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Sourcecode: udev version File versions

sysfs_dir.c

/*
 * sysfs_dir.c
 *
 * Directory utility functions for libsysfs
 *
 * Copyright (C) IBM Corp. 2003-2005
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */
#include "libsysfs.h"
#include "sysfs.h"

static int sort_char(void *new, void *old)
{
      return ((strncmp((char *)new, (char *)old, 
                  strlen((char *)new))) < 0 ? 1 : 0);
}

/**
 * sysfs_del_name: free function for sysfs_open_subsystem_list
 * @name: memory area to be freed
 */
static void sysfs_del_name(void *name)
{
      free(name);
}

/**
 * sysfs_del_attribute: routine for dlist integration
 */
static void sysfs_del_attribute(void *attr)
{
      sysfs_close_attribute((struct sysfs_attribute *)attr);
}

/**
 * attr_name_equal: compares attributes by name
 * @a: attribute name for comparison
 * @b: sysfs_attribute to be compared.
 * returns 1 if a==b->name or 0 if not equal
 */
static int attr_name_equal(void *a, void *b)
{
      if (!a || !b)
            return 0;

      if (strcmp(((char *)a), ((struct sysfs_attribute *)b)->name) == 0)
            return 1;

      return 0;
}

/**
 * sysfs_close_attribute: closes and cleans up attribute
 * @sysattr: attribute to close.
 */
void sysfs_close_attribute(struct sysfs_attribute *sysattr)
{
      if (sysattr) {
            if (sysattr->value)
                  free(sysattr->value);
            free(sysattr);
      }
}

/**
 * alloc_attribute: allocates and initializes attribute structure
 * returns struct sysfs_attribute with success and NULL with error.
 */
static struct sysfs_attribute *alloc_attribute(void)
{
      return (struct sysfs_attribute *)
                  calloc(1, sizeof(struct sysfs_attribute));
}

/**
 * sysfs_open_attribute: creates sysfs_attribute structure
 * @path: path to attribute.
 * returns sysfs_attribute struct with success and NULL with error.
 */
struct sysfs_attribute *sysfs_open_attribute(const char *path)
{
      struct sysfs_attribute *sysattr = NULL;
      struct stat fileinfo;

      if (!path) {
            errno = EINVAL;
            return NULL;
      }
      sysattr = alloc_attribute();
      if (!sysattr) {
            dprintf("Error allocating attribute at %s\n", path);
            return NULL;
      }
      if (sysfs_get_name_from_path(path, sysattr->name, 
                        SYSFS_NAME_LEN) != 0) {
            dprintf("Error retrieving attrib name from path: %s\n", path);
            sysfs_close_attribute(sysattr);
            return NULL;
      }
      safestrcpy(sysattr->path, path);
      if ((stat(sysattr->path, &fileinfo)) != 0) {
            dprintf("Stat failed: No such attribute?\n");
            sysattr->method = 0;
            free(sysattr);
            sysattr = NULL;
      } else {
            if (fileinfo.st_mode & S_IRUSR)
                  sysattr->method |= SYSFS_METHOD_SHOW;
            if (fileinfo.st_mode & S_IWUSR)
                  sysattr->method |= SYSFS_METHOD_STORE;
      }

      return sysattr;
}

/**
 * sysfs_read_attribute: reads value from attribute
 * @sysattr: attribute to read
 * returns 0 with success and -1 with error.
 */
int sysfs_read_attribute(struct sysfs_attribute *sysattr)
{
      char *fbuf = NULL;
      char *vbuf = NULL;
      ssize_t length = 0;
      long pgsize = 0;
      int fd;

