Open Radar

 
20-Jun-2010 01:56 PM Karl Kuehn:
Summary:

	When using hdiutil with the "imageinfo" command 

Steps to Reproduce:

	Run the attached script. It creates a trivial compressed dmg, then tries "hdiutil imageinfo" on it both with an absolute path, and a symlinked path, each 1000 times, then reports how many failures it encountered with each.

Expected Results:

	I would expect this to succeed 100% of the time with either form of path.

Actual Results:

	The absolute path always succeeds on all machines, but the symlinked one fails. I am seeing different failure rates:

iMac5,1
	10.6.4/10F569 (clean, just installed): about .5% failure rate
	10.5.8/ (clean, just installed): never seems to display the problem

iMac8,1
	10.6.4/10F569 (dirty, development machine): between 15 and 25% failure rate.

Regression:
	Unknown

Notes:
	While there is a strait-forward work-around for this issue, it is a nasty trap for people to fall into since their machine might exhibit the problem less the 1% of the time. My guess is that this is a race condition, but that is a thin guess.


============== Test script ==============
#!/bin/bash

# create a temproary folder with three items in it
TEMP_FOLDER=`/usr/bin/mktemp -d /tmp/hdiutilBugTest.XXXX`
/usr/bin/touch "$TEMP_FOLDER/a"
/usr/bin/touch "$TEMP_FOLDER/b"
/usr/bin/touch "$TEMP_FOLDER/c"

# create a compressed image from the temp folder
/usr/bin/hdiutil create -srcfolder "$TEMP_FOLDER" "$TEMP_FOLDER/testImage.dmg" 1>/dev/null

# create the symlink to the image
/bin/ln -s "testImage.dmg" "$TEMP_FOLDER/symlink"

SYMLINK_PATH="$TEMP_FOLDER/symlink"
ABSOLUTE_PATH="$TEMP_FOLDER/testImage.dmg"

PATHS[0]="$SYMLINK_PATH"
PATHS[1]="$ABSOLUTE_PATH"

REPEAT_COUNT=1000
IFS=$'\n'
for THIS_PATH in ${PATHS[@]}; do
	echo "Working on: $THIS_PATH"
	FAILED_COUNT=0
	i=0
	while [ $i -lt $REPEAT_COUNT ]; do
		/usr/bin/hdiutil imageinfo "$THIS_PATH" 1>/dev/null 2>/dev/null
		if [ $? -ne 0 ]; then
			let FAILED_COUNT=FAILED_COUNT+1
		else
			let SUCEEDED_COUNT=SUCEEDED_COUNT+1
		fi
		let i=i+1
	done
	echo "	Failed $FAILED_COUNT out of $REPEAT_COUNT times"
done

# delete the temp folder
if [ ! -z "$TEMP_FOLDER" ] && [ -d "$TEMP_FOLDER" ]; then
	/bin/rm -rf "$TEMP_FOLDER"
fi