perf probe: Expand given path to absolute path

Expand given path to absolute path in the option parser, except for a
module name.

Since realpath at later stage in processing several probe point, can be
called several times (even if currently doesn't, it can happen when we
expands the feature), it is waste of the performance.

Processing it once at the early stage can avoid that.

Changes from previous one:
 - Fix not to print null string.
 - Allocate memory for given path/module name everytime.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: systemtap@sourceware.org
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20131226054150.22364.12187.stgit@kbuild-fedora.novalocal
[ Clarified the pr_warning message as per David Ahern's suggestion ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-probe.c

@@ -169,6 +169,7 @@ static int opt_set_target(const struct option *opt, const char *str,
 			int unset __maybe_unused)
 {
 	int ret = -ENOENT;
+	char *tmp;
 
 	if  (str && !params.target) {
 		if (!strcmp(opt->long_name, "exec"))
@@ -180,7 +181,19 @@ static int opt_set_target(const struct option *opt, const char *str,
 		else
 			return ret;
 
-		params.target = str;
+		/* Expand given path to absolute path, except for modulename */
+		if (params.uprobes || strchr(str, '/')) {
+			tmp = realpath(str, NULL);
+			if (!tmp) {
+				pr_warning("Failed to get the absolute path of %s: %m\n", str);
+				return ret;
+			}
+		} else {
+			tmp = strdup(str);
+			if (!tmp)
+				return -ENOMEM;
+		}
+		params.target = tmp;
 		ret = 0;
 	}
 

tools/perf/util/probe-event.c

@@ -2281,7 +2281,7 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)
 	struct perf_probe_point *pp = &pev->point;
 	struct symbol *sym;
 	struct map *map = NULL;
-	char *function = NULL, *name = NULL;
+	char *function = NULL;
 	int ret = -EINVAL;
 	unsigned long long vaddr = 0;
 
@@ -2297,12 +2297,7 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)
 		goto out;
 	}
 
-	name = realpath(exec, NULL);
-	if (!name) {
-		pr_warning("Cannot find realpath for %s.\n", exec);
-		goto out;
-	}
-	map = dso__new_map(name);
+	map = dso__new_map(exec);
 	if (!map) {
 		pr_warning("Cannot find appropriate DSO for %s.\n", exec);
 		goto out;
@@ -2367,7 +2362,5 @@ static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)
 	}
 	if (function)
 		free(function);
-	if (name)
-		free(name);
 	return ret;
 }