[tip:perf/core] perf help: Make check_emacsclient_version to check strbuf APIs

[tip-bot for Masami Hiramatsu <tipbot@zytor.com>]

Commit-ID:  b72ca4039099e953f1ea2dbd58c201b14feb6605
Gitweb:     http://git.kernel.org/tip/b72ca4039099e953f1ea2dbd58c201b14feb6605
Author:     Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Tue, 10 May 2016 14:47:17 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 10 May 2016 11:56:14 -0300

perf help: Make check_emacsclient_version to check strbuf APIs

Make check_emacsclient_version() to check the return value of strbuf
APIs so that it can handle errors in strbuf.

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/20160510054716.6158.11755.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-help.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/tools/perf/builtin-help.c b/tools/perf/builtin-help.c
index bc1de9b..f9830c9 100644
--- a/tools/perf/builtin-help.c
+++ b/tools/perf/builtin-help.c
@@ -61,6 +61,7 @@ static int check_emacsclient_version(void)
 	struct child_process ec_process;
 	const char *argv_ec[] = { "emacsclient", "--version", NULL };
 	int version;
+	int ret = -1;
 
 	/* emacsclient prints its version number on stderr */
 	memset(&ec_process, 0, sizeof(ec_process));
@@ -71,7 +72,10 @@ static int check_emacsclient_version(void)
 		fprintf(stderr, "Failed to start emacsclient.\n");
 		return -1;
 	}
-	strbuf_read(&buffer, ec_process.err, 20);
+	if (strbuf_read(&buffer, ec_process.err, 20) < 0) {
+		fprintf(stderr, "Failed to read emacsclient version\n");
+		goto out;
+	}
 	close(ec_process.err);
 
 	/*
@@ -82,8 +86,7 @@ static int check_emacsclient_version(void)
 
 	if (prefixcmp(buffer.buf, "emacsclient")) {
 		fprintf(stderr, "Failed to parse emacsclient version.\n");
-		strbuf_release(&buffer);
-		return -1;
+		goto out;
 	}
 
 	version = atoi(buffer.buf + strlen("emacsclient"));
@@ -92,12 +95,11 @@ static int check_emacsclient_version(void)
 		fprintf(stderr,
 			"emacsclient version '%d' too old (< 22).\n",
 			version);
-		strbuf_release(&buffer);
-		return -1;
-	}
-
+	} else
+		ret = 0;
+out:
 	strbuf_release(&buffer);
-	return 0;
+	return ret;
 }
 
 static void exec_woman_emacs(const char *path, const char *page)