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114 lines
3.1 KiB
Go
114 lines
3.1 KiB
Go
/*
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Package rpm implements the rpm package file format.
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package main
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import (
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"fmt"
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"log"
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"github.com/cavaliergopher/rpm"
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)
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func main() {
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pkg, err := rpm.Open("golang-1.17.2-1.el7.x86_64.rpm")
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if err != nil {
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log.Fatal(err)
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}
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fmt.Println("Package:", pkg)
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fmt.Println("Summary:", pkg.Summary())
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// Output:
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// Package: golang-1.17.2-1.el7.x86_64
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// Summary: The Go Programming Language
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}
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For more information about the rpm file format, see:
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http://ftp.rpm.org/max-rpm/s1-rpm-file-format-rpm-file-format.html
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Packages are composed of two headers: the Signature header and the "Header"
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header. Each contains key-value pairs called tags. Tags map an integer key to a
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value whose data type will be one of the TagType types. Tag values can be
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decoded with the appropriate Tag method for the data type.
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Many known tags are available as Package methods. For example, RPMTAG_NAME and
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RPMTAG_BUILDTIME are available as Package.Name and Package.BuildTime
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respectively.
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fmt.Println(pkg.Name(), pkg.BuildTime())
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Tags can be retrieved and decoded from the Signature or Header headers directly
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using Header.GetTag and their tag identifier.
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const (
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RPMTagName = 1000
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RPMTagBuidlTime = 1006
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)
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fmt.Println(
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pkg.Header.GetTag(RPMTagName).String()),
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time.Unix(pkg.Header.GetTag(RPMTagBuildTime).Int64(), 0),
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)
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Header.GetTag and all Tag methods will return a zero value if the header or the
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tag do not exist, or if the tag has a different data type.
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You may enumerate all tags in a header with Header.Tags:
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for id, tag := range pkg.Header.Tags {
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fmt.Println(id, tag.Type, tag.Value)
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}
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Comparing versions
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In the rpm ecosystem, package versions are compared using EVR; epoch, version,
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release. Versions may be compared using the Compare function.
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if rpm.Compare(pkgA, pkgB) == 1 {
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fmt.Println("A is more recent than B")
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}
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Packages may be be sorted using the PackageSlice type which implements
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sort.Interface. Packages are sorted lexically by name ascending and then by
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version descending. Version is evaluated first by epoch, then by version string,
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then by release.
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sort.Sort(PackageSlice(pkgs))
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The Sort function is provided for your convenience.
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rpm.Sort(pkgs)
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Checksum validation
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Packages may be validated using MD5Check or GPGCheck. See the example for each
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function.
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Extracting files
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The payload of an rpm package is typically archived in cpio format and
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compressed with xz. To decompress and unarchive an rpm payload, the reader that
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read the rpm package headers will be positioned at the beginning of the payload
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and can be reused with the appropriate Go packages for the rpm payload format.
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You can check the archive format with Package.PayloadFormat and the compression
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algorithm with Package.PayloadCompression.
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For the cpio archive format, the following package is recommended:
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https://github.com/cavaliergopher/cpio
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For xz compression, the following package is recommended:
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https://github.com/ulikunitz/xz
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See README.md for a working example of extracting files from a cpio/xz rpm
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package using these packages.
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Example programs
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See cmd/rpmdump and cmd/rpminfo for example programs that emulate tools from the
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rpm ecosystem.
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*/
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package rpm
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