perf probe: Remove length limitation for showing available variables

Use struct strbuf instead of bare char[] to remove the length limitation
of variables in variable_list, so they will not disappear due to
overlength, and make preparation for adding more description for
variables.

Signed-off-by: He Kuang <hekuang@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1431336304-16863-1-git-send-email-hekuang@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 16d46e26edac25b0cdac387a34ded119835dd529..737c9dbe5643d4eb1e000f5cc6bcc8f785afb8c9 100644 (file)
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -848,19 +848,17 @@ Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
 /**
  * die_get_typename - Get the name of given variable DIE
  * @vr_die: a variable DIE
- * @buf: a buffer for result type name
- * @len: a max-length of @buf
+ * @buf: a strbuf for result type name
  *
- * Get the name of @vr_die and stores it to @buf. Return the actual length
- * of type name if succeeded. Return -E2BIG if @len is not enough long, and
- * Return -ENOENT if failed to find type name.
+ * Get the name of @vr_die and stores it to @buf. Return 0 if succeeded.
+ * and Return -ENOENT if failed to find type name.
  * Note that the result will stores typedef name if possible, and stores
  * "*(function_type)" if the type is a function pointer.
  */
-int die_get_typename(Dwarf_Die *vr_die, char *buf, int len)
+int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
 {
        Dwarf_Die type;
-       int tag, ret, ret2;
+       int tag, ret;
        const char *tmp = "";
 
        if (__die_get_real_type(vr_die, &type) == NULL)
@@ -871,8 +869,8 @@ int die_get_typename(Dwarf_Die *vr_die, char *buf, int len)
                tmp = "*";
        else if (tag == DW_TAG_subroutine_type) {
                /* Function pointer */
-               ret = snprintf(buf, len, "(function_type)");
-               return (ret >= len) ? -E2BIG : ret;
+               strbuf_addf(buf, "(function_type)");
+               return 0;
        } else {
                if (!dwarf_diename(&type))
                        return -ENOENT;
@@ -883,39 +881,35 @@ int die_get_typename(Dwarf_Die *vr_die, char *buf, int len)
                else if (tag == DW_TAG_enumeration_type)
                        tmp = "enum ";
                /* Write a base name */
-               ret = snprintf(buf, len, "%s%s", tmp, dwarf_diename(&type));
-               return (ret >= len) ? -E2BIG : ret;
-       }
-       ret = die_get_typename(&type, buf, len);
-       if (ret > 0) {
-               ret2 = snprintf(buf + ret, len - ret, "%s", tmp);
-               ret = (ret2 >= len - ret) ? -E2BIG : ret2 + ret;
+               strbuf_addf(buf, "%s%s", tmp, dwarf_diename(&type));
+               return 0;
        }
+       ret = die_get_typename(&type, buf);
+       if (ret == 0)
+               strbuf_addf(buf, "%s", tmp);
+
        return ret;
 }
 
 /**
  * die_get_varname - Get the name and type of given variable DIE
  * @vr_die: a variable DIE
- * @buf: a buffer for type and variable name
- * @len: the max-length of @buf
+ * @buf: a strbuf for type and variable name
  *
  * Get the name and type of @vr_die and stores it in @buf as "type\tname".
  */
-int die_get_varname(Dwarf_Die *vr_die, char *buf, int len)
+int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
 {
-       int ret, ret2;
+       int ret;
 
-       ret = die_get_typename(vr_die, buf, len);
+       ret = die_get_typename(vr_die, buf);
        if (ret < 0) {
                pr_debug("Failed to get type, make it unknown.\n");
-               ret = snprintf(buf, len, "(unknown_type)");
-       }
-       if (ret > 0) {
-               ret2 = snprintf(buf + ret, len - ret, "\t%s",
-                               dwarf_diename(vr_die));
-               ret = (ret2 >= len - ret) ? -E2BIG : ret2 + ret;
+               strbuf_addf(buf, "(unknown_type)");
        }
-       return ret;
+
+       strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
+
+       return 0;
 }
 

diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index 50a3cdc55fd7d45b4a70ae07a0efd2278ecc0e2b..60676fda48242b26980d23373e3de241345d8c10 100644 (file)
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -117,8 +117,8 @@ extern Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
                                  Dwarf_Die *die_mem);
 
 /* Get the name of given variable DIE */
-extern int die_get_typename(Dwarf_Die *vr_die, char *buf, int len);
+extern int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf);
 
 /* Get the name and type of given variable DIE, stored as "type\tname" */
-extern int die_get_varname(Dwarf_Die *vr_die, char *buf, int len);
+extern int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf);
 #endif

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 8b9e274f940c92ab7af3ede01d5c78103ff031fe..d7c2e90ab4ceb22b974ac237264e81bb53677c23 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1255,14 +1255,11 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
        return (ret < 0) ? ret : tf.ntevs;
 }
 
-#define MAX_VAR_LEN 64
-
 /* Collect available variables in this scope */
 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
 {
        struct available_var_finder *af = data;
        struct variable_list *vl;
-       char buf[MAX_VAR_LEN];
        int tag, ret;
 
        vl = &af->vls[af->nvls - 1];
@@ -1274,10 +1271,16 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
                                                af->pf.fb_ops, &af->pf.sp_die,
                                                NULL);
                if (ret == 0) {
-                       ret = die_get_varname(die_mem, buf, MAX_VAR_LEN);
-                       pr_debug2("Add new var: %s\n", buf);
-                       if (ret > 0)
-                               strlist__add(vl->vars, buf);
+                       struct strbuf buf;
+
+                       strbuf_init(&buf, 64);
+                       ret = die_get_varname(die_mem, &buf);
+                       pr_debug2("Add new var: %s\n", buf.buf);
+                       if (ret == 0) {
+                               strlist__add(vl->vars,
+                                       strbuf_detach(&buf, NULL));
+                       }
+                       strbuf_release(&buf);
                }
        }