GDB: Introduce "info linker-namespaces" command

Continuing to improve GDB's ability to debug linker namespaces, this
commit adds the command "info linker- namespaces". The command is
similar to "info sharedlibrary" but focused on improved readability
when the inferior has multiple linker namespaces active. This command
can be used in 2 different ways, with or without an argument.

When called without argument, the command will print the number of
namespaces, and for each active namespace, it's identifier, how many
libraries are loaded in it, and all the libraries (in a similar table to
what "info sharedlibrary" shows). As an example, this is what GDB's
output could look like:

  (gdb) info linker-namespaces
  There are 2 linker namespaces loaded
  There are 3 libraries loaded in linker namespace [[0]]
  Displaying libraries for linker namespace [[0]]:
  From                To                  Syms Read   Shared Object Library
  0x00007ffff7fc6000  0x00007ffff7fff000  Yes         /lib64/ld-linux-x86-64.so.2
  0x00007ffff7ebc000  0x00007ffff7fa2000  Yes (*)     /lib64/libm.so.6
  0x00007ffff7cc9000  0x00007ffff7ebc000  Yes (*)     /lib64/libc.so.6
  (*): Shared library is missing debugging information.

  There are 4 libraries loaded in linker namespace [[1]]
  Displaying libraries for linker namespace [[1]]:
  From                To                  Syms Read   Shared Object Library
  0x00007ffff7fc6000  0x00007ffff7fff000  Yes         /lib64/ld-linux-x86-64.so.2
  0x00007ffff7fb9000  0x00007ffff7fbe000  Yes         gdb.base/dlmopen-ns-ids/dlmopen-lib.so
  0x00007ffff7bc4000  0x00007ffff7caa000  Yes (*)     /lib64/libm.so.6
  0x00007ffff79d1000  0x00007ffff7bc4000  Yes (*)     /lib64/libc.so.6
  (*): Shared library is missing debugging information.

When called with an argument, the argument must be a namespace
identifier (either with or without the square brackets decorators). In
this situation, the command will truncate the output to only show the
relevant information for the requested namespace. For example:

  (gdb) info linker-namespaces 0
  There are 3 libraries loaded in linker namespace [[0]]
  Displaying libraries for linker namespace [[0]]:
  From                To                  Syms Read   Shared Object Library
  0x00007ffff7fc6000  0x00007ffff7fff000  Yes         /lib64/ld-linux-x86-64.so.2
  0x00007ffff7ebc000  0x00007ffff7fa2000  Yes (*)     /lib64/libm.so.6
  0x00007ffff7cc9000  0x00007ffff7ebc000  Yes (*)     /lib64/libc.so.6
  (*): Shared library is missing debugging information.

The test gdb.base/dlmopen-ns-id.exp has been extended to test this new
command.  Because some gcc and glibc defaults can change between
systems, we are not guaranteed to always have libc and libm loaded in a
namespace, so we can't guarantee the number of libraries, but the range
of the result is 2, so we can still check for glaring issues.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-by: Kevin Buettner <kevinb@redhat.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
index 1af57d1..8f52199 100644
--- a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
+++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
@@ -159,5 +159,83 @@ proc_with_prefix test_conv_vars {} {
     gdb_continue_to_end "" continue 1
 }
 
+# Run several tests relating to the command "info namespaces".
+proc test_info_linker_namespaces {} {
+    clean_restart $::binfile
+
+    if { ![runto_main] } {
+	return
+    }
+
+    with_test_prefix "info linker-namespaces" {
+	gdb_breakpoint [gdb_get_line_number "TAG: first dlclose"]
+	gdb_continue_to_breakpoint "TAG: first dlclose"
+    }
+
+    # First, test printing a single namespace, and ensure all of
+    # them are correct, using both syntaxes.
+    set found_all_libs false
+    gdb_test_multiple "info linker-namespaces \[\[0\]\]" "print namespace 0" -lbl {
+	-re "^\r\nThere are ($::decimal) libraries loaded in linker namespace \\\[\\\[0\\\]\\\]" {
+	    # Some systems may add libc and libm to every loaded namespace,
+	    # others may load only one or neither, because the SO doesn't
+	    # actually use either library.  The best we can do is check if
+	    # we found the dynamic linker, and up to 2 more libraries.
+	    set libs $expect_out(1,string)
+	    set found_all_libs [expr $libs - 1 <= 2]
+	    exp_continue
+	}
+	-re "^\r\n$::gdb_prompt $" {
+	    gdb_assert $found_all_libs "the correct number of libraries was reported"
+	}
+	-re "(^\r\n)?\[^\r\n\]+(?=\r\n)" {
+	    exp_continue
+	}
+    }
+    foreach_with_prefix ns {1 2 3} {
+	set found_test_so false
+	set found_all_libs false
+	gdb_test_multiple "info linker-namespaces $ns" "print namespace $ns" -lbl {
+	    -re "^\r\nThere are ($::decimal) libraries loaded in linker namespace \\\[\\\[$ns\\\]\\\]" {
+		set libs $expect_out(1,string)
+		# Some systems may add libc and libm to every loaded namespace,
+		# others may load only one or neither, because the SO doesn't
+		# actually use either library.  The best we can do is check if
+		# we found the dynamic linker, the test SO, and maybe up to 2
+		# more libraries.
+		set found_all_libs [expr $libs - 2 <= 2]
+		exp_continue
+	    }
+	    -re "^\r\n\[^\r\n\]+${::binfile_lib}\[^\r\n\]*(?=\r\n)" {
+		set found_test_so true
+		exp_continue
+	    }
+	    -re "^\r\n$::gdb_prompt $" {
+		gdb_assert $found_test_so "this testfle's SO was reported"
+		gdb_assert $found_all_libs "the correct number of libraries was reported"
+	    }
+	    -re "(^\r\n)?\[^\r\n\]+(?=\r\n)" {
+		exp_continue
+	    }
+	}
+    }
+
+    # These patterns are simpler, and purposefully glob multiple lines.
+    # The point is to ensure that we find and display all the namespaces,
+    # without worrying about the libraries printed, since that was tested
+    # above.
+    gdb_test "info linker-namespaces" \
+	[multi_line "There are 4 linker namespaces loaded" \
+		    "There are $::decimal libraries loaded in linker namespace ..0.." \
+		    ".*" \
+		    "There are $::decimal libraries loaded in linker namespace ..1.." \
+		    ".*" \
+		    "There are $::decimal libraries loaded in linker namespace ..2.." \
+		    ".*" \
+		    "There are $::decimal libraries loaded in linker namespace ..3.." \
+		    ".*" ] "print namespaces with no argument"
+}
+
 test_info_shared
 test_conv_vars
+test_info_linker_namespaces