psc@lzaz.ATT.COM (Paul S. R. Chisholm) (05/13/87)
< "I'm *not* expendable, I'm *not* stupid, and I'm *NOT* going!" >
Maybe I'm missing the point, but I can't see any way to read a
directory (or subdirectory) using the DOS functions. The obvious thing
is to just open "FOO" (or "FOO."), but I got an "Access denied" error
code. I supposed I could use the BIOS diskette services to find the
FAT, and chain my way through the root directory and any necessary
subdirectories till I find my subdirectory, calculating the sectors by
hand. No, I'm not getting burned by the "c:\newline\backsp" bug (where
C programmers use backslash for DOS pathnames, and forget C also used
backslashes for magic characters). I don't want to write to the
directory, only see what files are in it and how long they are (without
reading all of all the files), perhaps recursively.
There are forty-two thousand versions of the UNIX(R) ls command for
DOS, so it can't be *that* hard . . . unless there's a DOS stat()
function in the C library you're using. There will be in the next
version of the one I'm using, I hope. (Don't ask.)
Follow up if you must, reply by mail if you can; I'll summarize.
-Paul S. R. Chisholm, UUCP {ihnp4,cbosgd,allegra,vax135,mtune}!lznv!psc
AT&T Mail !psrchisholm, Internet psc@lznv.att.com
I'm not speaking for my employer, I'm just speaking my mind.
I'm not speaking for the company, I'm just speaking my mind.psc@lzaz.ATT.COM (Paul S. R. Chisholm) (05/13/87)
Maybe I'm missing the point, but I can't see any way to read a
directory (or subdirectory) using the DOS functions. The obvious thing
is to just open "FOO" (or "FOO."), but I got an "Access denied" error
code. I supposed I could use the BIOS diskette services to find the
FAT, and chain my way through the root directory and any necessary
subdirectories till I find my subdirectory, calculating the sectors by
hand. No, I'm not getting burned by the "c:\newline\backsp" bug (where
C programmers use backslash for DOS pathnames, and forget C also used
backslashes for magic characters). I don't want to write to the
directory, only see what files are in it and how long they are (without
reading all of all the files), perhaps recursively.
There are forty-two thousand versions of the UNIX(R) ls command for
DOS, so it can't be *that* hard . . . unless there's a DOS stat()
function in the C library you're using. There will be in the next
version of the one I'm using, I hope. (Don't ask.)
Follow up if you must, reply by mail if you can; I'll summarize.
-Paul S. R. Chisholm, UUCP {ihnp4,cbosgd,allegra,vax135,mtune}!lznv!psc
AT&T Mail !psrchisholm, Internet psc@lznv.att.com
I'm not speaking for my employer, I'm just speaking my mind.dhesi@bsu-cs.UUCP (05/16/87)
In article <63@lzaz.ATT.COM> psc@lzaz.ATT.COM (Paul S. R. Chisholm) writes: >Maybe I'm missing the point, but I can't see any way to read a >directory (or subdirectory) using the DOS functions. The MS-DOS calls FindFirst and FindNext accept an attribute byte and a filename pattern and return the names of all matching files. If the attribute byte is correctly supplied the names will include directories too. One you have the name of a directory, you can then append "*.*" to its name and use FindFirst and FindNext again recursively. These calls will also return some additional information such as file size and date. -- Rahul Dhesi UUCP: {ihnp4,seismo}!{iuvax,pur-ee}!bsu-cs!dhesi
madd@bucsb.bu.edu.UUCP (Jim "Jack" Frost) (05/17/87)
In article <63@lzaz.ATT.COM> psc@lzaz.ATT.COM (Paul S. R. Chisholm) writes: >Maybe I'm missing the point, but I can't see any way to read a >directory (or subdirectory) using the DOS functions. The obvious thing >is to just open "FOO" (or "FOO."), but I got an "Access denied" error >code. I supposed I could use the BIOS diskette services to find the >FAT, and chain my way through the root directory and any necessary >subdirectories till I find my subdirectory, calculating the sectors by >hand. No, I'm not getting burned by the "c:\newline\backsp" bug (where >C programmers use backslash for DOS pathnames, and forget C