From: Michael Tremer <michael.tremer@ipfire.org>
Date: Tue, 9 Aug 2022 14:46:04 +0000 (+0000)
Subject: cgroup: Implement legacy way to kill processes
X-Git-Tag: 0.9.28~545
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=034ba70ea197ad6a80627edec7798d09bde5260f;p=pakfire.git

cgroup: Implement legacy way to kill processes

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/libpakfire/cgroup.c b/src/libpakfire/cgroup.c
index 873d13dae..2d7d8a3d5 100644
--- a/src/libpakfire/cgroup.c
+++ b/src/libpakfire/cgroup.c
@@ -20,6 +20,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <sys/types.h>
 
@@ -229,6 +230,35 @@ ERROR:
 	return fd;
 }
 
+static int pakfire_cgroup_access(struct pakfire_cgroup* cgroup, const char* path,
+		int mode, int flags) {
+	return faccessat(cgroup->fd, path, mode, flags);
+}
+
+static FILE* pakfire_cgroup_open_file(struct pakfire_cgroup* cgroup,
+		const char* path, const char* mode) {
+	FILE* f = NULL;
+
+	// Open cgroup.procs
+	int fd = openat(cgroup->fd, "cgroup.procs", O_CLOEXEC);
+	if (fd < 0) {
+		ERROR(cgroup->pakfire, "%s: Could not open %s: %m\n",
+			pakfire_cgroup_name(cgroup), path);
+		goto ERROR;
+	}
+
+	// Convert into file handle
+	f = fdopen(fd, mode);
+	if (!f)
+		goto ERROR;
+
+ERROR:
+	if (fd)
+		close(fd);
+
+	return f;
+}
+
 static ssize_t pakfire_cgroup_read(struct pakfire_cgroup* cgroup, const char* path,
 		char* buffer, size_t length) {
 	ssize_t bytes_read = -1;
@@ -498,15 +528,72 @@ struct pakfire_cgroup* pakfire_cgroup_unref(struct pakfire_cgroup* cgroup) {
 	return NULL;
 }
 
+static int pakfire_cgroup_procs_callback(struct pakfire_cgroup* cgroup,
+		int (*callback)(struct pakfire_cgroup* cgroup, pid_t pid, void* data), void* data) {
+	int r = 0;
+
+	// Check if we have a callback
+	if (!callback) {
+		errno = EINVAL;
+		return 1;
+	}
+
+	// Open cgroup.procs
+	FILE* f = pakfire_cgroup_open_file(cgroup, "cgroup.procs", "r");
+	if (!f)
+		return 1;
+
+	char* line = NULL;
+	size_t l = 0;
+
+	// Walk through all PIDs
+	while (1) {
+		ssize_t bytes_read = getline(&line, &l, f);
+		if (bytes_read < 0)
+			break;
+
+		// Parse PID
+		pid_t pid = strtol(line, NULL, 10);
+
+		// Call callback function
+		r = callback(cgroup, pid, data);
+		if (r)
+			break;
+	}
+
+	// Cleanup
+	fclose(f);
+
+	return r;
+}
+
+static int send_sigkill(struct pakfire_cgroup* cgroup, const pid_t pid, void* data) {
+	DEBUG(cgroup->pakfire, "Sending signal SIGKILL to PID %d\n", pid);
+
+	int r = kill(pid, SIGKILL);
+	if (r < 0 && errno != ESRCH) {
+		ERROR(cgroup->pakfire, "Could not send signal SIGKILL to PID %d: %m\n", pid);
+		return r;
+	}
+
+	return r;
+}
+
 /*
 	Immediately kills all processes in this cgroup
 */
 int pakfire_cgroup_killall(struct pakfire_cgroup* cgroup) {
-	int r = pakfire_cgroup_write(cgroup, "cgroup.kill", "1");
-	if (r)
-		ERROR(cgroup->pakfire, "Could not kill processes: %m\n");
+	DEBUG(cgroup->pakfire, "%s: Killing all processes\n", pakfire_cgroup_name(cgroup));
 
-	return r;
+	// Do we have support for cgroup.kill?
+	int r = pakfire_cgroup_access(cgroup, "cgroup.kill", F_OK, 0);
+
+	// Fall back to the legacy version
+	if (r && errno == ENOENT) {
+		return pakfire_cgroup_procs_callback(cgroup, send_sigkill, NULL);
+	}
+
+	return pakfire_cgroup_write(cgroup, "cgroup.kill", "1");
 }
 
 /*