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Fix some more error handling #163

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merged 2 commits into from May 6, 2022
Merged

Fix some more error handling #163

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29b078d
Run gofmt
javierhonduco May 4, 2022
20c5ee9
Fix more error handling
javierhonduco May 4, 2022
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1 change: 0 additions & 1 deletion helpers/btfhub.go
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@@ -1,2 +1 @@
package helpers

75 changes: 36 additions & 39 deletions libbpfgo.go
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Expand Up @@ -566,30 +566,30 @@ func (b *BPFMap) SetType(mapType MapType) error {

func (b *BPFMap) Pin(pinPath string) error {
path := C.CString(pinPath)
errC := C.bpf_map__pin(b.bpfMap, path)
ret, errC := C.bpf_map__pin(b.bpfMap, path)
C.free(unsafe.Pointer(path))
if errC != 0 {
return fmt.Errorf("failed to pin map %s to path %s: %w", b.name, pinPath, syscall.Errno(-errC))
if ret != 0 {
return fmt.Errorf("failed to pin map %s to path %s: %w", b.name, pinPath, errC)
}
return nil
}

func (b *BPFMap) Unpin(pinPath string) error {
path := C.CString(pinPath)
errC := C.bpf_map__unpin(b.bpfMap, path)
ret, errC := C.bpf_map__unpin(b.bpfMap, path)
C.free(unsafe.Pointer(path))
if errC != 0 {
return fmt.Errorf("failed to unpin map %s from path %s: %w", b.name, pinPath, syscall.Errno(-errC))
if ret != 0 {
return fmt.Errorf("failed to unpin map %s from path %s: %w", b.name, pinPath, errC)
}
return nil
}

func (b *BPFMap) SetPinPath(pinPath string) error {
path := C.CString(pinPath)
errC := C.bpf_map__set_pin_path(b.bpfMap, path)
ret, errC := C.bpf_map__set_pin_path(b.bpfMap, path)
C.free(unsafe.Pointer(path))
if errC != 0 {
return fmt.Errorf("failed to set pin for map %s to path %s: %w", b.name, pinPath, syscall.Errno(-errC))
if ret != 0 {
return fmt.Errorf("failed to set pin for map %s to path %s: %w", b.name, pinPath, errC)
}
return nil
}
Expand All @@ -600,9 +600,9 @@ func (b *BPFMap) SetPinPath(pinPath string) error {
// Note: for ring buffer and perf buffer, maxEntries is the
// capacity in bytes.
func (b *BPFMap) Resize(maxEntries uint32) error {
errC := C.bpf_map__set_max_entries(b.bpfMap, C.uint(maxEntries))
if errC != 0 {
return fmt.Errorf("failed to resize map %s to %v: %w", b.name, maxEntries, syscall.Errno(-errC))
ret, errC := C.bpf_map__set_max_entries(b.bpfMap, C.uint(maxEntries))
if ret != 0 {
return fmt.Errorf("failed to resize map %s to %v: %w", b.name, maxEntries, errC)
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Why don't we want to use syscall.Errno(-errC)? In these cases you're using %w for errC, which is an int.

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The second argument's type of any CGO call is error, which is the errno already.

It's confusing because Go doesn't require us to bind all the return values of a function, and before, as errC was the sole function return value we were reading, it was in reality the return value, which is a C.int, and not what we want.

That's why passing it to syscall.Errno always resulted in -1, EPERM(#147) [1]

[1]: For completeness, it returns -1on failure before libbpf 1.0, which hasn't been released yet, or if LibbpfStrictModeDirectErrs is not used (https://github.com/libbpf/libbpf/wiki/Libbpf-1.0-migration-guide).

Hope this makes sense, let me know if this is not what you meant!

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Ah yes of course, my confusion. I'd like to standardize naming of CGO errors that are int's as errorCode and the second return of type error as errno. I can handle that in the future.

}
return nil
}
Expand Down Expand Up @@ -634,10 +634,7 @@ func (b *BPFMap) GetPinPath() string {

func (b *BPFMap) IsPinned() bool {
isPinned := C.bpf_map__is_pinned(b.bpfMap)
if isPinned == C.bool(true) {
return true
}
return false
return isPinned == C.bool(true)
}

func (b *BPFMap) KeySize() int {
Expand All @@ -660,9 +657,9 @@ func (b *BPFMap) GetValue(key unsafe.Pointer) ([]byte, error) {
value := make([]byte, b.ValueSize())
valuePtr := unsafe.Pointer(&value[0])

