Changeset 5067 for lm-sensors/branches/lm-sensors-3.0.0/lib/sysfs.c

Timestamp:

12/10/07 14:30:22 (4 years ago)

Author:

khali

Message:

libsensors: No longer depend on libsysfs.
Instead, access sysfs directly, using 3 embedded helper
functions. My motivations for doing this are:
* As far as I know, libsysfs is no longer maintained.
* libsysfs does much more than we need. For example, when asking for a
device attribute list, libsysfs will read the contents and permissions
of all attributes. Not only does this waste CPU cycles per se, but in
the case of hwmon driver it also triggers register reads, which can be
slow for SMBus chips.
* libsysfs enforces the difference between devices and class devices,
while future changes will be easier if we can handle both types alike.

Files:

• lm-sensors/branches/lm-sensors-3.0.0/lib/sysfs.c (modified) (13 diffs)

lm-sensors/branches/lm-sensors-3.0.0/lib/sysfs.c

@@ -29 +29 @@
 #include <limits.h>
 #include <errno.h>
-#include <sysfs/libsysfs.h>
+#include <dirent.h>
 #include "data.h"
 #include "error.h"
@@ -35 +35 @@
 #include "general.h"
 #include "sysfs.h"
+
+
+/****************************************************************************/
+
+#define ATTR_MAX        128
+
+/*
+ * Read an attribute from sysfs
+ * Returns a pointer to a freshly allocated string; free it yourself.
+ * If the file doesn't exist or can't be read, NULL is returned.
+ */
+static char *sysfs_read_attr(const char *device, const char *attr)
+{
+        char path[NAME_MAX];
+        char buf[ATTR_MAX], *p;
+        FILE *f;
+
+        snprintf(path, NAME_MAX, "%s/%s", device, attr);
+
+        if (!(f = fopen(path, "r")))
+                return NULL;
+        p = fgets(buf, ATTR_MAX, f);
+        fclose(f);
+        if (!p)
+                return NULL;
+
+        /* Last byte is a '\n'; chop that off */
+        p = strndup(buf, strlen(buf) - 1);
+        if (!p)
+                sensors_fatal_error(__FUNCTION__, "out of memory");
+        return p;
+}
+
+/*
+ * Call an arbitrary function for each class device of the given class
+ * Returns 0 on success (all calls returned 0), a positive errno for
+ * local errors, or a negative error value if any call fails.
+ */
+static int sysfs_foreach_classdev(const char *class_name,
+                                   int (*func)(char *, const char*))
+{
+        char path[NAME_MAX];
+        int path_off, ret;
+        DIR *dir;
+        struct dirent *ent;
+
+        path_off = snprintf(path, NAME_MAX, "%s/class/%s",
+                            sensors_sysfs_mount, class_name);
+        if (!(dir = opendir(path)))
+                return errno;
+
+        ret = 0;
+        while (!ret && (ent = readdir(dir))) {
+                if (ent->d_name[0] == '.')      /* skip hidden entries */
+                        continue;
+
+                snprintf(path + path_off, NAME_MAX - path_off, "/%s",
+                         ent->d_name);
+                ret = func(path, ent->d_name);
+        }
+
+        closedir(dir);
+        return ret;
+}
+
+/*
+ * Call an arbitrary function for each device of the given bus type
+ * Returns 0 on success (all calls returned 0), a positive errno for
+ * local errors, or a negative error value if any call fails.
+ */
+static int sysfs_foreach_busdev(const char *bus_type,
+                                 int (*func)(char *, const char*))
+{
+        char path[NAME_MAX];
+        int path_off, ret;
+        DIR *dir;
+        struct dirent *ent;
+
+        path_off = snprintf(path, NAME_MAX, "%s/bus/%s/devices",
+                            sensors_sysfs_mount, bus_type);
+        if (!(dir = opendir(path)))
+                return errno;
+
+        ret = 0;
+        while (!ret && (ent = readdir(dir))) {
+                if (ent->d_name[0] == '.')      /* skip hidden entries */
+                        continue;
+
+                snprintf(path + path_off, NAME_MAX - path_off, "/%s",
+                         ent->d_name);
+                ret = func(path, ent->d_name);
+        }
+
+        closedir(dir);
+        return ret;
+}
+
+/****************************************************************************/
 
 char sensors_sysfs_mount[NAME_MAX];
@@ -177 +275 @@
 }
 
+static int sensors_get_attr_mode(const char *device, const char *attr)
+{
+        char path[NAME_MAX];
+        struct stat st;
+        int mode = 0;
+
+        snprintf(path, NAME_MAX, "%s/%s", device, attr);
+        if (!stat(path, &st)) {
+                if (st.st_mode & S_IRUSR)
+                        mode |= SENSORS_MODE_R;
+                if (st.st_mode & S_IWUSR)
+                        mode |= SENSORS_MODE_W;
+        }
+        return mode;
+}
+
 static int sensors_read_dynamic_chip(sensors_chip_features *chip,
-                                     struct sysfs_device *sysdir)
+                                     const char *dev_path)
 {
         int i, fnum = 0, sfnum = 0, prev_slot;
-        struct sysfs_attribute *attr;
-        struct dlist *attrs;
+        DIR *dir;
+        struct dirent *ent;
         sensors_subfeature *all_subfeatures;
         sensors_subfeature *dyn_subfeatures;
@@ -189 +303 @@
         sensors_subfeature_type sftype;
 
-        attrs = sysfs_get_device_attributes(sysdir);
-
-        if (attrs == NULL)
-                return -ENOENT;
+        if (!(dir = opendir(dev_path)))
+                return -errno;
 
         /* We use a large sparse table at first to store all found
@@ -202 +314 @@
                 sensors_fatal_error(__FUNCTION__, "Out of memory");
 
-        dlist_for_each_data(attrs, attr, struct sysfs_attribute) {
-                char *name = attr->name;
+        while ((ent = readdir(dir))) {
+                char *name = ent->d_name;
                 int nr;
+
+                if (ent->d_name[0] == '.')
+                        continue;
 
                 sftype = sensors_subfeature_get_type(name, &nr);
@@ -258 +373 @@
                 if (!(sftype & 0x80))
                         all_subfeatures[i].flags |= SENSORS_COMPUTE_MAPPING;
-                if (attr->method & SYSFS_METHOD_SHOW)
-                        all_subfeatures[i].flags |= SENSORS_MODE_R;
-                if (attr->method & SYSFS_METHOD_STORE)
-                        all_subfeatures[i].flags |= SENSORS_MODE_W;
+                all_subfeatures[i].flags |= sensors_get_attr_mode(dev_path, name);
 
                 sfnum++;
         }
+        closedir(dir);
 
         if (!sfnum) { /* No subfeature */
@@ -334 +447 @@
         struct stat statbuf;
 
-        /* libsysfs will return success even if sysfs is not mounted,
-           so we have to double-check */
-        if (sysfs_get_mnt_path(sensors_sysfs_mount, NAME_MAX)
-         || stat(sensors_sysfs_mount, &statbuf) < 0
+        snprintf(sensors_sysfs_mount, NAME_MAX, "%s", "/sys");
+        if (stat(sensors_sysfs_mount, &statbuf) < 0
          || statbuf.st_nlink <= 2)      /* Empty directory */
                 return 0;
@@ -345 +456 @@
 
 /* returns: 0 if successful, !0 otherwise */
-static int sensors_read_one_sysfs_chip(struct sysfs_device *dev)
+static int sensors_read_one_sysfs_chip(char *dev_path, const char *dev_name)
 {
         int domain, bus, slot, fn;
         int err = -SENSORS_ERR_KERNEL;
-        struct sysfs_attribute *attr, *bus_attr;
-        char bus_path[SYSFS_PATH_MAX];
+        char *bus_attr;
+        char bus_path[NAME_MAX];
         sensors_chip_features entry;
 
         /* ignore any device without name attribute */
-        if (!(attr = sysfs_get_device_attr(dev, "name")))
+        if (!(entry.chip.prefix = sysfs_read_attr(dev_path, "name")))
                 return 0;
 
-        /* NB: attr->value[attr->len-1] == '\n'; chop that off */
-        entry.chip.prefix = strndup(attr->value, attr->len - 1);
-        if (!entry.chip.prefix)
-                sensors_fatal_error(__FUNCTION__, "out of memory");
-
-        entry.chip.path = strdup(dev->path);
+        entry.chip.path = strdup(dev_path);
         if (!entry.chip.path)
                 sensors_fatal_error(__FUNCTION__, "out of memory");
 
