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-rw-r--r--lib/sysfs.c705
1 files changed, 705 insertions, 0 deletions
diff --git a/lib/sysfs.c b/lib/sysfs.c
new file mode 100644
index 0000000..7b2c5f7
--- /dev/null
+++ b/lib/sysfs.c
@@ -0,0 +1,705 @@
+/*
+ * Copyright (C) 2011 Karel Zak <kzak@redhat.com>
+ */
+
+#include <ctype.h>
+
+#include "c.h"
+#include "at.h"
+#include "pathnames.h"
+#include "sysfs.h"
+
+char *sysfs_devno_attribute_path(dev_t devno, char *buf,
+ size_t bufsiz, const char *attr)
+{
+ int len;
+
+ if (attr)
+ len = snprintf(buf, bufsiz, _PATH_SYS_DEVBLOCK "/%d:%d/%s",
+ major(devno), minor(devno), attr);
+ else
+ len = snprintf(buf, bufsiz, _PATH_SYS_DEVBLOCK "/%d:%d",
+ major(devno), minor(devno));
+
+ return (len < 0 || (size_t) len + 1 > bufsiz) ? NULL : buf;
+}
+
+int sysfs_devno_has_attribute(dev_t devno, const char *attr)
+{
+ char path[PATH_MAX];
+ struct stat info;
+
+ if (!sysfs_devno_attribute_path(devno, path, sizeof(path), attr))
+ return 0;
+ if (stat(path, &info) == 0)
+ return 1;
+ return 0;
+}
+
+char *sysfs_devno_path(dev_t devno, char *buf, size_t bufsiz)
+{
+ return sysfs_devno_attribute_path(devno, buf, bufsiz, NULL);
+}
+
+dev_t sysfs_devname_to_devno(const char *name, const char *parent)
+{
+ char buf[PATH_MAX], *path = NULL;
+ dev_t dev = 0;
+
+ if (strncmp("/dev/", name, 5) == 0) {
+ /*
+ * Read from /dev
+ */
+ struct stat st;
+
+ if (stat(name, &st) == 0)
+ dev = st.st_rdev;
+ else
+ name += 5; /* unaccesible, or not node in /dev */
+ }
+
+ if (!dev && parent) {
+ /*
+ * Create path to /sys/block/<parent>/<name>/dev
+ */
+ int len = snprintf(buf, sizeof(buf),
+ _PATH_SYS_BLOCK "/%s/%s/dev", parent, name);
+ if (len < 0 || (size_t) len + 1 > sizeof(buf))
+ return 0;
+ path = buf;
+
+ } else if (!dev) {
+ /*
+ * Create path to /sys/block/<name>/dev
+ */
+ int len = snprintf(buf, sizeof(buf),
+ _PATH_SYS_BLOCK "/%s/dev", name);
+ if (len < 0 || (size_t) len + 1 > sizeof(buf))
+ return 0;
+ path = buf;
+ }
+
+ if (path) {
+ /*
+ * read devno from sysfs
+ */
+ FILE *f;
+ int maj = 0, min = 0;
+
+ f = fopen(path, "r");
+ if (!f)
+ return 0;
+
+ if (fscanf(f, "%d:%d", &maj, &min) == 2)
+ dev = makedev(maj, min);
+ fclose(f);
+ }
+ return dev;
+}
+
+/*
+ * Returns devname (e.g. "/dev/sda1") for the given devno.
+ *
+ * Note that the @buf has to be large enough to store /sys/dev/block/<maj:min>
+ * symlinks.
+ *
+ * Please, use more robust blkid_devno_to_devname() in your applications.
