fs: get file size

fs: add samefile

docs/markdown/Fs-module.md

@@ -36,9 +36,27 @@ by the string is a symbolic link.
 
 ### hash
 
-The `hash` method computes the requested hash sum of a file.
+The `fs.hash(filename)` method computes the requested hash sum of a file.
 The available hash methods include: md5, sha1, sha224, sha256, sha384, sha512.
 
+### samefile
+
+The `fs.samefile(filename1, filename2)` method allows determining if two filenames refer to the same file.
+Perhaps a meson.build file in one place refer to a symlink and in another place a
+relative path and/or absolute path. The `samefile` method allows determining if these
+are the same file.
+
+Examples:
+
+```meson
+x = 'foo.txt'
+y = 'sub/../foo.txt'
+z = 'bar.txt'  # a symlink pointing to foo.txt
+
+fs.samefile(x, y)  # true
+fs.samefile(x, z)  # true
+```
+
 
 ## Filename modification
 

mesonbuild/modules/fs.py

@@ -31,10 +31,17 @@ class FSModule(ExtensionModule):
         super().__init__(interpreter)
         self.snippets.add('generate_dub_file')
 
+    def _resolve_dir(self, state: 'ModuleState', arg: str) -> Path:
+        """
+        resolves (makes absolute) a directory relative to calling meson.build,
+        if not already absolute
+        """
+        return Path(state.source_root) / state.subdir / Path(arg).expanduser()
+
     def _check(self, check: str, state: 'ModuleState', args: typing.Sequence[str]) -> ModuleReturnValue:
         if len(args) != 1:
             MesonException('fs.{} takes exactly one argument.'.format(check))
-        test_file = Path(state.source_root) / state.subdir / Path(args[0]).expanduser()
+        test_file = self._resolve_dir(state, args[0])
         return ModuleReturnValue(getattr(test_file, check)(), [])
 
     @stringArgs
@@ -62,7 +69,7 @@ class FSModule(ExtensionModule):
     def hash(self, state: 'ModuleState', args: typing.Sequence[str], kwargs: dict) -> ModuleReturnValue:
         if len(args) != 2:
             MesonException('method takes exactly two arguments.')
-        file = Path(state.source_root) / state.subdir / Path(args[0]).expanduser()
+        file = self._resolve_dir(state, args[0])
         if not file.is_file():
             raise MesonException('{} is not a file and therefore cannot be hashed'.format(file))
         try:
@@ -73,6 +80,35 @@ class FSModule(ExtensionModule):
         h.update(file.read_bytes())
         return ModuleReturnValue(h.hexdigest(), [])
 
+    @stringArgs
+    @noKwargs
+    def size(self, state: 'ModuleState', args: typing.Sequence[str], kwargs: dict) -> ModuleReturnValue:
+        if len(args) != 1:
+            MesonException('method takes exactly one argument.')
+        file = self._resolve_dir(state, args[0])
+        if not file.is_file():
+            raise MesonException('{} is not a file and therefore cannot be sized'.format(file))
+        try:
+            return ModuleReturnValue(file.stat().st_size, [])
+        except ValueError:
+            raise MesonException('{} size could not be determined'.format(args[0]))
+
+    @stringArgs
+    @noKwargs
+    def samefile(self, state: 'ModuleState', args: typing.Sequence[str], kwargs: dict) -> ModuleReturnValue:
+        if len(args) != 2:
+            MesonException('method takes exactly two arguments.')
+        file1 = self._resolve_dir(state, args[0])
+        file2 = self._resolve_dir(state, args[1])
+        if not file1.exists():
+            raise MesonException('{} is not a file, symlink or directory and therefore cannot be compared'.format(file1))
+        if not file2.exists():
+            raise MesonException('{} is not a file, symlink or directory and therefore cannot be compared'.format(file2))
+        try:
+            return ModuleReturnValue(file1.samefile(file2), [])
+        except OSError:
+            raise MesonException('{} could not be compared to {}'.format(file1, file2))
+
     @stringArgs
     @noKwargs
     def with_suffix(self, state: 'ModuleState', args: typing.Sequence[str], kwargs: dict) -> ModuleReturnValue:

test cases/common/227 fs module/meson.build

@@ -54,5 +54,19 @@ sha256 = fs.hash('subdir/subdirfile.txt', 'sha256')
 assert(md5 == 'd0795db41614d25affdd548314b30b3b', 'md5sum did not match')
 assert(sha256 == 'be2170b0dae535b73f6775694fffa3fd726a43b5fabea11b7342f0605917a42a', 'sha256sum did not match')
 
+# -- size
+
+size = fs.size('subdir/subdirfile.txt')
+assert(size == 19, 'file size not found correctly')
+
+# -- are filenames referring to the same file?
+f1 = 'meson.build'
+f2 = 'subdir/../meson.build'
+assert(fs.samefile(f1, f2), 'samefile not realized')
+assert(not fs.samefile(f1, 'subdir/subdirfile.txt'), 'samefile known bad comparison')
+
+if not is_windows and build_machine.system() != 'cygwin'
+  assert(fs.samefile('a_symlink', 'meson.build'), 'symlink samefile fail')
+endif
 
 subdir('subdir')