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-rw-r--r--lib/fs.c369
1 files changed, 369 insertions, 0 deletions
diff --git a/lib/fs.c b/lib/fs.c
new file mode 100644
index 0000000..3752931
--- /dev/null
+++ b/lib/fs.c
@@ -0,0 +1,369 @@
+/*
+ * fs.c filesystem APIs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors: David Ahern <dsa@cumulusnetworks.com>
+ *
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/mount.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+
+#include "utils.h"
+
+#ifndef HAVE_HANDLE_AT
+# include <sys/syscall.h>
+#endif
+
+#define CGROUP2_FS_NAME "cgroup2"
+
+/* if not already mounted cgroup2 is mounted here for iproute2's use */
+#define MNT_CGRP2_PATH "/var/run/cgroup2"
+
+
+#ifndef HAVE_HANDLE_AT
+struct file_handle {
+ unsigned handle_bytes;
+ int handle_type;
+ unsigned char f_handle[];
+};
+
+static int name_to_handle_at(int dirfd, const char *pathname,
+ struct file_handle *handle, int *mount_id, int flags)
+{
+ return syscall(__NR_name_to_handle_at, dirfd, pathname, handle,
+ mount_id, flags);
+}
+
+static int open_by_handle_at(int mount_fd, struct file_handle *handle, int flags)
+{
+ return syscall(__NR_open_by_handle_at, mount_fd, handle, flags);
+}
+#endif
+
+/* return mount path of first occurrence of given fstype */
+static char *find_fs_mount(const char *fs_to_find)
+{
+ char path[4096];
+ char fstype[128]; /* max length of any filesystem name */
+ char *mnt = NULL;
+ FILE *fp;
+
+ fp = fopen("/proc/mounts", "r");
+ if (!fp) {
+ fprintf(stderr,
+ "Failed to open mounts file: %s\n", strerror(errno));
+ return NULL;
+ }
+
+ while (fscanf(fp, "%*s %4095s %127s %*s %*d %*d\n",
+ path, fstype) == 2) {
+ if (strcmp(fstype, fs_to_find) == 0) {
+ mnt = strdup(path);
+ break;
+ }
+ }
+
+ fclose(fp);
+
+ return mnt;
+}
+
+/* caller needs to free string returned */
+char *find_cgroup2_mount(bool do_mount)
+{
+ char *mnt = find_fs_mount(CGROUP2_FS_NAME);
+
+ if (mnt)
+ return mnt;
+
+ if (!do_mount) {
+ fprintf(stderr, "Failed to find cgroup2 mount\n");
+ return NULL;
+ }
+
+ mnt = strdup(MNT_CGRP2_PATH);
+ if (!mnt) {
+ fprintf(stderr, "Failed to allocate memory for cgroup2 path\n");
+ return NULL;
+
+ }
+
+ if (make_path(mnt, 0755)) {
+ fprintf(stderr, "Failed to setup cgroup2 directory\n");
+ free(mnt);
+ return NULL;
+ }
+
+ if (mount("none", mnt, CGROUP2_FS_NAME, 0, NULL)) {
+ /* EBUSY means already mounted */
+ if (errno == EBUSY)
+ goto out;
+
+ if (errno == ENODEV) {
+ fprintf(stderr,
+ "Failed to mount cgroup2. Are CGROUPS enabled in your kernel?\n");
+ } else {
+ fprintf(stderr,
+ "Failed to mount cgroup2: %s\n",
+ strerror(errno));
+ }
+ free(mnt);
+ return NULL;
+ }
+out:
+ return mnt;
+}
+
+__u64 get_cgroup2_id(const char *path)
+{
+ char fh_buf[sizeof(struct file_handle) + sizeof(__u64)] = { 0 };
+ struct file_handle *fhp = (struct file_handle *)fh_buf;
+ union {
+ __u64 id;
+ unsigned char bytes[sizeof(__u64)];
+ } cg_id = { .id = 0 };
+ char *mnt = NULL;
+ int mnt_fd = -1;
+ int mnt_id;
+
+ if (!path) {
+ fprintf(stderr, "Invalid cgroup2 path\n");
+ return 0;
+ }
+
+ fhp->handle_bytes = sizeof(__u64);
+ if (name_to_handle_at(AT_FDCWD, path, fhp, &mnt_id, 0) < 0) {
+ /* try at cgroup2 mount */
+
+ while (*path == '/')
+ path++;
+ if (*path == '\0') {
+ fprintf(stderr, "Invalid cgroup2 path\n");
+ goto out;
+ }
+
+ mnt = find_cgroup2_mount(false);
+ if (!mnt)
+ goto out;
+
+ mnt_fd = open(mnt, O_RDONLY);
+ if (mnt_fd < 0) {
+ fprintf(stderr, "Failed to open cgroup2 mount\n");
+ goto out;
+ }
+
+ fhp->handle_bytes = sizeof(__u64);