also used >backslashes for magic characters). I don't want to write to the >directory, only see what files are in it and how long they are (without >reading all of all the files), perhaps recursively. I'm not going to give you straight code for it, but here's an outlie of how to do it. Most of the information here came from the MSDOS Tech Ref manual, so you can always just go look it up. 1) You need to tell msdos where the DTA address is, because this is where the info is going to be stored. This is function 1AH. Set AH=1AH, DS and DX to the address of the DTA (DS:DX), and do an INT 21H. I don't remember how big the DTA area is supposed to be, so you'll have to look it up or experiment. 2) Call "FIND FIRST", which is function 4EH. To call this, set AH=4EH, DS:DX should point to an ASCIIZ pathname with matching characters (like "????????.???" to find any file). CX should contain the file attribute. File attributes are: 01H Read only file 02H Hidden file 04H System file 10H Subdirectory 20H Archived file 3) The returned data will be in the DTA area, and will be formatted as follows: 21 bytes of stuff ("Reserved for DOS use on subsequent "FIND NEXT" calls) 1 byte (file attribute) 2 bytes (file time) 2 bytes (file date) 2 bytes (low byte of file size) 2 bytes (high byte of file size) 13 bytes (name and extension of file found, followed by a zero byte) I won't get into decoding date and time right now, but you can always look it up. 4) To find subsequent matches, use the "FIND NEXT" command, which is function 4FH. It assumes that "FIND FIRST" has already been found and uses the DTA information to find the next entry. 5) As soon as no more entries are to be found, AX will be set to 18 (decimal, 12H) indicating "no more files." Note that SOMETIMES a null file name will be returned in the call before you receive the 12H return code. This is from personal experience. The Turbo Pascal Tutorial gives a good description (and a nice routine) of how to get a directory. I hacked it into a general purpose routine to return a linked list of entries. There are probably some books out there that describe how to do this as well.... Hope this is helpful. Happy hacking! %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Jim Frost * The Madd Hacker | UUCP: ..!harvard!bu-cs!bucsb!madd H H | ARPA: madd@bucsb.bu.edu H-C-C-OH <- heehee +---------+---------------------------------- H H | "We are strangers in a world we never made"
tim@j.cc.purdue.edu (Timothy Lange) (05/17/87)
Using an extended FCB with the proper file name (or wild cards), and the attribute for 'directory' will allow you to find and open directory files. The thing I ran into was the size of the directory file is always returned as zero! No big deal though, you know you have at least one cluster to work with and when you find a directory entry that is all zeroes that is the end of the file. So I just reset the size to something large and write my code to detect end of file by looking at the values in each directory entry. I wrote my own directory alphabetizer once, so it can be done fairly easiely. -- Timothy Lange / PC Learning Resource Center / Mathmatical Sciences Bldg. Purdue University Computing Center / West Lafayette, IN 47907 317-494-1787 / tim@j.cc.purdue.edu
psfales@ihlpe.ATT.COM (Peter Fales) (05/19/87)
In article <62@lzaz.ATT.COM>, psc@lzaz.ATT.COM (Paul S. R. Chisholm) writes: > > Maybe I'm missing the point, but I can't see any way to read a > directory (or subdirectory) using the DOS functions. The obvious thing > is to just open "FOO" (or "FOO."), but I got an "Access denied" error > code. The standard trick is use the DOS functions "find first" and "find next" to find all files which match "dir/subdir1/subdir2/*.*" or whatever. It is likely that your compiler library has functions to simplify this procedure. In my compiler they are called opendir() and readdir(), I believe the names are stolen from similar functions under BSD UNIX. -- Peter Fales UUCP: ...ihnp4!ihlpe!psfales work: (312) 979-7784 AT&T Information Systems, IW 1Z-243 1100 E. Warrenville Rd., IL 60566