559 lines
10 KiB
C
559 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <ctype.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/vfs.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/mount.h>
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#include "fs.h"
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#include "debug-internal.h"
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#define _STR(x) #x
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#define STR(x) _STR(x)
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#ifndef SYSFS_MAGIC
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#define SYSFS_MAGIC 0x62656572
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#endif
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#ifndef PROC_SUPER_MAGIC
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#define PROC_SUPER_MAGIC 0x9fa0
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#endif
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#ifndef DEBUGFS_MAGIC
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#define DEBUGFS_MAGIC 0x64626720
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#endif
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#ifndef TRACEFS_MAGIC
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#define TRACEFS_MAGIC 0x74726163
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#endif
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#ifndef HUGETLBFS_MAGIC
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#define HUGETLBFS_MAGIC 0x958458f6
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#endif
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#ifndef BPF_FS_MAGIC
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#define BPF_FS_MAGIC 0xcafe4a11
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#endif
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static const char * const sysfs__fs_known_mountpoints[] = {
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"/sys",
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0,
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};
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static const char * const procfs__known_mountpoints[] = {
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"/proc",
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0,
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};
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#ifndef DEBUGFS_DEFAULT_PATH
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#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
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#endif
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static const char * const debugfs__known_mountpoints[] = {
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DEBUGFS_DEFAULT_PATH,
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"/debug",
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0,
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};
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#ifndef TRACEFS_DEFAULT_PATH
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#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
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#endif
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static const char * const tracefs__known_mountpoints[] = {
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TRACEFS_DEFAULT_PATH,
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"/sys/kernel/debug/tracing",
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"/tracing",
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"/trace",
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0,
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};
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static const char * const hugetlbfs__known_mountpoints[] = {
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0,
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};
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static const char * const bpf_fs__known_mountpoints[] = {
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"/sys/fs/bpf",
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0,
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};
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struct fs {
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const char *name;
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const char * const *mounts;
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char path[PATH_MAX];
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bool found;
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bool checked;
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long magic;
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};
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enum {
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FS__SYSFS = 0,
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FS__PROCFS = 1,
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FS__DEBUGFS = 2,
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FS__TRACEFS = 3,
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FS__HUGETLBFS = 4,
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FS__BPF_FS = 5,
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};
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#ifndef TRACEFS_MAGIC
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#define TRACEFS_MAGIC 0x74726163
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#endif
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static struct fs fs__entries[] = {
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[FS__SYSFS] = {
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.name = "sysfs",
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.mounts = sysfs__fs_known_mountpoints,
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.magic = SYSFS_MAGIC,
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.checked = false,
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},
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[FS__PROCFS] = {
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.name = "proc",
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.mounts = procfs__known_mountpoints,
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.magic = PROC_SUPER_MAGIC,
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.checked = false,
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},
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[FS__DEBUGFS] = {
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.name = "debugfs",
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.mounts = debugfs__known_mountpoints,
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.magic = DEBUGFS_MAGIC,
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.checked = false,
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},
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[FS__TRACEFS] = {
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.name = "tracefs",
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.mounts = tracefs__known_mountpoints,
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.magic = TRACEFS_MAGIC,
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.checked = false,
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},
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[FS__HUGETLBFS] = {
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.name = "hugetlbfs",
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.mounts = hugetlbfs__known_mountpoints,
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.magic = HUGETLBFS_MAGIC,
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.checked = false,
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},
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[FS__BPF_FS] = {
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.name = "bpf",
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.mounts = bpf_fs__known_mountpoints,
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.magic = BPF_FS_MAGIC,
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.checked = false,
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},
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};
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static bool fs__read_mounts(struct fs *fs)
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{
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bool found = false;
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char type[100];
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FILE *fp;
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fp = fopen("/proc/mounts", "r");
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if (fp == NULL)
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return NULL;
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while (!found &&
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fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
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fs->path, type) == 2) {
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if (strcmp(type, fs->name) == 0)
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found = true;
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}
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fclose(fp);
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fs->checked = true;
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return fs->found = found;
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}
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static int fs__valid_mount(const char *fs, long magic)
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{
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struct statfs st_fs;
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if (statfs(fs, &st_fs) < 0)
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return -ENOENT;
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else if ((long)st_fs.f_type != magic)
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return -ENOENT;
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return 0;
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}
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static bool fs__check_mounts(struct fs *fs)
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{
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const char * const *ptr;
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ptr = fs->mounts;
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while (*ptr) {
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if (fs__valid_mount(*ptr, fs->magic) == 0) {
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fs->found = true;
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strcpy(fs->path, *ptr);
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return true;
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}
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ptr++;
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}
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return false;
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}
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static void mem_toupper(char *f, size_t len)
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{
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while (len) {
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*f = toupper(*f);
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f++;
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len--;
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}
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}
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/*
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* Check for "NAME_PATH" environment variable to override fs location (for
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* testing). This matches the recommendation in Documentation/admin-guide/sysfs-rules.rst
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* for SYSFS_PATH.