+ if (name_to_handle_at(mnt_fd, path, fhp, &mnt_id, 0) < 0) {
+ fprintf(stderr, "Failed to get cgroup2 ID: %s\n",
+ strerror(errno));
+ goto out;
+ }
+ }
+ if (fhp->handle_bytes != sizeof(__u64)) {
+ fprintf(stderr, "Invalid size of cgroup2 ID\n");
+ goto out;
+ }
+
+ memcpy(cg_id.bytes, fhp->f_handle, sizeof(__u64));
+
+out:
+ if (mnt_fd >= 0)
+ close(mnt_fd);
+ free(mnt);
+
+ return cg_id.id;
+}
+
+#define FILEID_INO32_GEN 1
+
+/* caller needs to free string returned */
+char *get_cgroup2_path(__u64 id, bool full)
+{
+ char fh_buf[sizeof(struct file_handle) + sizeof(__u64)] = { 0 };
+ struct file_handle *fhp = (struct file_handle *)fh_buf;
+ union {
+ __u64 id;
+ unsigned char bytes[sizeof(__u64)];
+ } cg_id = { .id = id };
+ int mnt_fd = -1, fd = -1;
+ char link_buf[PATH_MAX];
+ char *path = NULL;
+ char fd_path[64];
+ int link_len;
+ char *mnt = NULL;
+
+ if (!id) {
+ fprintf(stderr, "Invalid cgroup2 ID\n");
+ goto out;
+ }
+
+ mnt = find_cgroup2_mount(false);
+ if (!mnt)
+ goto out;
+
+ mnt_fd = open(mnt, O_RDONLY);
+ if (mnt_fd < 0) {
+ fprintf(stderr, "Failed to open cgroup2 mount\n");
+ goto out;
+ }
+
+ fhp->handle_bytes = sizeof(__u64);
+ fhp->handle_type = FILEID_INO32_GEN;
+ memcpy(fhp->f_handle, cg_id.bytes, sizeof(__u64));
+
+ fd = open_by_handle_at(mnt_fd, fhp, 0);
+ if (fd < 0) {
+ fprintf(stderr, "Failed to open cgroup2 by ID\n");
+ goto out;
+ }
+
+ snprintf(fd_path, sizeof(fd_path), "/proc/self/fd/%d", fd);
+ link_len = readlink(fd_path, link_buf, sizeof(link_buf) - 1);
+ if (link_len < 0) {
+ fprintf(stderr,
+ "Failed to read value of symbolic link %s\n",
+ fd_path);
+ goto out;
+ }
+ link_buf[link_len] = '\0';
+
+ if (full)
+ path = strdup(link_buf);
+ else
+ path = strdup(link_buf + strlen(mnt));
+ if (!path)
+ fprintf(stderr,
+ "Failed to allocate memory for cgroup2 path\n");
+
+out:
+ if (fd >= 0)
+ close(fd);
+ if (mnt_fd >= 0)
+ close(mnt_fd);
+ free(mnt);
+
+ return path;
+}
+
+int make_path(const char *path, mode_t mode)
+{
+ char *dir, *delim;
+ int rc = -1;
+
+ delim = dir = strdup(path);
+ if (dir == NULL) {
+ fprintf(stderr, "strdup failed copying path");
+ return -1;
+ }
+
+ /* skip '/' -- it had better exist */
+ if (*delim == '/')
+ delim++;
+
+ while (1) {
+ delim = strchr(delim, '/');
+ if (delim)
+ *delim = '\0';
+
+ rc = mkdir(dir, mode);
+ if (rc && errno != EEXIST) {
+ fprintf(stderr, "mkdir failed for %s: %s\n",
+ dir, strerror(errno));
+ goto out;
+ }
+
+ if (delim == NULL)
+ break;
+
+ *delim = '/';
+ delim++;
+ if (*delim == '\0')
+ break;
+ }
+ rc = 0;
+out:
+ free(dir);
+
+ return rc;
+}
+
+int get_command_name(const char *pid, char *comm, size_t len)
+{
+ char path[PATH_MAX];
+ char line[128];
+ FILE *fp;
+
+ if (snprintf(path, sizeof(path),
+ "/proc/%s/status", pid) >= sizeof(path)) {
+ return -1;
+ }
+
+ fp = fopen(path, "r");
+ if (!fp)
+ return -1;
+
+ comm[0] = '\0';
+ while (fgets(line, sizeof(line), fp)) {
+ char *nl, *name;
+
+ name = strstr(line, "Name:");
+ if (!name)
+ continue;
+
+ name += 5;
+ while (isspace(*name))
+ name++;
+
+ nl = strchr(name, '\n');
+ if (nl)
+ *nl = '\0';
+
+ strlcpy(comm, name, len);
+ break;
+ }
+
+ fclose(fp);
+
+ return 0;
+}
+
+int get_task_name(pid_t pid, char *name, size_t len)
+{
+ char path[PATH_MAX];
+ FILE *f;
+
+ if (!pid)
+ return -1;
+
+ if (snprintf(path, sizeof(path), "/proc/%d/comm", pid) >= sizeof(path))
+ return -1;
+
+ f = fopen(path, "r");
+ if (!f)
+ return -1;
+
+ if (!fgets(name, len, f))
+ return -1;
+
+ /* comm ends in \n, get rid of it */
+ name[strcspn(name, "\n")] = '\0';
+
+ fclose(f);
+
+ return 0;
+}