[PATCH] Java profiling: opagent: fwrite_unlocked failed

Note: The patch below has already been committed upstream.

-----------------------------------------------------------------

Java profiling: opagent: fwrite_unlocked failed

Certain Java Virtual Machines do not provide full code information in
the JNI callbacks to oprofile's java agent library; in particular,
the code size argument may be set to zero even if the code address
is non-null. The libopagent/opagent.c:op_write_native_code function
was not properly handling this case and would print the message
   opagent: fwrite_unlocked failed
and return a -1, causing the caller to display a message like
   Error: op_write_native_code(): Success

This patch fixes that issue.

Signed-off-by: Maynard Johnson <[email protected]>
---
 libopagent/opagent.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/libopagent/opagent.c b/libopagent/opagent.c
index 59b7bb6..f280880 100644
--- a/libopagent/opagent.c
+++ b/libopagent/opagent.c
@@ -376,7 +376,9 @@ again:
 	    fwrite_unlocked(symbol_name, sz_symb_name, 1, dumpfile)) {
 		size_t expected_sz, sz;
 		expected_sz = sz = 0;
-		if (code) {
+		// Note: Some JVMs always pass size=zero, so it's not enough just to check
+		// if 'code' is non-null.
+		if (code && size) {
 			sz = fwrite_unlocked(code, size, 1, dumpfile);
 			expected_sz++;
 		}
@@ -390,7 +392,7 @@ again:
 		funlockfile(dumpfile);
 		flock(dumpfd, LOCK_UN);
 		if (sz != expected_sz) {
-			printf("opagent: fwrite_unlocked failed");
+			printf("opagent: fwrite_unlocked failed\n");
 			return -1;
 		}
 		return 0;
-- 
1.7.1


------------------------------------------------------------------------------
Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer
Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports
Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper
Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer
http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk