Properly detect Linux with glibc to detect what's not

libs/nacl/native_client/src/shared/imc/posix/nacl_imc_posix.cc

@@ -80,9 +80,8 @@ static int AshmemCreateRegion(size_t size) {
 int NaClWouldBlock(void) {
   return errno == EAGAIN;
 }
-
 int NaClGetLastErrorString(char* buffer, size_t length) {
-#if NACL_LINUX && !NACL_ANDROID
+#if NACL_LINUX && defined(__GLIBC__)
   char* message;
   /*
    * Note some Linux distributions provide only GNU version of strerror_r().

src/common/FileSystem.cpp

@@ -192,14 +192,12 @@ inline int my_open(Str::StringRef path, openMode_t mode)
 	int fd = _open_osfhandle(reinterpret_cast<intptr_t>(h), modes[mode_] | O_BINARY | O_NOINHERIT);
 	if (fd == -1)
 		CloseHandle(h);
-#elif defined(__FreeBSD__) || defined(__APPLE__)
-	// O_CLOEXEC is supported in macOS from 10.7 onwards
-	int fd = open(path.c_str(), modes[mode_] | O_CLOEXEC, 0666);
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 	int fd = open64(path.c_str(), modes[mode_] | O_CLOEXEC | O_LARGEFILE, 0666);
-#elif defined(__native_client__)
-	// This doesn't actually work, but it's not used anyways
-	int fd = open(path.c_str(), modes[mode_], 0666);
+#else
+	// This doesn't actually work in Native Client, but it's not used anyways.
+	// O_CLOEXEC is supported in macOS from 10.7 onwards.
+	int fd = open(path.c_str(), modes[mode_] | O_CLOEXEC, 0666);
 #endif
 
 #ifndef _WIN32
@@ -238,47 +236,47 @@ inline offset_t my_ftell(FILE* fd)
 {
 #ifdef _WIN32
 	return _ftelli64(fd);
-#elif defined(__FreeBSD__) || defined(__APPLE__) || defined(__native_client__)
-	return ftello(fd);
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 	return ftello64(fd);
+#else
+	return ftello(fd);
 #endif
 }
 inline int my_fseek(FILE* fd, offset_t off, int whence)
 {
 #ifdef _WIN32
 	return _fseeki64(fd, off, whence);
-#elif defined(__FreeBSD__) || defined(__APPLE__) || defined(__native_client__)
-	return fseeko(fd, off, whence);
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 	return fseeko64(fd, off, whence);
+#else
+	return fseeko(fd, off, whence);
 #endif
 }
 #ifdef _WIN32
 typedef struct _stati64 my_stat_t;
-#elif defined(__FreeBSD__) || defined(__APPLE__) || defined(__native_client__)
-using my_stat_t = struct stat;
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 using my_stat_t = struct stat64;
+#else
+using my_stat_t = struct stat;
 #endif
 inline int my_fstat(int fd, my_stat_t* st)
 {
 #ifdef _WIN32
 	return _fstati64(fd, st);
-#elif defined(__FreeBSD__) || defined(__APPLE__) || defined(__native_client__)
-	return fstat(fd, st);
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 	return fstat64(fd, st);
+#else
+	return fstat(fd, st);
 #endif
 }
 inline int my_stat(Str::StringRef path, my_stat_t* st)
 {
 #ifdef _WIN32
 	return _wstati64(Str::UTF8To16(path).c_str(), st);
-#elif defined(__FreeBSD__) || defined(__APPLE__) || defined(__native_client__)
-	return stat(path.c_str(), st);
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 	return stat64(path.c_str(), st);
+#else
+	return stat(path.c_str(), st);
 #endif
 }
 inline intptr_t my_pread(int fd, void* buf, size_t count, offset_t offset)
@@ -294,10 +292,10 @@ inline intptr_t my_pread(int fd, void* buf, size_t count, offset_t offset)
 		return -1;
 	}
 	return bytesRead;
-#elif defined(__FreeBSD__) || defined(__APPLE__) || defined(__native_client__)
-	return pread(fd, buf, count, offset);
-#elif defined(__linux__)
+#elif defined(__linux__) && defined(__GLIBC__)
 	return pread64(fd, buf, count, offset);
+#else
+	return pread(fd, buf, count, offset);
 #endif
 }