      if (!sysattr) {
            errno = EINVAL;
            return -1;
      }
      if (!(sysattr->method & SYSFS_METHOD_SHOW)) {
            dprintf("Show method not supported for attribute %s\n",
                  sysattr->path);
            errno = EACCES;
            return -1;
      }
      pgsize = getpagesize();
      fbuf = (char *)calloc(1, pgsize+1);
      if (!fbuf) {
            dprintf("calloc failed\n");
            return -1;
      }
      if ((fd = open(sysattr->path, O_RDONLY)) < 0) {
            dprintf("Error reading attribute %s\n", sysattr->path);
            free(fbuf);
            return -1;
      }
      length = read(fd, fbuf, pgsize);
      if (length < 0) {
            dprintf("Error reading from attribute %s\n", sysattr->path);
            close(fd);
            free(fbuf);
            return -1;
      }
      if (sysattr->len > 0) {
            if ((sysattr->len == length) && 
                        (!(strncmp(sysattr->value, fbuf, length)))) {
                  close(fd);
                  free(fbuf);
                  return 0;
            }
            free(sysattr->value);
      }
      sysattr->len = length;
      close(fd);
      vbuf = (char *)realloc(fbuf, length+1);
      if (!vbuf) {
            dprintf("realloc failed\n");
            free(fbuf);
            return -1;
      }
      sysattr->value = vbuf;

      return 0;
}

/**
 * sysfs_write_attribute: write value to the attribute
 * @sysattr: attribute to write
 * @new_value: value to write
 * @len: length of "new_value"
 * returns 0 with success and -1 with error.
 */
int sysfs_write_attribute(struct sysfs_attribute *sysattr,
            const char *new_value, size_t len)
{
      int fd;
      int length;

      if (!sysattr || !new_value || len == 0) {
            errno = EINVAL;
            return -1;
      }

      if (!(sysattr->method & SYSFS_METHOD_STORE)) {
            dprintf ("Store method not supported for attribute %s\n",
                  sysattr->path);
            errno = EACCES;
            return -1;
      }
      if (sysattr->method & SYSFS_METHOD_SHOW) {
            /*
             * read attribute again to see if we can get an updated value 
             */
            if ((sysfs_read_attribute(sysattr))) {
                  dprintf("Error reading attribute\n");
                  return -1;
            }
            if ((strncmp(sysattr->value, new_value, sysattr->len)) == 0) {
                  dprintf("Attr %s already has the requested value %s\n",
                              sysattr->name, new_value);
                  return 0;   
            }
      }
      /*
       * open O_WRONLY since some attributes have no "read" but only
       * "write" permission 
       */
      if ((fd = open(sysattr->path, O_WRONLY)) < 0) {
            dprintf("Error reading attribute %s\n", sysattr->path);
            return -1;
      }

      length = write(fd, new_value, len);
      if (length < 0) {
            dprintf("Error writing to the attribute %s - invalid value?\n",
                  sysattr->name);
            close(fd);
            return -1;
      } else if ((unsigned int)length != len) {
            dprintf("Could not write %zd bytes to attribute %s\n", 
                              len, sysattr->name);
            /* 
             * since we could not write user supplied number of bytes,
             * restore the old value if one available
             */
            if (sysattr->method & SYSFS_METHOD_SHOW) {
                  length = write(fd, sysattr->value, sysattr->len);
                  close(fd);
                  return -1;
            }
      }

      /*
       * Validate length that has been copied. Alloc appropriate area
       * in sysfs_attribute. Verify first if the attribute supports reading
       * (show method). If it does not, do not bother
       */ 
      if (sysattr->method & SYSFS_METHOD_SHOW) {
            if (length != sysattr->len) {
                  sysattr->value = (char *)realloc
                        (sysattr->value, length);
                  sysattr->len = length;
                  safestrcpymax(sysattr->value, new_value, length);
            } else {
                  /*"length" of the new value is same as old one */ 
                  safestrcpymax(sysattr->value, new_value, length);
            }
      }
                  
      close(fd);  
      return 0;
}

/**
 * add_attribute: open and add attribute at path to given directory
 * @dev: device whose attribute is to be added
 * @path: path to attribute
 * returns pointer to attr added with success and NULL with error.
 */
static struct sysfs_attribute *add_attribute(void *dev, const char *path)
{
      struct sysfs_attribute *attr;

      attr = sysfs_open_attribute(path);
      if (!attr) {
            dprintf("Error opening attribute %s\n",   path);
            return NULL;
      }
      if (attr->method & SYSFS_METHOD_SHOW) {
            if (sysfs_read_attribute(attr)) {
                  dprintf("Error reading attribute %s\n",   path);
                  sysfs_close_attribute(attr);
                  return NULL;
            }
      }

