[PATCH 2/4] gdbserver: Add debug-file option

Alan Hayward
2019-04-16T10:17:50Z

Add command line option to send all debug output to a given file.
Always default back to stderr.

Add matching monitor command. Add documentation.

gdb/doc/ChangeLog:

2019-04-16 Alan Hayward <alan.hayward@arm.com>

* gdb.texinfo
(Other Command-Line Arguments for gdbserver): Add debug-file
option.
(Monitor Commands for gdbserver): Likewise.
(gdbserver man): Likewise.

gdb/gdbserver/ChangeLog:

2019-04-16 Alan Hayward <alan.hayward@arm.com>

* debug.c (debug_set_output): New function.
(debug_vprintf): Send output to debug_file.
(debug_flush): Likewise.
* debug.h (debug_set_output): New declaration.
* server.c (handle_monitor_command): Add debug-file option.
(captured_main): Likewise.
---
gdb/doc/gdb.texinfo | 16 ++++++++++++++--
gdb/gdbserver/debug.c | 42 +++++++++++++++++++++++++++++++++++++++---
gdb/gdbserver/debug.h | 5 +++++
gdb/gdbserver/server.c | 6 ++++++
4 files changed, 64 insertions(+), 5 deletions(-)

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index f410d026b8..1716466609 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -21332,8 +21332,11 @@ The @option{--debug} option tells @code{gdbserver} to display extra
status information about the debugging process.
@cindex @option{--remote-debug}, @code{gdbserver} option
The @option{--remote-debug} option tells @code{gdbserver} to display
-remote protocol debug output. These options are intended for
-@code{gdbserver} development and for bug reports to the developers.
+remote protocol debug output.
+@cindex @option{--debug-file}, @code{gdbserver} option
+The @option{--debug-file=filename} option tells @code{gdbserver} to
+write any debug output to the given file. These options are intended
+for @code{gdbserver} development and for bug reports to the developers.

@cindex @option{--debug-format}, @code{gdbserver} option
The @option{--debug-format=option1[,option2,...]} option tells
@@ -21433,6 +21436,10 @@ Disable or enable general debugging messages.
Disable or enable specific debugging messages associated with the remote
protocol (@pxref{Remote Protocol}).

+@item monitor set debug-file filename
+@itemx monitor set debug-file
+Send any debug output to the given file, or to stderr.
+
@item monitor set debug-format option1@r{[},option2,...@r{]}
Specify additional text to add to debugging messages.
Possible options are:
@@ -44563,6 +44570,11 @@ Instruct @code{gdbserver} to display remote protocol debug output.
This option is intended for @code{gdbserver} development and for bug reports to
the developers.

+@item --debug-file=filename
+Instruct @code{gdbserver} to send any debug output to the given file.
+This option is intended for @code{gdbserver} development and for bug reports to
+the developers.
+
@item --debug-format=option1@r{[},option2,...@r{]}
Instruct @code{gdbserver} to include extra information in each line
of debugging output.
diff --git a/gdb/gdbserver/debug.c b/gdb/gdbserver/debug.c
index 7c4c77afe2..53647c1ea6 100644
--- a/gdb/gdbserver/debug.c
+++ b/gdb/gdbserver/debug.c
@@ -23,6 +23,9 @@
int remote_debug = 0;
#endif

+/* Output file for debugging. Default to standard error. */
+FILE *debug_file = stderr;
+
/* Enable miscellaneous debugging output. The name is historical - it
was originally used to debug LinuxThreads support. */
int debug_threads;
@@ -30,6 +33,39 @@ int debug_threads;
/* Include timestamps in debugging output. */
int debug_timestamp;

+#if !defined (IN_PROCESS_AGENT)
+
+/* See debug.h. */
+
+void
+debug_set_output (const char *new_debug_file)
+{
+ /* Close any existing file and reset to standard error. */
+ if (debug_file != stderr)
+ {
+ fclose (debug_file);
+ }
+ debug_file = stderr;
+
+ /* Catch empty filenames. */
+ if (new_debug_file == nullptr || strlen (new_debug_file) == 0)
+ return;
+
+ FILE *fptr = fopen (new_debug_file, "w");
+
+ if (fptr == nullptr)
+ {
+ debug_printf ("Cannot open %s for writing. %s. Switching to stderr.\n",
+ new_debug_file, strerror (errno));
+ return;
+ }
+
+ debug_file = fptr;
+ return;
+}
+
+#endif
+
/* Print a debugging message.
If the text begins a new line it is preceded by a timestamp.
We don't get fancy with newline checking, we just check whether the
@@ -50,11 +86,11 @@ debug_vprintf (const char *format, va_list ap)
seconds s = duration_cast<seconds> (now.time_since_epoch ());
microseconds us = duration_cast<microseconds> (now.time_since_epoch ()) - s;

- fprintf (stderr, "%ld.%06ld ", (long) s.count (), (long) us.count ());
+ fprintf (debug_file, "%ld.%06ld ", (long) s.count (), (long) us.count ());
}
#endif

- vfprintf (stderr, format, ap);
+ vfprintf (debug_file, format, ap);

#if !defined (IN_PROCESS_AGENT)
if (*format)
@@ -69,7 +105,7 @@ debug_vprintf (const char *format, va_list ap)
void
debug_flush (void)
{
- fflush (stderr);
+ fflush (debug_file);
}

/* Notify the user that the code is entering FUNCTION_NAME.
diff --git a/gdb/gdbserver/debug.h b/gdb/gdbserver/debug.h
index c8d5e3365e..f65c91c9eb 100644
--- a/gdb/gdbserver/debug.h
+++ b/gdb/gdbserver/debug.h
@@ -21,6 +21,11 @@

#if !defined (IN_PROCESS_AGENT)
extern int remote_debug;
+
+/* Switch all debug output to DEBUG_FILE. If DEBUG_FILE is nullptr or an
+ empty string, or if the file cannot be opened, then debug output is sent to
+ stderr. */
+void debug_set_output (const char *debug_file);
#endif

extern int debug_threads;
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 3f6c849dbc..36510ad1b2 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -1403,6 +1403,10 @@ handle_monitor_command (char *mon, char *own_buf)
write_enn (own_buf);
}
}
+ else if (strcmp (mon, "set debug-file") == 0)
+ debug_set_output (nullptr);
+ else if (startswith (mon, "set debug-file "))
+ debug_set_output (mon + sizeof ("set debug-file ") - 1);
else if (strcmp (mon, "help") == 0)
monitor_show_help ();
else if (strcmp (mon, "exit") == 0)
@@ -3649,6 +3653,8 @@ captured_main (int argc, char *argv[])
}
else if (strcmp (*next_arg, "--remote-debug") == 0)
remote_debug = 1;
+ else if (startswith (*next_arg, "--debug-file="))
+ debug_set_output ((*next_arg) + sizeof ("--debug-file=") -1);
else if (strcmp (*next_arg, "--disable-packet") == 0)
{
gdbserver_show_disableable (stdout);
--
2.20.1 (Apple Git-117)