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-rw-r--r--tools/lib/api/fs/fs.c558
1 files changed, 558 insertions, 0 deletions
diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
new file mode 100644
index 000000000..82f53d81a
--- /dev/null
+++ b/tools/lib/api/fs/fs.c
@@ -0,0 +1,558 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/vfs.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mount.h>
+
+#include "fs.h"
+#include "debug-internal.h"
+
+#define _STR(x) #x
+#define STR(x) _STR(x)
+
+#ifndef SYSFS_MAGIC
+#define SYSFS_MAGIC 0x62656572
+#endif
+
+#ifndef PROC_SUPER_MAGIC
+#define PROC_SUPER_MAGIC 0x9fa0
+#endif
+
+#ifndef DEBUGFS_MAGIC
+#define DEBUGFS_MAGIC 0x64626720
+#endif
+
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC 0x74726163
+#endif
+
+#ifndef HUGETLBFS_MAGIC
+#define HUGETLBFS_MAGIC 0x958458f6
+#endif
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC 0xcafe4a11
+#endif
+
+static const char * const sysfs__fs_known_mountpoints[] = {
+ "/sys",
+ 0,
+};
+
+static const char * const procfs__known_mountpoints[] = {
+ "/proc",
+ 0,
+};
+
+#ifndef DEBUGFS_DEFAULT_PATH
+#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
+#endif
+
+static const char * const debugfs__known_mountpoints[] = {
+ DEBUGFS_DEFAULT_PATH,
+ "/debug",
+ 0,
+};
+
+
+#ifndef TRACEFS_DEFAULT_PATH
+#define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
+#endif
+
+static const char * const tracefs__known_mountpoints[] = {
+ TRACEFS_DEFAULT_PATH,
+ "/sys/kernel/debug/tracing",
+ "/tracing",
+ "/trace",
+ 0,
+};
+
+static const char * const hugetlbfs__known_mountpoints[] = {
+ 0,
+};
+
+static const char * const bpf_fs__known_mountpoints[] = {
+ "/sys/fs/bpf",
+ 0,
+};
+
+struct fs {
+ const char *name;
+ const char * const *mounts;
+ char path[PATH_MAX];
+ bool found;
+ bool checked;
+ long magic;
+};
+
+enum {
+ FS__SYSFS = 0,
+ FS__PROCFS = 1,
+ FS__DEBUGFS = 2,
+ FS__TRACEFS = 3,
+ FS__HUGETLBFS = 4,
+ FS__BPF_FS = 5,
+};
+
+#ifndef TRACEFS_MAGIC
+#define TRACEFS_MAGIC 0x74726163
+#endif
+
+static struct fs fs__entries[] = {
+ [FS__SYSFS] = {
+ .name = "sysfs",
+ .mounts = sysfs__fs_known_mountpoints,
+ .magic = SYSFS_MAGIC,
+ .checked = false,
+ },
+ [FS__PROCFS] = {
+ .name = "proc",
+ .mounts = procfs__known_mountpoints,
+ .magic = PROC_SUPER_MAGIC,
+ .checked = false,
+ },
+ [FS__DEBUGFS] = {
+ .name = "debugfs",
+ .mounts = debugfs__known_mountpoints,
+ .magic = DEBUGFS_MAGIC,
+ .checked = false,
+ },
+ [FS__TRACEFS] = {
+ .name = "tracefs",
+ .mounts = tracefs__known_mountpoints,
+ .magic = TRACEFS_MAGIC,
+ .checked = false,
+ },
+ [FS__HUGETLBFS] = {
+ .name = "hugetlbfs",
+ .mounts = hugetlbfs__known_mountpoints,
+ .magic = HUGETLBFS_MAGIC,
+ .checked = false,
+ },
+ [FS__BPF_FS] = {
+ .name = "bpf",
+ .mounts = bpf_fs__known_mountpoints,
+ .magic = BPF_FS_MAGIC,
+ .checked = false,
+ },
+};
+
+static bool fs__read_mounts(struct fs *fs)
+{
+ bool found = false;
+ char type[100];
+ FILE *fp;
+
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL)
+ return NULL;
+
+ while (!found &&
+ fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+ fs->path, type) == 2) {
+
+ if (strcmp(type, fs->name) == 0)
+ found = true;
+ }
+
+ fclose(fp);
+ fs->checked = true;
+ return fs->found = found;
+}
+
+static int fs__valid_mount(const char *fs, long magic)
+{
+ struct statfs st_fs;
+
+ if (statfs(fs, &st_fs) < 0)
+ return -ENOENT;
+ else if ((long)st_fs.f_type != magic)
+ return -ENOENT;
+
+ return 0;
+}
+
+static bool fs__check_mounts(struct fs *fs)
+{
+ const char * const *ptr;
+
+ ptr = fs->mounts;
+ while (*ptr) {
+ if (fs__valid_mount(*ptr, fs->magic) == 0) {
+ fs->found = true;
+ strcpy(fs->path, *ptr);
+ return true;
+ }
+ ptr++;
+ }
+
+ return false;
+}
+
+static void mem_toupper(char *f, size_t len)
+{
+ while (len) {
+ *f = toupper(*f);
+ f++;
+ len--;
+ }
+}
+
+/*
+ * Check for "NAME_PATH" environment variable to override fs location (for
+ * testing). This matches the recommendation in Documentation/admin-guide/sysfs-rules.rst
+ * for SYSFS_PATH.
