1. Re: database.e db_open_noeds?]
- Posted by Derek Parnell <ddparnell at bigpond.com> Mar 28, 2002
- 392 views
This is a multi-part message in MIME format. ------=_NextPart_000_0059_01C1D720.10B97740 charset="iso-8859-2" ----- Original Message ----- From: "Salix" <salix at freemail.hu> To: "EUforum" <EUforum at topica.com> Subject: [Fwd: database.e db_open_noeds?] > -------- Original Message -------- > Subject: database.e db_open_noeds? > Date: Wed, 27 Mar 2002 11:01:28 +0100 > From: Salix <salix at freemail.hu> > To: EUforum <EUforum at topica.com> > > Hello all, > > Is there any return code for db_open() like DB_OPEN_NOEDS? How do you > recognize that a file you wanted to open is actually not an Euphoria > Database System file? (Any code or tipp is welcome.) There is no way supplied by RDS to do this. I've attached a file that you can include in your application. It contains a function called db_validate(). It takes a file name as parameter and returns a sequence as a result. If the first element returned is a 1, then the file is a valid EDS database. Otherwise the second element is an error code that identifies what was wrong with the file. As it checks nearly every byte in the file, it can take a while for large databases. --------- Derek. ------=_NextPart_000_0059_01C1D720.10B97740 Content-Type: application/octet-stream; name="dbval.e" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="dbval.e" include file.e without trace without profile without warning without type_check constant DB_MAGIC = 77, FREE_COUNT = 7, SIZEOF_TABLE_HEADER = 16, I2B = 249, -- 2-byte signed integer follows I3B = 250, -- 3-byte signed integer follows I4B = 251, -- 4-byte signed integer follows F4B = 252, -- 4-byte f.p. number follows F8B = 253, -- 8-byte f.p. number follows S1B = 254, -- sequence, 1-byte length follows, then elements -- S4B = 255, -- sequence, 4-byte length follows, then elements INIT_FREE = 5, KnownVersions = {{0,5}, {2,3}}, BADINT = #100000000 global constant kOpenFailed = 1, kNotEDS = 2, kTableSeek = 3, kInitialSeek = 4, kTableCount = 5, kTableNamePtr = 6, kRecCnt = 7, kBlkCnt = 8, kTableIndexPtr = 9, kTableNameSeek = 10, kTableName = 11, kIndexSeek = 12, kRecordCnt = 13, kRecordPtr = 14, kRecordSeek = 15, kKeyPtr = 16, kKeySeek = 17, kDataPtr = 18, kDataSeek = 19, kNextTableSeek = 20, kFreeCountSeek = 21, kFreeChainSeek = 22, kFreeChainPtr = 23, kFreeCount = 24, kFreeChainAddr = 25, kFreeChainSize = 26, kKeyData = 27, kDataData = 28, kFreeCountTooHigh = 29, kFreeList = 30, kFreeListSpace = 31, kFreeListSeek = 32, kFreeChainSizeChk = 33, kVersion = 34 function get_string(integer fn) -- read a 0-terminated string at current position in database file sequence s integer c s = "" while 1 do c = getc(fn) if c = -1 then return -1 elsif c = 0 then exit end if s &= c end while return s end function function get4(integer fn) -- read 4-byte value at current position in database file integer b0, b1, b2, b3 b0 = getc(fn) b1 = getc(fn) b2 = getc(fn) b3 = getc(fn) if b0 < 0 or b1 < 0 or b2 < 0 or b3 < 0 then return BADINT else return b0 + #100*b1 + #10000*b2 + #1000000*b3 end if end function function validate_data(integer fn) -- validate a compressed Euphoria object from disk integer c, v atom len c = getc(fn) if c < 0 then return 0 end if if c < I2B then v = 0 elsif c = I2B then v = 2 elsif c = I3B then v = 3 elsif c = I4B then v = 4 elsif c = F4B then v = 4 elsif c = F8B then v = 8 else -- sequence if c = S1B then len = getc(fn) if len < 0 then return 0 end if else len = get4(fn) if len = BADINT then return 0 end if end if for i = 1 to len do if validate_data(fn) = 0 then return 0 end if end for return 1 end if for i = 1 to v do c = getc(fn) if c < 0 then return 0 end if end for return 1 end function global function db_validate(sequence pFileName) -- Validates a EDS database. object void, sObj integer magic, minor, major integer fn atom tables, ntables, tname, trecords, t_header, tnrecs, key_ptr, data_ptr, size, addr, tindex