Make add-symbol-file's address argument optional

The (first) .text section must be always specified as the second
non-option argument.  The documentation states that GDB cannot
figure out this address by itself.  This is true if the object file
was indeed relocated, but it is also confusing, because all other
sections can be omitted and will use the address provided by BFD.

gdb/ChangeLog:
2018-06-28  Petr Tesarik  <ptesarik@suse.cz>

	* symfile.c (add_symbol_file_command, _initialize_symfile): Do not
	require the second argument.  If omitted, load sections at the
	addresses specified in the file.

gdb/doc/ChangeLog:
2018-06-28  Petr Tesarik  <ptesarik@suse.cz>

	* gdb.texinfo (Files): The address argument for "add-symbol-file"
	is no longer mandatory.

gdb/testsuite/ChangeLog:
2018-06-28  Petr Tesarik  <ptesarik@suse.cz>

	* gdb.base/relocate.exp: Test add-symbol-file behavior when the
	address argument is omitted.

7 files changed, 55 insertions, 23 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4bc3204..f17c1a1 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2018-06-28  Petr Tesarik  <ptesarik@suse.cz>
 
+	* symfile.c (add_symbol_file_command, _initialize_symfile): Do not
+	require the second argument.  If omitted, load sections at the
+	addresses specified in the file.
+
+2018-06-28  Petr Tesarik  <ptesarik@suse.cz>
+
 	* symfile.c (symbol_file_command, symbol_file_add_main_1)
 	(_initialize_symfile): Add option "-o" to symbol-file to add an
 	offset to each section of the symbol file.
diff --git a/gdb/NEWS b/gdb/NEWS
index 1017465..54c0f1d 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -6,6 +6,9 @@
 * The 'symbol-file' command now accepts an '-o' option to add a relative
   offset to all sections.
 
+* The 'add-symbol-file' command no longer requires the second argument
+  (address of the text section).
+
 * The endianness used with the 'set endian auto' mode in the absence of
   an executable selected for debugging is now the last endianness chosen
   either by one of the 'set endian big' and 'set endian little' commands
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index f312873..9fd3d3c 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,5 +1,10 @@
 2018-06-28  Petr Tesarik  <ptesarik@suse.cz>
 
+	* gdb.texinfo (Files): The address argument for "add-symbol-file"
+	is no longer mandatory.
+
+2018-06-28  Petr Tesarik  <ptesarik@suse.cz>
+
 	* gdb.texinfo (Files): Document "symbol-file -o offset".
 
 2018-06-14  Tom de Vries  <tdevries@suse.de>
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 3282562..64c511d 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -18918,18 +18918,17 @@ the program is running.  To do this, use the @code{kill} command
 
 @kindex add-symbol-file
 @cindex dynamic linking
-@item add-symbol-file @var{filename} @var{address}
-@itemx add-symbol-file @var{filename} @var{address} @r{[} -readnow @r{|} -readnever @r{]}
-@itemx add-symbol-file @var{filename} @var{address} -s @var{section} @var{address} @dots{}
+@item add-symbol-file @var{filename} @r{[} -readnow @r{|} -readnever @r{]} @r{[} @var{textaddress} @r{]} @r{[} -s @var{section} @var{address} @dots{} @r{]}
 The @code{add-symbol-file} command reads additional symbol table
 information from the file @var{filename}.  You would use this command
 when @var{filename} has been dynamically loaded (by some other means)
-into the program that is running.  The @var{address} should give the memory
-address at which the file has been loaded; @value{GDBN} cannot figure
-this out for itself.  You can additionally specify an arbitrary number
-of @samp{-s @var{section} @var{address}} pairs, to give an explicit
-section name and base address for that section.  You can specify any
-@var{address} as an expression.
+into the program that is running.  The @var{textaddress} parameter gives
+the memory address at which the file's text section has been loaded.
+You can additionally specify the base address of other sections using
+an arbitrary number of @samp{-s @var{section} @var{address}} pairs.
+If a section is omitted, @value{GDBN} will use its default addresses
+as found in @var{filename}.  Any @var{address} or @var{textaddress}
+can be given as an expression.
 
