[PATCH 3/4] gdb: make get_chars_per_line return an unsigned value

[Andrew Burgess <aburgess@redhat.com>]

I noticed that get_chars_per_line currently returns an 'int', but the
value it is returning, from utils.c, is an 'unsigned int'.  In some
cases this can cause weird behaviour as an unlimited width terminal
will have UINT_MAX characters per line, which will appear as negative
when returned from get_chars_per_line.

This has been the case since get_chars_per_line was added in commit:

  commit 2f2287318b33ddf855a692fcc191f6b25caf4644
  Date:   Wed Dec 16 18:18:40 2020 +0100

      [gdb/cli] Add a progress meter

Lets make get_chars_per_line return an unsigned value, and update all
the uses of this function to hold the result in an unsigned variable.

I ran into this issue when looking at print_gdb_hints (from top.c)
where a very large get_chars_per_line() value would appear negative,
and so the startup hints would be printed without a box when really
they should have been boxed.

There's no tests with this commit yet as print_gdb_hints has other
bugs which will be fixed in the next commit.  At this point I'll add
some tests.
---
 gdb/cli-out.c | 4 ++--
 gdb/top.c     | 2 +-
 gdb/utils.c   | 3 ++-
 gdb/utils.h   | 5 +++--
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/gdb/cli-out.c b/gdb/cli-out.c
index 27a82f607eb..1e52734802c 100644
--- a/gdb/cli-out.c
+++ b/gdb/cli-out.c
@@ -298,7 +298,7 @@ cli_ui_out::do_progress_notify (const std::string &msg,
 				const char *unit,
 				double howmuch, double total)
 {
-  int chars_per_line = get_chars_per_line ();
+  unsigned int chars_per_line = get_chars_per_line ();
   struct ui_file *stream = get_unbuffered (m_streams.back ());
   cli_progress_info &info (m_progress_info.back ());
 
@@ -385,7 +385,7 @@ void
 cli_ui_out::clear_progress_notify ()
 {
   struct ui_file *stream = get_unbuffered (m_streams.back ());
-  int chars_per_line = get_chars_per_line ();
+  unsigned int chars_per_line = get_chars_per_line ();
 
   scoped_restore save_pagination
     = make_scoped_restore (&pagination_enabled, false);
diff --git a/gdb/top.c b/gdb/top.c
index a8ce1a5321d..1aefe74b394 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -1414,7 +1414,7 @@ box_one_message (ui_file *stream, std::string message, int width)
 void
 print_gdb_hints (struct ui_file *stream)
 {
-  int width = get_chars_per_line ();
+  unsigned int width = get_chars_per_line ();
 
   /* Arbitrarily setting maximum width to 80 characters, so that
      things are big and visible but not overwhelming.  */
diff --git a/gdb/utils.c b/gdb/utils.c
index ffe0d639e3a..d322843925b 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -1548,9 +1548,10 @@ gdb_flush (struct ui_file *stream)
 
 /* See utils.h.  */
 
-int
+unsigned int
 get_chars_per_line ()
 {
+  gdb_assert (chars_per_line > 0);
   return chars_per_line;
 }
 
diff --git a/gdb/utils.h b/gdb/utils.h
index 0e28f9424e5..6316547653e 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -157,9 +157,10 @@ extern void wrap_here (int);
 
 extern void reinitialize_more_filter (void);
 
-/* Return the number of characters in a line.  */
+/* Return the number of characters in a line.  Will never be zero, but can
+   be UINT_MAX, which indicates unlimited characters per line.  */
 
-extern int get_chars_per_line ();
+extern unsigned int get_chars_per_line ();
 
 extern bool pagination_enabled;
 
-- 
2.47.1