mdbx-cmake: support of MDBX_USE_FALLOCATE for CMake and Conan.

src/config.h.in

@@ -63,6 +63,11 @@
 
 #cmakedefine01 MDBX_USE_MINCORE
 
+#cmakedefine MDBX_USE_FALLOCATE_AUTO
+#ifndef MDBX_USE_FALLOCATE_AUTO
+#cmakedefine01 MDBX_USE_FALLOCATE
+#endif /* MDBX_USE_FALLOCATE */
+
 /* Build Info */
 #ifndef MDBX_BUILD_TIMESTAMP
 #cmakedefine MDBX_BUILD_TIMESTAMP "@MDBX_BUILD_TIMESTAMP@"

src/global.c

@@ -379,6 +379,7 @@ __dll_export
 #else /* Windows */
     " MDBX_LOCKING=" MDBX_LOCKING_CONFIG
     " MDBX_USE_OFDLOCKS=" MDBX_USE_OFDLOCKS_CONFIG
+    " MDBX_USE_FALLOCATE=" MDBX_USE_FALLOCATE_CONFIG
 #endif /* !Windows */
     " MDBX_CACHELINE_SIZE=" MDBX_STRINGIFY(MDBX_CACHELINE_SIZE)
     " MDBX_CPU_WRITEBACK_INCOHERENT=" MDBX_STRINGIFY(MDBX_CPU_WRITEBACK_INCOHERENT)

src/options.h

@@ -358,7 +358,7 @@
 #error MDBX_USE_COPYFILERANGE must be defined as 0 or 1
 #endif /* MDBX_USE_COPYFILERANGE */
 
-/** Advanced: Using posix_fallocate() or fcntl(F_PREALLOCATE) (autodetection by default). */
+/** Advanced: Using posix_fallocate() or fcntl(F_PREALLOCATE) on OSX (autodetection by default). */
 #ifndef MDBX_USE_FALLOCATE
 #if defined(__APPLE__)
 #define MDBX_USE_FALLOCATE 0 /* Too slow and unclean, but not required to prevent SIGBUS */
@@ -367,8 +367,11 @@
 #else
 #define MDBX_USE_FALLOCATE 0
 #endif
+#define MDBX_USE_FALLOCATE_CONFIG "AUTO=" MDBX_STRINGIFY(MDBX_USE_FALLOCATE)
 #elif !(MDBX_USE_FALLOCATE == 0 || MDBX_USE_FALLOCATE == 1)
 #error MDBX_USE_FALLOCATE must be defined as 0 or 1
+#else
+#define MDBX_USE_FALLOCATE_CONFIG MDBX_STRINGIFY(MDBX_USE_FALLOCATE)
 #endif /* MDBX_USE_FALLOCATE */
 
 //------------------------------------------------------------------------------