segfault and teach lib/args.c that "I(opt):;" short opt
 with no argument returns NULL same as --opt without =

---
 lib/args.c        | 11 ++++++-----
 toys/posix/date.c |  2 +-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/lib/args.c b/lib/args.c
index ac83a0fe..f5d3dc24 100644
--- a/lib/args.c
+++ b/lib/args.c
@@ -131,7 +131,7 @@ struct getoptflagstate
 };
 
 // Use getoptflagstate to parse one command line option from argv
-static int gotflag(struct getoptflagstate *gof, struct opts *opt)
+static int gotflag(struct getoptflagstate *gof, struct opts *opt, int shrt)
 {
   unsigned long long i;
   int type;
@@ -168,7 +168,8 @@ static int gotflag(struct getoptflagstate *gof, struct opts *opt)
   }
 
   // Does this option take an argument?
-  if (!gof->arg) {
+  if (!gof->arg || (shrt && !gof->arg[1])) {
+    gof->arg = 0;
     if (opt->flags & 8) return 0;
     gof->arg = "";
   } else gof->arg++;
@@ -445,7 +446,7 @@ void get_optflags(void)
         }
 
         // Long option parsed, handle option.
-        gotflag(&gof, catch);
+        gotflag(&gof, catch, 0);
         continue;
       }
 
@@ -458,7 +459,7 @@ void get_optflags(void)
     // At this point, we have the args part of -args.  Loop through
     // each entry (could be -abc meaning -a -b -c)
     saveflags = toys.optflags;
-    while (*gof.arg) {
+    while (gof.arg && *gof.arg) {
 
       // Identify next option char.
       for (catch = gof.opts; catch; catch = catch->next)
@@ -466,7 +467,7 @@ void get_optflags(void)
           if (!((catch->flags&4) && gof.arg[1])) break;
 
       // Handle option char (advancing past what was used)
-      if (gotflag(&gof, catch) ) {
+      if (gotflag(&gof, catch, 1) ) {
         toys.optflags = saveflags;
         gof.arg = toys.argv[gof.argc];
         goto notflag;
diff --git a/toys/posix/date.c b/toys/posix/date.c
index ead72e15..86c2d343 100644
--- a/toys/posix/date.c
+++ b/toys/posix/date.c
@@ -138,7 +138,7 @@ void date_main(void)
 
   if (FLAG(I)) {
     char *iso_formats[] = {"%F","%FT%H%:z","%FT%R%:z","%FT%T%:z","%FT%T,%N%:z"};
-    int i = stridx("dhmsn", *TT.I ? *TT.I : 'd');
+    int i = stridx("dhmsn", (TT.I && *TT.I) ? *TT.I : 'd');
 
     if (i<0) help_exit("bad -I: %s", TT.I);
     format_string = xstrdup(iso_formats[i]);
-- 
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