perf util: Fix do_read() to fail on EOF instead of busy-looping

While toying with perf, I've noticed that perf record can
easily enter a busy loop when doing something as silly as:

    $ perf record -A ls

Yeah, do_read here really wants to read a known size, not being
able to should die(), not busy-loop ;)

That was the cause for the bug.

Signed-off-by: Pierre Habouzit <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Paul Mackerras <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 95a44bcfc2dc5c7042f57dfe3ed49e6d5b1398a2..b92a457ca32e2eb156f8f9f3311e281579171a99 100644 (file)
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -185,6 +185,8 @@ static void do_read(int fd, void *buf, size_t size)
 
                if (ret < 0)
                        die("failed to read");
+               if (ret == 0)
+                       die("failed to read: missing data");
 
                size -= ret;
                buf += ret;