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update: find root device instead of hard-coding /dev/mmcblk0p*

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This should allow using gokrazy from a USB drive.
This commit is contained in:
Michael Stapelberg 2018-06-12 22:19:13 +02:00
parent 9063e4526a
commit 34f12d9ada
1 changed files with 25 additions and 6 deletions
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31
update.go
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@ -18,10 +18,29 @@ import (
"github.com/gokrazy/internal/fat"
)
var rootRe = regexp.MustCompile(`root=/dev/mmcblk0p([2-3])`)
var (
rootRe = regexp.MustCompile(`root=/dev/(?:mmcblk0p|sda)([2-3])`)
rootDeviceRe = regexp.MustCompile(`root=(/dev/(?:mmcblk0p|sda))`)
)
// mustFindRootDevice returns the device from which gokrazy was booted. It is
// safe to append a partition number to the resulting string. mustFindRootDevice
// works once /proc is mounted.
func mustFindRootDevice() string {
cmdline, err := ioutil.ReadFile("/proc/cmdline")
if err != nil {
panic(err)
}
matches := rootDeviceRe.FindStringSubmatch(string(cmdline))
if len(matches) != 2 {
panic(fmt.Sprintf("mustFindRootDevice: kernel command line %q did not match %v", string(cmdline), rootRe))
}
return matches[1]
}
func switchRootPartition(newRootPartition string) error {
f, err := os.OpenFile("/dev/mmcblk0p1", os.O_RDWR, 0600)
f, err := os.OpenFile(mustFindRootDevice()+"1", os.O_RDWR, 0600)
if err != nil {
return err
}
@ -45,7 +64,7 @@ func switchRootPartition(newRootPartition string) error {
return err
}
rep := rootRe.ReplaceAllLiteral(b, []byte("root=/dev/mmcblk0p"+newRootPartition))
rep := rootRe.ReplaceAllLiteral(b, []byte("root="+mustFindRootDevice()+newRootPartition))
if _, err := f.Write(rep); err != nil {
return err
}
@ -127,12 +146,12 @@ func initUpdate() error {
return fmt.Errorf("root partition %q (from %q) is unexpectedly neither 2 nor 3", rootPartition, matches[0])
}
http.HandleFunc("/update/boot", nonConcurrentUpdateHandler("/dev/mmcblk0p1"))
http.HandleFunc("/update/root", nonConcurrentUpdateHandler("/dev/mmcblk0p"+inactiveRootPartition))
http.HandleFunc("/update/boot", nonConcurrentUpdateHandler(mustFindRootDevice()+"1"))
http.HandleFunc("/update/root", nonConcurrentUpdateHandler(mustFindRootDevice()+inactiveRootPartition))
http.HandleFunc("/update/switch", nonConcurrentSwitchHandler(inactiveRootPartition))
// bakery updates only the boot partition, which would reset the active root
// partition to 2.
updateHandler := nonConcurrentUpdateHandler("/dev/mmcblk0p1")
updateHandler := nonConcurrentUpdateHandler(mustFindRootDevice() + "1")
http.HandleFunc("/update/bootonly", func(w http.ResponseWriter, r *http.Request) {
updateHandler(w, r)
if err := switchRootPartition(rootPartition); err != nil {