At 16:16 +0800 2009/05/03, bill lam wrote:
>On Sat, 02 May 2009, Joey K Tuttle wrote:
>> My question today is - why do the jmf routines require that I have
>> write access to a file even though I'm opening it as read only? Some
>> files I would like to look at in a map are not mine and while I have
>> group or world read access, I can't map them, even explicitly saying
>> read-only - unhappiness...
>
>That should be a bug. Can you give a procedure to reproduce the error?
>
Sure - for those who like the nity gritty, in a Darwin terminal
session (Linux gives exactly same results) -
iMg5:~ jkt$ echo "A man a plan Panama" > palindrome
iMg5:~ jkt$ ls -l palindrome
-rw-r--r-- 1 jkt jkt 20 May 3 07:47 palindrome
iMg5:~ jkt$ chmod 444 palindrome # make read-only even for owner
iMg5:~ jkt$ ls -l palindrome
-r--r--r-- 1 jkt jkt 20 May 3 07:47 palindrome
iMg5:~ jkt$ ja # start j
version ''
Installer: j602a_mac_powerpc.dmg
Engine: j602/2008-03-03/16:45
Library: 6.02.023ProductName: Mac OS X
ProductVersion: 10.5.6
BuildVersion: 9G55
java version "1.5.0_16" Java(TM) 2 Runtime Environment, Standard
Edition (build 1.5.0_16-b06-284) Java HotSpot(TM) Client VM (build
1.5.0_16-133, mixed mode, sharing)
load 'jmf'
2 map_jmf_ 'x';'palindrome';'';1
|bad file name/access: assert
| 'bad file name/access' assert fh~:_1
exit 0
iMg5:~ jkt$ chmod 666 palindrome # let everyone write - not very secure
iMg5:~ jkt$ ls -l palindrome
-rw-rw-rw- 1 jkt jkt 20 May 3 07:47 palindrome
iMg5:~ jkt$ date # showing that time has gone by...
Sun May 3 07:51:24 PDT 2009
iMg5:~ jkt$ ja
load 'jmf'
2 map_jmf_ 'x';'palindrome';'';1
x =. |. x
|read-only data
| x =.|.x
NB. Good! What I asked for.
unmap_jmf_ 'x'
0
2 map_jmf_ 'x';'palindrome' NB. map it for read-write
x =. |. x
NB. OK - except ...
unmap_jmf_ 'x'
0
exit 0
iMg5:~ jkt$ # Note that mod date is unchanged even though time has gone by
iMg5:~ jkt$ ls -l palindrome
-rw-rw-rw- 1 jkt jkt 20 May 3 07:47 palindrome
iMg5:~ jkt$ cat palindrome # but the file was, in fact, modified.
amanaP nalp a nam A
- joey
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