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nimd
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Added shutdown hooks support and unmounting of all handlers upon exit

This commit is contained in:
Nocturn9x 2021-12-01 12:00:07 +01:00
parent 7652a2c1cf
commit 26f98cec52
4 changed files with 81 additions and 25 deletions
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4
Dockerfile
View File

@ -3,7 +3,9 @@ FROM nimlang/nim AS builder
COPY . /code
WORKDIR /code
RUN nim c -o:nimd --passL:"-static" src/main.nim
# Removes any already existing binary so that when compilation fails the container stops
RUN rm -f /code/nimd
RUN nim -d:release --opt:size --passL:"-static" --gc:markAndSweep c -o:nimd src/main
RUN cp /code/nimd /sbin/nimd
FROM alpine:latest

11
src/core/mainloop.nim
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@ -13,25 +13,26 @@
# limitations under the License.
import segfaults # Makes us catch segfaults as NilAccessDefect exceptions!
import strformat
import posix
import os
import ../util/[logging, disks, misc]
proc mainLoop*(logger: Logger, mountDisks: bool = true) =
proc mainLoop*(logger: Logger, mountDisks: bool = true, fstab: string = "/etc/fstab") =
## NimD's main execution loop
try:
addShutdownHandler(unmountAllDisks)
if mountDisks:
logger.info("Mounting filesystem")
logger.info("Mounting virtual disks")
mountVirtualDisks(logger)
logger.info("Mounting real disks")
mountRealDisks(logger)
mountRealDisks(logger, fstab)
else:
logger.info("Skipping disk mounting, did we restart after a critical error?")
except IndexDefect: # Check parseFileSystemTable for more info on this catch block
logger.fatal("Improperly formatted /etc/fstab, exiting")
except:
logger.fatal(&"A fatal error has occurred while mounting disks, booting cannot continue. Error -> {getCurrentExceptionMsg()}")
nimDExit(logger, 131)
logger.info("Disks mounted")
logger.info("Processing boot runlevel")

