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cr-dump.c
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cr-dump.c
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#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <signal.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/vfs.h>
#include <sys/sendfile.h>
#include <sched.h>
#include <sys/resource.h>
#include <linux/seccomp.h>
#include "protobuf.h"
#include "protobuf/fdinfo.pb-c.h"
#include "protobuf/fs.pb-c.h"
#include "protobuf/mm.pb-c.h"
#include "protobuf/creds.pb-c.h"
#include "protobuf/core.pb-c.h"
#include "protobuf/file-lock.pb-c.h"
#include "protobuf/rlimit.pb-c.h"
#include "protobuf/siginfo.pb-c.h"
#include "asm/types.h"
#include "list.h"
#include "imgset.h"
#include "file-ids.h"
#include "kcmp-ids.h"
#include "compiler.h"
#include "crtools.h"
#include "cr_options.h"
#include "servicefd.h"
#include "syscall.h"
#include "ptrace.h"
#include "util.h"
#include "namespaces.h"
#include "image.h"
#include "proc_parse.h"
#include "parasite.h"
#include "parasite-syscall.h"
#include "files.h"
#include "files-reg.h"
#include "shmem.h"
#include "sk-inet.h"
#include "pstree.h"
#include "mount.h"
#include "tty.h"
#include "net.h"
#include "sk-packet.h"
#include "cpu.h"
#include "elf.h"
#include "cgroup.h"
#include "file-lock.h"
#include "page-xfer.h"
#include "kerndat.h"
#include "stats.h"
#include "mem.h"
#include "page-pipe.h"
#include "posix-timer.h"
#include "vdso.h"
#include "vma.h"
#include "cr-service.h"
#include "plugin.h"
#include "irmap.h"
#include "sysfs_parse.h"
#include "action-scripts.h"
#include "aio.h"
#include "security.h"
#include "lsm.h"
#include "asm/dump.h"
//<underscore>
#include "image-remote.h"
#define NR_ATTEMPTS 5
static char loc_buf[PAGE_SIZE];
static void close_vma_file(struct vma_area *vma)
{
if (vma->vm_file_fd < 0)
return;
if (vma->e->status & VMA_AREA_SOCKET)
return;
if (vma->file_borrowed)
return;
if (vma_area_is(vma, VMA_AREA_AIORING))
return;
close(vma->vm_file_fd);
}
void free_mappings(struct vm_area_list *vma_area_list)
{
struct vma_area *vma_area, *p;
list_for_each_entry_safe(vma_area, p, &vma_area_list->h, list) {
close_vma_file(vma_area);
if (!vma_area->file_borrowed)
free(vma_area->vmst);
free(vma_area);
}
INIT_LIST_HEAD(&vma_area_list->h);
vma_area_list->nr = 0;
}
int collect_mappings(pid_t pid, struct vm_area_list *vma_area_list)
{
int ret = -1;
pr_info("\n");
pr_info("Collecting mappings (pid: %d)\n", pid);
pr_info("----------------------------------------\n");
ret = parse_smaps(pid, vma_area_list);
if (ret < 0)
goto err;
pr_info("Collected, longest area occupies %lu pages\n", vma_area_list->longest);
pr_info_vma_list(&vma_area_list->h);
pr_info("----------------------------------------\n");
err:
return ret;
}
static int dump_sched_info(int pid, ThreadCoreEntry *tc)
{
int ret;
struct sched_param sp;
BUILD_BUG_ON(SCHED_OTHER != 0); /* default in proto message */
ret = sched_getscheduler(pid);
if (ret < 0) {
pr_perror("Can't get sched policy for %d", pid);
return -1;
}
pr_info("%d has %d sched policy\n", pid, ret);
tc->has_sched_policy = true;
tc->sched_policy = ret;
if ((ret == SCHED_RR) || (ret == SCHED_FIFO)) {
ret = sched_getparam(pid, &sp);
if (ret < 0) {
pr_perror("Can't get sched param for %d", pid);
return -1;
}
pr_info("\tdumping %d prio for %d\n", sp.sched_priority, pid);
tc->has_sched_prio = true;
tc->sched_prio = sp.sched_priority;
}
/*
* The nice is ignored for RT sched policies, but is stored
* in kernel. Thus we have to take it with us in the image.
