8560 MUSDU System Reference Manual FBR(5) ___________________________________________________________________________ FBR(5) NAME fbr - file backup and restore format SYNTAX #include <sys/types.h> #include <fbr.h> DESCRIPTION Fbr saves and restores directories and files on a floppy disk archive, preserving aliases (multiple links to the same file). The archive consists of: Boot block - Block zero is reserved for a copy of a stand-alone boot program. Directory area - This area contains directory information for all files and directories on the archive. The first entry in this area is dedicated to the archive label. Data area - The data of all files on the archive is stored here. The format of a directory entry (as given in the include file) fol- lows. To increase the portability of archives, this structure is read and written in PDP-11 format regardless of what machine fbr_is running on. #define PATHLEN 106 /* space for path */ struct fbrent { char fbr_path[PATHLEN]; /* pathname */ unsigned short fbr_mode; short fbr_uid; /* owner's userI^AD */ short fbr_gid; /* owner's groupID */ off_t fbr_size; /* size in bytes */ time_t fbr_acct; /* access date-time */ time_t fbr_modt; /* modify date-time */ unsigned fbr_fblk; /* firs^At data block */ char fbr_zero; /* unused */ char fbr_chks; /* checksum */ }; The path field is the pathname of the file when archived, less any redundant slashes or initial './'. It is null-terminated if less than PATHLEN bytes long. The mode, uid, gid, size, and access and modifi- cation date-times are in the same format as their corresponding i-node fields. As in the file system, an available entry has a mode of zero. The fblk field contains the block number of the first data block allo- cated to this file. The zero field is unused. The checksum field contains a number such that the sum of the first 127 bytes of the 1 FBR(5) 8560 MUSDU System Reference Manual ___________________________________________________________________________ directory entry and the complement of the checksum is zero. Each file's data starts on a block boundary and occupies max(1,((size + 511) / 512) contiguous blocks. At least one archive block is allo- cated to each archived file or directory so that aliases (multiple links) can be properly recorded. Each directory archived is treated as an empty file (I.E. no directory's data is stored). All entries representing links to a given file are identical. In particular, the fblk field in each link's entry contains the same block number. The archive label directory entry contains the following information: path A comment about this archive. mode Set by fbr to a file readable/writeable/executable by all. Other- wise unused. uid The userID of the user who created this archive. gid The groupID of the same. size The total number of bytes in the data area of the archive. This field in combination with the fblk field, records the size of both the directory area and the entire archive. acct The date-time that this archive was created - not its access time. modt The date-time that this archive was last altered. fblk The block number of the first archive block following the direc- tory area. checksum (same as any other directory entry.) SEE_ALSO fbr(1), stat(2).