-A option processing in fdisk(8)

[Paul Goyette <paul%whooppee.com@localhost>]

Currently, fdisk uses the following code to parse the -A option:

                case 'A':       /* Partition alignment[/offset] */
                        if (sscanf(optarg, "%u/%u%n", &ptn_alignment,
                                    &ptn_0_offset, &n) < 1
                            || optarg[n] != 0
                            || ptn_0_offset > ptn_alignment)
                                errx(1, "Bad argument to the -A flag.");
                        if (ptn_0_offset == 0)
                                ptn_0_offset = ptn_alignment;
                        break;

This doesn't seem right, and in actual practice using '-A 2048' results 
in the "Bad argument" error message.  I think this is because &n is 
still set to zero since the scan never gets that far.

It seems to me that this should be rewritten as

                case 'A':       /* Partition alignment[/offset] */
                        ptn_0_offset = 0;
                        if (sscanf(optarg, "%u%n/%u%n", &ptn_alignment,
                                    &n, &ptn_0_offset, &n) < 1
                            || optarg[n] != 0
                            || ptn_0_offset > ptn_alignment)
                                errx(1, "Bad argument to the -A flag.");
                        if (ptn_0_offset == 0)
                                ptn_0_offset = ptn_alignment;
                        break;

This would cause &n to be set as soon as the first numeric value was 
sscanf'd, whether or not it is followed by a '/%u'.

Comments?


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