Added sync() system call for testing purposes. Added SIGSTP signal handler. Removed CtrlCException. Added dummy SIGCHLD handler for future process reaping. NimD now creates some symlinks at startup so Linux ports of BSD software don't crash. Moved exists procedure to misc module. UnmountAllDisks now unmounts the source instead of the target. Other minor fixes and typos

.dockerignore

@@ -0,0 +1,3 @@
+.git
+nimd
+src/main

Dockerfile

@@ -6,6 +6,7 @@ WORKDIR /code
 # Removes any already existing binary so that when compilation fails the container stops
 RUN rm -f /code/nimd
 RUN rm -f /code/main
+RUN nimble install syscall -y
 RUN nim -d:release --opt:size --passL:"-static" --gc:orc -d:useMalloc c -o:nimd src/main
 RUN cp /code/nimd /sbin/nimd
 

src/core/mainloop.nim

@@ -35,8 +35,12 @@ proc mainLoop*(logger: Logger, mountDisks: bool = true, fstab: string = "/etc/fs
         logger.fatal(&"A fatal error has occurred while preparing filesystem, booting cannot continue. Error -> {getCurrentExceptionMsg()}")
         nimDExit(logger, 131)
     logger.info("Disks mounted")
+    logger.debug("Calling sync() just in case")
+    doSync(logger)
     logger.info("Setting hostname")
     logger.debug(&"Hostname was set to '{setHostname(logger)}'")
+    logger.info("Creating symlinks")
+    createSymlinks(logger)
     logger.info("Processing boot runlevel")
     # TODO
     logger.info("Processing default runlevel")
@@ -46,9 +50,6 @@ proc mainLoop*(logger: Logger, mountDisks: bool = true, fstab: string = "/etc/fs
         try:
             # TODO
             sleepSeconds(5)
-        except CtrlCException:
-            logger.warning("Main process received SIGINT: exiting")  # TODO: Ignore this once we stop testing on our local machines lol
-            nimDExit(logger, 130, emerg=false)  # 130 - Interrupted by SIGINT
         except:
             logger.critical(&"A critical error has occurred while running, restarting the mainloop! Error -> {getCurrentExceptionMsg()}")
             # We *absolutely* cannot die

src/main.nim

@@ -37,11 +37,14 @@ proc main(logger: Logger) =
         logger.fatal(&"NimD must run as root, but current user id is {uid}")
         quit(EPERM)   # EPERM - Operation not permitted
     logger.debug("Setting up dummy signal handlers")
-    onSignal(SIGABRT, SIGALRM, SIGHUP, SIGILL, SIGKILL, SIGQUIT, SIGSTOP, SIGSEGV,
+    onSignal(SIGABRT, SIGALRM, SIGHUP, SIGILL, SIGKILL, SIGQUIT, SIGSTOP, SIGSEGV, SIGTSTP,
             SIGTRAP, SIGTERM, SIGPIPE, SIGUSR1, SIGUSR2, 6, SIGFPE, SIGBUS, SIGURG, SIGINT):  # 6 is SIGIOT
         # Can't capture local variables because this implicitly generates
         # a noconv procedure
         getDefaultLogger().warning(&"Ignoring signal {sig} ({strsignal(sig)})")  # Nim injects the variable "sig" into the scope. Gotta love those macros
+    logger.debug("Setting up SIGCHLD signal handler")
+    onSignal(SIGCHLD):
+        reapProcess(getDefaultLogger())
     logger.debug("Starting uninterruptible mainloop")
     mainLoop(logger)
 

src/util/disks.nim

@@ -115,16 +115,6 @@ proc umount*(target: string): int = int(umount(cstring(target)))
 proc umount2*(target: string, flags: int): int = int(umount2(cstring(target), cint(flags)))
 
