从其他地方可以看到 docx，xlsx和pttx是ZIP。将它们上传到我的Web应用程序时，file（通过libmagic和python-magic）将其检测为ZIP。
我将文件的内容作为Blob存储在数据库中，但是自然地我不想让用户相信它是哪种文件类型。因此，我想file在下载过程中信任并自动生成一个文件名。
我知道可以修改，/etc/magic但是格式（magic(5)）对我来说太复杂了。我在Debian bugs上找到了关于该问题的bug报告，但是由于它是从2008年开始的，因此似乎无法很快得到修复。
我猜我唯一的选择是确实信任用户（但仍将内容存储为blob），并且仅根据文件名检查文件扩展名。这样，我可以禁止某些扩展并允许其他扩展。当用户重新下载他的文件时，他可以通过任何方式上传它。但是，如果与他人共享文件，此解决方案是不安全的，因为您可以简单地重命名文件以允许上传。
有任何想法吗？
最后，我找到了docx等的幻数列表，但无法将其转换为magic(5)格式。
Answers:
您可以使用
0 string PK\x03\x04\x14\x00\x06\x00 Microsoft Office Open XML Format
/ etc / magic中的内容，以根据您提供的信息识别常规文件类型。
（但是，这可能并不通用：PK\x03\x04\x00\x14\x08\x08在LibreOffice生成的XLSX文件开始时就已经观察到。）
更高版本的Ubuntu可以正确识别.docx，.pptx和.xlsx文件。在文件实用程序的源代码中进行挖掘，我发现了~/file-5.09/magic/Magdir/msooxml用于标识的文件。您可以获取文件的副本并将其添加到/etc/magic文件中。
包括已更新至v 1.5的文件副本
# $File: msooxml,v 1.5 2014/08/05 07:38:45 christos Exp $
# msooxml: file(1) magic for Microsoft Office XML
# From: Ralf Brown <ralf.brown@gmail.com>
# .docx, .pptx, and .xlsx are XML plus other files inside a ZIP
# archive. The first member file is normally "[Content_Types].xml".
# but some libreoffice generated files put this later. Perhaps skip
# the "[Content_Types].xml" test?
# Since MSOOXML doesn't have anything like the uncompressed "mimetype"
# file of ePub or OpenDocument, we'll have to scan for a filename
# which can distinguish between the three types
# start by checking for ZIP local file header signature
0 string PK\003\004
!:strength +10
# make sure the first file is correct
>0x1E regex \\[Content_Types\\]\\.xml|_rels/\\.rels
# skip to the second local file header
# since some documents include a 520-byte extra field following the file
# header, we need to scan for the next header
>>(18.l+49) search/2000 PK\003\004
# now skip to the *third* local file header; again, we need to scan due to a
# 520-byte extra field following the file header
>>>&26 search/1000 PK\003\004
# and check the subdirectory name to determine which type of OOXML
# file we have. Correct the mimetype with the registered ones:
# http://technet.microsoft.com/en-us/library/cc179224.aspx
>>>>&26 string word/ Microsoft Word 2007+
!:mime application/vnd.openxmlformats-officedocument.wordprocessingml.document
>>>>&26 string ppt/ Microsoft PowerPoint 2007+
!:mime application/vnd.openxmlformats-officedocument.presentationml.presentation
>>>>&26 string xl/ Microsoft Excel 2007+
!:mime application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
>>>>&26 default x Microsoft OOXML
---
但是将V1.2留作后代。
随着文件包的更新，在上面包含链接的副本可能会过时。
#------------------------------------------------------------------------------
# $File: msooxml,v 1.2 2013/01/25 23:04:37 christos Exp $
# msooxml: file(1) magic for Microsoft Office XML
# From: Ralf Brown <ralf.brown@gmail.com>
# .docx, .pptx, and .xlsx are XML plus other files inside a ZIP
# archive. The first member file is normally "[Content_Types].xml".
# Since MSOOXML doesn't have anything like the uncompressed "mimetype"
# file of ePub or OpenDocument, we'll have to scan for a filename
# which can distinguish between the three types
# start by checking for ZIP local file header signature
0 string PK\003\004
# make sure the first file is correct
>0x1E string [Content_Types].xml
# skip to the second local file header
# since some documents include a 520-byte extra field following the file
# header, we need to scan for the next header
>>(18.l+49) search/2000 PK\003\004
# now skip to the *third* local file header; again, we need to scan due to a
# 520-byte extra field following the file header
>>>&26 search/1000 PK\003\004
# and check the subdirectory name to determine which type of OOXML
# file we have
# Correct the mimetype with the registered ones:
# http://technet.microsoft.com/en-us/library/cc179224.aspx
>>>>&26 string word/ Microsoft Word 2007+
!:mime application/vnd.openxmlformats-officedocument.wordprocessingml.document
>>>>&26 string ppt/ Microsoft PowerPoint 2007+
!:mime application/vnd.openxmlformats-officedocument.presentationml.presentation
>>>>&26 string xl/ Microsoft Excel 2007+
!:mime application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
>>>>&26 default x Microsoft OOXML
!:strength +10
~/file-5.11/magic/Magdir/msooxml源的错误，但对于我正在使用的某些powerpoint示例文件不起作用。不过，其中的版本file-5.17效果很好（也许与制表符或... dunno有关）。
file5.04上执行，如@ stanley-c所述，它会将MIME类型标记截断为64个字符（但警告您）。我还尝试了Mac OS X Mavericks，但无法使其应用规则（尽管它警告我不要转义第二条规则中的[和。）。
如果使用libreoffice的docx，则可以在/ etc / magic中添加内容（如下）：
# start by checking for ZIP local file header signature
0 string PK\003\004
!:strength +10
>1104 search/300 PK\003\004
# and check the subdirectory name to determine which type of OOXML
# file we have. Correct the mimetype with the registered ones:
# http://technet.microsoft.com/en-us/library/cc179224.aspx
>>&26 string word/ Microsoft Word 2007+
!:mime application/vnd.openxmlformats-officedocument.wordprocessingml.document
>>&26 string ppt/ Microsoft PowerPoint 2007+
!:mime application/vnd.openxmlformats-officedocument.presentationml.presentation
>>&26 string xl/ Microsoft Excel 2007+
!:mime application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
>>&26 default x Microsoft OOXML