perf ui browser: Fix ui popup argv browser for many entries

Fix the argv ui browser code to correctly display more entries than fit
on the screen without crashing. The problem was some type confusion with
pointer types in the ->seek function. Do the argv arithmetic correctly
with char ** pointers. Also add some asserts to find overruns and limit
the display function correctly.

Then finally remove a workaround for this in the res sample browser.

Committer testing:

1) Resize the x terminal to have just some 5 lines

2) Use 'perf report --samples 1' to activate the sample browser options
   in the menu

3) Press ENTER, this will cause the crash:

  # perf report --samples 1
  perf: Segmentation fault
  -------- backtrace --------
  perf[0x5a514a]
  /lib64/libc.so.6(+0x385bf)[0x7f27281b55bf]
  /lib64/libc.so.6(+0x161a67)[0x7f27282dea67]
  /lib64/libslang.so.2(SLsmg_write_wrapped_string+0x82)[0x7f272874a0b2]
  perf(ui_browser__argv_refresh+0x77)[0x5939a7]
  perf[0x5924cc]
  perf(ui_browser__run+0x39)[0x593449]
  perf(ui__popup_menu+0x83)[0x5a5263]
  perf[0x59f421]
  perf(perf_evlist__tui_browse_hists+0x3a0)[0x5a3780]
  perf(cmd_report+0x2746)[0x447136]
  perf[0x4a95fe]
  perf(main+0x61c)[0x42dc6c]
  /lib64/libc.so.6(__libc_start_main+0xf2)[0x7f27281a1412]
  perf(_start+0x2d)[0x42de9d]
  #

After applying this patch no crash takes place in such situation.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20190311144502.15423-12-andi@firstfloor.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browser.c

@@ -611,14 +611,16 @@ void ui_browser__argv_seek(struct ui_browser *browser, off_t offset, int whence)
 		browser->top = browser->entries;
 		break;
 	case SEEK_CUR:
-		browser->top = browser->top + browser->top_idx + offset;
+		browser->top = (char **)browser->top + offset;
 		break;
 	case SEEK_END:
-		browser->top = browser->top + browser->nr_entries - 1 + offset;
+		browser->top = (char **)browser->entries + browser->nr_entries - 1 + offset;
 		break;
 	default:
 		return;
 	}
+	assert((char **)browser->top < (char **)browser->entries + browser->nr_entries);
+	assert((char **)browser->top >= (char **)browser->entries);
 }
 
 unsigned int ui_browser__argv_refresh(struct ui_browser *browser)
@@ -630,7 +632,9 @@ unsigned int ui_browser__argv_refresh(struct ui_browser *browser)
 		browser->top = browser->entries;
 
 	pos = (char **)browser->top;
-	while (idx < browser->nr_entries) {
+	while (idx < browser->nr_entries &&
+	       row < (unsigned)SLtt_Screen_Rows - 1) {
+		assert(pos < (char **)browser->entries + browser->nr_entries);
 		if (!browser->filter || !browser->filter(browser, *pos)) {
 			ui_browser__gotorc(browser, row, 0);
 			browser->write(browser, pos, row);

tools/perf/ui/browsers/res_sample.c

@@ -36,9 +36,6 @@ int res_sample_browse(struct res_sample *res_samples, int num_res,
 	struct res_sample *r;
 	char extra_format[256];
 
-	/* For now since ui__popup_menu doesn't like lists that don't fit */
-	num_res = max(min(SLtt_Screen_Rows - 4, num_res), 0);
-
 	names = calloc(num_res, sizeof(char *));
 	if (!names)
 		return -1;