In 990_verify_rootfs.sh fix issue rear#3021 (rear#3250)

In build/default/990_verify_rootfs.sh
for each 'not found' shared object
(i.e. a shared object that was 'not found' by 'ldd')
check whether or not the shared object
may exist nevertheless in the recovery system
and if yes, we may sufficiently safely assume
things are OK in the ReaR recovery system
so we do not report it as missing to the user
(for debugging we have all in the log), see
rear#3021 (comment)
Additionally in 990_verify_rootfs.sh
more consistent level when messages are shown,
i.e. now only LogPrint and LogPrintError
to show nothing (except errors) when not in verbose mode
and all messages when in verbose mode
to make the messages as a whole
better understandable by the user.

usr/share/rear/build/default/990_verify_rootfs.sh

@@ -70,9 +70,13 @@ DebugPrint "Testing each binary with 'ldd' and look for 'not found' libraries wi
 local backup_tool_LD_LIBRARY_PATH=""
 local binary=""
 local broken_binary_LD_LIBRARY_PATH=""
-local broken_binaries="no"
 local fatal_missing_library="no"
 local ldd_output=""
+local not_found_output=""
+local not_found_library=""
+local junk=""
+local actually_found_library=""
+local actually_missing_libraries="no"
 # Third-party backup tools may use LD_LIBRARY_PATH to find their libraries
 # so that for testing such third-party backup tools we must also use their
 # special LD_LIBRARY_PATH here, otherwise just use the default:
@@ -159,27 +163,26 @@ for binary in $( find $ROOTFS_DIR -type f \( -executable -o -name '*.so' -o -nam
         broken_binary_LD_LIBRARY_PATH=$backup_tool_LD_LIBRARY_PATH
         Log "$binary requires additional libraries with backup tool specific LD_LIBRARY_PATH=$backup_tool_LD_LIBRARY_PATH"
     fi
-    # All tests had a 'not found' shared object dependency so the binary requires additional libraries
-    # without LD_LIBRARY_PATH and with LD_LIBRARY_PATH and with backup tool specific LD_LIBRARY_PATH:
-    broken_binaries="yes"
+    # At this point all tests had a 'not found' shared object dependency so the binary requires additional libraries
+    # without LD_LIBRARY_PATH and with LD_LIBRARY_PATH and with backup tool specific LD_LIBRARY_PATH.
     # Only for programs (i.e. files in a .../bin/... or .../sbin/... directory) treat a missing library as fatal
     # unless specified when a 'not found' reported library is not fatal (when the 'ldd' test was false alarm):
     if grep -q '/[s]*bin/' <<<"$binary" ; then
         # With an empty NON_FATAL_BINARIES_WITH_MISSING_LIBRARY grep -E '' would always match:
         if test "$NON_FATAL_BINARIES_WITH_MISSING_LIBRARY" ; then
             # A program with missing library is treated as fatal when it does not match the pattern:
             if grep -E -q "$NON_FATAL_BINARIES_WITH_MISSING_LIBRARY" <<<"$binary" ; then
-                LogPrintError "$binary requires additional libraries (specified as non-fatal)"
+                LogPrint "$binary requires libraries were 'ldd' shows 'not found' (specified as non-fatal)"
             else
-                LogPrintError "$binary requires additional libraries (fatal error)"
+                LogPrint "$binary requires libraries were 'ldd' shows 'not found' (fatal error)"
                 fatal_missing_library="yes"
             fi
         else
-            LogPrintError "$binary requires additional libraries (fatal error)"
+            LogPrint "$binary requires libraries were 'ldd' shows 'not found' (fatal by default)"
             fatal_missing_library="yes"
         fi
     else
-        LogPrintError "$binary requires additional libraries"
+        LogPrint "$binary requires libraries were 'ldd' shows 'not found'"
     fi
     # Run the same ldd call as above but now keep its whole stdout output.
     # The ldd call that results the final 'not found' shared object is the last of the above ldd calls that was run.
@@ -191,10 +194,27 @@ for binary in $( find $ROOTFS_DIR -type f \( -executable -o -name '*.so' -o -nam
     fi
     # Have the whole ldd output only in the log:
     Log "$ldd_output"
-    # Show only the missing libraries to the user to not flood his screen with tons of other ldd output lines:
-    PrintError "$( grep 'not found' <<<"$ldd_output" )"
+    # For each 'not found' shared object (i.e. a shared object that was 'not found' by 'ldd')
+    # check whether or not the shared object may exist nevertheless in the ReaR recovery system
+    # and if yes, we may sufficiently safely assume things are OK in the ReaR recovery system
+    # so we do not report it as missing to the user (for debugging we have all in the log)
+    # cf. https://github.com/rear/rear/issues/3021#issuecomment-2165453757
+    not_found_output="$( grep 'not found' <<<"$ldd_output" )"
+    # not_found_output is a string of multiple lines (separated by \n) that look e.g. like
+    #   libsystemd-shared-255.4-1.fc40.so => not found
+    #   /path/to/library => not found
+    while read not_found_library junk ; do
+        # We prefer a simple 'grep -q' pipe over dealing with find -name versus -path options:
+        if actually_found_library="$( find $ROOTFS_DIR -xdev | grep "$not_found_library" )" ; then
+            LogPrint "$binary requires $not_found_library which was not found by 'ldd' but exists as $actually_found_library"
+        else
+            actually_missing_libraries="yes"
+            # Show only the missing libraries to the user to not flood his screen with tons of other ldd output lines:
+            LogPrintError "$binary requires $not_found_library which could not be found in the ReaR recovery system"
+        fi
+    done <<<"$not_found_output"
 done
-is_true $broken_binaries && LogPrintError "ReaR recovery system in '$ROOTFS_DIR' needs additional libraries, check $RUNTIME_LOGFILE for details"
+is_true $actually_missing_libraries && LogPrintError "ReaR recovery system in '$ROOTFS_DIR' needs additional libraries, check $RUNTIME_LOGFILE for details"
 is_true $fatal_missing_library && keep_build_dir
 
 # Testing that each program in the PROGS array can be found as executable command within the recovery system