SERVER-30839 prevent buildscripts/combine_reports.py from overwriting report.json

1 files changed, 28 insertions, 14 deletions

diff --git a/buildscripts/combine_reports.py b/buildscripts/combine_reports.py
index d7fe0eb5ece..e0e81569a80 100755
--- a/buildscripts/combine_reports.py
+++ b/buildscripts/combine_reports.py
@@ -14,9 +14,9 @@ import sys
 from optparse import OptionParser
 
 # Get relative imports to work when the package is not installed on the PYTHONPATH.
-if __name__ == "__main__" and __package__ is None:
-    sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
-    from buildscripts.resmokelib.testing import report
+sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+from buildscripts.resmokelib.testing import report
+from buildscripts.resmokelib import utils
 
 
 def read_json_file(json_file):
@@ -37,8 +37,18 @@ def report_exit(combined_test_report):
     return ret
 
 
-def main():
+def check_error(input_count, output_count):
+    """
+    Error if both input and output exist, or if neither exist.
+    """
+    if (not input_count) and (not output_count):
+        raise ValueError("None of the input file(s) or output file exists")
+
+    elif input_count and output_count:
+        raise ValueError("Both input file and output files exist")
 
+
+def main():
     usage = "usage: %prog [options] report1.json report2.json ..."
     parser = OptionParser(description=__doc__, usage=usage)
     parser.add_option("-o", "--output-file",
@@ -47,10 +57,6 @@ def main():
                       help="If '-', then the combined report file is written to stdout."
                            " Any other value is treated as the output file name. By default,"
                            " output is written to stdout.")
-    parser.add_option("-m", "--ignore-missing-reports",
-                      dest="ignore_missing",
-                      action="store_true",
-                      help="Ignore any input report file that does not exist.")
     parser.add_option("-x", "--no-report-exit",
                       dest="report_exit",
                       default=True,
@@ -63,25 +69,33 @@ def main():
         sys.exit("No report files were specified")
 
     report_files = args
+    report_files_count = len(report_files)
     test_reports = []
+
     for report_file in report_files:
         try:
             report_file_json = read_json_file(report_file)
             test_reports.append(report.TestReport.from_dict(report_file_json))
         except IOError as e:
             # errno.ENOENT is the error code for "No such file or directory".
-            if options.ignore_missing and e.errno == errno.ENOENT:
-                print("Ignoring missing file {}".format(report_file))
+            if e.errno == errno.ENOENT:
+                report_file_count -= 1
                 continue
             raise
 
     combined_test_report = report.TestReport.combine(*test_reports)
     combined_report = combined_test_report.as_dict()
-    if options.outfile != "-":
-        with open(options.outfile, "w") as fstream:
-            json.dump(combined_report, fstream)
+
+    if options.outfile == "-":
+        outfile_exists = False  # Nothing will be overridden when writing to stdout.
     else:
-        print(json.dumps(combined_report))
+        outfile_exists = os.path.exists(options.outfile)
+
+    check_error(report_files_count, outfile_exists)
+
+    if not outfile_exists:
+        with utils.open_or_use_stdout(options.outfile) as fh:
+            json.dump(combined_report, fh)
 
     if options.report_exit:
         sys.exit(report_exit(combined_test_report))