fix(build): silence OpenWrt _FORTIFY_SOURCE redefinition warnings

CMakeLists.txt

@@ -147,8 +147,37 @@ if(PLATFORM_LINUX OR PLATFORM_FREEBSD)
   target_compile_options(rtp2httpd PRIVATE -fstack-protector-strong)
   # _FORTIFY_SOURCE requires optimization >= -O1
   if(NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
-    target_compile_definitions(rtp2httpd PRIVATE _FORTIFY_SOURCE=2)
+    # Toolchains often already define this macro:
+    #   OpenWrt CFLAGS:        -D_FORTIFY_SOURCE=1
+    #   Debian/Ubuntu gcc spec: -D_FORTIFY_SOURCE=3 (when optimizing)
+    # Forcing -D_FORTIFY_SOURCE=2 on top of that produces
+    #   <command-line>: warning: "_FORTIFY_SOURCE" redefined
+    # and can silently weaken a higher distro default. Only add level 2
+    # when the compiler/flags do not already provide one.
+    include(CheckCSourceCompiles)
+    set(_rtp2httpd_saved_required_flags "${CMAKE_REQUIRED_FLAGS}")
+    set(_rtp2httpd_saved_required_quiet "${CMAKE_REQUIRED_QUIET}")
+    set(CMAKE_REQUIRED_QUIET TRUE)
+    # -O2 lets gcc spec files inject their default _FORTIFY_SOURCE.
+    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -O2")
+    check_c_source_compiles(
+      "#ifndef _FORTIFY_SOURCE\n#error \"_FORTIFY_SOURCE not predefined\"\n#endif\nint main(void) { return 0; }\n"
+      RTP2HTTPD_HAS_PREDEFINED_FORTIFY_SOURCE)
+    set(CMAKE_REQUIRED_FLAGS "${_rtp2httpd_saved_required_flags}")
+    set(CMAKE_REQUIRED_QUIET "${_rtp2httpd_saved_required_quiet}")
+    unset(_rtp2httpd_saved_required_flags)
+    unset(_rtp2httpd_saved_required_quiet)
+    if(NOT RTP2HTTPD_HAS_PREDEFINED_FORTIFY_SOURCE)
+      target_compile_definitions(rtp2httpd PRIVATE _FORTIFY_SOURCE=2)
+      set(RTP2HTTPD_FORTIFY_SOURCE "2 (project)")
+    else()
+      set(RTP2HTTPD_FORTIFY_SOURCE "toolchain default")
+    endif()
+  else()
+    set(RTP2HTTPD_FORTIFY_SOURCE "disabled (Debug)")
   endif()
+else()
+  set(RTP2HTTPD_FORTIFY_SOURCE "not applied")
 endif()
 
 # ── Libraries ───────────────────────────────────────────────────────
@@ -177,5 +206,6 @@ message(STATUS "  Platform:       ${CMAKE_SYSTEM_NAME}")
 message(STATUS "  Compiler:       ${CMAKE_C_COMPILER_ID} ${CMAKE_C_COMPILER_VERSION}")
 message(STATUS "  Build type:     ${CMAKE_BUILD_TYPE}")
 message(STATUS "  Aggressive opt: ${ENABLE_AGGRESSIVE_OPT}")
+message(STATUS "  Fortify:        ${RTP2HTTPD_FORTIFY_SOURCE}")
 message(STATUS "  Install prefix: ${CMAKE_INSTALL_PREFIX}")
 message(STATUS "")

src/rtsp.c

@@ -2965,7 +2965,7 @@ static void rtsp_parse_play_metadata(rtsp_session_t *session, const struct phr_h
     scale = strtod(scale_buf, &end);
     while (end && (*end == ' ' || *end == '\t'))
       end++;
-    if (end != scale_buf && end && *end == '\0' && errno != ERANGE && isfinite(scale)) {
+    if (end != scale_buf && end && *end == '\0' && errno != ERANGE && double_is_finite(scale)) {
       metadata->playback_scale = scale;
       metadata->playback_scale_known = 1;
     }
@@ -3072,7 +3072,7 @@ static int rtsp_parse_npt_time(const char *value, const char **end_out, double *
 
   errno = 0;
   first_component = strtod(value, &component_end);
-  if (component_end == value || errno == ERANGE || !isfinite(first_component) || first_component < 0.0)
+  if (component_end == value || errno == ERANGE || !double_is_finite(first_component) || first_component < 0.0)
     return -1;
 
   if (*component_end != ':') {
@@ -3099,11 +3099,11 @@ static int rtsp_parse_npt_time(const char *value, const char **end_out, double *
 
   errno = 0;
   seconds = strtod(seconds_start, &seconds_end);
-  if (seconds_end == seconds_start || errno == ERANGE || !isfinite(seconds) || seconds < 0.0 || seconds >= 60.0)
+  if (seconds_end == seconds_start || errno == ERANGE || !double_is_finite(seconds) || seconds < 0.0 || seconds >= 60.0)
     return -1;
 
   double total = first_component * 3600.0 + (double)minutes * 60.0 + seconds;
-  if (!isfinite(total))
+  if (!double_is_finite(total))
     return -1;
 
   *end_out = seconds_end;

src/stream.c

@@ -13,7 +13,6 @@
 #include "status.h"
 #include "utils.h"
 #include <arpa/inet.h>
-#include <math.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #include <stdbool.h>
@@ -260,7 +259,7 @@ void stream_send_http_headers(connection_t *conn, const char *content_type, cons
                                         metadata->upstream_payload) < 0;
 
   /* A value we cannot render exactly is dropped rather than approximated. */
-  if (metadata->playback_scale_known && isfinite(metadata->playback_scale)) {
+  if (metadata->playback_scale_known && double_is_finite(metadata->playback_scale)) {
     if (stream_metadata_format_number(metadata->playback_scale, number, sizeof(number)) == 0)
       failed |= stream_metadata_append_header(headers, sizeof(headers), &length,
                                               stream_metadata_header_names[STREAM_HDR_PLAYBACK_SCALE], number) < 0;
@@ -272,7 +271,7 @@ void stream_send_http_headers(connection_t *conn, const char *content_type, cons
                                             stream_metadata_header_names[STREAM_HDR_PLAYBACK_RANGE],
                                             metadata->playback_range) < 0;
   }
-  if (metadata->media_duration_known && isfinite(metadata->media_duration)) {
+  if (metadata->media_duration_known && double_is_finite(metadata->media_duration)) {
     if (stream_metadata_format_number(metadata->media_duration, number, sizeof(number)) == 0)
       failed |= stream_metadata_append_header(headers, sizeof(headers), &length,
                                               stream_metadata_header_names[STREAM_HDR_MEDIA_DURATION], number) < 0;

src/utils.h

@@ -49,6 +49,22 @@ int64_t get_realtime_ms(void);
 #define max(a, b) ((a) > (b) ? (a) : (b))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
+/**
+ * Return 1 if `value` is a finite IEEE-754 double (not NaN or Inf).
+ *
+ * Inspects exponent bits instead of calling isfinite(). With -ffast-math /
+ * -ffinite-math-only, isfinite() is treated as always-true and Clang emits
+ * -Wnan-infinity-disabled.
+ */
+static inline int double_is_finite(double value) {
+  union {
+    double d;
+    uint64_t u;
+  } conv;
+  conv.d = value;
+  return ((conv.u >> 52) & 0x7ffULL) != 0x7ffULL;
+}
+
 /**
  * Set socket receive buffer size, trying SO_RCVBUFFORCE first.
  * SO_RCVBUFFORCE can exceed system limits but requires CAP_NET_ADMIN.