From 0aecf90263a2548c5d31c7bce6b978245e2ca16e Mon Sep 17 00:00:00 2001
From: Tim Segers <tsegers@pm.me>
Date: Thu, 30 Oct 2025 23:37:15 +0100
Subject: Deduce ext depth

---
 ext/util.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 ext/util.c

(limited to 'ext/util.c')

diff --git a/ext/util.c b/ext/util.c
new file mode 100644
index 0000000..42fe8ac
--- /dev/null
+++ b/ext/util.c
@@ -0,0 +1,93 @@
+#include <ctype.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/random.h>
+
+#include "util.h"
+
+int bin2hex(char *hex, size_t hexsize, const uint8_t *bin, size_t binlen)
+{
+    static const char hex_chars[] = "0123456789ABCDEF";
+
+    if (hex == NULL || bin == NULL || hexsize == 0)
+        return -1;
+
+    if (hexsize < (binlen * 2 + 1))
+        return -2;
+
+    for (size_t i = 0; i < binlen; ++i) {
+        hex[2 * i + 0] = hex_chars[(bin[i] >> 4) & 0xF];
+        hex[2 * i + 1] = hex_chars[(bin[i] >> 0) & 0xF];
+    }
+
+    hex[binlen * 2] = '\0';
+    return 0;
+}
+
+int hex2bin(uint8_t *bin, size_t binsize, const char *hex, size_t hexlen)
+{
+    size_t ibin = 0;
+
+    const int hi_reset = -1;
+    int hi = hi_reset;
+
+    for (size_t ihex = 0; ihex < hexlen; ihex++) {
+        char c = hex[ihex];
+
+        if (isspace((unsigned char) c))
+            continue;
+
+        /* invalid character */
+        if (!isxdigit((unsigned char) c))
+            return -1;
+
+        /* hex char encountered after bin is full */
+        if (ibin >= binsize)
+            return -2;
+
+        uint8_t val = (uint8_t) (isdigit(c) ? c - '0' : (tolower(c) - 'a' + 10));
+
+        if (hi < 0) {
+            /* process hi nibble */
+            hi = val;
+        } else {
+            /* process lo nibble, complete byte, reset hi nibble */
+            bin[ibin++] = (hi << 4) | val;
+            hi = hi_reset;
+        }
+    }
+
+    /* odd number of hex chars */
+    if (hi != hi_reset)
+        return -3;
+
+    return (int) ibin;
+}
+
+void randombytes(uint8_t *buf, uint64_t n)
+{
+    while (n > 0) {
+        ssize_t nbread;
+
+        do {
+            nbread = getrandom(buf, n, 0);
+        } while (nbread == -1 && errno == EINTR);
+
+        if (nbread < 0)
+            exit(1);
+
+        buf += nbread;
+        n -= nbread;
+    }
+}
+
+void memzero(void *ptr, size_t num)
+{
+    volatile unsigned char *volatile ptr_ = (volatile unsigned char *volatile) ptr;
+    size_t i = (size_t) 0U;
+
+    while (i < num)
+        ptr_[i++] = 0U;
+}
-- 
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