A Web-based News Reader
| Subject | Re: Having problems with uncompress of zip file created by std.zlib | |||||||||||||||||||||||||||
| From | Ben Hinkle <bhinkle4@juno.com> | |||||||||||||||||||||||||||
| Date | Sat, 28 Aug 2004 20:49:03 -0400 | |||||||||||||||||||||||||||
| Newsgroups | digitalmars.D | |||||||||||||||||||||||||||
It looks like a bug in std.zlib.uncompress. The code if (!destlen) destlen = srcbuf.length * 2 + 1; doesn't always allocate enough space for the result. When I change the 1 to 100 (or something big like that) all the examples in your test work. I have no idea what the "right" value should be. I was just playing around with different values. -Ben Lynn Allan wrote: > <alert comment="newbie"> > > I'm still having problems so I removed the std.file logic to better > illustrate the misbehavior I'm seeing. The exceptions thrown seem related > to the size of the buffer handled by std.zlib.uncompress. Or that I never > really woke up this morning??? > > The code is similar to Walter B.'s sample code for using zip, except using > larger buffers and doesn't "reuse" the original src buffer as the > destination of uncompress. Eventually, I want to read in a 1.1 meg plain > text file that has been compressed with std.zlib.compress from about 4.1 > meg. The application will use std.zlib.uncompress and proceed. The > original uncompressed buffer will be read in from a file, but this > simplified sample code just uses arrays to check what happens when a plain > text buffer is compressed, and then uncompressed. > > To summarize, main declares different text buffers of varying sizes and > then calls CompressThenUncompress. Oddly, the same CompressThenUncompress > code (below) that works for a buffer of 30 ubytes may fail inconsistently > with 60 ubytes. The way the buffer is declared also seems to make a > difference. > > There seems to be a 'threshold' of about 50 bytes, but that isn't > consistent either. I suspect that I'm confused about declaring arrays of > ubytes?? > > I've included the code below, which may be hard to view depending on word > wrap. It may be more viewable at: > http://dsource.org/forums/viewtopic.php?t=321 > > Am I doing something wrong or leaving out a step or three? The output from > running the program is shown at the bottom.. > > </alert> > > // ******************************* > // ******************************* > import std.zlib; > import std.stdio; > > void CompressThenUncompress (ubyte[] src) > { > try { > ubyte[] dst = cast(ubyte[])std.zlib.compress(cast(void[])src); > writef("src.length: ", src.length, " dst: ", dst.length); > ubyte[] uncompressedBuf; > uncompressedBuf = cast(ubyte[])std.zlib.uncompress(cast(void[])dst); > writefln(" ... Got past std.zlib.uncompress. dst.length: ", > dst.length); assert(src.length == uncompressedBuf.length); > assert(src == uncompressedBuf); > } > catch { > writefln(" ... Exception thrown when src.length = ", src.length, ". > Keep > going"); > } > } > > char[] outerBuf30 = "000000000011111111112222222222"; > char[] outerBuf40 = "0000000000111111111122222222223333333333"; > char[] outerBuf50 = "00000000001111111111222222222233333333334444444444"; > char[] outerBuf100 = "00000000001111111111222222222233333333334444444444" > "01234567890123456789012345678901234567890123456789"; > > void main (char[][] args) > { > char[] buf32 = "0123456789 0123456789 0123456789"; > CompressThenUncompress(cast(ubyte[])buf32); // Works ok > > char[] buf40 = "0123456789 0123456789 0123456789 0123456"; > CompressThenUncompress(cast(ubyte[])buf40); // Works ok > > char[] buf60 = "0123456789 0123456789 0123456789 0123456790 123456789 > 123456"; > CompressThenUncompress(cast(ubyte[])buf60); // Throws exception > > ubyte[] ubuf60 = cast(ubyte[])"0123456789 0123456789 0123456789 " > "0123456790 123456789 123456"; > CompressThenUncompress(ubuf60); // Throws exception > > char[] buf80 = "0123456789012345678901234567890123456789" > "0123456789012345678901234567890123456789"; > CompressThenUncompress(cast(ubyte[])buf80); // Throws