From 2a963ff008e5302e8961ed2c2b5bd9fd97f7a462 Mon Sep 17 00:00:00 2001
From: doomfrawen <doomfrawen@users.noreply.github.com>
Date: Sun, 9 Aug 2026 09:18:22 -0700
Subject: [PATCH] Fix Windows/MinGW build: reserved 'errno' parameter name,
 missing err.h

- usage(FILE *stream, int errno) uses the reserved identifier 'errno'
  as a parameter name. MinGW's <errno.h> (pulled in transitively)
  defines errno as a macro expanding to a function call, which
  mangles this declaration/definition and produces
  'passing argument 2 of usage makes pointer from integer without a
  cast'. Renamed to exit_code.

- nfc-utils.h/.c include <err.h>, a BSD/glibc-only header not
  provided by MinGW-w64. The only function actually used from it is
  warnx() (via the DBG/WARN/ERR macros), so on _WIN32 this adds a
  small static inline warnx() shim instead, and drops the redundant
  second #include <err.h> in nfc-utils.c (nfc-utils.h already
  provides it).
---
 src/mfoc.c      |  4 ++--
 src/mfoc.h      |  2 +-
 src/nfc-utils.c |  1 -
 src/nfc-utils.h | 15 ++++++++++++++-
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/mfoc.c b/src/mfoc.c
index 9887553..3a6e1ac 100644
--- a/src/mfoc.c
+++ b/src/mfoc.c
@@ -753,7 +753,7 @@ int main(int argc, char *const argv[])
   exit(EXIT_FAILURE);
 }
 
-void usage(FILE *stream, int errno)
+void usage(FILE *stream, int exit_code)
 {
   fprintf(stream, "Usage: mfoc [-h] [-k key] [-f file] ... [-P probnum] [-T tolerance] [-O output]\n");
   fprintf(stream, "\n");
@@ -776,7 +776,7 @@ void usage(FILE *stream, int errno)
   fprintf(stream, "\n");
   fprintf(stream, "This is mfoc version %s.\n", PACKAGE_VERSION);
   fprintf(stream, "For more information, run: 'man mfoc'.\n");
-  exit(errno);
+  exit(exit_code);
 }
 
 void mf_init(mfreader *r)
diff --git a/src/mfoc.h b/src/mfoc.h
index 9ea7547..8b09274 100644
--- a/src/mfoc.h
+++ b/src/mfoc.h
@@ -82,7 +82,7 @@ typedef struct {
 } countKeys;
 
 
-void usage(FILE *stream, int errno);
+void usage(FILE *stream, int exit_code);
 void mf_init(mfreader *r);
 void mf_configure(nfc_device *pdi);
 void mf_select_tag(nfc_device *pdi, nfc_target *pnt);
diff --git a/src/nfc-utils.c b/src/nfc-utils.c
index 5c0a264..f5b13b1 100644
--- a/src/nfc-utils.c
+++ b/src/nfc-utils.c
@@ -37,7 +37,6 @@
  * @brief Provide some examples shared functions like print, parity calculation, options parsing.
  */
 #include <nfc/nfc.h>
-#include <err.h>
 
 #include "nfc-utils.h"
 
diff --git a/src/nfc-utils.h b/src/nfc-utils.h
index 8c52d4c..54af06f 100644
--- a/src/nfc-utils.h
+++ b/src/nfc-utils.h
@@ -43,7 +43,20 @@
 
 #  include <stdlib.h>
 #  include <string.h>
-#  include <err.h>
+#  ifdef _WIN32
+#    include <stdio.h>
+#    include <stdarg.h>
+static inline void warnx(const char *fmt, ...)
+{
+  va_list ap;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+  fprintf(stderr, "\n");
+}
+#  else
+#    include <err.h>
+#  endif
 
 /**
  * @macro DBG