58
src/util/disks.nim
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@ -20,7 +20,7 @@ import logging
import misc
const virtualFileSystems: seq[tuple[source: cstring, target: cstring, filesystemtype: cstring, mountflags: culong, data: cstring]] = @[
(source: cstring("proc"), target: cstring("/proc"), filesystemtype: cstring("proc"), mountflags: culong(0), data: cstring("nosuid,noexec,nodev")),
(source: cstring("proc"), target: cstring("/proc"), filesystemtype: cstring("procfs"), mountflags: culong(0), data: cstring("nosuid,noexec,nodev")),
(source: cstring("sys"), target: cstring("/sys"), filesystemtype: cstring("sysfs"), mountflags: culong(0), data: cstring("nosuid,noexec,nodev")),
(source: cstring("run"), target: cstring("/run"), filesystemtype: cstring("tmpfs"), mountflags: culong(0), data: cstring("mode=0755,nosuid,nodev")),
(source: cstring("dev"), target: cstring("/dev"), filesystemtype: cstring("devtmpfs"), mountflags: culong(0), data: cstring("mode=0755,nosuid")),
@ -30,14 +30,14 @@ const virtualFileSystems: seq[tuple[source: cstring, target: cstring, filesystem
]
proc parseFileSystemTable*(fstab: string): seq[tuple[source: cstring, target: cstring, filesystemtype: cstring, mountflags: culong, data: cstring]] =
## Parses the contents of the given file (the contents of /etc/fstab)
## and returns a sequence of tuples with elements source, target,
## filesystemtype, mountflags and data as required by mount in sys/mount.h
## which is wrapped below. An improperly formatted fstab will cause this
## function to error out with an IndexDefect exception (when an fstab entry is
## incomplete) that should be caught by the caller. No other checks other than
## very basic syntax are performed, as that job is delegated to the operating
## system.
## Parses the contents of the given file (the contents of /etc/fstab or /etc/mtab
## most of the time, but this is not enforced in any way) and returns a sequence
## of tuples with elements source, target, filesystemtype, mountflags and data
## as required by mount/umount/umount2 in sys/mount.h which is wrapped below.
## An improperly formatted fstab will cause this function to error out with an
## IndexDefect exception (when an entry is incomplete) that should be caught by
## the caller. No other checks other than very basic syntax are performed, as
## that job is delegated to the operating system.
var temp: seq[string] = @[]
var line: string = ""
for l in fstab.splitlines():
@ -50,17 +50,20 @@ proc parseFileSystemTable*(fstab: string): seq[tuple[source: cstring, target: cs
# in our temporary list
temp = line.split().filterIt(it != "").join(" ").split(maxsplit=6)
result.add((source: cstring(temp[0]), target: cstring(temp[1]), filesystemtype: cstring(temp[2]), mountflags: culong(0), data: cstring(temp[3])))
echo result[^1]
# Nim wrappers around C functionality in sys/mount.h on Linux
proc mount*(source: cstring, target: cstring, filesystemtype: cstring,
mountflags: culong, data: pointer): cint {.header: "sys/mount.h", importc.}
mountflags: culong, data: pointer): cint {.header: "sys/mount.h", importc.}
proc umount*(target: cstring): cint {.header: "sys/mount.h", importc.}
proc umount2*(target: cstring, flags: cint): cint {.header: "sys/mount.h", importc.}
proc mountRealDisks*(logger: Logger) =
proc mountRealDisks*(logger: Logger, fstab: string = "/etc/fstab") =
## Mounts real disks from /etc/fstab
try:
logger.info("Reading disk entries from /etc/fstab")
for entry in parseFileSystemTable(readFile("/etc/fstab")):
logger.info(&"Reading disk entries from {fstab}")
for entry in parseFileSystemTable(readFile(fstab)):
logger.debug(&"Mounting filesystem {entry.source} ({entry.filesystemtype}) at {entry.target} with mount option(s) {entry.data}")
logger.trace(&"Calling mount({entry.source}, {entry.target}, {entry.filesystemtype}, {entry.mountflags}, {entry.data})")
var retcode = mount(entry.source, entry.target, entry.filesystemtype, entry.mountflags, entry.data)
@ -72,7 +75,7 @@ proc mountRealDisks*(logger: Logger) =
else:
logger.debug(&"Mounted {entry.source} at {entry.target}")
except IndexDefect: # Check parseFileSystemTable for more info on this catch block
logger.fatal("Improperly formatted /etc/fstab, exiting")
logger.fatal("Improperly formatted fstab, exiting")
nimDExit(logger, 131)
@ -91,4 +94,27 @@ proc mountVirtualDisks*(logger: Logger) =
logger.fatal("Failed mounting vital system disk partition, system is likely corrupted, booting cannot continue")
nimDExit(logger, 131) # ENOTRECOVERABLE - State not recoverable
else:
logger.debug(&"Mounted {entry.source} at {entry.target}")
logger.debug(&"Mounted {entry.source} at {entry.target}")
proc unmountAllDisks*(logger: Logger, code: int) =
## Unmounts all currently mounted disks, including the ones that
## were not mounted trough fstab and virtual filesystems
try:
logger.info(&"Reading disk entries from /proc/mounts")
for entry in parseFileSystemTable(readFile("/proc/mounts")):
echo entry
logger.debug(&"Unmounting filesystem {entry.source} ({entry.filesystemtype}) from {entry.target}")
logger.trace(&"Calling umount({entry.source})")
var retcode = umount(entry.source)
logger.trace(&"umount({entry.source}) returned {retcode}")
if retcode == -1:
logger.error(&"Unmounting disk {entry.source} has failed with error {posix.errno}: {posix.strerror(posix.errno)}")
# Resets the error code
posix.errno = cint(0)
else:
logger.debug(&"Unmounted {entry.source} from {entry.target}")
except IndexDefect: # Check parseFileSystemTable for more info on this catch block
logger.fatal("Improperly formatted /etc/mtab, exiting")
nimDExit(logger, 131)

33
src/util/misc.nim
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@ -11,20 +11,47 @@
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
## Default signal handlers, exit procedures and helpers
## to allow a clean shutdown of NimD
import os
import strformat
import logging
var shutdownHandlers: seq[proc (logger: Logger, code: int)] = @[]
proc addShutdownHandler*(handler: proc (logger: Logger, code: int)) =
shutdownHandlers.add(handler)
proc removeShutdownHandler*(handler: proc (logger: Logger, code: int)) =
shutdownHandlers.delete(shutdownHandlers.find(handler))
proc nimDExit*(logger: Logger, code: int) =
logger.warning("The system is being shut down, beginning child process termination")
logger.warning("The system is being shut down!")
# TODO
logger.info("Processing shutdown runlevel")
# TODO
logger.warning("Process termination complete, sending final shutdown signal")
logger.info("Running shutdown handlers")
try:
for handler in shutdownHandlers:
handler(logger, code)
except:
logger.error(&"An error has occurred while calling shutdown handlers. Error -> {getCurrentExceptionMsg()}")
# Note: continues calling handlers!
logger.info("Terminating child processes with SIGINT")
# TODO
quit(code)
logger.info("Terminating child processes with SIGKILL")
# TODO
logger.warning("Shutdown procedure complete, sending final termination signal")
# TODO
quit(code) # Replace with syscall(REBOOT, ...)
proc sleepSeconds*(amount: SomeInteger) = sleep(amount * 1000)