Improved posix module, added new posix_utils module (#10723)

lib/posix/posix_utils.nim

@@ -0,0 +1,101 @@
+#
+#            Nim's Runtime Library
+#    (c) Copyright 2019 Federico Ceratto and other Nim contributors
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## A set of helpers for the POSIX module.
+## Raw interfaces are in the other posix*.nim files.
+
+# Where possible, contribute OS-independent procs in `os <os.html>`_ instead.
+
+{.deadCodeElim: on.}  # dce option deprecated
+
+import posix
+
+type Uname* = object
+  sysname*, nodename*, release*, version*, machine*: string
+
+template charArrayToString(input: typed): string =
+  $cstring(addr input)
+
+proc uname*(): Uname =
+  ## Provides system information in a `Uname` struct with sysname, nodename,
+  ## release, version and machine attributes.
+
+  when defined(posix):
+    runnableExamples:
+      echo uname().nodename, uname().release, uname().version
+      doAssert uname().sysname.len != 0
+
+  var u: Utsname
+  if uname(u) != 0:
+    raise newException(OSError, $strerror(errno))
+
+  result.sysname = charArrayToString u.sysname
+  result.nodename = charArrayToString u.nodename
+  result.release = charArrayToString u.release
+  result.version = charArrayToString u.version
+  result.machine = charArrayToString u.machine
+
+proc fsync*(fd: int) =
+ ## synchronize a file's buffer cache to the storage device
+ if fsync(fd.cint) != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc stat*(path: string): Stat =
+  ## Returns file status in a `Stat` structure
+  if stat(path.cstring, result) != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc memoryLock*(a1: pointer, a2: int) =
+  ## Locks pages starting from a1 for a1 bytes and prevent them from being swapped.
+  if mlock(a1, a2) != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc memoryLockAll*(flags: int) =
+  ## Locks all memory for the running process to prevent swapping.
+  ##
+  ## example::
+  ##
+  ##   memoryLockAll(MCL_CURRENT or MCL_FUTURE)
+  if mlockall(flags.cint) != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc memoryUnlock*(a1: pointer, a2: int) =
+  ## Unlock pages starting from a1 for a1 bytes and allow them to be swapped.
+  if munlock(a1, a2) != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc memoryUnlockAll*() =
+  ## Unlocks all memory for the running process to allow swapping.
+  if munlockall() != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc sendSignal*(pid: Pid, signal: int) =
+  ## Sends a signal to a running process by calling `kill`.
+  ## Raise exception in case of failure e.g. process not running.
+  if kill(pid, signal.cint) != 0:
+    raise newException(OSError, $strerror(errno))
+
+proc mkstemp*(prefix: string): (string, File) =
+  ## Creates a unique temporary file from a prefix string. Adds a six chars suffix.
+  ## The file is created with perms 0600.
+  ## Returs the filename and a file opened in r/w mode.
+  var tmpl = cstring(prefix & "XXXXXX")
+  let fd = mkstemp(tmpl)
+  var f: File
+  if open(f, fd, fmReadWrite):
+    return ($tmpl, f)
+  raise newException(OSError, $strerror(errno))
+
+proc mkdtemp*(prefix: string): string =
+  ## Creates a unique temporary directory from a prefix string. Adds a six chars suffix.
+  ## The directory is created with permissions 0700. Returns the directory name.
+  var tmpl = cstring(prefix & "XXXXXX")
+  if mkdtemp(tmpl) == nil:
+    raise newException(OSError, $strerror(errno))
+  return $tmpl
+