1.\" 2.\" Copyright (c) 2001 Joerg Wunsch 3.\" 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.\" 29.Dd May 14, 2001 30.Os 31.Dt FDREAD 1 32.Sh NAME 33.Nm fdread 34.Nd read floppy disks 35.Sh SYNOPSIS 36.Nm 37.Op Fl qr 38.Op Fl d Ar device 39.Op Fl f Ar fillbyte 40.Op Fl o Ar file 41.Nm 42.Op Fl d Ar device 43.Fl I Ar numsects 44.Op Fl t Ar trackno 45.Sh DESCRIPTION 46The 47.Nm 48utility reads floppy disks. Effective read blocking based on the track 49size is performed, and floppy-specific error recovery of otherwise 50bad blocks can be enabled. 51.Pp 52.Nm 53will always read an entire floppy medium, and write its contents to 54the respective output file. Unlike other tools like 55.Xr dd 1 , 56.Nm 57automatically uses a read block size that is more efficient than 58reading single blocks (usually one track of data at a time), but 59falls back to reading single floppy sectors in case of an input/output 60error occurred, in order to obtain as much valid data as possible. 61While 62.Nm 63is working, kernel error reporting for floppy errors is turned off, so 64the console and/or syslog are not flooded with kernel error messages. 65.Pp 66The 67.Nm 68utility accepts the following options: 69.Bl -tag -width indent 70.It Fl q 71Turn on quiet mode. By default, the medium parameters of the device 72are being written to standard error output, progress will be indicated 73by the approximate number of kilobytes read so far, and errors will be 74printed out in detail, including the information about the location of 75recovered data in the output. In quiet mode, none of these messages 76will be generated. 77.It Fl r 78Enable error recovery. By default, 79.Nm 80stops after the first unrecovered read error, much like 81.Xr dd 1 82does. In recovery mode, however, one of two recovery actions will be 83taken: 84.Bl -bullet 85.It 86If the error was a CRC error in the data field, the 87kernel is told to ignore the error, and data are transferred to the 88output file anyway. 89.Bf -emphasis 90Note that this will cause the erroneous data 91to be included in the output file! 92.Ef 93Still, this is the best recovery action that can be taken at all. 94.It 95All other errors are really fatal (usually, the FDC didn't find the 96sector ID fields), thus a dummy block with fill 97bytes will be included in the output file. 98.El 99.Pp 100Unless operating in quiet mode, the action taken and the location of 101the error in the output file will be displayed. 102.It Fl d Ar device 103Specify the input floppy device, defaulting to 104.Pa /dev/fd0 . 105The parameter 106.Ar device 107must be a valid floppy disk device. 108.It Fl f Ar fillbyte 109Value of the fill byte used for dummy blocks in the output file in 110recovery mode. Defaults to 111.Ql 0xf0 . 112(Mnemonic: 113.Dq foo . ) 114The value can be specified using the usual C language notation of 115the number base. 116.It Fl o Ar file 117Specify the output file to be 118.Ar file . 119By default, the data will be written to standard output. 120.It Fl I Ar numsects 121Read 122.Ar numsects 123sector ID fields, and write out their contents to standard output. 124Each sector ID field contains recorded values for the cylinder number 125.Pq Ql C , 126the head number 127.Pq Ql H , 128the record number (sector number starting with 1) 129.Pq Ql R , 130and the 131.Em sector shift value 132.Po 1330 = 128 bytes, 1 = 256 bytes, 2 = 512 bytes, 3 = 1024 bytes 134.Pc 135.Pq Ql N . 136The 137.Fl I 138option is mutually exclusive with all other options except 139.Fl d Ar device 140and 141.Fl t Ar trackno . 142.It Fl t Ar trackno 143Specify the track number (cylinder number * number of heads + head 144number) to read the sector ID fields from; only allowed together with 145the 146.Fl I Ar numsects 147option. 148.El 149.Sh FILES 150.Bl -tag -width /dev/fd0 151.It Pa /dev/fd0 152Default device to read from. 153.El 154.Sh DIAGNOSTICS 155.Nm 156sets the exit value according to 157.Xr sysexits 3 . 158In recovery mode, the exit value will be set to 159.Dv EX_IOERR 160if any error occurred during processing (even in quiet mode). 161.Pp 162Unless running in quiet mode, upon encountering an error, the status 163of the floppy disc controller (FDC) will be printed out, both in 164hexadecimal form, followed by a textual description that translates 165those values into a human-readable form for the most common error 166cases that can happen in a PC environment. 167.Pp 168The FDC error status includes the three FDC status registers 169.Ql ST0 , 170.Ql ST1 , 171and 172.Ql ST2 , 173as well as the location of the error (physical cylinder, head, and sector 174number, plus the 175.Dq sector shift value , 176respectively). See the manual for the NE765 or compatible for details 177about the status register contents. 178.Pp 179The FDC's status is then examined to determine whether the error is 180deemed to be recoverable. If error recovery was requested, the 181location of the bad block in the output file is indicated by its 182(hexadecimal) bounds. Also, a summary line indicating the total number 183of transfer errors will be printed before exiting. 184.Sh SEE ALSO 185.Xr dd 1 , 186.Xr fdwrite 1 , 187.Xr sysexits 3 , 188.Xr fdc 4 , 189.Xr fdcontrol 8 190.Sh HISTORY 191The 192.Nm 193utility was written mainly to provide a means of recovering at least some of 194the data on bad media, and to obviate the need to invoke 195.Xr dd 1 196with too many hard to memorize options that might be useful to handle 197a floppy. 198.Pp 199The command appeared in 200.Fx 5.0 . 201.Sh AUTHORS 202Program and man page by 203.An J\(:org Wunsch . 204.Sh BUGS 205Concurrent traffic on the second floppy drive located at the same FDC 206will make error recovery attempts pointless, since the FDC status 207obtained after a read error occurred cannot be guaranteed to actually 208belong to the erroneous transfer. Thus using option 209.Fl r 210is only reliable if 211.Ar device 212is the only active drive on that controller. 213.Pp 214No attempt beyond the floppy error retry mechanism of 215.Xr fdc 4 216is made in order to see whether bad sectors could still be read 217without errors by trying multiple times. 218.Pp 219Bits that are (no longer) available on the floppy medium cannot be 220guessed by 221.Nm . 222