Re: [PATCH v2 4/4] Add an optional offset option to the "add-symbol-file" command

Simon Marchi
2018-06-26T02:52:10Z

On 2018-06-11 08:08, Petr Tesarik wrote:
> @@ -2195,7 +2206,13 @@ add_symbol_file_command (const char *args, int
> from_tty)
> At this point, we don't know what file type this is,
> so we can't determine what section names are valid. */
> }
> - if (section_addrs.size () == 0)
> + if (seen_offset)
> + printf_unfiltered (_("%s offset by %s\n"),
> + (section_addrs.size () == 0
> + ? _(" with all sections")
> + : _("with other sections")),
> + paddress (gdbarch, offset));
> + else if (section_addrs.size () == 0)

Nice little detail, the message that adapts to how the command was used.

You can use ".empty ()" instead of .size () == 0" (in the previous
patches too).

> printf_unfiltered ("\n");
>
> if (from_tty && (!query ("%s", "")))
> @@ -2204,6 +2221,42 @@ add_symbol_file_command (const char *args, int
> from_tty)
> objf = symbol_file_add (filename.get (), add_flags, &section_addrs,
> flags);
>
> + if (seen_offset)
> + {
> + std::vector<struct section_offsets> new_offsets
> (objf->num_sections,
> + { offset });
> +
> + std::vector<const struct other_sections *> sect_addrs_sorted
> + = addrs_section_sort (section_addrs);
> +
> + section_addr_info objf_addrs
> + = build_section_addr_info_from_objfile (objf);
> + std::vector<const struct other_sections *> objf_addrs_sorted
> + = addrs_section_sort (objf_addrs);
> +
> + std::vector<const struct other_sections *>::iterator
> sect_sorted_iter
> + = sect_addrs_sorted.begin ();
> + for (const struct other_sections *objf_sect : objf_addrs_sorted)
> + {
> + const char *objf_name = addr_section_name (objf_sect->name.c_str
> ());
> + int cmp = -1;
> +
> + while (cmp < 0 && sect_sorted_iter != sect_addrs_sorted.end ())
> + {
> + const struct other_sections *sect = *sect_sorted_iter;
> + const char *sect_name = addr_section_name (sect->name.c_str
> ());
> + cmp = strcmp (sect_name, objf_name);
> + if (cmp <= 0)
> + ++sect_sorted_iter;
> + }
> +
> + if (cmp == 0)
> + new_offsets[objf_sect->sectindex].offsets[0] = 0;
> + }
> +
> + objfile_relocate (objf, new_offsets.data ());
> + }
> +

Could this new code be in a separate function? This one is starting to
get long.

Also, could you add a bit of comments to explain the intent of the code?
There is a lot of magic going on, it's a bit hard to read.

> diff --git a/gdb/testsuite/gdb.base/relocate.exp
> b/gdb/testsuite/gdb.base/relocate.exp
> index a3af8cea61..119495dd94 100644
> --- a/gdb/testsuite/gdb.base/relocate.exp
> +++ b/gdb/testsuite/gdb.base/relocate.exp
> @@ -235,6 +235,62 @@ set new_function_foo_addr [get_var_address
> function_foo]
> gdb_assert {${new_function_foo_addr} == ${function_foo_addr} +
> $offset} \
> "function foo is moved by offset"
>
> +# Load the object using add-symbol-file with an offset and check that
> +# all addresses are moved by that offset.
> +
> +set offset 0x10000
> +clean_restart
> +gdb_test "add-symbol-file -o $offset $binfile" \
> + "Reading symbols from ${binfile}\.\.\.done\." \
> + "add-symbol-file with offset" \
> + "add symbol table from file \".*${testfile}\\.o\" with all
> sections offset by $offset\[\r\n\]+\\(y or n\\) " \
> + "y"
> +
> +# Make sure the address of a static variable is moved by offset.
> +set new_static_foo_addr [get_var_address static_foo]
> +gdb_assert { ${new_static_foo_addr} == ${static_foo_addr} + $offset }
> \
> + "static variable foo is moved by offset"
> +
> +# Make sure the address of a global variable is moved by offset.
> +set new_global_foo_addr [get_var_address global_foo]
> +gdb_assert { ${new_global_foo_addr} == ${global_foo_addr} + $offset }
> \
> + "global variable foo is moved by offset"
> +
> +# Make sure the address of a function is moved by offset.
> +set new_function_foo_addr [get_var_address function_foo]
> +gdb_assert { ${new_function_foo_addr} == ${function_foo_addr} +
> $offset } \
> + "function foo is moved by offset"
> +
> +# Re-load the object giving an explicit address for .text
> +
> +set text [ format "0x%x" [expr ${function_foo_addr} + 0x20000] ]
> +clean_restart
> +gdb_test "add-symbol-file $binfile -o $offset $text" \
> + "Reading symbols from ${binfile}\.\.\.done\." \
> + "add-symbol-file with offset, text address given" \
> + "add symbol table from file \".*${testfile}\\.o\" at\[
> \t\r\n\]+\.text_addr = ${text}\[\r\n\]+with other sections offset by
> ${offset}\[\r\n\]+\\(y or n\\) " \
> + "y"
> +
> +# Make sure function has a different addresses now.

"has a different addresses" -> "has a different address", repeated a few
times.

Simon