diff options
Diffstat (limited to 'Modules/ExternalData.cmake')
| -rw-r--r-- | Modules/ExternalData.cmake | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/Modules/ExternalData.cmake b/Modules/ExternalData.cmake index d6fbae9aaf..b439636f5c 100644 --- a/Modules/ExternalData.cmake +++ b/Modules/ExternalData.cmake @@ -1101,7 +1101,14 @@ 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}") |