Simplify err_build_SYS_str_reasons

This is currently done in a rather silly way. Shift the index by 1
and avoid weird pointer dances. Rather than relying on static
initialization, use code to obviate a comment.

ok beck joshua jsing

1 files changed, 13 insertions, 19 deletions

diff --git a/src/lib/libcrypto/err/err.c b/src/lib/libcrypto/err/err.c
index 25fbb03875..f03a4431e7 100644
--- a/src/lib/libcrypto/err/err.c
+++ b/src/lib/libcrypto/err/err.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: err.c,v 1.75 2024/11/02 12:46:36 tb Exp $ */
+/* $OpenBSD: err.c,v 1.76 2025/05/20 09:25:40 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -484,33 +484,27 @@ err_build_SYS_str_reasons(void)
 {
         /* malloc cannot be used here, use static storage instead */
         static char strerror_tab[NUM_SYS_STR_REASONS][LEN_SYS_STR_REASON];
+        const char *errstr;
         int save_errno;
         int i;
 
         /* strerror(3) will set errno to EINVAL when i is an unknown errno. */
         save_errno = errno;
-        for (i = 1; i <= NUM_SYS_STR_REASONS; i++) {
-                ERR_STRING_DATA *str = &SYS_str_reasons[i - 1];
-
-                str->error = (unsigned long)i;
-                if (str->string == NULL) {
-                        char (*dest)[LEN_SYS_STR_REASON] =
-                            &(strerror_tab[i - 1]);
-                        const char *src = strerror(i);
-                        if (src != NULL) {
-                                strlcpy(*dest, src, sizeof *dest);
-                                str->string = *dest;
-                        }
+        for (i = 0; i < NUM_SYS_STR_REASONS; i++) {
+                ERR_STRING_DATA *str = &SYS_str_reasons[i];
+
+                str->error = i + 1;
+                str->string = "unknown";
+
+                if ((errstr = strerror((int)str->error)) != NULL) {
+                        strlcpy(strerror_tab[i], errstr, sizeof(strerror_tab[i]));
+                        str->string = strerror_tab[i];
                 }
-                if (str->string == NULL)
-                        str->string = "unknown";
         }
         errno = save_errno;
 
-        /*
-         * Now we still have SYS_str_reasons[NUM_SYS_STR_REASONS] = {0, NULL},
-         * as required by ERR_load_strings.
-         */
+        SYS_str_reasons[NUM_SYS_STR_REASONS].error = 0;
+        SYS_str_reasons[NUM_SYS_STR_REASONS].string = NULL;
 }
 #endif