Fix compilation on BSD/macOS

No functional change

Author: anematode

src/shm.h

@@ -36,7 +36,7 @@
 #include <utility>
 #include <variant>
 
-#if !defined(_WIN32) && !defined(__ANDROID__)
+#if defined(__linux__) && !defined(__ANDROID__)
     #include "shm_linux.h"
 #endif
 
@@ -60,7 +60,7 @@
         #define NOMINMAX
     #endif
     #include <windows.h>
-#else
+#elif defined(__linux__)
     #include <cstring>
     #include <fcntl.h>
     #include <pthread.h>
@@ -407,7 +407,7 @@ class SharedMemoryBackend {
     std::string last_error_message;
 };
 
-#elif !defined(__ANDROID__)
+#elif defined(__linux__) && !defined(__ANDROID__)
 
 template<typename T>
 class SharedMemoryBackend {
@@ -538,7 +538,7 @@ struct SystemWideSharedConstant {
         std::snprintf(buf, sizeof(buf), "Local\\sf_%zu$%zu$%zu", content_hash, executable_hash, discriminator);
         std::string shm_name = buf;
 
-#if !defined(_WIN32)
+#if defined(__linux__) && !defined(__ANDROID__)
         // POSIX shared memory names must start with a slash
         shm_name = "/sf_" + createHashString(shm_name);
 

src/shm_linux.h

@@ -19,6 +19,10 @@
 #ifndef SHM_LINUX_H_INCLUDED
 #define SHM_LINUX_H_INCLUDED
 
+#if !defined(__linux__) || defined(__ANDROID__)
+#error shm_linux.h should not be included on this platform.
+#endif
+
 #include <atomic>
 #include <cassert>
 #include <cerrno>
@@ -40,15 +44,8 @@
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>
-
-#if defined(__NetBSD__) || defined(__DragonFly__) || defined(__linux__)
-    #include <limits.h>
-    #define SF_MAX_SEM_NAME_LEN NAME_MAX
-#elif defined(__APPLE__)
-    #define SF_MAX_SEM_NAME_LEN 31
-#else
-    #define SF_MAX_SEM_NAME_LEN 255
-#endif
+#include <limits.h>
+#define SF_MAX_SEM_NAME_LEN NAME_MAX
 
 #include "misc.h"