*/
errno = 0;
ret = getpriority(PRIO_PROCESS, pid);
if (errno) {
pr_perror("Can't get nice for %d", pid);
return -1;
}
pr_info("\tdumping %d nice for %d\n", ret, pid);
tc->has_sched_nice = true;
tc->sched_nice = ret;
return 0;
}
struct cr_imgset *glob_imgset;
static int collect_fds(pid_t pid, struct parasite_drain_fd *dfds)
{
struct dirent *de;
DIR *fd_dir;
int n;
pr_info("\n");
pr_info("Collecting fds (pid: %d)\n", pid);
pr_info("----------------------------------------\n");
fd_dir = opendir_proc(pid, "fd");
if (!fd_dir)
return -1;
n = 0;
while ((de = readdir(fd_dir))) {
if (dir_dots(de))
continue;
if (n > PARASITE_MAX_FDS - 1)
return -ENOMEM;
dfds->fds[n++] = atoi(de->d_name);
}
dfds->nr_fds = n;
pr_info("Found %d file descriptors\n", n);
pr_info("----------------------------------------\n");
closedir(fd_dir);
return 0;
}
static int fill_fd_params_special(int fd, struct fd_parms *p)
{
*p = FD_PARMS_INIT;
if (fstat(fd, &p->stat) < 0) {
pr_perror("Can't fstat exe link");
return -1;
}
if (get_fd_mntid(fd, &p->mnt_id))
return -1;
return 0;
}
static int dump_task_exe_link(pid_t pid, MmEntry *mm)
{
struct fd_parms params;
int fd, ret = 0;
fd = open_proc(pid, "exe");
if (fd < 0)
return -1;
if (fill_fd_params_special(fd, ¶ms))
return -1;
if (fd_id_generate_special(¶ms, &mm->exe_file_id))
ret = dump_one_reg_file(fd, mm->exe_file_id, ¶ms);
close(fd);
return ret;
}
static int dump_task_fs(pid_t pid, struct parasite_dump_misc *misc, struct cr_imgset *imgset)
{
struct fd_parms p;
FsEntry fe = FS_ENTRY__INIT;
int fd, ret;
fe.has_umask = true;
fe.umask = misc->umask;
fd = open_proc(pid, "cwd");
if (fd < 0)
return -1;
if (fill_fd_params_special(fd, &p))
return -1;
if (fd_id_generate_special(&p, &fe.cwd_id)) {
ret = dump_one_reg_file(fd, fe.cwd_id, &p);
if (ret < 0)
return ret;
}
close(fd);
fd = open_proc(pid, "root");
if (fd < 0)
return -1;
if (fill_fd_params_special(fd, &p))
return -1;
if (fd_id_generate_special(&p, &fe.root_id)) {
ret = dump_one_reg_file(fd, fe.root_id, &p);
if (ret < 0)
return ret;
}
close(fd);
pr_info("Dumping task cwd id %#x root id %#x\n",
fe.cwd_id, fe.root_id);
return pb_write_one(img_from_set(imgset, CR_FD_FS), &fe, PB_FS);
}
static inline u_int64_t encode_rlim(unsigned long val)
{
return val == RLIM_INFINITY ? -1 : val;
}
static int dump_task_rlimits(int pid, TaskRlimitsEntry *rls)
{
int res;
for (res = 0; res <rls->n_rlimits ; res++) {
struct rlimit lim;
if (prlimit(pid, res, NULL, &lim)) {
pr_perror("Can't get rlimit %d", res);
return -1;
}
rls->rlimits[res]->cur = encode_rlim(lim.rlim_cur);
rls->rlimits[res]->max = encode_rlim(lim.rlim_max);
}
return 0;
}
static int dump_filemap(pid_t pid, struct vma_area *vma_area,
const struct cr_imgset *imgset)
{
struct fd_parms p = FD_PARMS_INIT;
VmaEntry *vma = vma_area->e;
int ret = 0;
u32 id;
BUG_ON(!vma_area->vmst);
p.stat = *vma_area->vmst;
p.mnt_id = vma_area->mnt_id;
/*
* AUFS support to compensate for the kernel bug
* exposing branch pathnames in map_files.
*
* If the link found in vma_get_mapfile() pointed
* inside a branch, we should use the pathname
* from root that was saved in vma_area->aufs_rpath.
