[PATCH] Proposed fix for oprofile JIT bad event spec error

Hi Oprofile-devs,
Attached is a fix for a problem we have seen recently when
trying to profile against java/JIT workloads.
    
The error floated to the user at opreport time is:
    
  opreport error: parse_event_spec(): bad event specification: 165624.0x
    
Where the 165624 value will match the PIDs of the processes being profiled.
    
This ends up being an issue with how we are building the string for the file
that contains the ELF blob for the java/JIT code (i.e.  12345.jo).  We were
not truncating our 'path' string such that when we strncpy'd it into our
path-and-file variable, we were getting part of an address range (12345.0x)
instead of the desired .jo suffix.
    
The code has been updated to correct that.  Sniff testing shows we are
now successfully processing the .jo contents, and no longer seeing the bad
event spec error.
    
Tested locally, this appears to resolve the issue.
    
    agents/jvmti/libjvmti_oprofile.c:
     - update strncpy call to avoid gcc warning on strncpy parameters.
    opjitconv/opjitconv.c:
     - update logic around calculation of elf_file_size, and rework snprintf
     calls so we properly truncate the input string.
    
     Signed-off-by: Will Schmidt  <[email protected]>

---


diff --git a/agents/jvmti/libjvmti_oprofile.c b/agents/jvmti/libjvmti_oprofile.c
index 40f9979..b518eb1 100644
--- a/agents/jvmti/libjvmti_oprofile.c
+++ b/agents/jvmti/libjvmti_oprofile.c
@@ -174,11 +174,11 @@ static void JNICALL cb_compiled_method_load(jvmtiEnv * jvmti,
 
 	{
 	int cnt = strlen(method_name) + strlen(class_signature) +
 		strlen(method_signature) + 2;
 	char buf[cnt];
-	strncpy(buf, class_signature, cnt - 1);
+	strncpy(buf, class_signature, sizeof(buf) - 1);
 	strncat(buf, method_name, cnt - strlen(buf) - 1);
 	strncat(buf, method_signature, cnt - strlen(buf) - 1);
 	if (op_write_native_code(agent_hdl, buf,
 				 (uint64_t)(uintptr_t) code_addr,
 				 code_addr, code_size)) {
diff --git a/opjitconv/opjitconv.c b/opjitconv/opjitconv.c
index c55d8b1..5b46142 100644
--- a/opjitconv/opjitconv.c
+++ b/opjitconv/opjitconv.c
@@ -311,10 +311,11 @@ static int process_jit_dumpfile(char const * dmp_pathname,
 	int jofd;
 	struct stat file_stat;
 	time_t dumpfile_modtime;
 	struct op_jitdump_info dmp_info;
 	char * elf_file = NULL;
+	char * tempstring = NULL;
 	char * proc_id = NULL;
 	char const * anon_dir;
 	char const * dumpfilename = rindex(dmp_pathname, '/');
 	/* temporary copy of dump file created for conversion step */
 	char * tmp_dumpfile;
@@ -388,15 +389,16 @@ chk_proc_id:
 			rc = OP_JIT_CONV_FAIL;
 			goto free_res2;
 		}
 		result_dir_length = ++anon_path_seg - anon_dir;
 		/* create final ELF file name */
-		elf_file_size = result_dir_length
+		elf_file_size = result_dir_length + strlen("/")
 			+ strlen(proc_id) + strlen(".jo") + 1;
 		elf_file = xmalloc(elf_file_size);
-		snprintf(elf_file, elf_file_size, "%s%s.jo",
-			 anon_dir, proc_id);
+		tempstring = xmalloc(elf_file_size);
+		snprintf(tempstring, result_dir_length, "%s",anon_dir);
+		snprintf(elf_file, elf_file_size, "%s/%s.jo",tempstring,proc_id);
 		/* create temporary ELF file name */
 		tmp_elffile_size = strlen(tmp_conv_dir) + 1
 			+ strlen(proc_id) + strlen(".jo") + 1;
 		tmp_elffile = xmalloc(tmp_elffile_size);
 		snprintf(tmp_elffile, tmp_elffile_size, "%s/%s.jo",