1 #ifndef _PROCFS_TYPE_H 2 #define _PROCFS_TYPE_H 3 4 typedef void *data_t; /* abstract data type; can hold pointer */ 5 6 struct load { 7 clock_t ticks; /* in this umber of ticks: */ 8 long proc_load; /* .. the CPU had this load */ 9 }; 10 11 /* ProcFS supports two groups of files: dynamic files, which are created within 12 * process-specific (PID) directories, and static files, which are global. For 13 * both, the following structure is used to construct the files. 14 * 15 * For dynamic files, the rules are simple: only regular files are supported 16 * (although partial support for symbolic links is already present), and the 17 * 'data' field must be filled with a pointer to a function of the type: 18 * 19 * void (*)(int slot) 20 * 21 * The function will be called whenever a read request for the file is made; 22 * 'slot' contains the kernel slot number of the process being queried (so for 23 * the PM and VFS process tables, NR_TASKS has to be subtracted from the slot 24 * number to find the right slot). The function is expected to produce 25 * appropriate output using the buf_printf() function. 26 * 27 * For static files, regular files and directories are supported. For 28 * directories, the 'data' field must be a pointer to another 'struct file' 29 * array that specifies the contents of the directory - this directory will 30 * the be created recursively. For regular files, the 'data' field must point 31 * to a function of the type: 32 * 33 * void (*)(void) 34 * 35 * Here too, the function will be called upon a read request, and it is 36 * supposed to "fill" the file using buf_printf(). Obviously, for static files, 37 * there is no slot number. 38 * 39 * For both static and dynamic files, 'mode' must specify the file type as well 40 * as the access mode, and in both cases, each array is terminated with an 41 * entry that has its name set to NULL. 42 */ 43 /* The internal link between static/dynamic files/directories and VTreeFS' 44 * indexes and cbdata values is as follows: 45 * - Dynamic directories are always PID directories in the root directory. 46 * They are generated automatically, and are not specified using a "struct 47 * file" structure. Their index is their slot number, so that getdents() 48 * calls always return any PID at most once. Their cbdata value is the PID of 49 * the process associated with that dynamic directory, for the purpose of 50 * comparing old and new PIDs after updating process tables (without having 51 * to atoi() the directory's name). 52 * - Dynamic files are always in such a dynamic directory. Their index is the 53 * array index into the "struct file" array of pid files (pid_files[]). They 54 * are indexed at all, because they may be deleted at any time due to inode 55 * shortages, independently of other dynamic files in the same directory, and 56 * recreating them without index would again risk possibly inconsistent 57 * getdents() results, where for example the same file shows up twice. 58 * VTreeFS currently does not distinguish between indexed and delatable files 59 * and hence, all dynamic files must be indexed so as to be deletable anyway. 60 * - Static directories have no index (they are not and must not be deletable), 61 * and although their cbdata is their associated 'data' field from their 62 * "struct file" entries, their cbdata value is currently not relied on 63 * anywhere. Then again, as of writing, there are no static directories at 64 * all. 65 * - Static files have no index either (for the same reason). Their cbdata is 66 * also their 'data' field from the "struct file" entry creating the file, 67 * and this is used to actually call the callback function directly. 68 */ 69 struct file { 70 char *name; /* file name, maximum length PNAME_MAX */ 71 mode_t mode; /* file mode, including file type */ 72 data_t data; /* custom data associated with this file */ 73 }; 74 75 #endif /* _PROCFS_TYPE_H */ 76