From 0c4fbb7ed90cf052733b3893a740cb51e3f8f13b Mon Sep 17 00:00:00 2001
From: Tom Thorogood <me+github@tomthorogood.co.uk>
Date: Fri, 2 Apr 2021 23:09:26 +1030
Subject: [PATCH] Print logging and debugging messages to stderr

---
 fido2/log.c  | 6 +++---
 fido2/util.c | 4 ++--
 pc/device.c  | 6 +++---
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fido2/log.c b/fido2/log.c
index bb9a41ad..9baade6c 100644
--- a/fido2/log.c
+++ b/fido2/log.c
@@ -72,7 +72,7 @@ void LOG(uint32_t tag, const char * filename, int num, const char * fmt, ...)
     {
         if (tag & tagtable[i].tagn)
         {
-            if (tagtable[i].tag[0] && !(tag & TAG_NO_TAG)) printf("[%s] ", tagtable[i].tag);
+            if (tagtable[i].tag[0] && !(tag & TAG_NO_TAG)) fprintf(stderr, "[%s] ", tagtable[i].tag);
             i = 0;
             break;
         }
@@ -86,12 +86,12 @@ void LOG(uint32_t tag, const char * filename, int num, const char * fmt, ...)
 #ifdef ENABLE_FILE_LOGGING
     if (tag & TAG_FILENO)
     {
-        printf("%s:%d: ", filename, num);
+        fprintf(stderr, "%s:%d: ", filename, num);
     }
 #endif
     va_list args;
     va_start(args, fmt);
-    vprintf(fmt, args);
+    vfprintf(stderr, fmt, args);
     va_end(args);
 }
 
diff --git a/fido2/util.c b/fido2/util.c
index 6092f77e..f6a68474 100644
--- a/fido2/util.c
+++ b/fido2/util.c
@@ -11,7 +11,7 @@ void dump_hex(uint8_t * buf, int size)
 {
     while(size--)
     {
-        printf("%02x ", *buf++);
+        fprintf(stderr, "%02x ", *buf++);
     }
-    printf("\n");
+    fprintf(stderr, "\n");
 }
diff --git a/pc/device.c b/pc/device.c
index 5c9b4aca..deed3db2 100644
--- a/pc/device.c
+++ b/pc/device.c
@@ -202,7 +202,7 @@ void usbhid_close()
 void int_handler(int i)
 {
     usbhid_close();
-    printf("SIGINT... exiting.\n");
+    fprintf(stderr, "SIGINT... exiting.\n");
     exit(0);
 }
 
@@ -364,7 +364,7 @@ void authenticator_initialize()
     uint8_t * mem;
     if (access(state_file, F_OK) != -1)
     {
-        printf("state file exists\n");
+        fprintf(stderr, "state file exists\n");
         f = fopen(state_file, "rb");
         if (f== NULL)
         {
@@ -398,7 +398,7 @@ void authenticator_initialize()
     }
     else
     {
-        printf("state file does not exist, creating it\n");
+        fprintf(stderr, "state file does not exist, creating it\n");
         f = fopen(state_file, "wb+");
         if (f== NULL)
         {