dump: Make dump_task_core work on fd

This routine is used for dumping tasks, threads and zombies. For the
last two the whole fdset is not allocated thus it will be better to
use single fd in this case.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -716,9 +716,8 @@ err:
 	return ret;
 }
 
-static int dump_task_core(struct core_entry *core, const struct cr_fdset *fdset)
+static int dump_task_core(struct core_entry *core, int fd_core)
 {
-	int fd_core = fdset->fds[CR_FD_CORE];
 	int ret;
 
 	lseek(fd_core, MAGIC_OFFSET, SEEK_SET);
@@ -729,10 +728,7 @@ static int dump_task_core(struct core_entry *core, const struct cr_fdset *fdset)
 	core->header.arch	= HEADER_ARCH_X86_64;
 	core->header.flags	= 0;
 
-	ret = write_img(fd_core, core);
-
-	free(core);
-	return ret;
+	return write_img(fd_core, core);
 }
 
 static int dump_task_core_all(pid_t pid, const struct proc_pid_stat *stat,
@@ -790,7 +786,7 @@ static int dump_task_core_all(pid_t pid, const struct proc_pid_stat *stat,
 	core->tc.task_state = TASK_ALIVE;
 	core->tc.exit_code = 0;
 
-	return dump_task_core(core, cr_fdset);
+	ret = dump_task_core(core, cr_fdset->fds[CR_FD_CORE]);
 
 err_free:
 	free(core);
@@ -1183,17 +1179,17 @@ err:
 	return ret;
 }
 
-static int dump_task_thread(struct parasite_ctl *parasite_ctl,
-			    pid_t pid, const struct cr_fdset *cr_fdset)
+static int dump_task_thread(struct parasite_ctl *parasite_ctl, pid_t pid)
 {
-	struct core_entry *core		= xzalloc(sizeof(*core));
-	int ret				= -1;
+	struct core_entry *core;
+	int ret = -1, fd_core;
 	unsigned int *taddr;
 
 	pr_info("\n");
 	pr_info("Dumping core for thread (pid: %d)\n", pid);
 	pr_info("----------------------------------------\n");
 
+	core = xzalloc(sizeof(*core));
 	if (!core)
 		goto err;
 
@@ -1205,7 +1201,7 @@ static int dump_task_thread(struct parasite_ctl *parasite_ctl,
 	ret = parasite_dump_tid_addr_seized(parasite_ctl, pid, &taddr);
 	if (ret) {
 		pr_err("Can't dump tid address for pid %d", pid);
-		goto err;
+		goto err_free;
 	}
 
 	pr_info("%d: tid_address=%p\n", pid, taddr);
@@ -1216,35 +1212,43 @@ static int dump_task_thread(struct parasite_ctl *parasite_ctl,
 	core->tc.task_state = TASK_ALIVE;
 	core->tc.exit_code = 0;
 
-	return dump_task_core(core, cr_fdset);
+	fd_core = open_image(CR_FD_CORE, O_RDWR | O_CREAT | O_EXCL, pid);
+	if (fd_core < 0)
+		goto err_free;
+
+	ret = dump_task_core(core, fd_core);
 
+	close(fd_core);
 err_free:
 	free(core);
 err:
 	pr_info("----------------------------------------\n");
-
 	return ret;
 }
 
 static int dump_one_zombie(const struct pstree_item *item,
-			   const struct proc_pid_stat *pps,
-			   struct cr_fdset *cr_fdset)
+			   const struct proc_pid_stat *pps)
 {
 	struct core_entry *core;
-	int ret;
-
-	cr_fdset = cr_dump_fdset_open(item->pid, CR_FD_DESC_CORE, cr_fdset);
-	if (cr_fdset == NULL)
-		return -1;
+	int ret = -1, fd_core;
 
 	core = xzalloc(sizeof(*core));
 	if (core == NULL)
-		return -1;
+		goto err;
 
 	core->tc.task_state = TASK_DEAD;
 	core->tc.exit_code = pps->exit_code;
 
-	return dump_task_core(core, cr_fdset);
+	fd_core = open_image(CR_FD_CORE, O_RDWR | O_CREAT | O_EXCL, item->pid);
+	if (fd_core < 0)
+		goto err_free;
+
+	ret = dump_task_core(core, fd_core);
+	close(fd_core);
+err_free:
+	xfree(core);
+err:
+	return ret;
 }
 
 static struct proc_pid_stat pps_buf;
@@ -1253,7 +1257,6 @@ static int dump_task_threads(struct parasite_ctl *parasite_ctl,
 			     const struct pstree_item *item)
 {
 	int i;
-	struct cr_fdset *cr_fdset_thread = NULL;
 
 	if (item->nr_threads == 1)
 		return 0;
@@ -1263,22 +1266,11 @@ static int dump_task_threads(struct parasite_ctl *parasite_ctl,
 		if (item->pid == item->threads[i])
 			continue;
 
-		cr_fdset_thread = cr_dump_fdset_open(item->threads[i], CR_FD_DESC_CORE, NULL);
-		if (!cr_fdset_thread)
-			goto err;
-
-		if (dump_task_thread(parasite_ctl,
-					item->threads[i], cr_fdset_thread))
-			goto err;
-
-		close_cr_fdset(&cr_fdset_thread);
+		if (dump_task_thread(parasite_ctl, item->threads[i]))
+			return -1;
 	}
 
 	return 0;
-
-err:
-	close_cr_fdset(&cr_fdset_thread);
-	return -1;
 }
 
 static int dump_one_task(const struct pstree_item *item, struct cr_fdset *cr_fdset)
@@ -1305,7 +1297,7 @@ static int dump_one_task(const struct pstree_item *item, struct cr_fdset *cr_fds
 		goto err;
 
 	if (item->state == TASK_DEAD)
-		return dump_one_zombie(item, &pps_buf, cr_fdset);
+		return dump_one_zombie(item, &pps_buf);
 
 	ret = -1;
 	if (!cr_dump_fdset_open(item->pid, CR_FD_DESC_TASK, cr_fdset))