[lttng-dev] [PATCH] lttng-tools lttng commands add_context.c: Plug memory leaks

[Thibault, Daniel]

In lttng-tools lttng/commands/add_context.c, the instances of struct ctx_type that are malloc'ed were not cleaned up in most error cases.  Consider for example what the original code did with 'lttng add-context -t nice -h'.
------------------------------
>From e0b21686e686050369ecb929cb6c6ea78afcdb87 Thu, 26 Jan 2012 13:03:43 -0500
From: Daniel U. Thibault <daniel.thibault at drdc-rddc.gc.ca>
Date: Thu, 26 Jan 2012 13:03:29 -0500
Subject: [PATCH] lttng-tools lttng commands add_context.c: Plug memory leaks

diff --git a/src/bin/lttng/commands/add_context.c b/src/bin/lttng/commands/add_context.c
index 075b270..d0f5b6f 100644
--- a/src/bin/lttng/commands/add_context.c
+++ b/src/bin/lttng/commands/add_context.c
@@ -383,7 +383,7 @@
 		goto error;
 	}
 
-	/* Iterate over all context type given */
+	/* Iterate over all the context types given */
 	cds_list_for_each_entry(type, &ctx_type_list.head, list) {
 		context.ctx = type->opt->ctx_type;
 		if (context.ctx == LTTNG_EVENT_CONTEXT_PERF_COUNTER) {
@@ -420,17 +420,18 @@
 }
 
 /*
- * Add context on channel or event.
+ * Add context to channel or event.
  */
 int cmd_add_context(int argc, const char **argv)
 {
-	int index, opt, ret = CMD_SUCCESS;
+	int index, opt, ret;
 	static poptContext pc;
 	struct ctx_type *type, *tmptype;
 	char *session_name = NULL;
 
 	if (argc < 2) {
 		usage(stderr);
+		ret = CMD_ERROR;
 		goto end;
 	}
 
@@ -440,24 +441,30 @@
 	while ((opt = poptGetNextOpt(pc)) != -1) {
 		switch (opt) {
 		case OPT_HELP:
-			usage(stderr);
+			usage(stdout);
 			ret = CMD_SUCCESS;
 			goto end;
 		case OPT_TYPE:
-			type = malloc(sizeof(struct ctx_type));
-			if (type == NULL) {
-				perror("malloc ctx_type");
-				ret = -1;
-				goto end;
-			}
+			//Look up the index of opt_type in ctx_opts[] first,
+			//so we don't have to free(type) on failure
 			index = find_ctx_type_idx(opt_type);
 			if (index < 0) {
 				ERR("Unknown context type %s", opt_type);
+				ret = CMD_ERROR;
+				goto end;
+			}
+			type = malloc(sizeof(struct ctx_type));
+			if (type == NULL) {
+				perror("malloc ctx_type");
+				ret = CMD_FATAL;
 				goto end;
 			}
 			type->opt = &ctx_opts[index];
 			if (type->opt->ctx_type == -1) {
 				ERR("Unknown context type %s", opt_type);
+				free(type);
+				ret = CMD_ERROR;
+				goto end;
 			} else {
 				cds_list_add(&type->list, &ctx_type_list.head);
 			}
@@ -482,7 +489,7 @@
 	if (!opt_session_name) {
 		session_name = get_session_name();
 		if (session_name == NULL) {
-			ret = -1;
+			ret = CMD_ERROR;
 			goto end;
 		}
 	} else {
@@ -491,11 +498,11 @@
 
 	ret = add_context(session_name);
 
+end:
 	/* Cleanup allocated memory */
 	cds_list_for_each_entry_safe(type, tmptype, &ctx_type_list.head, list) {
 		free(type);
 	}
 
-end:
 	return ret;
 }
------------------------------

Daniel U. Thibault
R & D pour la défense Canada - Valcartier (RDDC Valcartier) / Defence R&D Canada - Valcartier (DRDC Valcartier)
Système de systèmes (SdS) / System of Systems (SoS)
Solutions informatiques et expérimentations (SIE) / Computing Solutions and Experimentations (CSE)
2459 Boul. Pie XI Nord
Québec, QC  G3J 1X5
CANADA
Vox : (418) 844-4000 x4245
Fax : (418) 844-4538
NAC: 918V QSDJ
Gouvernement du Canada / Government of Canada
<http://www.valcartier.drdc-rddc.gc.ca/>