diff options
Diffstat (limited to 'Modules/ExternalData.cmake')
| -rw-r--r-- | Modules/ExternalData.cmake | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/Modules/ExternalData.cmake b/Modules/ExternalData.cmake index d6fbae9aa..189374be4 100644 --- a/Modules/ExternalData.cmake +++ b/Modules/ExternalData.cmake @@ -941,14 +941,15 @@ function(_ExternalData_link_or_copy src dst) file(RELATIVE_PATH tgt "${dst_dir}" "${src}") endif() endif() - execute_process(COMMAND "${CMAKE_COMMAND}" -E create_symlink "${tgt}" "${tmp}" RESULT_VARIABLE result) + # Create link (falling back to copying if there's a problem). + file(CREATE_LINK "${tgt}" "${tmp}" RESULT result COPY_ON_ERROR SYMBOLIC) else() # Create a copy. - execute_process(COMMAND "${CMAKE_COMMAND}" -E copy "${src}" "${tmp}" RESULT_VARIABLE result) + file(COPY_FILE "${src}" "${tmp}" RESULT result) endif() if(result) file(REMOVE "${tmp}") - message(FATAL_ERROR "Failed to create\n ${tmp}\nfrom\n ${obj}") + message(FATAL_ERROR "Failed to create:\n \"${tmp}\"\nfrom:\n \"${obj}\"\nwith error:\n ${result}") endif() # Atomically create/replace the real destination. @@ -1101,7 +1102,14 @@ function(_ExternalData_download_object name hash algo var_obj var_success var_er set(success 1) if(found) - file(RENAME "${tmp}" "${obj}") + # Atomically create the object. If we lose a race with another process, + # do not replace it. Content-addressing ensures it has what we expect. + file(RENAME "${tmp}" "${obj}" NO_REPLACE RESULT result) + if (result STREQUAL "NO_REPLACE") + file(REMOVE "${tmp}") + elseif (result) + message(FATAL_ERROR "Failed to rename:\n \"${tmp}\"\nto:\n \"${obj}\"\nwith error:\n ${result}") + endif() message(STATUS "Downloaded object: \"${obj}\"") elseif(EXISTS "${staged}") set(obj "${staged}") |