Archived:Getting trailer and header info from GZIP files using Symbian C++
m (Lpvalente -) |
|||
| (13 intermediate revisions by 5 users not shown) | |||
| Line 1: | Line 1: | ||
| − | + | [[Category:Symbian C++]][[Category:Code Snippet]][[Category:Files/Data]][[Category:S60 3rd Edition FP1]][[Category:Code Snippet]] | |
| − | + | {{Archived|timestamp=20120313130335|user=roy.debjit| }} | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | {| | + | |
| − | + | ||
| − | + | ||
| − | |} | + | |
| + | {{ArticleMetaData <!-- v1.2 --> | ||
| + | |sourcecode= <!-- Link to example source code (e.g. [[Media:The Code Example ZIP.zip]]) --> | ||
| + | |installfile= <!-- Link to installation file (e.g. [[Media:The Installation File.sis]]) --> | ||
| + | |devices= Nokia N93 | ||
| + | |sdk= <!-- SDK(s) built and tested against (e.g. [http://linktosdkdownload/ Nokia Qt SDK 1.1]) --> | ||
| + | |platform= S60 3rd Edition, FP1 | ||
| + | |devicecompatability= <!-- Compatible devices (e.g.: All* (must have GPS) ) --> | ||
| + | |dependencies= <!-- Any other/external dependencies e.g.: Google Maps Api v1.0 --> | ||
| + | |signing= <!-- Empty or one of Self-Signed, DevCert, Manufacturer --> | ||
| + | |capabilities= <!-- Capabilities required by the article/code example (e.g. Location, NetworkServices. --> | ||
| + | |keywords= RFile, EZGZipFile, TEZGZipHeader, TEZGZipTrailer, RFile::Open(),EZGZipFile::IsGzipFileL(), EZGZipFile::LocateAndReadTrailerL(), EZGZipFile::ReadHeaderL(),EZGZipFile::EFText,EZGZipFile::EFHcrc, EZGZipFile::EFExtra,EZGZipFile::EFName,EZGZipFile::EFComment | ||
| + | |language= <!-- Language category code for non-English topics - e.g. Lang-Chinese --> | ||
| + | |translated-by= <!-- [[User:XXXX]] --> | ||
| + | |translated-from-title= <!-- Title only --> | ||
| + | |translated-from-id= <!-- Id of translated revision --> | ||
| + | |review-by= <!-- After re-review: [[User:username]] --> | ||
| + | |review-timestamp= <!-- After re-review: YYYYMMDD --> | ||
| + | |update-by= <!-- After significant update: [[User:username]]--> | ||
| + | |update-timestamp= <!-- After significant update: YYYYMMDD --> | ||
| + | |creationdate= 20080506 | ||
| + | |author= [[User:Aknyman]] | ||
| + | <!-- The following are not in current metadata --> | ||
| + | |subcategory= Files/Data | ||
| + | |id= CS000948 | ||
| + | }} | ||
| + | |||
==Overview== | ==Overview== | ||
| − | This snippet shows how to get the trailer and the header info from | + | {{Abstract|This snippet shows how to get the trailer and the header info from GZIP files.}} |
| − | The trailer part of | + | The trailer part of GZIP file should contain the following data: |
* CRC32 | * CRC32 | ||
| − | * | + | * Input size (calculated from the original uncompressed data) |
| − | The actual | + | The actual GZIP header is defined to contain the following fields: |
| − | * | + | * Fixed value for ID1 = 31 |
| − | * | + | * Fixed value for ID2 = 139 |
| − | * | + | * Compression method (8 is the standard) |
| − | * | + | * Flags (0 = no flags are set) |
| − | * | + | * Modification time (time stamp in Unix format) |
| − | * | + | * Extra flags (maximum compression - fastest algorithm) |
* Operating System | * Operating System | ||
| Line 145: | Line 153: | ||
==Postconditions== | ==Postconditions== | ||
| − | The trailer and header info from the given | + | The trailer and header info from the given GZIP file is printed to the console. |
==See also== | ==See also== | ||
| − | [[ | + | [[Archived:Compressing and decompressing GZIP files using Symbian C++]] |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | The GZIP format is specified in http://www.faqs.org/rfcs/rfc1952.html. | |
Latest revision as of 01:56, 16 September 2012
Archived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.
