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|
package main
import (
"fmt"
"github.com/cilium/ebpf"
)
func main() {
DocVariablesSetConst()
DocVariablesSetGlobal()
}
// Full example written to be displayed in its entirety, so is commented generously.
func DocVariablesSetConst() {
// Load the object file from disk using a bpf2go-generated scaffolding.
spec, err := loadVariables()
if err != nil {
panicf("loading CollectionSpec: %s", err)
}
// Set the 'const_u32' variable to 42 in the CollectionSpec.
want := uint32(42) // (1)!
if err := spec.Variables["const_u32"].Set(want); err != nil {
panicf("setting variable: %s", err)
}
// Load the CollectionSpec.
//
// Note: modifying spec.Variables after this point is ineffectual!
// Modifying *Spec resources does not affect loaded/running BPF programs.
var obj variablesPrograms
if err := spec.LoadAndAssign(&obj, nil); err != nil {
panicf("loading BPF program: %s", err)
}
fmt.Println("Running program with const_u32 set to", want)
// Dry-run the BPF program with an empty context.
ret, _, err := obj.ConstExample.Test(make([]byte, 15)) // (2)!
if err != nil {
panicf("running BPF program: %s", err)
}
if ret != want {
panicf("unexpected return value %d", ret)
}
fmt.Println("BPF program returned", ret)
// Output:
// Running program with const_u32 set to 42
// BPF program returned 42
}
func DocVariablesSetGlobal() {
spec, err := loadVariables()
if err != nil {
panicf("loading CollectionSpec: %s", err)
}
// DocVariablesSetGlobalU16 {
set := uint16(9000)
if err := spec.Variables["global_u16"].Set(set); err != nil {
panicf("setting variable: %s", err)
}
// }
coll, err := ebpf.NewCollection(spec)
if err != nil {
panicf("loading BPF program: %s", err)
}
fmt.Println("Running program with global_u16 set to", set)
// DocVariablesSetGlobalRun {
for range 3 {
ret, _, err := coll.Programs["global_example"].Test(make([]byte, 15))
if err != nil {
panicf("running BPF program: %s", err)
}
fmt.Println("BPF program returned", ret)
}
// Output:
// Running program with global_u16 set to 9000
// BPF program returned 9000
// BPF program returned 9001
// BPF program returned 9002
// }
// DocVariablesGetGlobalU16 {
var global_u16 uint16
if err := coll.Variables["global_u16"].Get(&global_u16); err != nil {
panicf("getting variable: %s", err)
}
fmt.Println("Variable global_u16 is now", global_u16)
// Output:
// Variable global_u16 is now 9003
// }
}
func panicf(format string, args ...interface{}) {
panic(fmt.Sprintf(format, args...))
}
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