+ */
+char *sysfs_devno_to_devpath(dev_t devno, char *buf, size_t bufsiz)
+{
+ struct sysfs_cxt cxt;
+ char *name;
+ size_t sz;
+ struct stat st;
+
+ if (sysfs_init(&cxt, devno, NULL))
+ return NULL;
+
+ name = sysfs_get_devname(&cxt, buf, bufsiz);
+ sysfs_deinit(&cxt);
+
+ if (!name)
+ return NULL;
+
+ sz = strlen(name);
+
+ if (sz + sizeof("/dev/") > bufsiz)
+ return NULL;
+
+ /* create the final "/dev/<name>" string */
+ memmove(buf + 5, name, sz + 1);
+ memcpy(buf, "/dev/", 5);
+
+ if (!stat(buf, &st) && S_ISBLK(st.st_mode) && st.st_rdev == devno)
+ return buf;
+
+ return NULL;
+}
+
+int sysfs_init(struct sysfs_cxt *cxt, dev_t devno, struct sysfs_cxt *parent)
+{
+ char path[PATH_MAX];
+ int fd, rc;
+
+ memset(cxt, 0, sizeof(*cxt));
+ cxt->dir_fd = -1;
+
+ if (!sysfs_devno_path(devno, path, sizeof(path)))
+ goto err;
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ goto err;
+ cxt->dir_fd = fd;
+
+ cxt->dir_path = strdup(path);
+ if (!cxt->dir_path)
+ goto err;
+ cxt->devno = devno;
+ cxt->parent = parent;
+ return 0;
+err:
+ rc = errno > 0 ? -errno : -1;
+ sysfs_deinit(cxt);
+ return rc;
+}
+
+void sysfs_deinit(struct sysfs_cxt *cxt)
+{
+ if (!cxt)
+ return;
+
+ if (cxt->dir_fd >= 0)
+ close(cxt->dir_fd);
+ free(cxt->dir_path);
+
+ cxt->devno = 0;
+ cxt->dir_fd = -1;
+ cxt->parent = NULL;
+ cxt->dir_path = NULL;
+}
+
+int sysfs_stat(struct sysfs_cxt *cxt, const char *attr, struct stat *st)
+{
+ int rc = fstat_at(cxt->dir_fd, cxt->dir_path, attr, st, 0);
+
+ if (rc != 0 && errno == ENOENT &&
+ strncmp(attr, "queue/", 6) == 0 && cxt->parent) {
+
+ /* Exception for "queue/<attr>". These attributes are available
+ * for parental devices only
+ */
+ return fstat_at(cxt->parent->dir_fd,
+ cxt->parent->dir_path, attr, st, 0);
+ }
+ return rc;
+}
+
+int sysfs_has_attribute(struct sysfs_cxt *cxt, const char *attr)
+{
+ struct stat st;
+
+ return sysfs_stat(cxt, attr, &st) == 0;
+}
+
+static int sysfs_open(struct sysfs_cxt *cxt, const char *attr)
+{
+ int fd = open_at(cxt->dir_fd, cxt->dir_path, attr, O_RDONLY);
+
+ if (fd == -1 && errno == ENOENT &&
+ strncmp(attr, "queue/", 6) == 0 && cxt->parent) {
+
+ /* Exception for "queue/<attr>". These attributes are available
+ * for parental devices only
+ */
+ fd = open_at(cxt->parent->dir_fd, cxt->dir_path, attr, O_RDONLY);
+ }
+ return fd;
+}
+
+ssize_t sysfs_readlink(struct sysfs_cxt *cxt, const char *attr,
+ char *buf, size_t bufsiz)
+{
+ if (!cxt->dir_path)
+ return -1;
+
+ if (attr)
+ return readlink_at(cxt->dir_fd, cxt->dir_path, attr, buf, bufsiz);
+
+ /* read /sys/dev/block/<maj:min> link */
+ return readlink(cxt->dir_path, buf, bufsiz);
+}
+
+DIR *sysfs_opendir(struct sysfs_cxt *cxt, const char *attr)
+{
+ DIR *dir;
+ int fd;
+
+ if (attr)
+ fd = sysfs_open(cxt, attr);
+ else
+ /* request to open root of device in sysfs (/sys/block/<dev>)
+ * -- we cannot use cxt->sysfs_fd directly, because closedir()
+ * will close this our persistent file descriptor.
+ */
+ fd = dup(cxt->dir_fd);
+
+ if (fd < 0)
+ return NULL;
+
+ dir = fdopendir(fd);
+ if (!dir) {
+ close(fd);
+ return NULL;
+ }
+ if (!attr)
+ rewinddir(dir);
+ return dir;
+}
+
+
+static FILE *sysfs_fopen(struct sysfs_cxt *cxt, const char *attr)
+{
+ int fd = sysfs_open(cxt, attr);
+
+ return fd < 0 ? NULL : fdopen(fd, "r");
+}
+
+
+static struct dirent *xreaddir(DIR *dp)
+{
+ struct dirent *d;
+
+ while ((d = readdir(dp))) {
+ if (!strcmp(d->d_name, ".") ||
+ !strcmp(d->d_name, ".."))