+ */
+static bool fs__env_override(struct fs *fs)
+{
+ char *override_path;
+ size_t name_len = strlen(fs->name);
+ /* name + "_PATH" + '\0' */
+ char upper_name[name_len + 5 + 1];
+
+ memcpy(upper_name, fs->name, name_len);
+ mem_toupper(upper_name, name_len);
+ strcpy(&upper_name[name_len], "_PATH");
+
+ override_path = getenv(upper_name);
+ if (!override_path)
+ return false;
+
+ fs->found = true;
+ fs->checked = true;
+ strncpy(fs->path, override_path, sizeof(fs->path) - 1);
+ fs->path[sizeof(fs->path) - 1] = '\0';
+ return true;
+}
+
+static const char *fs__get_mountpoint(struct fs *fs)
+{
+ if (fs__env_override(fs))
+ return fs->path;
+
+ if (fs__check_mounts(fs))
+ return fs->path;
+
+ if (fs__read_mounts(fs))
+ return fs->path;
+
+ return NULL;
+}
+
+static const char *fs__mountpoint(int idx)
+{
+ struct fs *fs = &fs__entries[idx];
+
+ if (fs->found)
+ return (const char *)fs->path;
+
+ /* the mount point was already checked for the mount point
+ * but and did not exist, so return NULL to avoid scanning again.
+ * This makes the found and not found paths cost equivalent
+ * in case of multiple calls.
+ */
+ if (fs->checked)
+ return NULL;
+
+ return fs__get_mountpoint(fs);
+}
+
+static const char *mount_overload(struct fs *fs)
+{
+ size_t name_len = strlen(fs->name);
+ /* "PERF_" + name + "_ENVIRONMENT" + '\0' */
+ char upper_name[5 + name_len + 12 + 1];
+
+ snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
+ mem_toupper(upper_name, name_len);
+
+ return getenv(upper_name) ?: *fs->mounts;
+}
+
+static const char *fs__mount(int idx)
+{
+ struct fs *fs = &fs__entries[idx];
+ const char *mountpoint;
+
+ if (fs__mountpoint(idx))
+ return (const char *)fs->path;
+
+ mountpoint = mount_overload(fs);
+
+ if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
+ return NULL;
+
+ return fs__check_mounts(fs) ? fs->path : NULL;
+}
+
+#define FS(name, idx) \
+const char *name##__mountpoint(void) \
+{ \
+ return fs__mountpoint(idx); \
+} \
+ \
+const char *name##__mount(void) \
+{ \
+ return fs__mount(idx); \
+} \
+ \
+bool name##__configured(void) \
+{ \
+ return name##__mountpoint() != NULL; \
+}
+
+FS(sysfs, FS__SYSFS);
+FS(procfs, FS__PROCFS);
+FS(debugfs, FS__DEBUGFS);
+FS(tracefs, FS__TRACEFS);
+FS(hugetlbfs, FS__HUGETLBFS);
+FS(bpf_fs, FS__BPF_FS);
+
+int filename__read_int(const char *filename, int *value)
+{
+ char line[64];
+ int fd = open(filename, O_RDONLY), err = -1;
+
+ if (fd < 0)
+ return -1;
+
+ if (read(fd, line, sizeof(line)) > 0) {
+ *value = atoi(line);
+ err = 0;
+ }
+
+ close(fd);
+ return err;
+}
+
+static int filename__read_ull_base(const char *filename,
+ unsigned long long *value, int base)
+{
+ char line[64];
+ int fd = open(filename, O_RDONLY), err = -1;
+
+ if (fd < 0)
+ return -1;
+
+ if (read(fd, line, sizeof(line)) > 0) {
+ *value = strtoull(line, NULL, base);
+ if (*value != ULLONG_MAX)
+ err = 0;
+ }
+
+ close(fd);
+ return err;
+}
+
+/*
+ * Parses @value out of @filename with strtoull.
+ * By using 16 for base to treat the number as hex.
+ */
+int filename__read_xll(const char *filename, unsigned long long *value)
+{
+ return filename__read_ull_base(filename, value, 16);
+}
+
+/*
+ * Parses @value out of @filename with strtoull.
+ * By using 0 for base, the strtoull detects the
+ * base automatically (see man strtoull).
+ */
+int filename__read_ull(const char *filename, unsigned long long *value)
+{
+ return filename__read_ull_base(filename, value, 0);
+}
+
+#define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */
+
+int filename__read_str(const char *filename, char **buf, size_t *sizep)
+{
+ size_t size = 0, alloc_size = 0;
+ void *bf = NULL, *nbf;
+ int fd, n, err = 0;
+ char sbuf[STRERR_BUFSIZE];
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return -errno;
+
+ do {
+ if (size == alloc_size) {
+ alloc_size += BUFSIZ;
+ nbf = realloc(bf, alloc_size);
+ if (!nbf) {
+ err = -ENOMEM;
+ break;
+ }
+
+ bf = nbf;
+ }
+
+ n = read(fd, bf + size, alloc_size - size);
+ if (n < 0) {
+ if (size) {
+ pr_warn("read failed %d: %s\n", errno,
+ strerror_r(errno, sbuf, sizeof(sbuf)));
+ err = 0;
+ } else
+ err = -errno;
+
+ break;
+ }
+
+ size += n;
+ } while (n > 0);
+
+ if (!err) {
+ *sizep = size;
+ *buf = bf;
+ } else
+ free(bf);
+
+ close(fd);
+ return err;
+}
+
+int filename__write_int(const char *filename, int value)
+{
+ int fd = open(filename, O_WRONLY), err = -1;
+ char buf[64];
+
+ if (fd < 0)
+ return err;
+
+ sprintf(buf, "%d", value);
+ if (write(fd, buf, sizeof(buf)) == sizeof(buf))
+ err = 0;
+
+ close(fd);
+ return err;
+}
+
+int procfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+ char path[PATH_MAX];
+ const char *procfs = procfs__mountpoint();
+
+ if (!procfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/%s", procfs, entry);
+
+ return filename__read_str(path, buf, sizep);
+}
+
+static int sysfs__read_ull_base(const char *entry,
+ unsigned long long *value, int base)
+{
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+ return filename__read_ull_base(path, value, base);
+}
+
+int sysfs__read_xll(const char *entry, unsigned long long *value)
+{
+ return sysfs__read_ull_base(entry, value, 16);
+}
+
+int sysfs__read_ull(const char *entry, unsigned long long *value)
+{
+ return sysfs__read_ull_base(entry, value, 0);
+}
+
+int sysfs__read_int(const char *entry, int *value)
+{
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+ return filename__read_int(path, value);
+}
+
+int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
+{
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
+
+ return filename__read_str(path, buf, sizep);
+}
+
+int sysfs__read_bool(const char *entry, bool *value)
+{
+ char *buf;
+ size_t size;
+ int ret;
+
+ ret = sysfs__read_str(entry, &buf, &size);
+ if (ret < 0)
+ return ret;
+
+ switch (buf[0]) {
+ case '1':
+ case 'y':
+ case 'Y':
+ *value = true;
+ break;
+ case '0':
+ case 'n':
+ case 'N':
+ *value = false;
+ break;
+ default:
+ ret = -1;
+ }
+
+ free(buf);
+
+ return ret;
+}
+int sysctl__read_int(const char *sysctl, int *value)
+{
+ char path[PATH_MAX];
+ const char *procfs = procfs__mountpoint();
+
+ if (!procfs)
+ return -1;
+
+ snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
+
+ return filename__read_int(path, value);
+}
+
+int sysfs__write_int(const char *entry, int value)
+{
+ char path[PATH_MAX];
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return -1;
+
+ if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
+ return -1;
+
+ return filename__write_int(path, value);
+}
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