fix: Fall back to emulation for unsupported posix_fallocate (#1222)

posix_fallocate can return EINVAL if filesystem doesn't support it. Fall back to emulation in this case.

E.g. ZFS does so on FreeBSD (haven't tested with ZFS on linux).

This fixes Utill::fallocate unit tests on ZFS.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/Util.cpp b/src/Util.cpp
index eaac8b95..e802a83b 100644
--- a/src/Util.cpp
+++ b/src/Util.cpp
@@ -482,8 +482,13 @@ int
 fallocate(int fd, long new_size)
 {
 #ifdef HAVE_POSIX_FALLOCATE
-  return posix_fallocate(fd, 0, new_size);
-#else
+  const int posix_fallocate_err = posix_fallocate(fd, 0, new_size);
+  if (posix_fallocate_err == 0 || posix_fallocate_err != EINVAL) {
+    return posix_fallocate_err;
+  }
+  // the underlying filesystem does not support the operation so fallback to
+  // lseeks
+#endif
   off_t saved_pos = lseek(fd, 0, SEEK_END);
   off_t old_size = lseek(fd, 0, SEEK_END);
   if (old_size == -1) {
@@ -510,7 +515,6 @@ fallocate(int fd, long new_size)
   lseek(fd, saved_pos, SEEK_SET);
   free(buf);
   return err;
-#endif
 }
 
 std::string