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558 lines
10 KiB
558 lines
10 KiB
// 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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