tools lib traceevent: Use asprintf when possible

It makes the code clearer and less error prone.

clearer:
- less code
- the code is now using the same format to create strings dynamically

less error prone:
- no magic number +2 +9 +5 to compute the size
- no copy&paste of the strings to compute the size and to concatenate

The function `asprintf` is not POSIX standard but the program
was already using it. Later it can be decided to use only POSIX
functions, then we can easly replace all the `asprintf(3)` with a local
implementation of that function.

Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Federico Vaga <federico.vaga@vaga.pv.it>
Link: http://lkml.kernel.org/r/20170802221558.9684-2-federico.vaga@vaga.pv.it
Link: http://lkml.kernel.org/r/20180112004822.686281649@goodmis.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 13 insertions, 22 deletions

diff --git a/tools/lib/traceevent/event-plugin.c b/tools/lib/traceevent/event-plugin.c
index a16756ae3526..d542cb60ca1a 100644
--- a/tools/lib/traceevent/event-plugin.c
+++ b/tools/lib/traceevent/event-plugin.c
@@ -120,12 +120,12 @@ char **traceevent_plugin_list_options(void)
                 for (op = reg->options; op->name; op++) {
                         char *alias = op->plugin_alias ? op->plugin_alias : op->file;
                         char **temp = list;
+                        int ret;
 
-                        name = malloc(strlen(op->name) + strlen(alias) + 2);
-                        if (!name)
+                        ret = asprintf(&name, "%s:%s", alias, op->name);
+                        if (ret < 0)
                                 goto err;
 
-                        sprintf(name, "%s:%s", alias, op->name);
                         list = realloc(list, count + 2);
                         if (!list) {
                                 list = temp;
@@ -290,17 +290,14 @@ load_plugin(struct pevent *pevent, const char *path,
         const char *alias;
         char *plugin;
         void *handle;
+        int ret;
 
-        plugin = malloc(strlen(path) + strlen(file) + 2);
-        if (!plugin) {
+        ret = asprintf(&plugin, "%s/%s", path, file);
+        if (ret < 0) {
                 warning("could not allocate plugin memory\n");
                 return;
         }
 
-        strcpy(plugin, path);
-        strcat(plugin, "/");
-        strcat(plugin, file);
-
         handle = dlopen(plugin, RTLD_NOW | RTLD_GLOBAL);
         if (!handle) {
                 warning("could not load plugin '%s'\n%s\n",
@@ -391,6 +388,7 @@ load_plugins(struct pevent *pevent, const char *suffix,
         char *home;
         char *path;
         char *envdir;
+        int ret;
 
         if (pevent->flags & PEVENT_DISABLE_PLUGINS)
                 return;
@@ -421,16 +419,12 @@ load_plugins(struct pevent *pevent, const char *suffix,
         if (!home)
                 return;
 
-        path = malloc(strlen(home) + strlen(LOCAL_PLUGIN_DIR) + 2);
-        if (!path) {
+        ret = asprintf(&path, "%s/%s", home, LOCAL_PLUGIN_DIR);
+        if (ret < 0) {
                 warning("could not allocate plugin memory\n");
                 return;
         }
 
-        strcpy(path, home);
-        strcat(path, "/");
-        strcat(path, LOCAL_PLUGIN_DIR);
-
         load_plugins_dir(pevent, suffix, path, load_plugin, data);
 
         free(path);
diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index 315df0a70265..2410afdcbcfe 100644
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -287,12 +287,10 @@ find_event(struct pevent *pevent, struct event_list **events,
                 sys_name = NULL;
         }
 
-        reg = malloc(strlen(event_name) + 3);
-        if (reg == NULL)
+        ret = asprintf(&reg, "^%s$", event_name);
+        if (ret < 0)
                 return PEVENT_ERRNO__MEM_ALLOC_FAILED;
 
-        sprintf(reg, "^%s$", event_name);
-
         ret = regcomp(&ereg, reg, REG_ICASE|REG_NOSUB);
         free(reg);
 
@@ -300,13 +298,12 @@ find_event(struct pevent *pevent, struct event_list **events,
                 return PEVENT_ERRNO__INVALID_EVENT_NAME;
 
         if (sys_name) {
-                reg = malloc(strlen(sys_name) + 3);
-                if (reg == NULL) {
+                ret = asprintf(&reg, "^%s$", sys_name);
+                if (ret < 0) {
                         regfree(&ereg);
                         return PEVENT_ERRNO__MEM_ALLOC_FAILED;
                 }
 
-                sprintf(reg, "^%s$", sys_name);
                 ret = regcomp(&sreg, reg, REG_ICASE|REG_NOSUB);
                 free(reg);
                 if (ret) {