Add posix_utils.osReleaseFile (#16452)

* Add posix_utils.osReleaseFile

* Update lib/posix/posix_utils.nim

Co-authored-by: flywind <43030857+xflywind@users.noreply.github.com>

* Update lib/posix/posix_utils.nim

Co-authored-by: flywind <43030857+xflywind@users.noreply.github.com>

* Add a basic sanity test

* Add a basic sanity test

* Add a basic sanity test

* Add a basic sanity test

* https://github.com/nim-lang/Nim/pull/16452#issuecomment-753364096

* Update lib/posix/posix_utils.nim

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

* Update lib/posix/posix_utils.nim

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

* Update changelog.md

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

Co-authored-by: flywind <43030857+xflywind@users.noreply.github.com>
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

changelog.md

@@ -85,6 +85,11 @@
 - Added `mimetypes.mimesMaxLen` thats equal to the length of the longest "mime" from `mimes`.
 
 
+
+- Added `posix_utils.osReleaseFile` to get system identification from `os-release` file on Linux and the BSDs.
+  https://www.freedesktop.org/software/systemd/man/os-release.html
+
+
 ## Language changes
 
 - `nimscript` now handles `except Exception as e`.

lib/posix/posix_utils.nim

@@ -11,7 +11,8 @@
 
 # Where possible, contribute OS-independent procs in `os <os.html>`_ instead.
 
-import posix
+import posix, parsecfg, os
+import std/private/since
 
 type Uname* = object
   sysname*, nodename*, release*, version*, machine*: string
@@ -107,3 +108,22 @@ proc mkdtemp*(prefix: string): string =
   if mkdtemp(tmpl) == nil:
     raise newException(OSError, $strerror(errno))
   return $tmpl
+
+proc osReleaseFile*(): Config {.since: (1, 5).} =
+  ## Gets system identification from `os-release` file and returns it as a `parsecfg.Config`.
+  ## You also need to import the `parsecfg` module to gain access to this object.
+  ## The `os-release` file is an official Freedesktop.org open standard.
+  ## Available in Linux and BSD distributions, except Android and Android-based Linux.
+  ## `os-release` file is not available on Windows and OS X by design.
+  ## * https://www.freedesktop.org/software/systemd/man/os-release.html
+  runnableExamples:
+    import parsecfg
+    when defined(linux):
+      let data = osReleaseFile()
+      doAssert data.getSectionValue("", "NAME").len > 0 ## the data is up to each distro.
+
+  # We do not use a {.strdefine.} because Standard says it *must* be that path.
+  for osReleaseFile in ["/etc/os-release", "/usr/lib/os-release"]:
+    if fileExists(osReleaseFile):
+      return loadConfig(osReleaseFile)
+  raise newException(IOError, "File not found: /etc/os-release, /usr/lib/os-release")