[tip:perfcounters/core] perf help: Fix bug when there's no perf-* command around

tip-bot for Ingo Molnar
2009-06-03T19:16:45Z

Commit-ID: 051cdc3c2d0e24443ac03aff03ee89807ec8c589
Gitweb: http://git.kernel.org/tip/051cdc3c2d0e24443ac03aff03ee89807ec8c589
Author: Ingo Molnar <mingo@elte.hu>
AuthorDate: Wed, 3 Jun 2009 20:09:11 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 3 Jun 2009 20:09:11 +0200

perf help: Fix bug when there's no perf-* command around

main_cmds can be empty - fix util/help.c to handle this case
without segfaulting.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
Documentation/perf_counter/util/help.c | 28 ++++++++++++++++------------
1 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/Documentation/perf_counter/util/help.c b/Documentation/perf_counter/util/help.c
index 397487f..6653f7d 100644
--- a/Documentation/perf_counter/util/help.c
+++ b/Documentation/perf_counter/util/help.c
@@ -298,7 +298,7 @@ static void add_cmd_list(struct cmdnames *cmds, struct cmdnames *old)

const char *help_unknown_cmd(const char *cmd)
{
- int i, n, best_similarity = 0;
+ int i, n = 0, best_similarity = 0;
struct cmdnames main_cmds, other_cmds;

memset(&main_cmds, 0, sizeof(main_cmds));
@@ -315,20 +315,24 @@ const char *help_unknown_cmd(const char *cmd)
sizeof(main_cmds.names), cmdname_compare);
uniq(&main_cmds);

- /* This reuses cmdname->len for similarity index */
- for (i = 0; i < main_cmds.cnt; ++i)
- main_cmds.names[i]->len =
- levenshtein(cmd, main_cmds.names[i]->name, 0, 2, 1, 4);
+ if (main_cmds.cnt) {
+ /* This reuses cmdname->len for similarity index */
+ for (i = 0; i < main_cmds.cnt; ++i)
+ main_cmds.names[i]->len =
+ levenshtein(cmd, main_cmds.names[i]->name, 0, 2, 1, 4);

- qsort(main_cmds.names, main_cmds.cnt,
- sizeof(*main_cmds.names), levenshtein_compare);
+ qsort(main_cmds.names, main_cmds.cnt,
+ sizeof(*main_cmds.names), levenshtein_compare);
+
+ best_similarity = main_cmds.names[0]->len;
+ n = 1;
+ while (n < main_cmds.cnt && best_similarity == main_cmds.names[n]->len)
+ ++n;
+ }

- best_similarity = main_cmds.names[0]->len;
- n = 1;
- while (n < main_cmds.cnt && best_similarity == main_cmds.names[n]->len)
- ++n;
if (autocorrect && n == 1) {
const char *assumed = main_cmds.names[0]->name;
+
main_cmds.names[0] = NULL;
clean_cmdnames(&main_cmds);
fprintf(stderr, "WARNING: You called a Git program named '%s', "
@@ -345,7 +349,7 @@ const char *help_unknown_cmd(const char *cmd)

fprintf(stderr, "perf: '%s' is not a perf-command. See 'perf --help'.\n", cmd);

- if (best_similarity < 6) {
+ if (main_cmds.cnt && best_similarity < 6) {
fprintf(stderr, "\nDid you mean %s?\n",
n < 2 ? "this": "one of these");