-        if (sscanf(dev->name, "%hd-%x", &entry.chip.bus.nr, &entry.chip.addr) == 2) {
+        if (sscanf(dev_name, "%hd-%x", &entry.chip.bus.nr, &entry.chip.addr) == 2) {
                 /* find out if legacy ISA or not */
                 if (entry.chip.bus.nr == 9191) {
@@ -374 +480 @@
                         entry.chip.bus.type = SENSORS_BUS_TYPE_I2C;
                         snprintf(bus_path, sizeof(bus_path),
-                                "%s/class/i2c-adapter/i2c-%d/device/name",
+                                "%s/class/i2c-adapter/i2c-%d/device",
                                 sensors_sysfs_mount, entry.chip.bus.nr);
 
-                        if ((bus_attr = sysfs_open_attribute(bus_path))) {
-                                if (sysfs_read_attribute(bus_attr)) {
-                                        sysfs_close_attribute(bus_attr);
-                                        goto exit_free;
-                                }
-
-                                if (bus_attr->value
-                                 && !strncmp(bus_attr->value, "ISA ", 4)) {
+                        if ((bus_attr = sysfs_read_attr(bus_path, "name"))) {
+                                if (!strncmp(bus_attr, "ISA ", 4)) {
                                         entry.chip.bus.type = SENSORS_BUS_TYPE_ISA;
                                         entry.chip.bus.nr = 0;
                                 }
 
-                                sysfs_close_attribute(bus_attr);
+                                free(bus_attr);
                         }
                 }
-        } else if (sscanf(dev->name, "spi%hd.%d", &entry.chip.bus.nr,
+        } else if (sscanf(dev_name, "spi%hd.%d", &entry.chip.bus.nr,
                           &entry.chip.addr) == 2) {
                 /* SPI */
                 entry.chip.bus.type = SENSORS_BUS_TYPE_SPI;
-        } else if (sscanf(dev->name, "%*[a-z0-9_].%d", &entry.chip.addr) == 1) {
+        } else if (sscanf(dev_name, "%*[a-z0-9_].%d", &entry.chip.addr) == 1) {
                 /* must be new ISA (platform driver) */
                 entry.chip.bus.type = SENSORS_BUS_TYPE_ISA;
                 entry.chip.bus.nr = 0;
-        } else if (sscanf(dev->name, "%x:%x:%x.%x", &domain, &bus, &slot, &fn) == 4) {
+        } else if (sscanf(dev_name, "%x:%x:%x.%x", &domain, &bus, &slot, &fn) == 4) {
                 /* PCI */
                 entry.chip.addr = (domain << 16) + (bus << 8) + (slot << 3) + fn;
@@ -412 +512 @@
         }
 
-        if (sensors_read_dynamic_chip(&entry, dev) < 0)
+        if (sensors_read_dynamic_chip(&entry, dev_path) < 0)
                 goto exit_free;
         if (!entry.subfeature) { /* No subfeature, discard chip */
@@ -431 +531 @@
 static int sensors_read_sysfs_chips_compat(void)
 {
-        struct sysfs_bus *bus;
-        struct dlist *devs;
-        struct sysfs_device *dev;
-        int ret = 0;
-
-        if (!(bus = sysfs_open_bus("i2c"))) {
-                if (errno && errno != ENOENT)
-                        ret = -SENSORS_ERR_KERNEL;
-                goto exit0;
-        }
-
-        if (!(devs = sysfs_get_bus_devices(bus))) {
-                if (errno && errno != ENOENT)
-                        ret = -SENSORS_ERR_KERNEL;
-                goto exit1;
-        }
-
-        dlist_for_each_data(devs, dev, struct sysfs_device)
-                if ((ret = sensors_read_one_sysfs_chip(dev)))
-                        goto exit1;
-
-exit1:
-        /* this frees bus and devs */
-        sysfs_close_bus(bus);
-
-exit0:
-        return ret;
+        int ret;
+
+        ret = sysfs_foreach_busdev("i2c", sensors_read_one_sysfs_chip);
+        if (ret && ret != ENOENT)
+                return -SENSORS_ERR_KERNEL;
+
+        return 0;
+}
+
+static int sensors_add_hwmon_device(char *path, const char *classdev)
+{
+        char device[NAME_MAX];
+        int path_off = strlen(path);
+        int dev_len;
+        (void)classdev; /* hide warning */
+
+        snprintf(path + path_off, NAME_MAX - path_off, "/device");
+        dev_len = readlink(path, device, NAME_MAX - 1);
+        if (dev_len < 0)
+                return -SENSORS_ERR_KERNEL;
+        device[dev_len] = '\0';
+
+        return sensors_read_one_sysfs_chip(path, strrchr(device, '/') + 1);
 }
 