*/
if (vma_area->aufs_rpath) {
struct fd_link aufs_link;
strcpy(aufs_link.name, vma_area->aufs_rpath);
aufs_link.len = strlen(aufs_link.name);
p.link = &aufs_link;
}
/* Flags will be set during restore in get_filemap_fd() */
if (fd_id_generate_special(&p, &id))
ret = dump_one_reg_file(vma_area->vm_file_fd, id, &p);
vma->shmid = id;
return ret;
}
static int check_sysvipc_map_dump(pid_t pid, VmaEntry *vma)
{
if (root_ns_mask & CLONE_NEWIPC)
return 0;
pr_err("Task %d with SysVIPC shmem map @%"PRIx64" doesn't live in IPC ns\n",
pid, vma->start);
return -1;
}
static int get_task_auxv(pid_t pid, MmEntry *mm)
{
auxv_t mm_saved_auxv[AT_VECTOR_SIZE];
int fd, i, ret;
pr_info("Obtaining task auvx ...\n");
fd = open_proc(pid, "auxv");
if (fd < 0)
return -1;
ret = read(fd, mm_saved_auxv, sizeof(mm_saved_auxv));
if (ret < 0) {
ret = -1;
pr_perror("Error reading %d's auxv", pid);
goto err;
} else {
mm->n_mm_saved_auxv = ret / sizeof(auxv_t);
for (i = 0; i < mm->n_mm_saved_auxv; i++)
mm->mm_saved_auxv[i] = (u64)mm_saved_auxv[i];
}
ret = 0;
err:
close_safe(&fd);
return ret;
}
// <underscore> This is where memory maps are dumped.
static int dump_task_mm(pid_t pid, const struct proc_pid_stat *stat,
const struct parasite_dump_misc *misc,
const struct vm_area_list *vma_area_list,
const struct cr_imgset *imgset)
{
MmEntry mme = MM_ENTRY__INIT;
struct vma_area *vma_area;
int ret = -1, i = 0;
pr_info("\n");
pr_info("Dumping mm (pid: %d)\n", pid);
pr_info("----------------------------------------\n");
mme.n_vmas = vma_area_list->nr;
mme.vmas = xmalloc(mme.n_vmas * sizeof(VmaEntry *));
if (!mme.vmas)
goto err;
list_for_each_entry(vma_area, &vma_area_list->h, list) {
VmaEntry *vma = vma_area->e;
pr_info_vma(vma_area);
if (!vma_entry_is(vma, VMA_AREA_REGULAR))
ret = 0;
else if (vma_entry_is(vma, VMA_AREA_SYSVIPC))
ret = check_sysvipc_map_dump(pid, vma);
else if (vma_entry_is(vma, VMA_ANON_SHARED))
ret = add_shmem_area(pid, vma);
else if (vma_entry_is(vma, VMA_FILE_PRIVATE) ||
vma_entry_is(vma, VMA_FILE_SHARED))
ret = dump_filemap(pid, vma_area, imgset);
else if (vma_entry_is(vma, VMA_AREA_SOCKET))
ret = dump_socket_map(vma_area);
else
ret = 0;
if (ret)
goto err;
mme.vmas[i++] = vma;
if (vma_entry_is(vma, VMA_AREA_AIORING)) {
ret = dump_aio_ring(&mme, vma_area);
if (ret)
goto err;
}
}
mme.mm_start_code = stat->start_code;
mme.mm_end_code = stat->end_code;
mme.mm_start_data = stat->start_data;
mme.mm_end_data = stat->end_data;
mme.mm_start_stack = stat->start_stack;
mme.mm_start_brk = stat->start_brk;
mme.mm_arg_start = stat->arg_start;
mme.mm_arg_end = stat->arg_end;
mme.mm_env_start = stat->env_start;
mme.mm_env_end = stat->env_end;
mme.mm_brk = misc->brk;
mme.dumpable = misc->dumpable;
mme.has_dumpable = true;
mme.n_mm_saved_auxv = AT_VECTOR_SIZE;
mme.mm_saved_auxv = xmalloc(pb_repeated_size(&mme, mm_saved_auxv));
if (!mme.mm_saved_auxv)
goto err;
if (get_task_auxv(pid, &mme))
goto err;
if (dump_task_exe_link(pid, &mme))
goto err;
ret = pb_write_one(img_from_set(imgset, CR_FD_MM), &mme, PB_MM);
xfree(mme.mm_saved_auxv);
free_aios(&mme);
err:
return ret;
}
static int dump_task_creds(struct parasite_ctl *ctl,
const struct cr_imgset *fds)
{
CredsEntry ce = CREDS_ENTRY__INIT;
pr_info("\n");
pr_info("Dumping creds for %d)\n", ctl->pid.real);
pr_info("----------------------------------------\n");
if (parasite_dump_creds(ctl, &ce) < 0)
return -1;
if (collect_lsm_profile(ctl->pid.real, &ce) < 0)
return -1;
return pb_write_one(img_from_set(fds, CR_FD_CREDS), &ce, PB_CREDS);
}
static int get_task_futex_robust_list(pid_t pid, ThreadCoreEntry *info)
{
struct robust_list_head *head = NULL;
size_t len = 0;
int ret;
ret = sys_get_robust_list(pid, &head, &len);
if (ret == -ENOSYS) {
/*
* If the kernel says get_robust_list is not implemented, then
* check whether set_robust_list is also not implemented, in
* that case we can assume it is empty, since set_robust_list
* is the only way to populate it. This case is possible when
* "futex_cmpxchg_enabled" is unset in the kernel.
