Support for libc variants without fseeko/ftello

Some older Android libc implementations don't support `fseeko` or `ftello`.
This commit adds a new compile-time macro `LIBC_NO_FSEEKO` as well as a usage in CMake for old Android APIs.

build/cmake/CMakeLists.txt

@@ -82,8 +82,19 @@ else ()
     add_definitions(-DZSTD_LEGACY_SUPPORT=0)
 endif ()
 
+get_cmake_property(_variableNames VARIABLES)
+list (SORT _variableNames)
+foreach (_variableName ${_variableNames})
+    message("${_variableName}=${${_variableName}}")
+endforeach()
+
 if (ANDROID)
     set(ZSTD_MULTITHREAD_SUPPORT_DEFAULT OFF)
+    # Old versions of bionic libc don't have fseeko/ftello
+    if ((NOT ${ANDROID_PLATFORM_LEVEL}) OR ${ANDROID_PLATFORM_LEVEL} VERSION_LESS 24)
+        message("Hi Android SDK")
+        add_compile_definitions(LIBC_NO_FSEEKO)
+    endif ()
 else()
     set(ZSTD_MULTITHREAD_SUPPORT_DEFAULT ON)
 endif()
@@ -153,6 +164,7 @@ if (ZSTD_BUILD_PROGRAMS)
     elseif(NOT ZSTD_BUILD_SHARED AND ZSTD_PROGRAMS_LINK_SHARED)
         message(SEND_ERROR "You need to build shared library to build zstd CLI")
     endif ()
+    message("Building program")
 
     add_subdirectory(programs)
 endif ()

contrib/seekable_format/zstdseek_decompress.c

@@ -77,7 +77,10 @@
 /* ************************************************************
 * Avoid fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW
 ***************************************************************/
-#if defined(_MSC_VER) && _MSC_VER >= 1400
+#if defined(LIBC_NO_FSEEKO)
+/* Some older libc implementations don't include these functions (e.g. Bionic < 24) */
+#define LONG_SEEK fseek
+#elif defined(_MSC_VER) && _MSC_VER >= 1400
 #   define LONG_SEEK _fseeki64
 #elif !defined(__64BIT__) && (PLATFORM_POSIX_VERSION >= 200112L) /* No point defining Large file for 64 bit */
 #   define LONG_SEEK fseeko

programs/fileio_common.h

@@ -79,7 +79,11 @@ extern UTIL_time_t g_displayClock;
 
 
 /* Avoid fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW */
-#if defined(_MSC_VER) && _MSC_VER >= 1400
+#if defined(LIBC_NO_FSEEKO)
+/* Some older libc implementations don't include these functions (e.g. Bionic < 24) */
+#define LONG_SEEK fseek
+#define LONG_TELL ftell
+#elif defined(_MSC_VER) && _MSC_VER >= 1400
 #   define LONG_SEEK _fseeki64
 #   define LONG_TELL _ftelli64
 #elif !defined(__64BIT__) && (PLATFORM_POSIX_VERSION >= 200112L) /* No point defining Large file for 64 bit */

programs/util.h

@@ -24,7 +24,10 @@
 /*-************************************************************
 *  Fix fseek()'s 2GiB barrier with MSVC, macOS, *BSD, MinGW
 ***************************************************************/
-#if defined(_MSC_VER) && (_MSC_VER >= 1400)
+#if defined(LIBC_NO_FSEEKO)
+/* Some older libc implementations don't include these functions (e.g. Bionic < 24) */
+#define UTIL_fseek fseek
+#elif defined(_MSC_VER) && (_MSC_VER >= 1400)
 #  define UTIL_fseek _fseeki64
 #elif !defined(__64BIT__) && (PLATFORM_POSIX_VERSION >= 200112L) /* No point defining Large file for 64 bit */
 #  define UTIL_fseek fseeko