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New API call iso_image_generator_is_running().

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Prevented a potential race condition between Ecma119Image disposal by
burn_source and final activities of ISO generator thread.
This commit is contained in:
Thomas Schmitt
2010-10-06 17:33:46 +02:00
parent bb28c69cae
commit 8a75d35c46
6 changed files with 84 additions and 15 deletions
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40
libisofs/ecma119.c
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@ -59,6 +59,12 @@ void ecma119_image_free(Ecma119Image *t)
if (t == NULL)
return;
if (t->refcount > 1) {
t->refcount--;
return;
}
if (t->root != NULL)
ecma119_node_free(t->root);
if (t->image != NULL)
@ -1315,6 +1321,12 @@ void *write_function(void *arg)
if (res <= 0)
goto write_error;
target->image->generator_is_running = 0;
/* Give up reference claim made in ecma119_image_new().
Eventually free target */
ecma119_image_free(target);
#ifdef Libisofs_with_pthread_exiT
pthread_exit(NULL);
#else
@ -1340,6 +1352,12 @@ void *write_function(void *arg)
/* Invalidate the transplanted checksum buffer in IsoImage */
iso_image_free_checksums(target->image, 0);
target->image->generator_is_running = 0;
/* Give up reference claim made in ecma119_image_new().
Eventually free target */
ecma119_image_free(target);
#ifdef Libisofs_with_pthread_exiT
pthread_exit(NULL);
#else
@ -1460,6 +1478,10 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
if (target == NULL) {
return ISO_OUT_OF_MEM;
}
/* This reference will be transfered to the burn_source and released by
bs_free_data.
*/
target->refcount = 1;
/* create the tree for file caching */
ret = iso_rbtree_new(iso_file_src_cmp, &(target->files));
@ -1923,9 +1945,24 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
pthread_attr_init(&(target->th_attr));
pthread_attr_setdetachstate(&(target->th_attr), PTHREAD_CREATE_JOINABLE);
/* To avoid race conditions with the caller, this mark must be set
before the thread starts. So the caller can rely on a value of 0
really meaning that the write has ended, and not that it might not have
begun yet.
In normal processing, the value will be changed to 0 at the end of
write_function().
*/
target->image->generator_is_running = 1;
/* Claim that target may not get destroyed by bs_free_data() before
write_function() is done with it */
target->refcount++;
ret = pthread_create(&(target->wthread), &(target->th_attr),
write_function, (void *) target);
if (ret != 0) {
target->refcount--;
iso_msg_submit(target->image->id, ISO_THREAD_ERROR, 0,
"Cannot create writer thread");
ret = ISO_THREAD_ERROR;
@ -1945,6 +1982,7 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
target_cleanup: ;
if(image_checksums_mad) /* No checksums is better than mad checksums */
iso_image_free_checksums(target->image, 0);
target->image->generator_is_running = 0;
ecma119_image_free(target);
return ret;
}
@ -1995,7 +2033,7 @@ static void bs_free_data(struct burn_source *bs)
iso_ring_buffer_get_times_full(target->buffer),
iso_ring_buffer_get_times_empty(target->buffer));
/* now we can safety free target */
/* The reference to target was inherited from ecma119_image_new() */
ecma119_image_free(target);
}