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*/
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static bool fs__env_override(struct fs *fs)
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{
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char *override_path;
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size_t name_len = strlen(fs->name);
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/* name + "_PATH" + '\0' */
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char upper_name[name_len + 5 + 1];
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memcpy(upper_name, fs->name, name_len);
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mem_toupper(upper_name, name_len);
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strcpy(&upper_name[name_len], "_PATH");
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override_path = getenv(upper_name);
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if (!override_path)
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return false;
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fs->found = true;
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fs->checked = true;
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strncpy(fs->path, override_path, sizeof(fs->path) - 1);
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fs->path[sizeof(fs->path) - 1] = '\0';
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return true;
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}
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static const char *fs__get_mountpoint(struct fs *fs)
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{
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if (fs__env_override(fs))
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return fs->path;
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if (fs__check_mounts(fs))
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return fs->path;
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if (fs__read_mounts(fs))
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return fs->path;
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return NULL;
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}
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static const char *fs__mountpoint(int idx)
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{
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struct fs *fs = &fs__entries[idx];
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if (fs->found)
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return (const char *)fs->path;
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/* the mount point was already checked for the mount point
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* but and did not exist, so return NULL to avoid scanning again.
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* This makes the found and not found paths cost equivalent
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* in case of multiple calls.
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*/
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if (fs->checked)
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return NULL;
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return fs__get_mountpoint(fs);
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}
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static const char *mount_overload(struct fs *fs)
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{
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size_t name_len = strlen(fs->name);
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/* "PERF_" + name + "_ENVIRONMENT" + '\0' */
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char upper_name[5 + name_len + 12 + 1];
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snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
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mem_toupper(upper_name, name_len);
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return getenv(upper_name) ?: *fs->mounts;
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}
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static const char *fs__mount(int idx)
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{
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struct fs *fs = &fs__entries[idx];
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const char *mountpoint;
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if (fs__mountpoint(idx))
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return (const char *)fs->path;
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mountpoint = mount_overload(fs);
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if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
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return NULL;
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return fs__check_mounts(fs) ? fs->path : NULL;
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}
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#define FS(name, idx) \
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const char *name##__mountpoint(void) \
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{ \
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return fs__mountpoint(idx); \
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} \
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\
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const char *name##__mount(void) \
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{ \
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return fs__mount(idx); \
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} \
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\
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bool name##__configured(void) \
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{ \
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return name##__mountpoint() != NULL; \
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}
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FS(sysfs, FS__SYSFS);
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FS(procfs, FS__PROCFS);
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FS(debugfs, FS__DEBUGFS);
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FS(tracefs, FS__TRACEFS);
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FS(hugetlbfs, FS__HUGETLBFS);
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FS(bpf_fs, FS__BPF_FS);
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int filename__read_int(const char *filename, int *value)
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{
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char line[64];
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int fd = open(filename, O_RDONLY), err = -1;
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if (fd < 0)
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return -1;
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if (read(fd, line, sizeof(line)) > 0) {
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*value = atoi(line);
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err = 0;
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}
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close(fd);
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return err;
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}
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static int filename__read_ull_base(const char *filename,
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unsigned long long *value, int base)
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{
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char line[64];
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int fd = open(filename, O_RDONLY), err = -1;
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if (fd < 0)
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return -1;
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if (read(fd, line, sizeof(line)) > 0) {
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*value = strtoull(line, NULL, base);
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if (*value != ULLONG_MAX)
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err = 0;
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}
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close(fd);
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return err;
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}
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/*
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* Parses @value out of @filename with strtoull.
