ICU-20858 Fix Windows data build failure with long paths
diff --git a/icu4c/source/python/icutools/databuilder/renderers/common_exec.py b/icu4c/source/python/icutools/databuilder/renderers/common_exec.py
index 838b121..3623441 100644
--- a/icu4c/source/python/icutools/databuilder/renderers/common_exec.py
+++ b/icu4c/source/python/icutools/databuilder/renderers/common_exec.py
@@ -120,12 +120,15 @@
# If the command line length on Windows exceeds the absolute maximum that CMD supports (8191), then
# we temporarily switch over to use PowerShell for the command, and then switch back to CMD.
# We don't want to use PowerShell for everything though, as it tends to be slower.
- if (platform == "windows") and (len(command_line) > 8190):
- if verbose:
- print("Command length exceeds the max length for CMD on Windows, using PowerShell instead.")
+ if (platform == "windows"):
previous_comspec = os.environ["COMSPEC"]
- os.environ["COMSPEC"] = 'powershell'
- changed_windows_comspec = True
+ # Add 7 to the length for the argument /c with quotes.
+ # For example: C:\WINDOWS\system32\cmd.exe /c "<command_line>"
+ if ((len(previous_comspec) + len(command_line) + 7) > 8190):
+ if verbose:
+ print("Command length exceeds the max length for CMD on Windows, using PowerShell instead.")
+ os.environ["COMSPEC"] = 'powershell'
+ changed_windows_comspec = True
if verbose:
print("Running: %s" % command_line)
returncode = subprocess.call(
