Creating User-Defined File Attributes
Craig E. Wills · 2005
Operating systems maintain a number of attributes about a file. Typically file systems support attributes such as access permissions, size and last modification time. On a Unix/Linux system, information about the standard set of attributes for a file can be obtained using the stat() system call. The standard Linux file system, ext2, supports additional attributes for a file that can be set. See the Linux man pages for the commands lsattr and chattr to see more details on these additional attributes. In addition to supporting standard file attributes, the Be Operating System supports user-defined attributes [1] 1. This feature allows users to attach (attribute,value) pairs to a file. For example, if each mail message a user receives is stored in its own file, then a “From” attribute could be attached to each file. The presense of this feature allows all files with a given attribute value to be easily identified. User-defined attributes also allow information to be stored about a file in addition to its content. For example, the icon position of the file in a window system, or the URL source of a downloaded Web document. In this project you will be adding user-defined file attributes to the Linux file system and creating user-level programs to set and use these attributes.