From 6ab9188d0cec3d887f537894ed669fe803049746 Mon Sep 17 00:00:00 2001
From: Dirk Engling <erdgeist@erdgeist.org>
Date: Sat, 24 Oct 2026 04:56:27 +0200
Subject: Implement a tiny mmap wrapper ourselves, replacing libowfat's wrapper

---
 ot_accesslist.c | 41 +++++++++++++++++++++++++++++++++++------
 tests/stubs.c   | 20 +++-----------------
 2 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/ot_accesslist.c b/ot_accesslist.c
index e20f42c..6315bc2 100644
--- a/ot_accesslist.c
+++ b/ot_accesslist.c
@@ -10,15 +10,19 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#ifdef WANT_DYNAMIC_ACCESSLIST
-#include <errno.h>
+#if defined(WANT_ACCESSLIST_BLACK) || defined(WANT_ACCESSLIST_WHITE)
+#include <fcntl.h>
+#include <stdint.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #endif
+#ifdef WANT_DYNAMIC_ACCESSLIST
+#include <errno.h>
+#endif
 
 /* Libowfat */
 #include "ip6.h"
-#include "mmap.h"
 
 /* Opentracker */
 #include "ot_accesslist.h"
@@ -120,12 +124,37 @@ size_t accesslist_parse_hashes(ot_hash *dest, size_t capacity, const char *buf,
   return count;
 }
 
+/* Map a file read only and report its size. Returns NULL if the file cannot
+   be opened, is empty, or is too large to map, leaving maplen untouched. */
+static const char *accesslist_map(const char *filename, size_t *maplen) {
+  struct stat  st;
+  const char  *map;
+  int          fd = open(filename, O_RDONLY);
+
+  if (fd < 0)
+    return NULL;
+
+  if (fstat(fd, &st) < 0 || st.st_size <= 0 || (uintmax_t)st.st_size > (uintmax_t)SIZE_MAX) {
+    close(fd);
+    return NULL;
+  }
+
+  map = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_SHARED, fd, 0);
+  close(fd);
+
+  if (map == MAP_FAILED)
+    return NULL;
+
+  *maplen = (size_t)st.st_size;
+  return map;
+}
+
 static void accesslist_readfile(void) {
   ot_accesslist *accesslist_new;
   const char    *map;
   size_t         maplen, capacity, found;
 
-  if ((map = mmap_read(g_accesslist_filename, &maplen)) == NULL) {
+  if ((map = accesslist_map(g_accesslist_filename, &maplen)) == NULL) {
     char *wd = getcwd(NULL, 0);
     fprintf(stderr, "Warning: Can't open accesslist file: %s (but will try to create it later, if necessary and possible).\nPWD: %s\n", g_accesslist_filename, wd);
     free(wd);
@@ -137,7 +166,7 @@ static void accesslist_readfile(void) {
   accesslist_new = accesslist_make(g_accesslist, capacity);
   if (!accesslist_new) {
     fprintf(stderr, "Warning: Not enough memory to allocate %zd bytes for accesslist buffer. May succeed later.\n", capacity * sizeof(ot_hash));
-    mmap_unmap(map, maplen);
+    munmap((void *)map, maplen);
     return;
   }
 
@@ -146,7 +175,7 @@ static void accesslist_readfile(void) {
   fprintf(stderr, "Added %zd info_hashes to accesslist\n", found);
 #endif
 
-  mmap_unmap(map, maplen);
+  munmap((void *)map, maplen);
 
   qsort(accesslist_new->list, found, sizeof(ot_hash), vector_compare_hash);
   accesslist_new->size = found;
diff --git a/tests/stubs.c b/tests/stubs.c
index febdd7b..ce93071 100644
--- a/tests/stubs.c
+++ b/tests/stubs.c
@@ -14,21 +14,7 @@
 void free_peerlist(ot_peerlist *peer_list) { (void)peer_list; }
 
 /* ot_accesslist.c is built with WANT_ACCESSLIST_BLACK so that the hash parser
-   is reachable. These four belong to accesslist_readfile and the reload
-   worker, neither of which any test drives. */
-time_t      g_now_seconds;
+   is reachable. These two belong to accesslist_readfile and the reload worker,
+   neither of which any test drives. */
+time_t       g_now_seconds;
 volatile int g_opentracker_running;
-
-const char *mmap_read(const char *filename, size_t *filesize);
-const char *mmap_read(const char *filename, size_t *filesize) {
-  (void)filename;
-  *filesize = 0;
-  return NULL;
-}
-
-int         mmap_unmap(const char *mapped, size_t maplen);
-int         mmap_unmap(const char *mapped, size_t maplen) {
-  (void)mapped;
-  (void)maplen;
-  return 0;
-}
-- 
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