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>

diff --git a/tools/perf/builtin-help.c b/tools/perf/builtin-help.c
index bc1de9b..f9830c9 100644 (file)
--- 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)