From ceefacca7f9516ac550d80224140ec403b4c4ecf Mon Sep 17 00:00:00 2001
From: Ashton Fagg <ashton@fagg.id.au>
Date: Sun, 6 Oct 2024 12:55:03 -0400
Subject: [PATCH] Fix absolute path error on Windows

---
 src/util-dir.c         | 10 +++++++++-
 src/util-dir_windows.c | 17 +++++++++++++++++
 src/util.h             |  2 ++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/util-dir.c b/src/util-dir.c
index b17deb6..26486c0 100644
--- a/src/util-dir.c
+++ b/src/util-dir.c
@@ -71,9 +71,15 @@ char* currentdir(void) {
   return append_trail_slash(q_(getcwd(buf,2048)));
 }
 
+int is_valid_path(const char *path) {
+  return path[0] == '/';
+}
+
 #else
+
 char* homedir(void);
 char* currentdir(void);
+int is_valid_path(const char *);
 #endif
 
 char* configdir(void) {
@@ -82,9 +88,10 @@ char* configdir(void) {
 
   if (env) /* note: env can be a NULL */
   {
-      if (env[0] != DIRSEP[0])   /* note: DIRSEP == \\ on windows, / on unix */
+      if (!is_valid_path(env))
       {
           cond_printf(0,"Error: %s must be absolute. Got: %s \n",c,env);
+	  abort();
       }
       s(c);                     /* note : this frees c. */
       return append_trail_slash(q(env));
@@ -143,3 +150,4 @@ char* basedir(void) {
   s(cd_);
   return configdir();
 }
+
diff --git a/src/util-dir_windows.c b/src/util-dir_windows.c
index 822fc98..0ee7166 100644
--- a/src/util-dir_windows.c
+++ b/src/util-dir_windows.c
@@ -64,4 +64,21 @@ char* currentdir(void) {
   char buf[2048];
   return append_trail_slash(q_(_getcwd(buf,2048)));
 }
+
+int is_valid_path(const char *path) {
+  //
+  // On Windows, an absolute path can technically
+  // start with a drive letter (i.e. c:\roswell),
+  // but could also be a UNC path (i.e. \\OTHERMACHINE\roswell).
+  //
+  // But, if invoked inside an msys2 shell we could get a UNIX-style path.
+  //
+  // It appears however that the latter two scenarios are not supported
+  // by other parts of the codebase, so we shall enforce here that only
+  // regular Windows-style paths are allowed.
+  //
+
+  return (isalpha(path[0]) && path[1] == ':'  && (path[2] == '\\' || path[2] == '/'));
+}
+
 #endif
diff --git a/src/util.h b/src/util.h
index a2e3585..e7d4509 100644
--- a/src/util.h
+++ b/src/util.h
@@ -13,6 +13,7 @@
 #include <string.h>
 #include <stdarg.h>
 #ifndef HAVE_WINDOWS_H
+#include <ctype.h>
 #include <pwd.h>
 #include <unistd.h>
 #include <grp.h>
@@ -142,6 +143,7 @@ int directory_exist_p (char* path);
 int change_directory(const char* path);
 int delete_directory(char* pathspec,int recursive);
 char* impldir(char* arch,char* os,char* impl,char* version);
+int is_valid_path(const char *path);
 /*util_file.c */
 int delete_file(char* pathspec);
 int rename_file(char* file,char* new_name);