perf tools: Fix the bash completion problem of 'perf --*'

The perf-completion.sh uses a predefined string '--help --version
--exec-path --html-path --paginate --no-pager --perf-dir --work-tree
--debugfs-dir' for the bash completion of 'perf --*', which has two
problems:

Problem 1: If the options of perf are changed (see handle_options() in
perf.c), the perf-completion.sh has to be changed at the same time. If
not, the bash completion of 'perf --*' and the options which perf
really supports will be inconsistent.

Problem 2: When typing another single character after 'perf --', e.g.
'h', and hit TAB key to get the bash completion of 'perf --h', the
character 'h' disappears at once. This is not what we want, we wish the
bash completion can return '--help --html-path' and then we can
continue to choose one.

To solve this problem, we add '--list-opts' to perf, which now supports
'perf --list-opts' directly, and its result can be used in bash
completion now.

Example:

Before this patch:

$ perf --h <-- hit TAB key after character 'h'
$ perf -- <-- 'h' disappears and no required result

After this patch:

$ perf --h <-- hit TAB key after character 'h'
--help --html-path <-- the required result

Signed-off-by: Yunlong Song <[e-mail]>
Tested-by: Arnaldo Carvalho de Melo <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/perf-completion.sh

···
 	# List perf subcommands or long options
 	if [ $cword -eq 1 ]; then
 		if [[ $cur == --* ]]; then
-			__perfcomp '--help --version \
-			--exec-path --html-path --paginate --no-pager \
-			--perf-dir --work-tree --debugfs-dir' -- "$cur"
+			cmds=$($cmd --list-opts)
 		else
 			cmds=$($cmd --list-cmds)
-			__perfcomp "$cmds" "$cur"
 		fi
+		__perfcomp "$cmds" "$cur"
 	# List possible events for -e option
 	elif [[ $prev == "-e" && "${words[1]}" == @(record|stat|top) ]]; then
 		evts=$($cmd list --raw-dump)

tools/perf/perf.c

···
 #include "util/quote.h"
 #include "util/run-command.h"
 #include "util/parse-events.h"
+#include "util/parse-options.h"
 #include "util/debug.h"
 #include <api/fs/debugfs.h>
 #include <pthread.h>
···
 	}
 }
 
+struct option options[] = {
+	OPT_ARGUMENT("help", "help"),
+	OPT_ARGUMENT("version", "version"),
+	OPT_ARGUMENT("exec-path", "exec-path"),
+	OPT_ARGUMENT("html-path", "html-path"),
+	OPT_ARGUMENT("paginate", "paginate"),
+	OPT_ARGUMENT("no-pager", "no-pager"),
+	OPT_ARGUMENT("perf-dir", "perf-dir"),
+	OPT_ARGUMENT("work-tree", "work-tree"),
+	OPT_ARGUMENT("debugfs-dir", "debugfs-dir"),
+	OPT_ARGUMENT("buildid-dir", "buildid-dir"),
+	OPT_ARGUMENT("list-cmds", "list-cmds"),
+	OPT_ARGUMENT("list-opts", "list-opts"),
+	OPT_ARGUMENT("debug", "debug"),
+	OPT_END()
+};
+
 static int handle_options(const char ***argv, int *argc, int *envchanged)
 {
 	int handled = 0;
···
 			for (i = 0; i < ARRAY_SIZE(commands); i++) {
 				struct cmd_struct *p = commands+i;
 				printf("%s ", p->cmd);
+			}
+			putchar('\n');
+			exit(0);
+		} else if (!strcmp(cmd, "--list-opts")) {
+			unsigned int i;
+
+			for (i = 0; i < ARRAY_SIZE(options)-1; i++) {
+				struct option *p = options+i;
+				printf("--%s ", p->long_name);
 			}
 			putchar('\n');
 			exit(0);