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Fix for issue #1167, added handling of errors which are returned by scaner #1253

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Oct 11, 2016
Merged

Fix for issue #1167, added handling of errors which are returned by scaner #1253

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77 changes: 58 additions & 19 deletions control/plugin/execution.go
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Original file line number Diff line number Diff line change
Expand Up @@ -115,21 +115,41 @@ func (e *ExecutablePlugin) Run(timeout time.Duration) (Response, error) {
e.cmd.Start()
e.captureStderr()
go func() {
for stdOutScanner.Scan() {
// The first chunk from the scanner is the plugin's response to the
// handshake. Once we've received that, we can begin to forward
// logs on to snapd's log.
if !respReceived {
respBytes := stdOutScanner.Bytes()
err = json.Unmarshal(respBytes, &resp)
respReceived = true
close(doneChan)
} else {
execLogger.WithFields(log.Fields{
"plugin": path.Base(e.cmd.Path()),
"io": "stdout",
}).Debug(stdOutScanner.Text())
for {
for stdOutScanner.Scan() {
// The first chunk from the scanner is the plugin's response to the
// handshake. Once we've received that, we can begin to forward
// logs on to snapd's log.
if !respReceived {
respBytes := stdOutScanner.Bytes()
err = json.Unmarshal(respBytes, &resp)
respReceived = true
close(doneChan)
} else {
execLogger.WithFields(log.Fields{
"plugin": path.Base(e.cmd.Path()),
"io": "stdout",
}).Debug(stdOutScanner.Text())
}
}

if errScanner := stdOutScanner.Err(); errScanner != nil {
reader := bufio.NewReader(e.stdout)
log, errRead := reader.ReadString('\n')
if errRead == io.EOF {
break
}

execLogger.
WithField("plugin", path.Base(e.cmd.Path())).
WithField("io", "stdout").
WithField("scanner_err", errScanner).
WithField("read_string_err", errRead).
Warn(log)

continue //scanner finished with errors so try to scan once again
}
break //scanner finished scanning without errors so break the loop
}
}()

Expand Down Expand Up @@ -167,12 +187,31 @@ func (e *ExecutablePlugin) Kill() error {
func (e *ExecutablePlugin) captureStderr() {
stdErrScanner := bufio.NewScanner(e.stderr)
go func() {
for stdErrScanner.Scan() {
execLogger.
WithField("io", "stderr").
WithField("plugin", path.Base(e.cmd.Path())).
Debug(stdErrScanner.Text())
for {
for stdErrScanner.Scan() {
execLogger.
WithField("plugin", path.Base(e.cmd.Path())).
WithField("io", "stderr").
Debug(stdErrScanner.Text())
}

if errScanner := stdErrScanner.Err(); errScanner != nil {
reader := bufio.NewReader(e.stderr)
log, errRead := reader.ReadString('\n')
if errRead == io.EOF {
break
}

execLogger.
WithField("plugin", path.Base(e.cmd.Path())).
WithField("io", "stderr").
WithField("scanner_err", errScanner).
WithField("read_string_err", errRead).
Warn(log)

continue //scanner finished with errors so try to scan once again
}
break //scanner finished scanning without errors so break the loop
}
}()
}
18 changes: 15 additions & 3 deletions plugin/collector/snap-plugin-collector-mock2/mock/mock.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,11 @@ limitations under the License.
package mock

import (
"bufio"
"fmt"
"log"
"math/rand"
"os"
"strings"
"time"

Expand Down Expand Up @@ -57,14 +59,24 @@ func (f *Mock) CollectMetrics(mts []plugin.MetricType) ([]plugin.MetricType, err
rand.Seed(time.Now().UTC().UnixNano())
metrics := []plugin.MetricType{}
for i := range mts {
if c, ok := mts[i].Config().Table()["long_print"]; ok && c.(ctypes.ConfigValueBool).Value {
if c, ok := mts[i].Config().Table()["long_stdout_log"]; ok && c.(ctypes.ConfigValueBool).Value {
letterBytes := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
longLine := []byte{}
for i := 0; i < 8193; i++ {
for i := 0; i < bufio.MaxScanTokenSize; i++ {
longLine = append(longLine, letterBytes[rand.Intn(len(letterBytes))])
}
fmt.Println(string(longLine))
fmt.Fprintln(os.Stdout, string(longLine))
}

if c, ok := mts[i].Config().Table()["long_stderr_log"]; ok && c.(ctypes.ConfigValueBool).Value {
letterBytes := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
longLine := []byte{}
for i := 0; i < bufio.MaxScanTokenSize; i++ {
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Is the goal here to append to longline until it is larger than the MaxScanTokenSize?

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Here the goal is to have longline with length equal to MaxScanTokenSize. The condition in Scan() method has following form:

if len(s.buf) >= s.maxTokenSize || len(s.buf) > maxInt/2 {
                s.setErr(ErrTooLong)
                return false
}

longLine = append(longLine, letterBytes[rand.Intn(len(letterBytes))])
}
fmt.Fprintln(os.Stderr, string(longLine))
}

if c, ok := mts[i].Config().Table()["panic"]; ok && c.(ctypes.ConfigValueBool).Value {
panic("Oops!")
}
Expand Down