Int 21/AH=11h

DOS 1+ - FIND FIRST MATCHING FILE USING FCB

AH = 11h
DS:DX -> unopened FCB (see #01345), may contain '?' wildcards

Return:
AL = status
00h successful
[DTA] unopened FCB for first matching file
FFh no matching filename, or bad FCB

Notes: The type of the returned FCB depends on whether the input FCB was a normal or an extended FCB. The data returned in the DTA (disk transfer area) is actually the drive number (or extended FCB header and drive number) followed by the file's directory entry (see #01352); this format happens to be compatible with an unopened FCB. For extended FCBs with search attribute 08h, the volume label (if any) will be returned even if the current directory is not the root dir.. DOS 3.0+ also allows the '*' wildcard. The search FCB at DS:DX must not be modified if AH=12h will be used to continue searching; DOS 3.3 has set the following parts of the FCB: 0Ch BYTE ??? 0Dh WORD directory entry number of matching file 0Fh WORD cluster number of current directory 11h 4 BYTEs ??? 15h BYTE drive number (1=A:). This function is used by many copy protection schemes to obtain the starting cluster of a file

BUG: Under Windows95, if a .EXE program ("MZ" header) rather than a true .COM calls this function from a DOS box, the ten bytes of the directory entry from 0Ch to 15h may be filled with zeros rather than the additional file times

See Also: AH=12h - AH=1Ah - AH=4Eh - INT 2F/AX=111Bh


Format of DOS directory entry:

Offset  Size    Description     (Table 01352)
00h  8 BYTEs   blank-padded filename
first character is set to E5h for deleted files (05h for
pending delete files under Novell DOS / OpenDOS)
08h  3 BYTEs   blank-padded file extension
0Bh    BYTE    attributes
0Ch 10 BYTEs   (MS-DOS 1.0-6.22) reserved
(DR DOS) used to store file password / owner (see #01354)
(see also INT 21/AX=4302h)
(Novell DOS 7) DELWATCH data (see #01354)
(MS-DOS 7/Windows95) additional file times (see #01353)
16h    WORD    time of creation or last update (see #01665 at AX=5700h)
18h    WORD    date of creation or last update (see #01666 at AX=5700h)
1Ah    WORD    starting cluster number (see also AX=440Dh/CX=0871h)
(may not be set in INT 21/AH=11h return data for FAT32 drives)
1Ch    DWORD   file size

See Also: #01355 - #02628 - #02629

Format of MS-DOS 7/Windows95 additional file times: Offset Size Description (Table 01353) 00h BYTE reserved 01h BYTE 10-millisecond units past creation time below 02h WORD file creation time 04h WORD file creation date 06h WORD last-access date 08h WORD (FAT32) high word of starting cluster number

Note: This data is stored beginning at offset 0Ch in a standard directory entry

See Also: #01352


Format of DR DOS 6/Novell DOS 7 additional file information:

Offset  Size    Description     (Table 01354)
0Ch    BYTE    reserved (00h)
(DOSPLUS v1.2) user-defined attributes for CP/M compatibility
(bit 7 = F1,...,bit 4 = F4, bits 3-0 reserved (0))
0Dh    BYTE    first character of original filename for deleted file
0Eh    WORD    encrypted file/directory password
10h    WORD    reserved (00h)
(Novell DOS 7 DELWATCH) original file time
cleared when file is undeleted or purged
12h    WORD    (DR DOS 6) file owner ID
(Novell DOS 7 DELWATCH) original file date
cleared when file is undeleted or purged
14h    WORD    single/multiuser file/directory access rights (see AX=4302h)
---deleted files---
16h    WORD    (Novell DOS 7 DELWATCH) time of deletion
18h    WORD    (Novell DOS 7 DELWATCH) date of deletion

Note: Offsets are within the full directory entry

See Also: #01352

Format of MS-DOS 7/Windows95 long-filename directory entry: Offset Size Description (Table 01355) 00h BYTE LFN record sequence and flags

bits 5-0:
Sequence number

bit 6:
Set if last long-filename record for file

bit 7:
Set if file deleted 01h 10 BYTEs long filename, first part 0Bh BYTE 0Fh (otherwise impossible file attribute, used as signature) 0Ch BYTE reserved??? (00h) 0Dh BYTE checksum for short filename 0Eh 12 BYTEs long filename, second part 1Ah WORD first cluster number (always 0000h for LFN records) 1Ch 4 BYTEs long filename, third part

Notes: Long-filename entries are always stored in the directory just prior to the short-name entry for a file. Multiple LFN records are used if the long filename does not fit into a single record. The short-filename checksum byte is computed by adding up the eleven bytes of the short filename, rotating the intermediate sum right one bit before adding the next character. The long filename is encoded as 16-bit Unicode characters; for most filenames, this appears in the directory as the ASCII character followed by 00h

See Also: #01352 - INT 21/AX=5704h - INT 21/AH=71h

Category: DOS Kernel - Int 21h - D

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