From a0e0018c9a7ef5ce7f6d2c3ae16aecbbd16a8f67 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 4 May 2024 16:18:53 +0200 Subject: Adding upstream version 6.1.0. Signed-off-by: Daniel Baumann --- lib/fs.c | 369 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 369 insertions(+) create mode 100644 lib/fs.c (limited to 'lib/fs.c') 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 + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "utils.h" + +#ifndef HAVE_HANDLE_AT +# include +#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; +} -- cgit v1.2.3