Implement minimal depmod-compatible applet for vx

- Added depmod.cpp to scan kernel module ELF files, read .modinfo, and emit metadata files.
- Implemented functionality to write binary trie indexes for libkmod/modprobe.
- Introduced command-line options for module processing.
- Created test script test_depmod.sh to verify help and version commands.

meson.build

@@ -1,7 +1,8 @@
-project('vx', 'c',
+project('vx', 'c', 'cpp',
   version : '0.2.0',
   default_options : [
     'c_std=c11',
+    'cpp_std=c++17',
     'warning_level=2',
   ],
 )
@@ -19,6 +20,7 @@ all_utils = [
   'xargs',
   'lspci',
   'setpci',
+  'depmod',
 ]
 
 requested_utils = get_option('utils')
@@ -45,6 +47,7 @@ enable_find = enabled_utils.contains('find')
 enable_xargs = enabled_utils.contains('xargs')
 enable_lspci = enabled_utils.contains('lspci')
 enable_setpci = enabled_utils.contains('setpci')
+enable_depmod = enabled_utils.contains('depmod')
 
 vx_cfg = configuration_data()
 vx_cfg.set10('VX_ENABLE_PATCH', enable_patch)
@@ -59,6 +62,7 @@ vx_cfg.set10('VX_ENABLE_FIND', enable_find)
 vx_cfg.set10('VX_ENABLE_XARGS', enable_xargs)
 vx_cfg.set10('VX_ENABLE_LSPCI', enable_lspci)
 vx_cfg.set10('VX_ENABLE_SETPCI', enable_setpci)
+vx_cfg.set10('VX_ENABLE_DEPMOD', enable_depmod)
 configure_file(output : 'vx-config.h', configuration : vx_cfg)
 
 # --- Portability shim for building BSD userland on Linux ---
@@ -163,6 +167,10 @@ setpci_src = files(
   'src/pci/setpci.c',
 )
 
+depmod_src = files(
+  'src/depmod/depmod.cpp',
+)
+
 pci_inc = include_directories('src/pci')
 
 gzip_defines = [
@@ -248,6 +256,11 @@ if enable_setpci
   vx_sources += setpci_src
 endif
 
+if enable_depmod
+  vx_sources += depmod_src
+  vx_dependencies += [dependency('zlib'), dependency('libzstd')]
+endif
+
 vx = executable('vx',
   vx_sources,
   include_directories : vx_include_dirs,
@@ -295,6 +308,9 @@ endif
 if enable_setpci
   install_applets += ['setpci']
 endif
+if enable_depmod
+  install_applets += ['depmod']
+endif
 
 foreach name : install_applets
   meson.add_install_script('sh', '-c',
@@ -348,6 +364,9 @@ endif
 if enable_setpci
   manpages += ['src/pci/setpci.8']
 endif
+if enable_depmod
+  manpages += ['src/depmod/depmod.8']
+endif
 
 install_man(manpages)
 
@@ -409,6 +428,9 @@ endif
 if enable_setpci
   test_targets += ['test_setpci']
 endif
+if enable_depmod
+  test_targets += ['test_depmod']
+endif
 
 foreach t : test_targets
   test(t, find_program('tests/' + t + '.sh'),