On Fri, Nov 30, 2012 at 7:01 PM, Mans Rullgard <mans.rullg...@linaro.org> wrote:
> On 30 November 2012 10:39, Ajeet Yadav <ajeet.yadav...@gmail.com> wrote:
>> Linux version 3.0.33 (Cortex A15)
>> Below program crashes with 2.14.1 glibc but runs fine with 2.11.1 glibc.
>>
>> #include <pthread.h>
>> #include <stdio.h>
>> #include <stdlib.h>
>> #include <signal.h>
>> #include <string.h>
>> #include <errno.h>
>>
>> #define MAX_LINE_SIZE 80
>>
>> #define MAX_THREAD 20
>> #define MAX_POPEN 10
>> #define MALLOC_SIZE 16
>>
>> void* pipe_thread(void *arg)
>> {
>> int i;
>> char *p = NULL;
>> FILE *fp[MAX_POPEN];
>> char shellCommand[MAX_LINE_SIZE];
>>
>> memset(shellCommand, 0x00, MAX_LINE_SIZE);
>> sprintf(shellCommand, "mount");
>> signal(SIGPIPE, SIG_IGN);
>>
>> while (1) {
>> for (i = 0; i < MAX_POPEN; ++i) {
>> fp[i] = popen(shellCommand, "r");
>> }
>>
>> if (p) {
>> free(p);
>> }
>>
>> for (i = 0; i < MAX_POPEN; ++i) {
>> if (fp[i])
>> pclose(fp[i]);
>> }
>>
>> p = malloc(MALLOC_SIZE);
>> if (p)
>> memset(p, 0, MALLOC_SIZE);
>> }
>> return NULL;
>> }
>>
>> int main(int argc, char *argv[])
>> {
>> int i;
>> pthread_t tid;
>>
>> for (i = 0; i < MAX_THREAD; ++i) {
>> pthread_create(&tid, NULL, &pipe_thread, (void*)NULL);
>> }
>> sleep(60);
>> }
>
> On returning from main(), all open streams are closed, but your threads are
> still running and might call pclose() on an already closed FILE, which is
> not allowed.
>
> --
> Mans Rullgard / mru
At first thank you for feedback, About code, their is sleep of 1
minutes, but I found that most of the time the code crashes before 1
minute is passed.
More important, is that this problem never occur on 2.11.1 glibc.
Yesturday I have been able to fix this issue with below patch, now
this problem no longer occurs.
But still my interest is 1> Why this patch fixes the problem ? 2> What
change between 2.11.1 and 2.14.1 caused this problem
-------------------------------------------------------------------------------
diff --git a/libio/iopopen.c b/libio/iopopen.c
index 1a5cc0f..888a57f 100644
--- a/libio/iopopen.c
+++ b/libio/iopopen.c
@@ -299,6 +299,7 @@ _IO_new_popen (command, mode)
new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
if (new_f == NULL)
return NULL;
+ memset(new_f, 0, sizeof (struct locked_FILE));
#ifdef _IO_MTSAFE_IO
new_f->fpx.file.file._lock = &new_f->lock;
#endif
--------------------------------------------------------------------------------------------
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