id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35818	Failing to save file with long names containing dots	Bruno Alla		"This started to happen as we updated to Djanho 5.1. We started seeing some `SuspiciousFileOperation` errors when our users were trying to upload long file names and wasn't initially clear why it started to happen only recently. 

After further investigation, it's only a problem when the file name contains a ""."" in the middle name, and which point the truncation logic trims too many characters, and end up with no base name on this line: https://github.com/django/django/blob/6bedb102e9708c6183caa51330f9bdeddf944d6a/django/core/files/storage/base.py#L106-L111

Here is a minimal reproduction:

{{{
# models.py
class Document(models.Model):
    file = models.FileField(upload_to=""documents/"")


# tests.py
class TestDocument(TestCase):
    def test_save_file(self):
        file_name = ""this.is.a.very.l"" + ""o"" * 100 + "".txt""
        Document.objects.create(file=SimpleUploadedFile(name=file_name, content=b""test""))
}}}

I created a GitHub repo  based off startproject with that code to make it easier to run: https://github.com/browniebroke/django-suspicious-filename-too-long-with-dot

The test passes on Django 5.0 but fails on Django 5.1 with the following exception:

{{{
django.core.exceptions.SuspiciousFileOperation: Storage can not find an available filename for ""documents/this_d01Yq4J.is.a.very.loooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.txt"". Please make sure that the corresponding file field allows sufficient ""max_length"".
}}}

From what I can tell, the bug starts on line 87, when we try to get the file extension: https://github.com/django/django/blob/6bedb102e9708c6183caa51330f9bdeddf944d6a/django/core/files/storage/base.py#L87  

On the next line, the extension is removed from the name to get the file root, which removes a lot more characters than expected, as the extension starts at the first ""."", instead of the last one. "	Bug	new	File uploads/storage	5.1	Normal				Unreviewed	0	0	0	0	0	0