*
* The following system call should always fail, even if it is
* implemented, in which case it will return -EINVAL because
* len should be greater than zero.
*/
if (sys_set_robust_list(NULL, 0) != -ENOSYS)
goto err;
head = NULL;
len = 0;
} else if (ret) {
goto err;
}
info->futex_rla = encode_pointer(head);
info->futex_rla_len = (u32)len;
return 0;
err:
pr_err("Failed obtaining futex robust list on %d\n", pid);
return -1;
}
static int get_task_personality(pid_t pid, u32 *personality)
{
int fd, ret = -1;
pr_info("Obtaining personality ... ");
fd = open_proc(pid, "personality");
if (fd < 0)
goto err;
ret = read(fd, loc_buf, sizeof(loc_buf) - 1);
close(fd);
if (ret >= 0) {
loc_buf[ret] = '\0';
*personality = atoi(loc_buf);
}
err:
return ret;
}
static DECLARE_KCMP_TREE(vm_tree, KCMP_VM);
static DECLARE_KCMP_TREE(fs_tree, KCMP_FS);
static DECLARE_KCMP_TREE(files_tree, KCMP_FILES);
static DECLARE_KCMP_TREE(sighand_tree, KCMP_SIGHAND);
static int dump_task_kobj_ids(struct pstree_item *item)
{
int new;
struct kid_elem elem;
int pid = item->pid.real;
TaskKobjIdsEntry *ids = item->ids;
elem.pid = pid;
elem.idx = 0; /* really 0 for all */
elem.genid = 0; /* FIXME optimize */
new = 0;
ids->vm_id = kid_generate_gen(&vm_tree, &elem, &new);
if (!ids->vm_id || !new) {
pr_err("Can't make VM id for %d\n", pid);
return -1;
}
new = 0;
ids->fs_id = kid_generate_gen(&fs_tree, &elem, &new);
if (!ids->fs_id || !new) {
pr_err("Can't make FS id for %d\n", pid);
return -1;
}
new = 0;
ids->files_id = kid_generate_gen(&files_tree, &elem, &new);
if (!ids->files_id || (!new && !shared_fdtable(item))) {
pr_err("Can't make FILES id for %d\n", pid);
return -1;
}
new = 0;
ids->sighand_id = kid_generate_gen(&sighand_tree, &elem, &new);
if (!ids->sighand_id || !new) {
pr_err("Can't make IO id for %d\n", pid);
return -1;
}
return 0;
}
int get_task_ids(struct pstree_item *item)
{
int ret;
item->ids = xmalloc(sizeof(*item->ids));
if (!item->ids)
goto err;
task_kobj_ids_entry__init(item->ids);
if (item->state != TASK_DEAD) {
ret = dump_task_kobj_ids(item);
if (ret)
goto err_free;
ret = dump_task_ns_ids(item);
if (ret)
goto err_free;
}
return 0;
err_free:
xfree(item->ids);
item->ids = NULL;
err:
return -1;
}
static int dump_task_ids(struct pstree_item *item, const struct cr_imgset *cr_imgset)
{
return pb_write_one(img_from_set(cr_imgset, CR_FD_IDS), item->ids, PB_IDS);
}
int dump_thread_core(int pid, CoreEntry *core, const struct parasite_dump_thread *ti)
{
int ret;
ThreadCoreEntry *tc = core->thread_core;
ret = get_task_futex_robust_list(pid, tc);
if (!ret)
ret = dump_sched_info(pid, tc);
if (!ret) {
core_put_tls(core, ti->tls);
CORE_THREAD_ARCH_INFO(core)->clear_tid_addr = encode_pointer(ti->tid_addr);
BUG_ON(!tc->sas);
copy_sas(tc->sas, &ti->sas);
if (ti->pdeath_sig) {
tc->has_pdeath_sig = true;
tc->pdeath_sig = ti->pdeath_sig;
}
}
return ret;
}
static int dump_task_core_all(struct pstree_item *item,