exception > > CompressThenUncompress(cast(ubyte[])"This string is 28 chars long"); > //ok > CompressThenUncompress(cast(ubyte[])"This string is 42 chars long " > "0123456789012"); > //ok > CompressThenUncompress(cast(ubyte[])"This string is 46 chars long " > "01234567890123456"); > //ok > CompressThenUncompress(cast(ubyte[])"This string is 60 chars long " > "0123456789012345678901234567890"); > //ok > CompressThenUncompress(cast(ubyte[])"This string is 80 chars long " > "0123456789012345678901234567890" > "12345678901234567890"); > //ok > > CompressThenUncompress(cast(ubyte[])outerBuf30); // ok > CompressThenUncompress(cast(ubyte[])outerBuf40); // Throws > exception > CompressThenUncompress(cast(ubyte[])outerBuf50); // Throws > exception > CompressThenUncompress(cast(ubyte[])outerBuf100); // Throws > exception > } > > // Results from running above code for different array declarations > src.length: 32 dst: 22 ... Got past std.zlib.uncompress. dst.length: 22 > src.length: 40 dst: 22 ... Got past std.zlib.uncompress. dst.length: 22 > src.length: 60 dst: 28 ... Exception thrown when src.length = 60. Keep > going > src.length: 60 dst: 28 ... Exception thrown when src.length = 60. Keep > going > src.length: 80 dst: 21 ... Exception thrown when src.length = 80. Keep > going > src.length: 28 dst: 34 ... Got past std.zlib.uncompress. dst.length: 34 > src.length: 42 dst: 46 ... Got past std.zlib.uncompress. dst.length: 46 > src.length: 46 dst: 46 ... Got past std.zlib.uncompress. dst.length: 46 > src.length: 60 dst: 46 ... Got past std.zlib.uncompress. dst.length: 46 > src.length: 80 dst: 46 ... Got past std.zlib.uncompress. dst.length: 46 > src.length: 30 dst: 16 ... Got past std.zlib.uncompress. dst.length: 16 > src.length: 40 dst: 19 ... Exception thrown when src.length = 40. Keep > going > src.length: 50 dst: 21 ... Exception thrown when src.length = 50. Keep > going > src.length: 100 dst: 33 ... Exception thrown when src.length = 100. Keep > going > > > "Walter" <newshound@digitalmars.com> wrote in message > news:cgper0$2hoh$1@digitaldaemon.com... >> The following test program does a simple read/write of a zip file. It > might >> be helpful. >> ---------------------------- >> >> import std.file; >> import std.date; >> import std.zip; >> import std.zlib; >> >> int main(char[][] args) >> { >> byte[] buffer; >> std.zip.ZipArchive zr; >> char[] zipname; >> ubyte[] data; >> >> testzlib(); >> if (args.length > 1) >> zipname = args[1]; >> else >> zipname = "test.zip"; >> buffer = cast(byte[])std.file.read(zipname); >> zr = new std.zip.ZipArchive(cast(void[])buffer); >> printf("comment = '%.*s'\n", zr.comment); >> zr.print(); >> >> foreach (ArchiveMember de; zr.directory) >> { >> de.print(); >> printf("date = '%.*s'\n", std.date.toString(std.date.toDtime(de.time))); >> >> arrayPrint(de.compressedData); >> >> data = zr.expand(de); >> printf("data = '%.*s'\n", data); >> } >> >> printf("**Success**\n"); >> >> zr = new std.zip.ZipArchive(); >> ArchiveMember am = new ArchiveMember(); >> am.compressionMethod = 8; >> am.name = "foo.bar"; >> //am.extra = cast(ubyte[])"ExTrA"; >> am.expandedData = cast(ubyte[])"We all live in a yellow submarine, a >> yellow submarine"; >> am.expandedSize = am.expandedData.length; >> zr.addMember(am); >> void[] data2 = zr.build(); >> std.file.write("foo.zip", cast(byte[])data2); >> >> return 0; >> } >> >> void arrayPrint(ubyte[] array) >> { >> //printf("array %p,%d\n", (void*)array, array.length); >> for (int i = 0; i < array.length; i++) >> { >> printf("%02x ", array[i]); >> if (((i + 1) & 15) == 0) >> printf("\n"); >> } >> printf("\n\n"); >> } >> >> void testzlib() >> { >> ubyte[] src = cast(ubyte[]) >> "the quick brown fox jumps over the lazy dog\r >> the quick brown fox jumps over the lazy dog\r >> "; >> ubyte[] dst; >> >> arrayPrint(src); >> dst = cast(ubyte[])std.zlib.compress(cast(void[])src); >> arrayPrint(dst); >> src = cast(ubyte[])std.zlib.uncompress(cast(void[])dst); >> arrayPrint(src); >> } >> >> | ||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||
