gdb: Respect field width and alignment for 'fmt' fields in CLI output

Currently the method 'cli_ui_out::do_field_fmt' has this comment:

  /* This is the only field function that does not align.  */

The reality is even slightly worse, the 'fmt' field type doesn't
respect either the field alignment or the field width.  In at least
one place in GDB we attempt to work around this lack of respect for
field width by adding additional padding manually.  But, as is often
the case, this is leading to knock on problems.

Conside the output for 'info breakpoints' when a breakpoint has
multiple locations.  This example is taken from the testsuite, from
test gdb.opt/inline-break.exp:

  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
  1.1                     y     0x00000000004004ae in func4b at /src/gdb/testsuite/gdb.opt/inline-break.c:64
  1.2                     y     0x0000000000400682 in func4b at /src/gdb/testsuite/gdb.opt/inline-break.c:64

The miss-alignment of the fields shown here is exactly as GDB
currently produces.

With this patch 'fmt' style fields are now first written into a
temporary buffer, and then written out as a 'string' field.  The
result is that the field width, and alignment should now be respected.
With this patch in place the output from GDB now looks like this:

  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  1       breakpoint     keep y   <MULTIPLE>
  1.1                         y   0x00000000004004ae in func4b at /src/gdb/testsuite/gdb.opt/inline-break.c:64
  1.2                         y   0x0000000000400682 in func4b at /src/gdb/testsuite/gdb.opt/inline-break.c:64

This patch has been tested on x86-64/Linux with no regressions,
however, the testsuite doesn't always spot broken output formatting or
alignment.  I have also audited all uses of 'fmt' fields that I could
find, and I don't think there are any other places that specifically
try to work around the lack of width/alignment, however, I could have
missed something.

gdb/ChangeLog:

	* breakpoint.c (print_one_breakpoint_location): Reduce whitespace,
	and remove insertion of extra spaces in GDB's output.
	* cli-out.c (cli_ui_out::do_field_fmt): Update header comment.
	Layout field into a temporary buffer, and then output it as a
	string field.

gdb/testsuite/ChangeLog:

	* gdb.opt/inline-break.exp: Add test that info breakpoint output
	is correctly aligned.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index fd9c1681f6d7d778f8211e64def388f86feb0423..66fe9c9f28f49a2b4e61f579bfb04624b2b26ce6 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2018-11-20  Andrew Burgess  <[email protected]>
+
+       * breakpoint.c (print_one_breakpoint_location): Reduce whitespace,
+       and remove insertion of extra spaces in GDB's output.
+       * cli-out.c (cli_ui_out::do_field_fmt): Update header comment.
+       Layout field into a temporary buffer, and then output it as a
+       string field.
+
 2018-11-20  Philippe Waroquiers  <[email protected]>
 
        * NEWS: Document the language choice done by

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 3d254344f2f9300d6286866b7f4dcabc7015b46e..6bd456ebbb8d93fe5fea78b3bd157ff7a13175b1 100644 (file)
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -6058,16 +6058,13 @@ print_one_breakpoint_location (struct breakpoint *b,
   else
     uiout->field_string ("disp", bpdisp_text (b->disposition));
 
-
   /* 4 */
   annotate_field (3);
   if (part_of_multiple)
     uiout->field_string ("enabled", loc->enabled ? "y" : "n");
   else
     uiout->field_fmt ("enabled", "%c", bpenables[(int) b->enable_state]);
-  uiout->spaces (2);
 
-  
   /* 5 and 6 */
   if (b->ops != NULL && b->ops->print_one != NULL)
     {

diff --git a/gdb/cli-out.c b/gdb/cli-out.c
index ad0a34ed39f025b8bb0e9b6079a8e71c65222620..9ffd6f01577548041739653032ee511d202e867d 100644 (file)
--- a/gdb/cli-out.c
+++ b/gdb/cli-out.c
@@ -165,7 +165,7 @@ cli_ui_out::do_field_string (int fldno, int width, ui_align align,
     field_separator ();
 }
 
-/* This is the only field function that does not align.  */
+/* Output field containing ARGS using printf formatting in FORMAT.  */
 
 void
 cli_ui_out::do_field_fmt (int fldno, int width, ui_align align,
@@ -175,10 +175,9 @@ cli_ui_out::do_field_fmt (int fldno, int width, ui_align align,
   if (m_suppress_output)
     return;
 
-  vfprintf_filtered (m_streams.back (), format, args);
+  std::string str = string_vprintf (format, args);
 
-  if (align != ui_noalign)
-    field_separator ();
+  do_field_string (fldno, width, align, fldname, str.c_str ());
 }
 
 void

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 8814cd3c81c8de4b32bf04cd95704ba1a06eb2f7..093603a89ec2a6f431b1f613951e1791267ddef2 100644 (file)
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-11-20  Andrew Burgess  <[email protected]>
+
+       * gdb.opt/inline-break.exp: Add test that info breakpoint output
+       is correctly aligned.
+
 2018-11-20  Philippe Waroquiers  <[email protected]>
 
        * gdb.ada/info_auto_lang.exp: New testcase.

diff --git a/gdb/testsuite/gdb.opt/inline-break.exp b/gdb/testsuite/gdb.opt/inline-break.exp
index aed38ed631fa9e174a0001cda45de0c650406061..06a08612371c57c1d6161b7f24615622e1c3fc9b 100644 (file)
--- a/gdb/testsuite/gdb.opt/inline-break.exp
+++ b/gdb/testsuite/gdb.opt/inline-break.exp
@@ -304,4 +304,40 @@ with_test_prefix "address" {
        "breakpoint hit presents stop at inlined function"
 }
 
+with_test_prefix "check alignment" {
+
+    clean_restart $binfile
+
+    if {![runto main]} {
+       untested "could not run to main"
+       continue
+    }
+
+    gdb_test "break func4b" \
+       "Breakpoint.*at.*func4b.*\\(2 locations\\)"
+
+    set expected_line_length -1
+    gdb_test_multiple "info break \$bpnum" "xxxx" {
+       -re "Num     Type           Disp Enb Address            What\r\n" {
+           exp_continue
+       }
+       -re "($decimal \[^\r\n\]+)<MULTIPLE>\[^\r\n\]+\r\n" {
+           if {$expected_line_length != -1} {
+               fail "multiple header lines seen"
+           }
+           set expected_line_length [string length $expect_out(1,string)]
+           exp_continue
+       }
+       -re "($decimal\.($decimal) \[^\r\n\]+)$hex\[^\r\n\]+\r\n" {
+           set len [string length $expect_out(1,string)]
+           set loc $expect_out(2,string)
+           gdb_assert {$len == $expected_line_length} \
+               "check alignment of location line $loc"
+           exp_continue
+       }
+       -re "$gdb_prompt $" {
+       }
+    }
+}
+
 unset -nocomplain results