 The symbol table of the file @var{filename} is added to the symbol table
 originally read with the @code{symbol-file} command.  You can use the
diff --git a/gdb/symfile.c b/gdb/symfile.c
index 461f60d..2a41fce 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -2161,29 +2161,26 @@ add_symbol_file_command (const char *args, int from_tty)
 
   validate_readnow_readnever (flags);
 
-  /* This command takes at least two arguments.  The first one is a
-     filename, and the second is the address where this file has been
-     loaded.  Abort now if this address hasn't been provided by the
-     user.  */
-  if (!seen_addr)
-    error (_("The address where %s has been loaded is missing"),
-	   filename.get ());
-
   /* Print the prompt for the query below.  And save the arguments into
      a sect_addr_info structure to be passed around to other
      functions.  We have to split this up into separate print
      statements because hex_string returns a local static
      string.  */
 
-  printf_unfiltered (_("add symbol table from file \"%s\" at\n"),
+  printf_unfiltered (_("add symbol table from file \"%s\""),
 		     filename.get ());
   section_addr_info section_addrs;
-  for (sect_opt &sect : sect_opts)
+  std::vector<sect_opt>::const_iterator it = sect_opts.begin ();
+  if (!seen_addr)
+    ++it;
+  for (; it != sect_opts.end (); ++it)
     {
       CORE_ADDR addr;
-      const char *val = sect.value;
-      const char *sec = sect.name;
+      const char *val = it->value;
+      const char *sec = it->name;
 
+      if (section_addrs.empty ())
+	printf_unfiltered (_(" at\n"));
       addr = parse_and_eval_address (val);
 
       /* Here we store the section offsets in the order they were
@@ -2198,6 +2195,8 @@ 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.empty ())
+    printf_unfiltered ("\n");
 
   if (from_tty && (!query ("%s", "")))
     error (_("Not confirmed."));
@@ -3793,8 +3792,8 @@ to execute.\n" READNOW_READNEVER_HELP), &cmdlist);
 
   c = add_cmd ("add-symbol-file", class_files, add_symbol_file_command, _("\
 Load symbols from FILE, assuming FILE has been dynamically loaded.\n\
-Usage: add-symbol-file FILE ADDR [-readnow | -readnever | \
--s SECT-NAME SECT-ADDR]...\n\
+Usage: add-symbol-file FILE [-readnow | -readnever] [ADDR] \
+[-s SECT-NAME SECT-ADDR]...\n\
 ADDR is the starting address of the file's text.\n\
 Each '-s' argument provides a section name and address, and\n\
 should be specified if the data and bss segments are not contiguous\n\
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index cea52c7..e3c9141 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2018-06-28  Petr Tesarik  <ptesarik@suse.cz>
 
+	* gdb.base/relocate.exp: Test add-symbol-file behavior when the
+	address argument is omitted.
+
+2018-06-28  Petr Tesarik  <ptesarik@suse.cz>
+
 	* gdb.base/relocate.exp: Add test for "symbol-file -o ".
 
 2018-06-27  Omair Javaid  <omair.javaid@linaro.org>
diff --git a/gdb/testsuite/gdb.base/relocate.exp b/gdb/testsuite/gdb.base/relocate.exp
index 77f6a88..2b4c4a7 100644
--- a/gdb/testsuite/gdb.base/relocate.exp
+++ b/gdb/testsuite/gdb.base/relocate.exp
@@ -73,6 +73,21 @@ gdb_test_multiple "add-symbol-file -s .text 0x200 $binfile 0x100" $test {
 	gdb_test "n" "Not confirmed\." $test
     }
 }
+# Check that passing a single "-s .text" is equivalent to passing
+# the text address in a positional argument.
+set test "add-symbol-file -s .text, no address"
+gdb_test_multiple "add-symbol-file $binfile -s .text 0x100" $test {
+    -re "add symbol table from file \"${binfile}\" at\r\n\t\.text_addr = 0x100\r\n\\(y or n\\) " {
+	gdb_test "n" "Not confirmed\." $test
+    }
+}
+# Check section addresses can be omitted.
+set test "add-symbol-file no address"
+gdb_test_multiple "add-symbol-file $binfile" $test {
+    -re "add symbol table from file \"${binfile}\"\r\n\\(y or n\\) " {
+	gdb_test "n" "Not confirmed\." $test
+    }
+}
 # Test that passing "--" disables option processing.
 gdb_test "add-symbol-file -- $binfile 0x100 -s .bss 0x3" \
     "Unrecognized argument \"-s\"" \