Re: IsReadableFileAtPath
Hi, thanks to all of you. After some days trynign and thinking, I have used lstat to check the filePermissions because I need to check thousands files per session. However I realized that Permissions and isReadableFile or isWritableFile or isDeletableFile are two different things, so please may you tell me whether my methods here below are right or wrong? Short version: IsReadableFile:filePath cPath = [mManager fileSystemRepresentationWithPath:filePath]; lstat(cPath, sb); return ((sb.st_mode S_IRUSR) != 0); IsWritableFile:filePath //I check here the ParentFolder of the filePath parentFolder = [filePath stringByDeletingLastPathComponent]; cPath = [mManager fileSystemRepresentationWithPath:parentFolder]; lstat(cPath, sb); return ((sb.st_mode (S_IWUSR | S_IXUSR)) != 0); IsDeletableFile:filePath the same as IsWritableFile:filePath above Will these methods work on any volume mounted on my desktop? (e.g. Local volume, remote volume, disk image volume, on webdav, smb, ftp, afp, hfs, on remote win disk...) Thanks Leo Da: Kevin Perry kpe...@apple.com Data: Mon, 1 Mar 2010 11:37:06 -0800 A: gMail.com mac.iphone@gmail.com Cc: cocoa-dev@lists.apple.com Oggetto: Re: IsReadableFileAtPath -Kevin On Mar 1, 2010, at 11:20 AM, gMail.com wrote: Hi, I need to check whether a file or a symlink could be really copied. I have just seen that the Cocoa API isReadableFileAtPath traverses the symlink, so, in case the target file is not readable, my app doesn't copy the symlink, while the Finder can properly do. So my app does wrong. The question is: How can I understand whether a file or symlink can really be copied? I have seen that isReadableFileAtPath uses the C command access which indeed traverses the symlink. So I cannot use it. So, any idea? And I wouldn't use the Carbon APIs because I need to compile for 64 bit. Thank you. Leonardo ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/kperry%40apple.com This email sent to kpe...@apple.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: IsReadableFileAtPath
On 8 Mar 2010, at 11:32, gMail.com wrote: Hi, thanks to all of you. After some days trynign and thinking, I have used lstat to check the filePermissions because I need to check thousands files per session. However I realized that Permissions and isReadableFile or isWritableFile or isDeletableFile are two different things, so please may you tell me whether my methods here below are right or wrong? Short version: That depends on the semantics you want for isReadableFile: and isWriteableFile: The code as written checks if the owner of the file can read or write it. However, you probably want to know if the currently running process can read or write it which may have a different answer if the owner of the process is not the same as the owner of the file. isDeleteableFile: is wrong. You need to check whether you have write access to the directory containing the file. See below script: monica:~ jeremyp$ mkdir foo monica:~ jeremyp$ cd foo monica:foo jeremyp$ touch foo monica:foo jeremyp$ chmod -w . monica:foo jeremyp$ ls -la total 0 dr-xr-xr-x3 jeremyp staff 102 8 Mar 11:49 . drwx--+ 115 jeremyp staff 3910 8 Mar 11:49 .. -rw-r--r--1 jeremyp staff 0 8 Mar 11:49 foo monica:foo jeremyp$ rm foo rm: foo: Permission denied IsReadableFile:filePath cPath = [mManager fileSystemRepresentationWithPath:filePath]; lstat(cPath, sb); return ((sb.st_mode S_IRUSR) != 0); IsWritableFile:filePath //I check here the ParentFolder of the filePath parentFolder = [filePath stringByDeletingLastPathComponent]; cPath = [mManager fileSystemRepresentationWithPath:parentFolder]; lstat(cPath, sb); return ((sb.st_mode (S_IWUSR | S_IXUSR)) != 0); IsDeletableFile:filePath the same as IsWritableFile:filePath above Will these methods work on any volume mounted on my desktop? (e.g. Local volume, remote volume, disk image volume, on webdav, smb, ftp, afp, hfs, on remote win disk...) Thanks Leo Da: Kevin Perry kpe...@apple.com Data: Mon, 1 Mar 2010 11:37:06 -0800 A: gMail.com mac.iphone@gmail.com Cc: cocoa-dev@lists.apple.com Oggetto: Re: IsReadableFileAtPath -Kevin On Mar 1, 2010, at 11:20 AM, gMail.com wrote: Hi, I need to check whether a file or a symlink could be really copied. I have just seen that the Cocoa API isReadableFileAtPath traverses the symlink, so, in case the target file is not readable, my app doesn't copy the symlink, while the Finder can properly do. So my app does wrong. The question is: How can I understand whether a file or symlink can really be copied? I have seen that isReadableFileAtPath uses the C command access which indeed traverses the symlink. So I cannot use it. So, any idea? And I wouldn't use the Carbon APIs because I need to compile for 64 bit. Thank you. Leonardo ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/kperry%40apple.com This email sent to kpe...@apple.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/adc%40jeremyp.net This email sent to a...@jeremyp.net __ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email __ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