+ continue;
+
+ /* blacklist here? */
+ break;
+ }
+ return d;
+}
+
+int sysfs_is_partition_dirent(DIR *dir, struct dirent *d, const char *parent_name)
+{
+ char path[256];
+
+#ifdef _DIRENT_HAVE_D_TYPE
+ if (d->d_type != DT_DIR &&
+ d->d_type != DT_LNK)
+ return 0;
+#endif
+ if (parent_name) {
+ const char *p = parent_name;
+ size_t len;
+
+ /* /dev/sda --> "sda" */
+ if (*parent_name == '/') {
+ p = strrchr(parent_name, '/');
+ if (!p)
+ return 0;
+ p++;
+ }
+
+ len = strlen(p);
+ if (strlen(d->d_name) <= len)
+ return 0;
+
+ /* partitions subdir name is
+ * "<parent>[:digit:]" or "<parent>p[:digit:]"
+ */
+ return strncmp(p, d->d_name, len) == 0 &&
+ ((*(d->d_name + len) == 'p' && isdigit(*(d->d_name + len + 1)))
+ || isdigit(*(d->d_name + len)));
+ }
+
+ /* Cannot use /partition file, not supported on old sysfs */
+ snprintf(path, sizeof(path), "%s/start", d->d_name);
+
+ return faccessat(dirfd(dir), path, R_OK, 0) == 0;
+}
+
+/*
+ * Converts @partno (partition number) to devno of the partition.
+ * The @cxt handles wholedisk device.
+ *
+ * Note that this code does not expect any special format of the
+ * partitions devnames.
+ */
+dev_t sysfs_partno_to_devno(struct sysfs_cxt *cxt, int partno)
+{
+ DIR *dir;
+ struct dirent *d;
+ char path[256];
+ dev_t devno = 0;
+
+ dir = sysfs_opendir(cxt, NULL);
+ if (!dir)
+ return 0;
+
+ while ((d = xreaddir(dir))) {
+ int n, maj, min;
+
+ if (!sysfs_is_partition_dirent(dir, d, NULL))
+ continue;
+
+ snprintf(path, sizeof(path), "%s/partition", d->d_name);
+ if (sysfs_read_int(cxt, path, &n))
+ continue;
+
+ if (n == partno) {
+ snprintf(path, sizeof(path), "%s/dev", d->d_name);
+ if (sysfs_scanf(cxt, path, "%d:%d", &maj, &min) == 2)
+ devno = makedev(maj, min);
+ break;
+ }
+ }
+
+ closedir(dir);
+ return devno;
+}
+
+
+int sysfs_scanf(struct sysfs_cxt *cxt, const char *attr, const char *fmt, ...)
+{
+ FILE *f = sysfs_fopen(cxt, attr);
+ va_list ap;
+ int rc;
+
+ if (!f)
+ return -EINVAL;
+ va_start(ap, fmt);
+ rc = vfscanf(f, fmt, ap);
+ va_end(ap);
+
+ fclose(f);
+ return rc;
+}
+
+
+int sysfs_read_s64(struct sysfs_cxt *cxt, const char *attr, int64_t *res)
+{
+ int64_t x = 0;
+
+ if (sysfs_scanf(cxt, attr, "%"SCNd64, &x) == 1) {
+ if (res)
+ *res = x;
+ return 0;
+ }
+ return -1;
+}
+
+int sysfs_read_u64(struct sysfs_cxt *cxt, const char *attr, uint64_t *res)
+{
+ uint64_t x = 0;
+
+ if (sysfs_scanf(cxt, attr, "%"SCNu64, &x) == 1) {
+ if (res)
+ *res = x;
+ return 0;
+ }
+ return -1;
+}
+
+int sysfs_read_int(struct sysfs_cxt *cxt, const char *attr, int *res)
+{
+ int x = 0;
+
+ if (sysfs_scanf(cxt, attr, "%d", &x) == 1) {
+ if (res)
+ *res = x;
+ return 0;
+ }
+ return -1;
+}
+
+char *sysfs_strdup(struct sysfs_cxt *cxt, const char *attr)
+{
+ char buf[1024];
+ return sysfs_scanf(cxt, attr, "%1023[^\n]", buf) == 1 ?
