Re: [PATCH -next] tools build: Check return value of fwrite_unlocked in jvmti_agent.c

[Wangshaobo (bobo)]

在 2020/7/30 18:03, Arnaldo Carvalho de Melo 写道:
Em Wed, Jul 29, 2020 at 04:47:36PM -0700, Ian Rogers escreveu:
On Fri, Jul 24, 2020 at 3:07 AM Wang ShaoBo <bobo.shaobow...@huawei.com> wrote:
Function jvmti_write_code called by compiled_method_load_cb may return
error in using fwrite_unlocked, this failure should be captured and
warned.

Signed-off-by: Wang ShaoBo <bobo.shaobow...@huawei.com>
---
  tools/perf/jvmti/jvmti_agent.c | 23 +++++++++++++++--------
  1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/tools/perf/jvmti/jvmti_agent.c b/tools/perf/jvmti/jvmti_agent.c
index 88108598d6e9..a1fe6aa16b6d 100644
--- a/tools/perf/jvmti/jvmti_agent.c
+++ b/tools/perf/jvmti/jvmti_agent.c
@@ -363,7 +363,7 @@ jvmti_write_code(void *agent, char const *sym,
         struct jr_code_load rec;
         size_t sym_len;
         FILE *fp = agent;
-       int ret = -1;
+       int ret;

         /* don't care about 0 length function, no samples */
         if (size == 0)
@@ -401,16 +401,23 @@ jvmti_write_code(void *agent, char const *sym,
         rec.code_index = code_generation++;

         ret = fwrite_unlocked(&rec, sizeof(rec), 1, fp);
-       fwrite_unlocked(sym, sym_len, 1, fp);
+       if (ret)
+               goto error;
Sorry, it seems I lost a reply to this. Won't ret here be the number
of items written and not an error code? Consequently all writes will
immediately goto error?
Yeah, I removed it from tmp.perf/core.

Wang, please address Ian review, and consider having just one out exit
label.

- Arnaldo
  

I am sorry I forgot what does fwrite_unlocked return, as same as fwrite 
error happens,

the return val is a short item count (or zero)  but not equals the items 
written. I have fixed

it and already sent v2 and address Ian review, thanks a lot.

... and i refer to the writing of function jvmti_write_debug_info() for 
giving out exit label,

thanks again,

- Wang ShaoBo

Thanks,
Ian

+       ret = fwrite_unlocked(sym, sym_len, 1, fp);
+       if (ret)
+               goto error;

-       if (code)
-               fwrite_unlocked(code, size, 1, fp);
+       if (code) {
+               ret = fwrite_unlocked(code, size, 1, fp);
+               if (ret)
+                       goto error;
+       }

         funlockfile(fp);
-
-       ret = 0;
-
-       return ret;
+       return 0;
+error:
+       funlockfile(fp);
+       return -1;
  }

  int
--
2.17.1