IsReadableFileAtPath
Hi, I need to check whether a file or a symlink could be really copied. I have just seen that the Cocoa API isReadableFileAtPath traverses the symlink, so, in case the target file is not readable, my app doesn't copy the symlink, while the Finder can properly do. So my app does wrong. The question is: How can I understand whether a file or symlink can really be copied? I have seen that isReadableFileAtPath uses the C command access which indeed traverses the symlink. So I cannot use it. So, any idea? And I wouldn't use the Carbon APIs because I need to compile for 64 bit. Thank you. Leonardo ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: IsReadableFileAtPath
On Mar 1, 2010, at 12:20 PM, gMail.com wrote: I need to check whether a file or a symlink could be really copied. I have just seen that the Cocoa API isReadableFileAtPath traverses the symlink, so, in case the target file is not readable, my app doesn't copy the symlink, while the Finder can properly do. So my app does wrong. The question is: How can I understand whether a file or symlink can really be copied? Maybe lstat() would better suit your needs? Nick Zitzmann http://www.chronosnet.com/ ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: IsReadableFileAtPath
On Mar 1, 2010, at 11:20 AM, gMail.com wrote: I have just seen that the Cocoa API isReadableFileAtPath traverses the symlink, so, in case the target file is not readable, my app doesn't copy the symlink, while the Finder can properly do. So my app does wrong. -isReadableFileAtPath is just a convenience. If you don't want to traverse symlinks, call -fileAttributesAtPath:traverseLink: and use NO for the second parameter. How can I understand whether a file or symlink can really be copied? You can't preflight file operations with 100% accuracy, because there's always a race condition — the file's permissions could be modified in between checking permission and doing the actual copy. You should still do the preflighting if it helps the user experience (by disabling a button, for example); but always be prepared to handle errors from the actual operation itself. If you don't need preflighting for your UI, just skip it. In other words, don't do the following: if (fileIsCopyable(file)) copyFile(file); Instead just call copyFile() and handle any error it returns. And I wouldn't use the Carbon APIs because I need to compile for 64 bit. The Carbon File Manager API is available in 64-bit, and it's perfectly appropriate to use it in Cocoa apps. It's only a subset of Carbon High-Level Toolbox APIs that aren't available in 64-bit (and you wouldn't be using those in a Cocoa app anyway.) —Jens ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: IsReadableFileAtPath
In general, this kind of check-then-do pattern opens the door for file system race conditions. The documentation for this method (and related methods) has a little more information about this in the Note section. Could you just try to copy the symlink and then deal with any errors that result? -Kevin On Mar 1, 2010, at 11:20 AM, gMail.com wrote: Hi, I need to check whether a file or a symlink could be really copied. I have just seen that the Cocoa API isReadableFileAtPath traverses the symlink, so, in case the target file is not readable, my app doesn't copy the symlink, while the Finder can properly do. So my app does wrong. The question is: How can I understand whether a file or symlink can really be copied? I have seen that isReadableFileAtPath uses the C command access which indeed traverses the symlink. So I cannot use it. So, any idea? And I wouldn't use the Carbon APIs because I need to compile for 64 bit. Thank you. Leonardo ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/kperry%40apple.com This email sent to kpe...@apple.com ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: IsReadableFileAtPath
On Mar 1, 2010, at 3:24 PM, Jens Alfke wrote: -isReadableFileAtPath is just a convenience. If you don't want to traverse symlinks, call -fileAttributesAtPath:traverseLink: and use NO for the second parameter. Unfortunately, fileAttributesAtPath:traverseLink: is deprecated. The replacement given is attributesOfItemAtPath:error:, which doesn’t traverse symlinks. However, the documentation claims that this behavior is not guaranteed, and may change in a future version of OS X. Sadly, there does not seem to be a non-deprecated replacement for fileAttributesAtPath:traverseLink: which has guaranteed behavior. The best thing to do is probably to use POSIX calls such as lstat(). Charles___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
