perf tools: Make alias handler to check return value of strbuf

Make alias handler and sq_quote_argv to check the return value of strbuf
APIs.

In sq_quote_argv() calls die(), but this fix handles strbuf failure as a
special case and returns to caller, since the caller - handle_alias()
also has to check the return value of other strbuf APIs and those checks
can be merged to one if() statement.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160510054725.6158.84597.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/perf.c

@@ -309,9 +309,11 @@ static int handle_alias(int *argcp, const char ***argv)
 			if (*argcp > 1) {
 				struct strbuf buf;
 
-				strbuf_init(&buf, PATH_MAX);
+				if (strbuf_init(&buf, PATH_MAX) < 0 ||
-				strbuf_addstr(&buf, alias_string);
+				    strbuf_addstr(&buf, alias_string) < 0 ||
-				sq_quote_argv(&buf, (*argv) + 1, PATH_MAX);
+				    sq_quote_argv(&buf, (*argv) + 1,
+						  PATH_MAX) < 0)
+					die("Failed to allocate memory.");
 				free(alias_string);
 				alias_string = buf.buf;
 			}

tools/perf/util/quote.c

@@ -17,38 +17,42 @@ static inline int need_bs_quote(char c)
 	return (c == '\'' || c == '!');
 }
 
-static void sq_quote_buf(struct strbuf *dst, const char *src)
+static int sq_quote_buf(struct strbuf *dst, const char *src)
 {
 	char *to_free = NULL;
+	int ret;
 
 	if (dst->buf == src)
 		to_free = strbuf_detach(dst, NULL);
 
-	strbuf_addch(dst, '\'');
+	ret = strbuf_addch(dst, '\'');
-	while (*src) {
+	while (!ret && *src) {
 		size_t len = strcspn(src, "'!");
-		strbuf_add(dst, src, len);
+		ret = strbuf_add(dst, src, len);
 		src += len;
-		while (need_bs_quote(*src)) {
+		while (!ret && need_bs_quote(*src))
-			strbuf_addstr(dst, "'\\");
+			ret = strbuf_addf(dst, "'\\%c\'", *src++);
-			strbuf_addch(dst, *src++);
-			strbuf_addch(dst, '\'');
-		}
 	}
-	strbuf_addch(dst, '\'');
+	if (!ret)
+		ret = strbuf_addch(dst, '\'');
 	free(to_free);
+
+	return ret;
 }
 
-void sq_quote_argv(struct strbuf *dst, const char** argv, size_t maxlen)
+int sq_quote_argv(struct strbuf *dst, const char** argv, size_t maxlen)
 {
-	int i;
+	int i, ret;
 
 	/* Copy into destination buffer. */
-	strbuf_grow(dst, 255);
+	ret = strbuf_grow(dst, 255);
-	for (i = 0; argv[i]; ++i) {
+	for (i = 0; !ret && argv[i]; ++i) {
-		strbuf_addch(dst, ' ');
+		ret = strbuf_addch(dst, ' ');
-		sq_quote_buf(dst, argv[i]);
+		if (ret)
+			break;
+		ret = sq_quote_buf(dst, argv[i]);
 		if (maxlen && dst->len > maxlen)
 			die("Too many or long arguments");
 	}
+	return ret;
 }

tools/perf/util/quote.h

@@ -24,6 +24,6 @@
  * sq_quote() in a real application.
  */
 
-void sq_quote_argv(struct strbuf *, const char **argv, size_t maxlen);
+int sq_quote_argv(struct strbuf *, const char **argv, size_t maxlen);
 
 #endif /* __PERF_QUOTE_H */