errC := C.bpf_map_lookup_elem(b.fd, key, valuePtr)
if errC != 0 {
return nil, fmt.Errorf("failed to lookup value %v in map %s: %w", key, b.name, syscall.Errno(-errC))
ret, errC := C.bpf_map_lookup_elem(b.fd, key, valuePtr)
if ret != 0 {
return nil, fmt.Errorf("failed to lookup value %v in map %s: %w", key, b.name, errC)
}
return value, nil
}
Expand Down Expand Up @@ -890,9 +887,9 @@ func (b *BPFMap) DeleteKey(key unsafe.Pointer) error {
// bpfmap.Update(keyPtr, valuePtr)
//
func (b *BPFMap) Update(key, value unsafe.Pointer) error {
errC := C.bpf_map_update_elem(b.fd, key, value, C.BPF_ANY)
if errC != 0 {
return fmt.Errorf("failed to update map %s: %w", b.name, syscall.Errno(-errC))
ret, errC := C.bpf_map_update_elem(b.fd, key, value, C.BPF_ANY)
if ret != 0 {
return fmt.Errorf("failed to update map %s: %w", b.name, errC)
}
return nil
}
Expand Down Expand Up @@ -953,10 +950,10 @@ func (it *BPFMapIterator) Err() error {

func (m *Module) GetProgram(progName string) (*BPFProg, error) {
cs := C.CString(progName)
prog, errno := C.bpf_object__find_program_by_name(m.obj, cs)
prog, errC := C.bpf_object__find_program_by_name(m.obj, cs)
C.free(unsafe.Pointer(cs))
if prog == nil {
return nil, fmt.Errorf("failed to find BPF program %s: %w", progName, errno)
return nil, fmt.Errorf("failed to find BPF program %s: %w", progName, errC)
}

return &BPFProg{
Expand All @@ -982,21 +979,21 @@ func (p *BPFProg) Pin(path string) error {
}

cs := C.CString(absPath)
errC := C.bpf_program__pin(p.prog, cs)
ret, errC := C.bpf_program__pin(p.prog, cs)
C.free(unsafe.Pointer(cs))
if errC != 0 {
return fmt.Errorf("failed to pin program %s to %s: %w", p.name, path, syscall.Errno(-errC))
if ret != 0 {
return fmt.Errorf("failed to pin program %s to %s: %w", p.name, path, errC)
}
p.pinnedPath = absPath
return nil
}

func (p *BPFProg) Unpin(path string) error {
cs := C.CString(path)
errC := C.bpf_program__unpin(p.prog, cs)
ret, errC := C.bpf_program__unpin(p.prog, cs)
C.free(unsafe.Pointer(cs))
if errC != 0 {
return fmt.Errorf("failed to unpin program %s to %s: %w", p.name, path, syscall.Errno(-errC))
if ret != 0 {
return fmt.Errorf("failed to unpin program %s to %s: %w", p.name, path, errC)
}
p.pinnedPath = ""
return nil
Expand Down Expand Up @@ -1148,17 +1145,17 @@ func (p *BPFProg) GetType() BPFProgType {

func (p *BPFProg) SetAutoload(autoload bool) error {
cbool := C.bool(autoload)
errC := C.bpf_program__set_autoload(p.prog, cbool)
if errC != 0 {
return fmt.Errorf("failed to set bpf program autoload: %w", syscall.Errno(-errC))
ret, errC := C.bpf_program__set_autoload(p.prog, cbool)
if ret != 0 {
return fmt.Errorf("failed to set bpf program autoload: %w", errC)
}
return nil
}

func (p *BPFProg) SetTracepoint() error {
errC := C.bpf_program__set_tracepoint(p.prog)
if errC != 0 {
return fmt.Errorf("failed to set bpf program as tracepoint: %w", syscall.Errno(-errC))
ret, errC := C.bpf_program__set_tracepoint(p.prog)
if ret != 0 {
return fmt.Errorf("failed to set bpf program as tracepoint: %w", errC)
}
return nil
}
Expand All @@ -1184,10 +1181,10 @@ func (p *BPFProg) AttachGeneric() (*BPFLink, error) {
// the BPF program to. To attach to a kernel function specify attachProgFD as 0
func (p *BPFProg) SetAttachTarget(attachProgFD int, attachFuncName string) error {
cs := C.CString(attachFuncName)
errC := C.bpf_program__set_attach_target(p.prog, C.int(attachProgFD), cs)
ret, errC := C.bpf_program__set_attach_target(p.prog, C.int(attachProgFD), cs)
C.free(unsafe.Pointer(cs))
if errC != 0 {
return fmt.Errorf("failed to set attach target for program %s %s %w", p.name, attachFuncName, syscall.Errno(-errC))
if ret != 0 {
return fmt.Errorf("failed to set attach target for program %s %s %w", p.name, attachFuncName, errC)
}
return nil
}
Expand Down
2 changes: 1 addition & 1 deletion libbpfgo_test.go
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Expand Up @@ -68,7 +68,7 @@ func Test_LoadAndAttach(t *testing.T) {
},
},
{
prog: "socket_connect",
prog: "socket_connect",
attachFn: func(prog *BPFProg, name string) (*BPFLink, error) {
if name != "" {
// to make the check for attaching with "foo" happy
Expand Down