From 4b7ad8ee4302299917884714f93060d36d6aaf68 Mon Sep 17 00:00:00 2001
From: Nicolas Williams <nico@twosigma.com>
Date: Mon, 17 Jan 2022 14:59:23 -0600
Subject: [PATCH] hx509: Fix strerror(negative); streamline code

Calling strerror() with a negative value is an error.

Besides fixing that, we streamline hx509_get_error_string(), making it much
simpler and easier to read.
---
 lib/hx509/error.c | 54 +++++++++++++++--------------------------------
 1 file changed, 17 insertions(+), 37 deletions(-)

diff --git a/lib/hx509/error.c b/lib/hx509/error.c
index 1ca9682d0..aee4f79e7 100644
--- a/lib/hx509/error.c
+++ b/lib/hx509/error.c
@@ -147,48 +147,28 @@ hx509_enomem(hx509_context context)
 HX509_LIB_FUNCTION char * HX509_LIB_CALL
 hx509_get_error_string(hx509_context context, int error_code)
 {
-    heim_error_t msg;
-    heim_string_t s;
-    char *str = NULL;
+    heim_string_t s = NULL;
+    const char *cstr = NULL;
+    char *str;
 
-    if (context == NULL) {
-        const char *sys_err_msg;
+    if (context) {
+        if (context->error &&
+            heim_error_get_code(context->error) == error_code &&
+            (s = heim_error_copy_string(context->error)))
+            cstr = heim_string_get_utf8(s);
 
-        /* This case should only happen on hx509_context_init() failure */
-        if ((sys_err_msg = strerror(error_code))) {
-            if (asprintf(&str, "hx509_context_init system error: %s (%d)",
-                         sys_err_msg, error_code) == -1)
-                return NULL;
-            return str;
-        }
-        if (asprintf(&str, "hx509_context_init unknown error: %d",
-                     error_code) == -1)
-            return NULL;
-        return str;
-    }
+        if (cstr == NULL)
+            cstr = com_right(context->et_list, error_code);
 
-    msg = context->error;
-    if (msg == NULL || heim_error_get_code(msg) != error_code) {
-	const char *cstr;
+        if (cstr == NULL && error_code > -1)
+            cstr = strerror(error_code);
+    } /* else this could be an error in hx509_context_init() */
 
-	cstr = com_right(context->et_list, error_code);
-	if (cstr)
-	    return strdup(cstr);
-	cstr = strerror(error_code);
-	if (cstr)
-	    return strdup(cstr);
-	if (asprintf(&str, "<unknown error: %d>", error_code) == -1)
-	    return NULL;
-	return str;
-    }
+    if (cstr == NULL)
+        cstr = error_message(error_code); /* never returns NULL */
 
-    s = heim_error_copy_string(msg);
-    if (s) {
-	const char *cstr = heim_string_get_utf8(s);
-	if (cstr)
-	    str = strdup(cstr);
-	heim_release(s);
-    }
+    str = strdup(cstr);
+    heim_release(s);
     return str;
 }