Attribute Functions

An Example

Before dropping straight into the reference on the fs_attr API, let's have a look at a simple sample of how to use some of its features. The sample code fragment below opens the attribute directory for a file named /boot/home/dirtylaundry and scans through all the attributes in the file, fetching their names and values.

DIR *d;
dirent_t *ent;
attr_info info;
int fd;
char *buffer;

d = fs_open_attr_dir("/boot/home/dirtylaundry");
if (d) {
   while (ent = fs_read_attr_dir(d)) {
   fd = open("/boot/home/dirtylaundry", O_RDONLY);
   fs_stat_attr(fd, ent->d_name, &info);
   buffer = (char *) malloc((size_t) info.size);
   if (buffer)
      fs_read_attr(fd, ent->d_name, info.type, 0, buffer,

This snippet begins by opening the attribute directory for the file, using the fs_open_attr_dir() function. If this is successful, it returns a pointer to a directory that contains the list of attributes. A while loop is used to read into ent each attribute from the attribute directory by calling fs_read_attr_dir(). The information this call provides includes the size and type of the attribute, as well as its name.

Once we know the name of the attribute, we can obtain the type and size of the attribute by calling fs_stat_attr(); now we have all the information needed to get the value of the attribute. After allocating a buffer to contain the value of the attribute, we pass the attribute's name (ent->d_name), and the type and size (info.type and info.size) into the fs_read_attr() function. The value of the attribute is stored in the buffer we specify.

This sample skimps a bit on error handling; you'll do better, of course.

Creative Commons License
Legal Notice
This work is licensed under a Creative Commons Attribution-Non commercial-No Derivative Works 3.0 License.