integer tblocks atom free_count, free_list, free_list_space atom max fn = open(pFileName, "rb") if fn = -1 then return {0, kOpenFailed} end if void = seek(fn, -1) max = where(fn) void = seek(fn, 0) if void != 0 then return {0, kInitialSeek} end if magic = getc(fn) if magic != DB_MAGIC then close(fn) return {0, kNotEDS} end if major = getc(fn) minor = getc(fn) if not find({major,minor}, KnownVersions) then close(fn) return {0, kVersion} end if tables = get4(fn) if tables < 0 or tables = BADINT or tables > max then close(fn) return {0, kNotEDS} end if void = seek(fn,tables) if void != 0 then close(fn) return {0, kTableSeek} end if ntables = get4(fn) if ntables < 0 or ntables = BADINT then close(fn) return {0, kTableCount} end if t_header = where(fn) for t = 1 to ntables do -- display the next table tname = get4(fn) if tname < 0 or tname = BADINT or tname > max then close(fn) return {0, kTableNamePtr, t} end if tnrecs = get4(fn) if tnrecs < 0 or BADINT then close(fn) return {0, kRecCnt, t} end if tblocks = get4(fn) if tblocks < 0 or tblocks = BADINT then close(fn) return {0, kBlkCnt, t} end if tindex = get4(fn) if tindex < 0 or tindex = BADINT or tindex > max then close(fn) return {0, kTableIndexPtr, t} end if void = seek(fn,tname) if void != 0 then close(fn) return {0, kTableNameSeek, t} end if sObj = get_string(fn) if equal(sObj, -1) then close(fn) return {0, kTableName, t} end if for b = 1 to tblocks do void = seek(fn, tindex+(b-1)*8) if void != 0 then close(fn) return {0, kIndexSeek,t,b} end if tnrecs = get4(fn) if tnrecs < 0 or tnrecs = BADINT then close(fn) return {0, kRecordCnt, t, b} end if trecords = get4(fn) if trecords < 0 or trecords = BADINT or trecords > max then close(fn) return {0, kRecordPtr, t, b} end if for r = 1 to tnrecs do -- check the record data void = seek(fn, trecords+(r-1)*4) if void != 0 then close(fn) return {0, kRecordSeek, t, b, r} end if key_ptr = get4(fn) if key_ptr < 0 or key_ptr = BADINT or key_ptr > max then close(fn) return {0, kKeyPtr, t, b, r} end if void = seek(fn, key_ptr) if void != 0 then close(fn) return {0, kKeySeek, t, b, r} end if data_ptr = get4(fn) if data_ptr < 0 or data_ptr = BADINT or data_ptr > max then close(fn) return {0, kDataPtr, t, b, r} end if if validate_data(fn) = 0 then close(fn) return {0, kKeyData, t, b, r} end if void = seek(fn, data_ptr) if void != 0 then close(fn) return {0, kDataSeek, t, b, r} end if if validate_data(fn) = 0 then close(fn) return {0, kDataData, t, b, r} end if end for end for t_header += SIZEOF_TABLE_HEADER void = seek(fn, t_header) if void != 0 then close(fn) return {0, kNextTableSeek, t} end if end for -- check the free list void = seek(fn, FREE_COUNT) if void != 0 then close(fn) return {0, kFreeCountSeek} end if free_count = get4(fn) if free_count < 0 or free_count = BADINT then close(fn) return {0, kFreeCount} end if if free_count > max/13 then close(fn) return {0, kFreeCountTooHigh} end if free_list = get4(fn) if free_list < 0 or free_list = BADINT then close(fn) return {0, kFreeChainPtr} end if if free_list > max then close(fn) return {0, kFreeList} end if void = seek(fn, free_list-4) if void != 0 then close(fn) return {0, kFreeChainSeek} end if free_list_space = get4(fn) if free_list_space = BADINT or free_list_space > max or free_list_space < INIT_FREE * 8 then close(fn) return {0, kFreeListSpace} end if for i = 1 to free_count do void = seek(fn, free_list+(i-1)*8) if void != 0 then close(fn) return {0, kFreeListSeek} end if addr = get4(fn) if addr = BADINT or addr < 0 or addr > (max-4) then close(fn) return {0, kFreeChainAddr, i} end if size = get4(fn) if size < 0 or size = BADINT then close(fn) return {0, kFreeChainSize, i} end if if (size + addr-4) > max then close(fn) return {0, kFreeChainSize, i} end if void = seek(fn, addr-4) if get4(fn) > size then close(fn) return {0, kFreeChainSizeChk, i} end if end for -- All clear. close(fn) return {1} end function ------=_NextPart_000_0059_01C1D720.10B97740--