const struct proc_pid_stat *stat,
const struct parasite_dump_misc *misc,
const struct cr_imgset *cr_imgset)
{
struct cr_img *img;
CoreEntry *core = item->core[0];
pid_t pid = item->pid.real;
int ret = -1;
pr_info("\n");
pr_info("Dumping core (pid: %d)\n", pid);
pr_info("----------------------------------------\n");
ret = get_task_personality(pid, &core->tc->personality);
if (ret < 0)
goto err;
if (item->creds->seccomp_mode != SECCOMP_MODE_DISABLED) {
pr_info("got seccomp mode %d for %d\n", item->creds->seccomp_mode, item->pid.virt);
core->tc->has_seccomp_mode = true;
core->tc->seccomp_mode = item->creds->seccomp_mode;
}
strncpy((char *)core->tc->comm, stat->comm, TASK_COMM_LEN);
core->tc->flags = stat->flags;
core->tc->task_state = item->state;
core->tc->exit_code = 0;
ret = dump_thread_core(pid, core, &misc->ti);
if (ret)
goto err;
ret = dump_task_rlimits(pid, core->tc->rlimits);
if (ret)
goto err;
core->tc->has_cg_set = true;
ret = dump_task_cgroup(item, &core->tc->cg_set);
if (ret)
goto err;
img = img_from_set(cr_imgset, CR_FD_CORE);
ret = pb_write_one(img, core, PB_CORE);
if (ret < 0)
goto err;
err:
pr_info("----------------------------------------\n");
return ret;
}
static int parse_children(pid_t pid, pid_t **_c, int *_n)
{
pid_t *ch = NULL;
int nr = 0;
DIR *dir;
struct dirent *de;
dir = opendir_proc(pid, "task");
if (dir == NULL)
return -1;
while ((de = readdir(dir))) {
int fd, len;
char *pos;
if (dir_dots(de))
continue;
fd = open_proc(pid, "task/%s/children", de->d_name);
if (fd < 0)
goto err;
len = read(fd, loc_buf, sizeof(loc_buf) - 1);
close(fd);
if (len < 0)
goto err;
loc_buf[len] = '\0';
pos = loc_buf;
while (1) {
pid_t val, *tmp;
val = strtol(pos, &pos, 0);
if (!val) {
BUG_ON(*pos != '\0');
break;
}
tmp = xrealloc(ch, (nr + 1) * sizeof(pid_t));
if (!tmp)
goto err;
ch = tmp;
ch[nr] = val;
nr++;
pos++; /* space goes after each pid */
}
}
*_c = ch;
*_n = nr;
closedir(dir);
return 0;
err:
closedir(dir);
xfree(ch);
return -1;
}
static inline bool child_collected(struct pstree_item *i, pid_t pid)
{
struct pstree_item *c;
list_for_each_entry(c, &i->children, sibling)
if (c->pid.real == pid)
return true;
return false;
}
static int collect_task(struct pstree_item *item);
static int collect_children(struct pstree_item *item)
{
pid_t *ch;
int ret, i, nr_children, nr_inprogress;
ret = parse_children(item->pid.real, &ch, &nr_children);
if (ret < 0)
return ret;
nr_inprogress = 0;
for (i = 0; i < nr_children; i++) {
struct pstree_item *c;
pid_t pid = ch[i];
/* Is it already frozen? */
if (child_collected(item, pid))
continue;
nr_inprogress++;
pr_info("Seized task %d, state %d\n", pid, ret);
c = alloc_pstree_item();
if (c == NULL) {
ret = -1;
goto free;
}
ret = seize_task(pid, item->pid.real, &c->creds);
if (ret < 0) {
/*
* Here is a race window between parse_children() and seize(),
* so the task could die for these time.
