defaults read deletes entire file when reading invalid plist

Number:rdar://37729361 Date Originated:20-Feb-2018 08:44 PM
Status:Open Resolved:
Product:macOS + SDK Product Version:10.13.3
Classification:Crash/Hang/Data Loss Reproducible:Always
If a plist is invalid (missing a closing tag for example) attempting to read the plist with `defaults read /path/to/plist` deletes the entire file.

Steps to Reproduce:
1) Create a plist `defaults write /Users/Shared/test test -string test
2) Convert the plist to xml `plutil -convert xml1 /Users/Shared/test.plist`
3) Edit the plist to remove a closing tag
4) Attempt to read the plist `defaults read /Users/Shared/test`

Expected Results:
Error that the file could not be read

Actual Results:
File is deleted


eholtam:Desktop eholtam$ ls -l test.plist 
-rw-------@ 1 eholtam  domain\Domain Users  219 Feb 20 20:37 test.plist

eholtam:Desktop eholtam$ cat test.plist 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "">
<plist version="1.0">

eholtam:Desktop eholtam$ defaults read /Users/eholtam/Desktop/test
2018-02-20 20:37:59.188 defaults[7734:40969] 
Domain /Users/eholtam/Desktop/test does not exist

eholtam:Desktop eholtam$ ls -l test.plist 
ls: test.plist: No such file or directory


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