From 4686f6bc61d6f9d1dbe12e4e67583a25cdb12040 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sun, 1 Dec 2024 06:02:26 -0700
Subject: [PATCH] repair executable-relative boot file search on NetBSD (#889)

---
 c/self-exe.c                     | 39 +++++++++++++++++++++++++++++++-
 release_notes/release_notes.stex |  6 +++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/c/self-exe.c b/c/self-exe.c
index fecc82fb1..cbcfcaf86 100644
--- a/c/self-exe.c
+++ b/c/self-exe.c
@@ -187,6 +187,33 @@ static char *get_self_path_platform() {
 }
 #endif
 
+#if defined(__NetBSD__)
+#define HAVE_GET_SELF_PATH_PLATFORM
+#include <sys/sysctl.h>
+static char *get_self_path_platform() {
+  int mib[4];
+  char *s;
+  size_t len;
+  int r;
+
+  mib[0] = CTL_KERN;
+  mib[1] = KERN_PROC_ARGS;
+  mib[2] = getpid();
+  mib[3] = KERN_PROC_PATHNAME;
+
+  r = sysctl(mib, 4, NULL, &len, NULL, 0);
+  if (r < 0)
+    return NULL;
+  s = malloc(len);
+  if (s == NULL)
+    return NULL;
+  r = sysctl(mib, 4, s, &len, NULL, 0);
+  if (r < 0)
+    return NULL;
+  return s;
+}
+#endif
+
 #if defined(__sun__) && defined(__svr4__)
 #define HAVE_GET_SELF_PATH_PLATFORM
 static char *get_self_path_platform() {
@@ -203,12 +230,22 @@ static char *get_self_path_platform() {
 static char *get_self_path_platform() { return copy_string("/proc/self/exe"); }
 #endif
 
-#if defined(__NetBSD__) || defined(__minix) || defined(__DragonFly__) ||       \
+#if defined(__minix) || defined(__DragonFly__) ||       \
     defined(__FreeBSD_kernel__) || defined(_AIX)
 #define HAVE_GET_SELF_PATH_PLATFORM
 static char *get_self_path_platform() { return copy_string("/proc/curproc/file"); }
 #endif
 
+#ifndef HAVE_GET_SELF_PATH_PLATFORM
+/* sysctl() approach should be used, instead, but leaving this here as a reminder
+   (1) to not switch back to "/proc" for NetBSD; and (2) if switching is somehow
+   needed, don't confuse "/proc/curproc/file" with "/proc/curproc/exe" */
+#if defined(__NetBSD__)
+#define HAVE_GET_SELF_PATH_PLATFORM
+static char *get_self_path_platform() { return copy_string("/proc/curproc/exe"); }
+#endif
+#endif
+
 #ifndef HAVE_GET_SELF_PATH_PLATFORM
 static char *get_self_path_platform() { return NULL; }
 #endif
diff --git a/release_notes/release_notes.stex b/release_notes/release_notes.stex
index 95b1cc685..24ca06876 100644
--- a/release_notes/release_notes.stex
+++ b/release_notes/release_notes.stex
@@ -2769,6 +2769,12 @@ in fasl files does not generally make sense.
 %-----------------------------------------------------------------------------
 \section{Bug Fixes}\label{section:bugfixes}
 
+\subsection{Repair executable-releative search for NetBSD (10.2.0)}
+
+An incorrect approach to finding the current executable's path on
+NetBSD meant that boot files could not be found relative to the
+executable.
+
 \subsection{Incorrect assembly code for threaded ARMv5 and earlier (10.1.0)}
 
 A bug that generated incorrect assembly code in threaded mode for ARMv5 and earlier