 
-proc exists(p: string): bool =
-    # Checks if a path exists. Thanks
-    # araq :)
-    try:
-        discard getFileInfo(p)
-        result = true
-    except OSError:
-        result = false
-
-
 proc checkDisksIsMounted(search: tuple[source, target, filesystemtype: string, mountflags: uint64, data: string, dump, pass: uint8], expand: bool = false): bool =
     ## Returns true if a disk is already mounted. If expand is true,
     ## symlinks are expanded and checked instead of doing a simple
@@ -211,9 +201,9 @@ proc unmountAllDisks*(logger: Logger, code: int) =
                 logger.debug(&"Skipping unmounting filesystem {entry.source} ({entry.filesystemtype}) from {entry.target}: not mounted")
                 continue
             logger.debug(&"Unmounting filesystem {entry.source} ({entry.filesystemtype}) from {entry.target}")
-            logger.trace(&"Calling umount2('{entry.target}', MNT_DETACH)")
-            retcode = umount2(entry.target, 2)   # 2 = MNT_DETACH - Since we're shutting down, we need the disks to be *gone*!
-            logger.trace(&"umount2('{entry.target}', MNT_DETACH) returned {retcode}")
+            logger.trace(&"Calling umount2('{entry.source}', MNT_DETACH)")
+            retcode = umount2(entry.source, 2)   # 2 = MNT_DETACH - Since we're shutting down, we need the disks to be *gone*!
+            logger.trace(&"umount2('{entry.source}', MNT_DETACH) returned {retcode}")
             if retcode == -1:
                 logger.error(&"Unmounting disk {entry.source} from {entry.target} has failed with error {posix.errno}: {posix.strerror(posix.errno)}")
                 # Resets the error code

src/util/misc.nim

@@ -17,16 +17,45 @@
 import os
 import strformat
 import strutils
+import syscall
 
 
 import logging
 
-type CtrlCException* = object of CatchableError
+# Note: This will work reliably only with absolute paths. Use with care
+const symlinks: array[7, tuple[dest, source: string]] = [
+    (dest: "/dev/fd", source: "/proc/self/fd"),
+    (dest: "/dev/fd/0", source: "/proc/self/fd/0"),
+    (dest: "/dev/fd/1", source: "/proc/self/fd/1"),
+    (dest: "/dev/fd/2", source: "/proc/self/fd/2"),
+    (dest: "/dev/std/in", source: "/proc/self/fd/0"),
+    (dest: "/dev/std/out", source: "/proc/self/fd/1"),
+    (dest: "/dev/std/err", source: "/proc/self/fd/2"),
+]
 
 
 var shutdownHandlers: seq[proc (logger: Logger, code: int)] = @[]
 
 
+proc doSync*(logger: Logger) =
+    logger.debug(&"Calling sync() syscall has returned {syscall(SYNC)}")    
+
+
+proc reapProcess*(logger: Logger) =
+    logger.debug("Handling SIGCHLD")
+    # TODO
+
+
+proc exists*(p: string): bool =
+    # Checks if a path exists. Thanks
+    # araq :)
+    try:
+        discard getFileInfo(p)
+        result = true
+    except OSError:
+        result = false
+
+
 proc addShutdownHandler*(handler: proc (logger: Logger, code: int), logger: Logger) =
     shutdownHandlers.add(handler)
 
@@ -83,7 +112,31 @@ proc setHostname*(logger: Logger): string =
     return hostname
 
 
+proc createSymlinks*(logger: Logger) =
+    ## Creates a set of symlinks needed
+    ## by stuff like Linux ports of BSD
+    ## software
+    for sym in symlinks:
+        try:
+            if not exists(sym.source):
+                logger.warning(&"Skipping creation of symbolic link from {sym.dest} to {sym.source}: destination does not exist")
+                continue
+            elif exists(sym.dest):
+                if symlinkExists(sym.dest) and sameFile(expandSymlink(sym.dest), sym.source):
+                    logger.debug(&"Skipping creation of symbolic link from {sym.dest} to {sym.source}: link already exists")
+                elif symlinkExists(sym.dest) and not sameFile(expandSymlink(sym.dest), sym.source):
+                    logger.warning(&"Attempted to create symbolic link from {sym.dest} to {sym.source}, but link already exists and points to {expandSymlink(sym.dest)}")
+                continue
+            logger.debug(&"Creating symbolic link from {sym.source} to {sym.dest}")
+            createSymlink(sym.dest, sym.source)
+        except:
+            logger.error(&"Failed to create symbolic link from {sym.dest} to {sym.source}: {getCurrentExceptionMsg()}")
+
+
+proc createDirectories*(logger: Logger) =
+    ## Creates 
+
 proc sleepSeconds*(amount: SomeInteger) = sleep(amount * 1000)
 
 
-proc strsignal*(sig: cint): cstring {.header:"string.h", importc.}
+proc strsignal*(sig: cint): cstring {.header: "string.h", importc.}