From 5ffb506e43cd8dd5ecd1945a93e854f1b735cfd5 Mon Sep 17 00:00:00 2001
From: Daniel Shahaf <d.s@daniel.shahaf.name>
Date: Fri, 20 Mar 2020 18:49:42 +0000
Subject: [PATCH 2/2] zsh/rlimits: Ensure option letters are unambiguous at
 runtime.

---
 Src/Builtins/rlimits.c | 15 +++++++++++++++
 Test/B12limit.ztst     | 10 ++++++++++
 2 files changed, 25 insertions(+)

diff --git a/Src/Builtins/rlimits.c b/Src/Builtins/rlimits.c
index c3c031fff..5c260e7db 100644
--- a/Src/Builtins/rlimits.c
+++ b/Src/Builtins/rlimits.c
@@ -181,11 +181,26 @@ set_resinfo(void)
 {
     int i;
     resinfo_T **resinfo_mutable;
+    char seen_letters[sizeof(known_resources)/sizeof(resinfo_T) + 1] = {0};
+    char *seen_p = seen_letters;
 
     resinfo_mutable = (resinfo_T **)zshcalloc(RLIM_NLIMITS*sizeof(resinfo_T *));
 
     for (i=0; i<sizeof(known_resources)/sizeof(resinfo_T); ++i) {
 	resinfo_mutable[known_resources[i].res] = &known_resources[i];
+
+	/* 
+	 * If this resource's option letter is already used, change its option
+	 * letter to 'N'.
+	 */
+	{
+	    char *current_letter = &known_resources[i].opt;
+	    if (*current_letter != 'N' && strchr(seen_letters, *current_letter)) {
+		DPUTS1(1, "duplicate ulimit option letter: %c", *current_letter);
+		*current_letter = 'N';
+	    }
+	    *seen_p++ = *current_letter;
+	}
     }
     for (i=0; i<RLIM_NLIMITS; ++i) {
 	if (!resinfo_mutable[i]) {
diff --git a/Test/B12limit.ztst b/Test/B12limit.ztst
index 5dd7afdbe..922751369 100644
--- a/Test/B12limit.ztst
+++ b/Test/B12limit.ztst
@@ -8,3 +8,13 @@
 F:A failure here does not indicate any error in zsh. It just means there
 F:is a resource in your system that is unknown to zsh developers. Please
 F:report this to zsh-workers mailing list.
+
+  () {
+    set -- ${(f)"$(ulimit -a)"}
+    set -- ${@%%:*}
+    typeset -aU unique_options=( "$@" )
+    # The value of $unique_options is, e.g., ( -t -f '-N 2' -s ... ).
+    (( $# == $#unique_options ))
+  }
+0:check if limit option letters are unique
+