From 04734e0ebc309f18dde0275323970dff98c928e8 Mon Sep 17 00:00:00 2001
From: Martin Pulec <martin.pulec@cesnet.cz>
Date: Tue, 26 Oct 2021 10:47:13 +0200
Subject: [PATCH] Define ug_strerror for thread-safe strerror abstraction

---
 src/audio/export.c       |  3 ++-
 src/debug.cpp            | 15 ++-------------
 src/utils/misc.c         | 17 +++++++++++++++++
 src/utils/misc.h         |  2 ++
 src/video_capture/v4l2.c |  8 ++------
 5 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/src/audio/export.c b/src/audio/export.c
index aa52c2cfb..1e2cf7d7b 100644
--- a/src/audio/export.c
+++ b/src/audio/export.c
@@ -51,6 +51,7 @@
 #include "audio/wav_writer.h"
 #include "debug.h"
 #include "export.h"
+#include "utils/misc.h" // ug_strerror
 #include "utils/ring_buffer.h"
 
 #define CACHE_SECONDS                   10
@@ -109,7 +110,7 @@ static void *audio_export_thread(void *arg)
                 const int sample_size = s->saved_format.bps * s->saved_format.ch_count;
                 int rc = wav_writer_write(s->wav, size / sample_size, data);
                 if (rc != 0) {
-                        fprintf(stderr, "[Audio export] Problem writing audio samples: %s\n", strerror(-rc));
+                        fprintf(stderr, "[Audio export] Problem writing audio samples: %s\n", ug_strerror(-rc));
                 }
 
                 free(data);
diff --git a/src/debug.cpp b/src/debug.cpp
index 5532d5157..dc5546065 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -58,6 +58,7 @@
 #include "host.h"
 #include "rang.hpp"
 #include "utils/color_out.h"
+#include "utils/misc.h" // ug_strerror
 
 using std::string;
 using std::unordered_map;
@@ -130,19 +131,7 @@ void log_msg(int level, const char *format, ...)
  */
 void log_perror(int level, const char *msg)
 {
-        constexpr int strerror_buf_len = 1024;
-        std::array<char, strerror_buf_len> strerror_buf;
-        const char *errstring;
-#ifdef _WIN32
-        strerror_s(strerror_buf.data(), strerror_buf.size(), errno); // C11 Annex K (bounds-checking interfaces)
-        errstring = strerror_buf.data();
-#elif ! defined _POSIX_C_SOURCE || (_POSIX_C_SOURCE >= 200112L && !  _GNU_SOURCE)
-        strerror_r(errno, strerror_buf.data(), strerror_buf.size()); // XSI version
-        errstring = strerror_buf.data();
-#else // GNU strerror_r version
-        errstring = strerror_r(errno, strerror_buf.data(), strerror_buf_len);
-#endif
-        log_msg(level, "%s: %s\n", msg, errstring);
+        log_msg(level, "%s: %s\n", msg, ug_strerror(errno));
 }
 
 /**
diff --git a/src/utils/misc.c b/src/utils/misc.c
index 72ef6bcd5..9835caabb 100644
--- a/src/utils/misc.c
+++ b/src/utils/misc.c
@@ -47,6 +47,8 @@
 #include "debug.h"
 #include "utils/misc.h"
 
+#define STRERROR_BUF_LEN 1024
+
 int clampi(long long val, int lo, int hi) {
         if (val < lo) {
                 return lo;
@@ -305,3 +307,18 @@ size_t urldecode(char *out, size_t max_len, const char *in)
 
         return len;
 }
+
+const char *ug_strerror(int errnum)
+{
+        static _Thread_local char strerror_buf[STRERROR_BUF_LEN];
+        const char *errstring = strerror_buf;
+#ifdef _WIN32
+        strerror_s(strerror_buf, sizeof strerror_buf, errnum); // C11 Annex K (bounds-checking interfaces)
+#elif ! defined _POSIX_C_SOURCE || (_POSIX_C_SOURCE >= 200112L && !  _GNU_SOURCE)
+        strerror_r(errnum, strerror_buf, sizeof strerror_buf); // XSI version
+#else // GNU strerror_r version
+        errstring = strerror_r(errnum, strerror_buf, sizeof strerror_buf);
+#endif
+
+        return errstring;
+}
diff --git a/src/utils/misc.h b/src/utils/misc.h
index ff0101d5d..6eacaf201 100644
--- a/src/utils/misc.h
+++ b/src/utils/misc.h
@@ -68,6 +68,8 @@ int urlencode_rfc3986_eval(int c);
 size_t urlencode(char *out, size_t max_len, const char *in, int (*eval_pass)(int c), bool space_plus_replace);
 size_t urldecode(char *out, size_t max_len, const char *in);
 
+const char *ug_strerror(int errnum);
+
 /**
  * @brief Creates FourCC word
  *
diff --git a/src/video_capture/v4l2.c b/src/video_capture/v4l2.c
index 7db4cb6ac..bd06bd77e 100644
--- a/src/video_capture/v4l2.c
+++ b/src/video_capture/v4l2.c
@@ -61,12 +61,9 @@
 #include "lib_common.h"
 #include "tv.h"
 #include "utils/list.h"
+#include "utils/misc.h" // ug_strerror
 #include "video.h"
 
-#ifndef _GNU_SOURCE
-#error "GNU variant of strerror_r is used below!"
-#endif
-
 /* prototypes of functions defined in this module */
 static void show_help(void);
 static void print_fps(int fd, struct v4l2_frmivalenum *param);
@@ -224,9 +221,8 @@ static void show_help()
                 int fd = open(name, O_RDWR);
                 if (fd == -1) {
                         if (errno != ENOENT) {
-                                char errbuf[1024];
                                 log_msg(LOG_LEVEL_WARNING, MOD_NAME "Unable to open input device %s: %s\n",
-                                                name, strerror_r(errno, errbuf, sizeof errbuf));
+                                                name, ug_strerror(errno));
                         }
                         continue;
                 }