perf tools: Fix ABI compatibility bug in print_event_desc()

This patches cleans up local variable types for msz and ret.
They need to be size_t and ssize_t respectively.

It also fixes a bug whereby perf would not read attr struct
with a different size than what it knows about.

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: peterz@infradead.org
Cc: acme@redhat.com
Cc: robert.richter@amd.com
Cc: ming.m.lin@intel.com
Cc: andi@firstfloor.org
Cc: asharma@fb.com
Cc: ravitillo@lbl.gov
Cc: vweaver1@eecs.utk.edu
Cc: khandual@linux.vnet.ibm.com
Cc: dsahern@gmail.com
Link: http://lkml.kernel.org/r/1328826068-11713-18-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 9 insertions, 10 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 666f18972fa3..6d580267d043 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1144,8 +1144,9 @@ static void print_event_desc(struct perf_header *ph, int fd, FILE *fp)
         uint64_t id;
         void *buf = NULL;
         char *str;
-        u32 nre, sz, nr, i, j, msz;
-        int ret;
+        u32 nre, sz, nr, i, j;
+        ssize_t ret;
+        size_t msz;
 
         /* number of events */
         ret = read(fd, &nre, sizeof(nre));
@@ -1162,25 +1163,23 @@ static void print_event_desc(struct perf_header *ph, int fd, FILE *fp)
         if (ph->needs_swap)
                 sz = bswap_32(sz);
 
-        /*
-         * ensure it is at least to our ABI rev
-         */
-        if (sz < (u32)sizeof(attr))
-                goto error;
-
         memset(&attr, 0, sizeof(attr));
 
-        /* read entire region to sync up to next field */
+        /* buffer to hold on file attr struct */
         buf = malloc(sz);
         if (!buf)
                 goto error;
 
         msz = sizeof(attr);
-        if (sz < msz)
+        if (sz < (ssize_t)msz)
                 msz = sz;
 
         for (i = 0 ; i < nre; i++) {
 
+                /*
+                 * must read entire on-file attr struct to
+                 * sync up with layout.
+                 */
                 ret = read(fd, buf, sz);
                 if (ret != (ssize_t)sz)
                         goto error;