depfixer: convert unused printing code to debugging functions

When installing with 'meson install --quiet' I'd get the following output:
This file does not have an rpath.
This file does not have a runpath.

(It turns out that of the couple hundred of binaries that are installed,
this message was generated for /usr/lib/systemd/boot/efi/linuxx64.elf.stub.)

There doesn't seem to be any good reason for this output by default. But those
functions can still be used for debugging. Under a debugger, returning the
string is just as useful as printing it, but more flexible. So let's suppress
printing of anything by default, but keep the extractor functions.

The code was somewhat inconsistent wrt. to when .decode() was done. But it
seems that we'll get can expect a decodable text string in all cases, so
just call .decode() everywhere, because it's nicer to print decoded strings.

mesonbuild/mesonlib/universal.py

@@ -87,6 +87,7 @@ __all__ = [
     'exe_exists',
     'expand_arguments',
     'extract_as_list',
+    'generate_list',
     'get_compiler_for_source',
     'get_filenames_templates_dict',
     'get_library_dirs',
@@ -1918,6 +1919,14 @@ def run_once(func: T.Callable[..., _T]) -> T.Callable[..., _T]:
     return wrapper
 
 
+def generate_list(func: T.Callable[..., T.Generator[_T, None, None]]) -> T.Callable[..., T.List[_T]]:
+    @wraps(func)
+    def wrapper(*args: T.Any, **kwargs: T.Any) -> T.List[_T]:
+        return list(func(*args, **kwargs))
+
+    return wrapper
+
+
 class OptionOverrideProxy(collections.abc.MutableMapping):
 
     '''Mimic an option list but transparently override selected option

mesonbuild/scripts/depfixer.py

@@ -21,7 +21,7 @@ import shutil
 import subprocess
 import typing as T
 
-from ..mesonlib import OrderedSet
+from ..mesonlib import OrderedSet, generate_list
 
 SHT_STRTAB = 3
 DT_NEEDED = 1
@@ -243,14 +243,14 @@ class Elf(DataSizes):
             if e.d_tag == 0:
                 break
 
-    def print_section_names(self) -> None:
+    @generate_list
+    def get_section_names(self) -> T.Generator[str, None, None]:
         section_names = self.sections[self.e_shstrndx]
         for i in self.sections:
             self.bf.seek(section_names.sh_offset + i.sh_name)
-            name = self.read_str()
+            yield self.read_str().decode()
-            print(name.decode())
 
-    def print_soname(self) -> None:
+    def get_soname(self) -> T.Optional[str]:
         soname = None
         strtab = None
         for i in self.dynamic:
@@ -259,10 +259,9 @@ class Elf(DataSizes):
             if i.d_tag == DT_STRTAB:
                 strtab = i
         if soname is None or strtab is None:
-            print("This file does not have a soname")
+            return None
-            return
         self.bf.seek(strtab.val + soname.val)
-        print(self.read_str())
+        return self.read_str().decode()
 
     def get_entry_offset(self, entrynum: int) -> T.Optional[int]:
         sec = self.find_section(b'.dynstr')
@@ -273,33 +272,28 @@ class Elf(DataSizes):
                 return res
         return None
 
-    def print_rpath(self) -> None:
+    def get_rpath(self) -> T.Optional[str]:
         offset = self.get_entry_offset(DT_RPATH)
         if offset is None:
-            print("This file does not have an rpath.")
+            return None
-        else:
+        self.bf.seek(offset)
-            self.bf.seek(offset)
+        return self.read_str().decode()
-            print(self.read_str())
 
-    def print_runpath(self) -> None:
+    def get_runpath(self) -> T.Optional[str]:
         offset = self.get_entry_offset(DT_RUNPATH)
         if offset is None:
-            print("This file does not have a runpath.")
+            return None
-        else:
+        self.bf.seek(offset)
-            self.bf.seek(offset)
+        return self.read_str().decode()
-            print(self.read_str())
 
-    def print_deps(self) -> None:
+    @generate_list
+    def get_deps(self) -> T.Generator[str, None, None]:
         sec = self.find_section(b'.dynstr')
-        deps = []
         for i in self.dynamic:
             if i.d_tag == DT_NEEDED:
-                deps.append(i)
+                offset = sec.sh_offset + i.val
-        for i in deps:
+                self.bf.seek(offset)
-            offset = sec.sh_offset + i.val
+                yield self.read_str().decode()
-            self.bf.seek(offset)
-            name = self.read_str()
-            print(name)
 
     def fix_deps(self, prefix: bytes) -> None:
         sec = self.find_section(b'.dynstr')
@@ -391,11 +385,9 @@ class Elf(DataSizes):
         return None
 
 def fix_elf(fname: str, rpath_dirs_to_remove: T.Set[bytes], new_rpath: T.Optional[bytes], verbose: bool = True) -> None:
-    with Elf(fname, verbose) as e:
+    if new_rpath is not None:
-        if new_rpath is None:
+        with Elf(fname, verbose) as e:
-            e.print_rpath()
+            # note: e.get_rpath() and e.get_runpath() may be useful
-            e.print_runpath()
-        else:
             e.fix_rpath(rpath_dirs_to_remove, new_rpath)
 
 def get_darwin_rpaths_to_remove(fname: str) -> T.List[str]: