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-rw-r--r--kernel/tools/lib/api/fs/fs.c199
1 files changed, 199 insertions, 0 deletions
diff --git a/kernel/tools/lib/api/fs/fs.c b/kernel/tools/lib/api/fs/fs.c
new file mode 100644
index 000000000..128ef6332
--- /dev/null
+++ b/kernel/tools/lib/api/fs/fs.c
@@ -0,0 +1,199 @@
+/* TODO merge/factor in debugfs.c here */
+
+#include <ctype.h>
+#include <errno.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 "debugfs.h"
+#include "fs.h"
+
+static const char * const sysfs__fs_known_mountpoints[] = {
+ "/sys",
+ 0,
+};
+
+static const char * const procfs__known_mountpoints[] = {
+ "/proc",
+ 0,
+};
+
+struct fs {
+ const char *name;
+ const char * const *mounts;
+ char path[PATH_MAX + 1];
+ bool found;
+ long magic;
+};
+
+enum {
+ FS__SYSFS = 0,
+ FS__PROCFS = 1,
+};
+
+static struct fs fs__entries[] = {
+ [FS__SYSFS] = {
+ .name = "sysfs",
+ .mounts = sysfs__fs_known_mountpoints,
+ .magic = SYSFS_MAGIC,
+ },
+ [FS__PROCFS] = {
+ .name = "proc",
+ .mounts = procfs__known_mountpoints,
+ .magic = PROC_SUPER_MAGIC,
+ },
+};
+
+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);
+ 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/sysfs-rules.txt
+ * 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;
+ strncpy(fs->path, override_path, sizeof(fs->path));
+ 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;
+
+ return fs__get_mountpoint(fs);
+}
+
+#define FS__MOUNTPOINT(name, idx) \
+const char *name##__mountpoint(void) \
+{ \
+ return fs__mountpoint(idx); \
+}
+
+FS__MOUNTPOINT(sysfs, FS__SYSFS);
+FS__MOUNTPOINT(procfs, FS__PROCFS);
+
+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;
+}
+
+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);
+}