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cgroup-util: allow cg_read_pid() to skip unmapped (zero) pids

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This commit is contained in:
Timo Rothenpieler
2024-05-14 16:12:20 +02:00
committed by Zbigniew Jędrzejewski-Szmek
parent 19614a08d1
commit 00f1714311
7 changed files with 49 additions and 33 deletions
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src/basic/cgroup-util.c
+28 -19
View File
@@ -95,7 +95,7 @@ int cg_enumerate_processes(const char *controller, const char *path, FILE **ret)
return cg_enumerate_items(controller, path, ret, "cgroup.procs");
}
int cg_read_pid(FILE *f, pid_t *ret) {
int cg_read_pid(FILE *f, pid_t *ret, CGroupFlags flags) {
unsigned long ul;
/* Note that the cgroup.procs might contain duplicates! See cgroups.txt for details. */
@@ -103,27 +103,33 @@ int cg_read_pid(FILE *f, pid_t *ret) {
assert(f);
assert(ret);
errno = 0;
if (fscanf(f, "%lu", &ul) != 1) {
for (;;) {
errno = 0;
if (fscanf(f, "%lu", &ul) != 1) {
if (feof(f)) {
*ret = 0;
return 0;
if (feof(f)) {
*ret = 0;
return 0;
}
return errno_or_else(EIO);
}
return errno_or_else(EIO);
if (ul > PID_T_MAX)
return -EIO;
/* In some circumstances (e.g. WSL), cgroups might contain unmappable PIDs from other
* contexts. These show up as zeros, and depending on the caller, can either be plain
* skipped over, or returned as-is. */
if (ul == 0 && !FLAGS_SET(flags, CGROUP_DONT_SKIP_UNMAPPED))
continue;
*ret = (pid_t) ul;
return 1;
}
if (ul <= 0)
return -EIO;
if (ul > PID_T_MAX)
return -EIO;
*ret = (pid_t) ul;
return 1;
}
int cg_read_pidref(FILE *f, PidRef *ret) {
int cg_read_pidref(FILE *f, PidRef *ret, CGroupFlags flags) {
int r;
assert(f);
@@ -132,7 +138,7 @@ int cg_read_pidref(FILE *f, PidRef *ret) {
for (;;) {
pid_t pid;
r = cg_read_pid(f, &pid);
r = cg_read_pid(f, &pid, flags);
if (r < 0)
return r;
if (r == 0) {
@@ -140,6 +146,9 @@ int cg_read_pidref(FILE *f, PidRef *ret) {
return 0;
}
if (pid == 0)
return -EREMOTE;
r = pidref_set_pid(ret, pid);
if (r >= 0)
return 1;
@@ -343,7 +352,7 @@ static int cg_kill_items(
for (;;) {
_cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
r = cg_read_pidref(f, &pidref);
r = cg_read_pidref(f, &pidref, /* flags = */ 0);
if (r < 0)
return RET_GATHER(ret, r);
if (r == 0)
@@ -938,7 +947,7 @@ int cg_is_empty(const char *controller, const char *path) {
if (r < 0)
return r;
r = cg_read_pid(f, &pid);
r = cg_read_pid(f, &pid, CGROUP_DONT_SKIP_UNMAPPED);
if (r < 0)
return r;
src/basic/cgroup-util.h
+9 -8
View File
@@ -183,20 +183,21 @@ typedef enum CGroupUnified {
int cg_path_open(const char *controller, const char *path);
int cg_cgroupid_open(int fsfd, uint64_t id);
typedef enum CGroupFlags {
CGROUP_SIGCONT = 1 << 0,
CGROUP_IGNORE_SELF = 1 << 1,
CGROUP_REMOVE = 1 << 2,
CGROUP_DONT_SKIP_UNMAPPED = 1 << 3,
} CGroupFlags;
int cg_enumerate_processes(const char *controller, const char *path, FILE **ret);
int cg_read_pid(FILE *f, pid_t *ret);
int cg_read_pidref(FILE *f, PidRef *ret);
int cg_read_pid(FILE *f, pid_t *ret, CGroupFlags flags);
int cg_read_pidref(FILE *f, PidRef *ret, CGroupFlags flags);
int cg_read_event(const char *controller, const char *path, const char *event, char **ret);
int cg_enumerate_subgroups(const char *controller, const char *path, DIR **ret);
int cg_read_subgroup(DIR *d, char **ret);
typedef enum CGroupFlags {
CGROUP_SIGCONT = 1 << 0,
CGROUP_IGNORE_SELF = 1 << 1,
CGROUP_REMOVE = 1 << 2,
} CGroupFlags;
typedef int (*cg_kill_log_func_t)(const PidRef *pid, int sig, void *userdata);
int cg_kill(const char *path, int sig, CGroupFlags flags, Set *s, cg_kill_log_func_t kill_log, void *userdata);