pSOSystem System Calls - Read

verify_vol pHILE+ System Calls
(correct fault) should be returned only if the FDB indicates the fault is fixable (refer
to the FDB description below). If status = 1 is returned for a non-fixable fault, it is
ignored and verification continues.
If verify_vol() is being used simply to verify volume correctness, then, when
called, faultp() can return a status of 0, which continues the rest of volume
verification, or a status of 2, which terminates verify_vol() and returns an error
to the caller.
verify_vol() can also be integrated into a “volume repair” utility with an operator
interface. This utility should implement faultp() so that it will
■ Display each fault in detail;
■ Indicate if the fault is fixable;
■ And if so, ask the user if he wants it fixed;
■ And if so, return status = 1 to verify_vol().
Faults that are not fixable may require additional user action. For example, you may
perform the following steps repeatedly:
1. Use verify_vol() to correct all fixable errors and obtain a list of non-fixable
errors.
2. Examine, copy, and delete the affected files, as required.
When step 1 produces no more faults, you can consider the volume corrected.
The Fault Descriptor Block (FDB)
The structure fault_desc_block defines the FDB in phile.h as follows:
typedef struct fault_desc_block {
unsigned long fdb_code; /* fault code */
unsigned long fdb_fn1; /* file number for file 1 */
unsigned long fdb_fn2; /* file number for file 2 */
char *fdb_path1; /* pathname for file 1 */
char *fdb_path2; /* pathname for file 2 */
unsigned long fdb_bn; /* block number */
unsigned long fdb_fixable;/* fault fixable indicator */
} FAULT_DESC_BLOCK;
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