+ strdup(buf) : NULL;
+}
+
+int sysfs_count_dirents(struct sysfs_cxt *cxt, const char *attr)
+{
+ DIR *dir;
+ int r = 0;
+
+ if (!(dir = sysfs_opendir(cxt, attr)))
+ return 0;
+
+ while (xreaddir(dir)) r++;
+
+ closedir(dir);
+ return r;
+}
+
+int sysfs_count_partitions(struct sysfs_cxt *cxt, const char *devname)
+{
+ DIR *dir;
+ struct dirent *d;
+ int r = 0;
+
+ if (!(dir = sysfs_opendir(cxt, NULL)))
+ return 0;
+
+ while ((d = xreaddir(dir))) {
+ if (sysfs_is_partition_dirent(dir, d, devname))
+ r++;
+ }
+
+ closedir(dir);
+ return r;
+}
+
+/*
+ * Returns slave name if there is only one slave, otherwise returns NULL.
+ * The result should be deallocated by free().
+ */
+char *sysfs_get_slave(struct sysfs_cxt *cxt)
+{
+ DIR *dir;
+ struct dirent *d;
+ char *name = NULL;
+
+ if (!(dir = sysfs_opendir(cxt, "slaves")))
+ return NULL;
+
+ while ((d = xreaddir(dir))) {
+ if (name)
+ goto err; /* more slaves */
+
+ name = strdup(d->d_name);
+ }
+
+ closedir(dir);
+ return name;
+err:
+ free(name);
+ closedir(dir);
+ return NULL;
+}
+
+/*
+ * Note that the @buf has to be large enough to store /sys/dev/block/<maj:min>
+ * symlinks.
+ */
+char *sysfs_get_devname(struct sysfs_cxt *cxt, char *buf, size_t bufsiz)
+{
+ char *name = NULL;
+ ssize_t sz;
+
+ sz = sysfs_readlink(cxt, NULL, buf, bufsiz - 1);
+ if (sz < 0)
+ return NULL;
+
+ buf[sz] = '\0';
+ name = strrchr(buf, '/');
+ if (!name)
+ return NULL;
+
+ name++;
+ sz = strlen(name);
+
+ memmove(buf, name, sz + 1);
+ return buf;
+}
+
+/* returns basename and keeps dirname in the @path */
+static char *stripoff_last_component(char *path)
+{
+ char *p = strrchr(path, '/');
+
+ if (!p)
+ return NULL;
+ *p = '\0';
+ return ++p;
+}
+
+static int get_dm_wholedisk(struct sysfs_cxt *cxt, char *diskname,
+ size_t len, dev_t *diskdevno)
+{
+ int rc = 0;
+ char *name;
+
+ /* Note, sysfs_get_slave() returns the first slave only,
+ * if there is more slaves, then return NULL
+ */
+ name = sysfs_get_slave(cxt);
+ if (!name)
+ return -1;
+
+ if (diskname && len) {
+ strncpy(diskname, name, len);
+ diskname[len - 1] = '\0';
+ }
+
+ if (diskdevno) {
+ *diskdevno = sysfs_devname_to_devno(name, NULL);
+ if (!*diskdevno)
+ rc = -1;
+ }
+
+ free(name);
+ return rc;
+}
+
+int sysfs_devno_to_wholedisk(dev_t dev, char *diskname,
+ size_t len, dev_t *diskdevno)
+{
+ struct sysfs_cxt cxt;
+ int is_part = 0;
+
+ if (!dev || sysfs_init(&cxt, dev, NULL) != 0)
+ return -1;
+
+ is_part = sysfs_has_attribute(&cxt, "partition");
+ if (!is_part) {
+ /*
+ * Extra case for partitions mapped by device-mapper.
+ *
+ * All regualar partitions (added by BLKPG ioctl or kernel PT
+ * parser) have the /sys/.../partition file. The partitions
+ * mapped by DM don't have such file, but they have "part"
+ * prefix in DM UUID.