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* By using 16 for base to treat the number as hex.
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*/
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int filename__read_xll(const char *filename, unsigned long long *value)
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{
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return filename__read_ull_base(filename, value, 16);
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}
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/*
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* Parses @value out of @filename with strtoull.
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* By using 0 for base, the strtoull detects the
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* base automatically (see man strtoull).
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*/
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int filename__read_ull(const char *filename, unsigned long long *value)
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{
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return filename__read_ull_base(filename, value, 0);
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}
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#define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */
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int filename__read_str(const char *filename, char **buf, size_t *sizep)
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{
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size_t size = 0, alloc_size = 0;
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void *bf = NULL, *nbf;
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int fd, n, err = 0;
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char sbuf[STRERR_BUFSIZE];
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fd = open(filename, O_RDONLY);
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if (fd < 0)
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return -errno;
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do {
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if (size == alloc_size) {
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alloc_size += BUFSIZ;
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nbf = realloc(bf, alloc_size);
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if (!nbf) {
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err = -ENOMEM;
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break;
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}
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bf = nbf;
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}
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n = read(fd, bf + size, alloc_size - size);
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if (n < 0) {
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if (size) {
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pr_warn("read failed %d: %s\n", errno,
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strerror_r(errno, sbuf, sizeof(sbuf)));
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err = 0;
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} else
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err = -errno;
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break;
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}
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size += n;
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} while (n > 0);
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if (!err) {
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*sizep = size;
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*buf = bf;
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} else
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free(bf);
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close(fd);
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return err;
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}
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int filename__write_int(const char *filename, int value)
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{
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int fd = open(filename, O_WRONLY), err = -1;
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char buf[64];
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if (fd < 0)
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return err;
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sprintf(buf, "%d", value);
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if (write(fd, buf, sizeof(buf)) == sizeof(buf))
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err = 0;
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close(fd);
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return err;
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}
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int procfs__read_str(const char *entry, char **buf, size_t *sizep)
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{
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char path[PATH_MAX];
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const char *procfs = procfs__mountpoint();
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if (!procfs)
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return -1;
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snprintf(path, sizeof(path), "%s/%s", procfs, entry);
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return filename__read_str(path, buf, sizep);
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}
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static int sysfs__read_ull_base(const char *entry,
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unsigned long long *value, int base)
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{
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char path[PATH_MAX];
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const char *sysfs = sysfs__mountpoint();
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if (!sysfs)
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return -1;
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snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
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return filename__read_ull_base(path, value, base);
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}
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int sysfs__read_xll(const char *entry, unsigned long long *value)
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{
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return sysfs__read_ull_base(entry, value, 16);
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}
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int sysfs__read_ull(const char *entry, unsigned long long *value)
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{
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return sysfs__read_ull_base(entry, value, 0);
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}
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int sysfs__read_int(const char *entry, int *value)
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{
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char path[PATH_MAX];
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const char *sysfs = sysfs__mountpoint();
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if (!sysfs)
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return -1;
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snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
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return filename__read_int(path, value);
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}
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int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
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{
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char path[PATH_MAX];
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const char *sysfs = sysfs__mountpoint();
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if (!sysfs)
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return -1;
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snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
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return filename__read_str(path, buf, sizep);
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}
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int sysfs__read_bool(const char *entry, bool *value)
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{
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char *buf;
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size_t size;
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int ret;
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ret = sysfs__read_str(entry, &buf, &size);
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if (ret < 0)
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return ret;
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switch (buf[0]) {
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case '1':
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case 'y':
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case 'Y':
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*value = true;
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break;
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case '0':
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case 'n':
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case 'N':
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*value = false;
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break;
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default:
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ret = -1;
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}
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free(buf);
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return ret;
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}
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int sysctl__read_int(const char *sysctl, int *value)
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{
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char path[PATH_MAX];
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const char *procfs = procfs__mountpoint();
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if (!procfs)
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return -1;
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snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
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return filename__read_int(path, value);
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}
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int sysfs__write_int(const char *entry, int value)
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{
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char path[PATH_MAX];
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const char *sysfs = sysfs__mountpoint();
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if (!sysfs)
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return -1;
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if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
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return -1;
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return filename__write_int(path, value);
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}
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