Article Metadata
Tested with
Devices(s): Nokia N93
Compatibility
Platform(s): S60 3rd Edition, FP1
Article
Keywords: RFile, EZGZipFile, TEZGZipHeader, TEZGZipTrailer, RFile::Open(),EZGZipFile::IsGzipFileL(), EZGZipFile::LocateAndReadTrailerL(), EZGZipFile::ReadHeaderL(),EZGZipFile::EFText,EZGZipFile::EFHcrc, EZGZipFile::EFExtra,EZGZipFile::EFName,EZGZipFile::EFComment
Created: aknyman
(06 May 2008)
Last edited: lpvalente
(16 Sep 2012)
Contents |
Overview
This snippet shows how to get the trailer and the header info from GZIP files.
The trailer part of GZIP file should contain the following data:
- CRC32
- Input size (calculated from the original uncompressed data)
The actual GZIP header is defined to contain the following fields:
- Fixed value for ID1 = 31
- Fixed value for ID2 = 139
- Compression method (8 is the standard)
- Flags (0 = no flags are set)
- Modification time (time stamp in Unix format)
- Extra flags (maximum compression - fastest algorithm)
- Operating System
This snippet can be self-signed.
MMP file
The following libraries are required:
LIBRARY efsrv.lib
LIBRARY ezlib.lib
Header file
Source file
#include <ezgzip.h>
#include <f32file.h>
void GetGZipFileTrailerAndHeaderInfoL(RFs& aRfs, const TDesC& aFileName)
{
RFile file;
TEZGZipHeader header;
TEZGZipTrailer trailer;
if (!EZGZipFile::IsGzipFileL(aRfs,aFileName))
{
_LIT(KIsNotGZipFile,"File:%S is not in GZip format\n");
console->Printf(KIsNotGZipFile,&aFileName);
console->Getch();
User::Leave(KErrGeneral);
}
EZGZipFile::LocateAndReadTrailerL(aRfs, aFileName, trailer);
_LIT(KTrailer,"CRC32 = %d size = %d\n");
console->Printf(KTrailer,trailer.iCrc32,trailer.iSize);
User::LeaveIfError(file.Open(aRfs,aFileName,EFileStream | EFileRead | EFileShareAny));
EZGZipFile::ReadHeaderL(file, header);
_LIT(KFileId1,"ID1 = %d\n");
console->Printf(KFileId1,header.iId1);
_LIT(KFileId2,"ID2 = %d\n");
console->Printf(KFileId2,header.iId2);
_LIT(KCompressionMethod,"compression method = %d\n");
console->Printf(KCompressionMethod,header.iCompressionMethod);
_LIT(KFlags,"flags = %d\n");
console->Printf(KFlags,header.iFlags);
_LIT(KTimeStamp,"time stamp = %d\n");
console->Printf(KTimeStamp,header.iTime);
_LIT(KExtraFlags,"extra flags %d\n");
console->Printf(KExtraFlags,header.iExtraFlags);
_LIT(KOS,"OS %d\n");
console->Printf(KOS,header.iOs);
if (header.iFlags & EZGZipFile::EFText)
{
_LIT(KText,"text flag set\n");
console->Printf(KText);
}
if (header.iFlags & EZGZipFile::EFHcrc)
{
_LIT(KCrc16,"CRC16 = %d\n");
console->Printf(KCrc16,header.iCrc);
}
if (header.iFlags & EZGZipFile::EFExtra)
{
_LIT(KExtraLength,"extra length %d\n");
console->Printf(KExtraLength,header.iXlen);
HBufC *buf = HBufC::NewLC(header.iExtra->Length());
buf->Des().Copy(*header.iExtra);
console->Printf(*buf);
CleanupStack::PopAndDestroy(); //buf
}
if (header.iFlags & EZGZipFile::EFName)
{
_LIT(KFName,"fname: %S\n");
HBufC *buf = HBufC::NewLC(header.iFname->Length());
buf->Des().Copy(*header.iFname);
console->Printf(KFName,buf);
CleanupStack::PopAndDestroy(); //buf
}
if (header.iFlags & EZGZipFile::EFComment)
{
_LIT(KComment,"comment: %S\n");
HBufC *buf = HBufC::NewLC(header.iComment->Length());
buf->Des().Copy(*header.iComment);
console->Printf(KComment,buf);
CleanupStack::PopAndDestroy(); //buf
}
}
Postconditions
The trailer and header info from the given GZIP file is printed to the console.
See also
Archived:Compressing and decompressing GZIP files using Symbian C++
The GZIP format is specified in http://www.faqs.org/rfcs/rfc1952.html.