+ */
+ char *uuid = sysfs_strdup(&cxt, "dm/uuid");
+ char *tmp = uuid;
+ char *prefix = uuid ? strsep(&tmp, "-") : NULL;
+
+ if (prefix && strncasecmp(prefix, "part", 4) == 0)
+ is_part = 1;
+ free(uuid);
+
+ if (is_part &&
+ get_dm_wholedisk(&cxt, diskname, len, diskdevno) == 0)
+ /*
+ * partitioned device, mapped by DM
+ */
+ goto done;
+
+ is_part = 0;
+ }
+
+ if (!is_part) {
+ /*
+ * unpartitioned device
+ */
+ if (diskname && len) {
+ if (!sysfs_get_devname(&cxt, diskname, len))
+ goto err;
+ }
+ if (diskdevno)
+ *diskdevno = dev;
+
+ } else {
+ /*
+ * partitioned device
+ * - readlink /sys/dev/block/8:1 = ../../block/sda/sda1
+ * - dirname ../../block/sda/sda1 = ../../block/sda
+ * - basename ../../block/sda = sda
+ */
+ char linkpath[PATH_MAX];
+ char *name;
+ int linklen;
+
+ linklen = sysfs_readlink(&cxt, NULL,
+ linkpath, sizeof(linkpath) - 1);
+ if (linklen < 0)
+ goto err;
+ linkpath[linklen] = '\0';
+
+ stripoff_last_component(linkpath); /* dirname */
+ name = stripoff_last_component(linkpath); /* basename */
+ if (!name)
+ goto err;
+
+ if (diskname && len) {
+ strncpy(diskname, name, len);
+ diskname[len - 1] = '\0';
+ }
+
+ if (diskdevno) {
+ *diskdevno = sysfs_devname_to_devno(name, NULL);
+ if (!*diskdevno)
+ goto err;
+ }
+ }
+
+done:
+ sysfs_deinit(&cxt);
+ return 0;
+err:
+ sysfs_deinit(&cxt);
+ return -1;
+}
+
+#ifdef TEST_PROGRAM_SYSFS
+#include <errno.h>
+#include <err.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+ struct sysfs_cxt cxt = UL_SYSFSCXT_EMPTY;
+ char *devname;
+ dev_t devno;
+ char path[PATH_MAX];
+ int i, is_part;
+ uint64_t u64;
+ ssize_t len;
+
+ if (argc != 2)
+ errx(EXIT_FAILURE, "usage: %s <devname>", argv[0]);
+
+ devname = argv[1];
+ devno = sysfs_devname_to_devno(devname, NULL);
+
+ if (!devno)
+ err(EXIT_FAILURE, "failed to read devno");
+
+ is_part = sysfs_devno_has_attribute(devno, "partition");
+
+ printf("NAME: %s\n", devname);
+ printf("DEVNO: %u (%d:%d)\n", (unsigned int) devno, major(devno), minor(devno));
+ printf("DEVNOPATH: %s\n", sysfs_devno_path(devno, path, sizeof(path)));
+ printf("DEVPATH: %s\n", sysfs_devno_to_devpath(devno, path, sizeof(path)));
+ printf("PARTITION: %s\n", is_part ? "YES" : "NOT");
+
+ if (sysfs_init(&cxt, devno, NULL))
+ return EXIT_FAILURE;
+
+ len = sysfs_readlink(&cxt, NULL, path, sizeof(path) - 1);
+ if (len > 0) {
+ path[len] = '\0';
+ printf("DEVNOLINK: %s\n", path);
+ }
+
+ if (!is_part) {
+ printf("First 5 partitions:\n");
+ for (i = 1; i <= 5; i++) {
+ dev_t dev = sysfs_partno_to_devno(&cxt, i);
+ if (dev)
+ printf("\t#%d %d:%d\n", i, major(dev), minor(dev));
+ }
+ }
+
+ printf("SLAVES: %d\n", sysfs_count_dirents(&cxt, "slaves"));
+
+ if (sysfs_read_u64(&cxt, "size", &u64))
+ printf("read SIZE failed\n");
+ else
+ printf("SIZE: %jd\n", u64);
+
+ if (sysfs_read_int(&cxt, "queue/hw_sector_size", &i))
+ printf("read SECTOR failed\n");
+ else
+ printf("SECTOR: %d\n", i);
+
+ printf("DEVNAME: %s\n", sysfs_get_devname(&cxt, path, sizeof(path)));
+
+ sysfs_deinit(&cxt);
+ return EXIT_SUCCESS;
+}
+#endif
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