* Don't worry, will try again on the next attempt. The number
* of attempts is restricted, so it will exit if something
* really wrong.
*/
ret = 0;
xfree(c);
continue;
}
c->pid.real = pid;
c->parent = item;
c->state = ret;
list_add_tail(&c->sibling, &item->children);
/* Here is a recursive call (Depth-first search) */
ret = collect_task(c);
if (ret < 0)
goto free;
}
free:
xfree(ch);
return ret < 0 ? ret : nr_inprogress;
}
static void unseize_task_and_threads(const struct pstree_item *item, int st)
{
int i;
if (item->state == TASK_DEAD)
return;
/*
* The st is the state we want to switch tasks into,
* the item->state is the state task was in when we seized one.
*/
unseize_task(item->pid.real, item->state, st);
for (i = 1; i < item->nr_threads; i++)
ptrace(PTRACE_DETACH, item->threads[i].real, NULL, NULL);
}
static void pstree_switch_state(struct pstree_item *root_item, int st)
{
struct pstree_item *item = root_item;
pr_info("Unfreezing tasks into %d\n", st);
for_each_pstree_item(item)
unseize_task_and_threads(item, st);
}
static pid_t item_ppid(const struct pstree_item *item)
{
item = item->parent;
return item ? item->pid.real : -1;
}
static inline bool thread_collected(struct pstree_item *i, pid_t tid)
{
int t;
if (i->pid.real == tid) /* thread leader is collected as task */
return true;
for (t = 0; t < i->nr_threads; t++)
if (tid == i->threads[t].real)
return true;
return false;
}
static int collect_threads(struct pstree_item *item)
{
struct pid *threads = NULL;
int nr_threads = 0, i = 0, ret, nr_inprogress, nr_stopped = 0;
ret = parse_threads(item->pid.real, &threads, &nr_threads);
if (ret < 0)
goto err;
if ((item->state == TASK_DEAD) && (nr_threads > 1)) {
pr_err("Zombies with threads are not supported\n");
goto err;
}
/* The number of threads can't be less than allready frozen */
item->threads = xrealloc(item->threads, nr_threads * sizeof(struct pid));
if (item->threads == NULL)
return -1;
if (item->nr_threads == 0) {
item->threads[0].real = item->pid.real;
item->nr_threads = 1;
}
nr_inprogress = 0;
for (i = 0; i < nr_threads; i++) {
pid_t pid = threads[i].real;
if (thread_collected(item, pid))
continue;
nr_inprogress++;
pr_info("\tSeizing %d's %d thread\n",
item->pid.real, pid);
ret = seize_task(pid, item_ppid(item), &item->creds);
if (ret < 0) {
/*
* Here is a race window between parse_threads() and seize(),
* so the task could die for these time.
* Don't worry, will try again on the next attempt. The number
* of attempts is restricted, so it will exit if something
* really wrong.
*/
continue;
}
BUG_ON(item->nr_threads + 1 > nr_threads);
item->threads[item->nr_threads].real = pid;
item->nr_threads++;
if (ret == TASK_DEAD) {
pr_err("Zombie thread not supported\n");
goto err;
}
if (ret == TASK_STOPPED) {
nr_stopped++;
}
}
if (nr_stopped && nr_stopped != nr_inprogress) {
pr_err("Individually stopped threads not supported\n");
goto err;
}
xfree(threads);
return nr_inprogress;
err:
xfree(threads);
return -1;
}
static int collect_loop(struct pstree_item *item,
int (*collect)(struct pstree_item *))
{
int attempts = NR_ATTEMPTS, nr_inprogress = 1;
/*
* While we scan the proc and seize the children/threads
* new ones can appear (with clone(CLONE_PARENT) or with
* pthread_create). Thus, after one go, we need to repeat
* the scan-and-freeze again collecting new arrivals. As
* new guys may appear again we do NR_ATTEMPTS passes and
* fail to seize the item if new tasks/threads still
* appear.
*/
while (nr_inprogress > 0 && attempts) {
attempts--;
nr_inprogress = collect(item);
}
/*
* We may fail to collect items or run out of attempts.
* In the former case nr_inprogress will be negative, in
* the latter -- positive. Thus it's enough just to check
* for "no more new stuff" and say "we're OK" if so.
*/
return (nr_inprogress == 0) ? 0 : -1;
}
static int collect_task(struct pstree_item *item)
{