@@ -463 +559 @@
 int sensors_read_sysfs_chips(void)
 {
-        struct sysfs_class *cls;
-        struct dlist *clsdevs;
-        struct sysfs_class_device *clsdev;
-        int ret = 0;
-
-        if (!(cls = sysfs_open_class("hwmon"))) {
+        int ret;
+
+        ret = sysfs_foreach_classdev("hwmon", sensors_add_hwmon_device);
+        if (ret == ENOENT) {
                 /* compatibility function for kernel 2.6.n where n <= 13 */
                 return sensors_read_sysfs_chips_compat();
         }
 
-        if (!(clsdevs = sysfs_get_class_devices(cls))) {
-                if (errno && errno != ENOENT)
-                        ret = -SENSORS_ERR_KERNEL;
-                goto exit;
-        }
-
-        dlist_for_each_data(clsdevs, clsdev, struct sysfs_class_device) {
-                struct sysfs_device *dev;
-                if (!(dev = sysfs_get_classdev_device(clsdev))) {
-                        ret = -SENSORS_ERR_KERNEL;
-                        goto exit;
-                }
-                if ((ret = sensors_read_one_sysfs_chip(dev)))
-                        goto exit;
-        }
-
-exit:
-        /* this frees cls and clsdevs */
-        sysfs_close_class(cls);
+        if (ret > 0)
+                ret = -SENSORS_ERR_KERNEL;
         return ret;
+}
+
+/* returns 0 if successful, !0 otherwise */
+static int sensors_add_i2c_bus(char *path, const char *classdev)
+{
+        sensors_bus entry;
+
+        if (sscanf(classdev, "i2c-%hd", &entry.bus.nr) != 1 ||
+            entry.bus.nr == 9191) /* legacy ISA */
+                return 0;
+        entry.bus.type = SENSORS_BUS_TYPE_I2C;
+
+        /* Get the adapter name from the classdev "name" attribute
+         * (Linux 2.6.20 and later). If it fails, fall back to
+         * the device "name" attribute (for older kernels). */
+        entry.adapter = sysfs_read_attr(path, "name");
+        if (!entry.adapter)
+                entry.adapter = sysfs_read_attr(path, "device/name");
+        if (entry.adapter)
+                sensors_add_proc_bus(&entry);
+
+        return 0;
 }
 
@@ -498 +597 @@
 int sensors_read_sysfs_bus(void)
 {
-        struct sysfs_class *cls;
-        struct dlist *clsdevs;
-        struct sysfs_class_device *clsdev;
-        sensors_bus entry;
-        int ret = 0;
-
-        if (!(cls = sysfs_open_class("i2c-adapter"))) {
-                if (errno && errno != ENOENT)
-                        ret = -SENSORS_ERR_KERNEL;
-                goto exit0;
-        }
-
-        if (!(clsdevs = sysfs_get_class_devices(cls))) {
-                if (errno && errno != ENOENT)
-                        ret = -SENSORS_ERR_KERNEL;
-                goto exit1;
-        }
-
-        dlist_for_each_data(clsdevs, clsdev, struct sysfs_class_device) {
-                struct sysfs_device *dev;
-                struct sysfs_attribute *attr;
-
-                /* Get the adapter name from the classdev "name" attribute
-                 * (Linux 2.6.20 and later). If it fails, fall back to
-                 * the device "name" attribute (for older kernels). */
-                if (!(attr = sysfs_get_classdev_attr(clsdev, "name"))
-                 && !((dev = sysfs_get_classdev_device(clsdev)) &&
-                      (attr = sysfs_get_device_attr(dev, "name"))))
-                        continue;
-
-                if (sscanf(clsdev->name, "i2c-%hd", &entry.bus.nr) != 1 ||
-                    entry.bus.nr == 9191) /* legacy ISA */
-                        continue;
-                entry.bus.type = SENSORS_BUS_TYPE_I2C;
-
-                /* NB: attr->value[attr->len-1] == '\n'; chop that off */
-                entry.adapter = strndup(attr->value, attr->len - 1);
-                if (!entry.adapter)
-                        sensors_fatal_error(__FUNCTION__, "out of memory");
-
-                sensors_add_proc_bus(&entry);
-        }
-
-exit1:
-        /* this frees *cls _and_ *clsdevs */
-        sysfs_close_class(cls);
-
-exit0:
-        return ret;
+        int ret;
+
+        ret = sysfs_foreach_classdev("i2c-adapter", sensors_add_i2c_bus);
+        if (ret && ret != ENOENT)
+                return -SENSORS_ERR_KERNEL;
+
+        return 0;
 }