      if (!((struct sysfs_device *)dev)->attrlist) {
            ((struct sysfs_device *)dev)->attrlist = dlist_new_with_delete
                  (sizeof(struct sysfs_attribute), sysfs_del_attribute);
      }
      dlist_unshift_sorted(((struct sysfs_device *)dev)->attrlist, 
                  attr, sort_list);

      return attr;
}

/*
 * get_attribute - given a sysfs_* struct and a name, return the 
 * sysfs_attribute corresponding to "name"
 * returns sysfs_attribute on success and NULL on error
 */
struct sysfs_attribute *get_attribute(void *dev, const char *name)
{
      struct sysfs_attribute *cur = NULL;
      char path[SYSFS_PATH_MAX];

      if (!dev || !name) {
            errno = EINVAL;
            return NULL;
      }

      if (((struct sysfs_device *)dev)->attrlist) {
            /* check if attr is already in the list */
            cur = (struct sysfs_attribute *)dlist_find_custom
                  ((((struct sysfs_device *)dev)->attrlist), 
                        (void *)name, attr_name_equal);
            if (cur)
                  return cur;
      }
      safestrcpymax(path, ((struct sysfs_device *)dev)->path, 
                  SYSFS_PATH_MAX);
      safestrcatmax(path, "/", SYSFS_PATH_MAX);
      safestrcatmax(path, name, SYSFS_PATH_MAX);
      if (!(sysfs_path_is_file(path)))
            cur = add_attribute((void *)dev, path);
      return cur;
}

/**
 * read_dir_links: grabs links in a specific directory
 * @sysdir: sysfs directory to read
 * returns list of link names with success and NULL with error.
 */
struct dlist *read_dir_links(const char *path)
{
      DIR *dir = NULL;
      struct dirent *dirent = NULL;
      char file_path[SYSFS_PATH_MAX], *linkname;
      struct dlist *linklist = NULL;

      if (!path) {
            errno = EINVAL;
            return NULL;
      }
      dir = opendir(path);
      if (!dir) {
            dprintf("Error opening directory %s\n", path);
            return NULL;
      }
      while ((dirent = readdir(dir)) != NULL) {
            if (0 == strcmp(dirent->d_name, "."))
                   continue;
            if (0 == strcmp(dirent->d_name, ".."))
                  continue;
            memset(file_path, 0, SYSFS_PATH_MAX);
            safestrcpy(file_path, path);
            safestrcat(file_path, "/");
            safestrcat(file_path, dirent->d_name);
            if ((sysfs_path_is_link(file_path)) == 0) {
                  if (!linklist) {
                        linklist = dlist_new_with_delete
                              (SYSFS_NAME_LEN, sysfs_del_name);
                        if (!linklist) {
                              dprintf("Error creating list\n");
                              return NULL;
                        }
                  }
                  linkname = (char *)calloc(1, SYSFS_NAME_LEN);
                  safestrcpymax(linkname, dirent->d_name, SYSFS_NAME_LEN);
                  dlist_unshift_sorted(linklist, linkname, sort_char);
            }
      }
      closedir(dir);
      return linklist;
}

/**
 * read_dir_subdirs: grabs subdirs in a specific directory
 * @sysdir: sysfs directory to read
 * returns list of directory names with success and NULL with error.
 */
struct dlist *read_dir_subdirs(const char *path)
{
      DIR *dir = NULL;
      struct dirent *dirent = NULL;
      char file_path[SYSFS_PATH_MAX], *dir_name;
      struct dlist *dirlist = NULL;

      if (!path) {
            errno = EINVAL;
            return NULL;
      }
      dir = opendir(path);
      if (!dir) {
            dprintf("Error opening directory %s\n", path);
            return NULL;
      }
      while ((dirent = readdir(dir)) != NULL) {
            if (0 == strcmp(dirent->d_name, "."))
                   continue;
            if (0 == strcmp(dirent->d_name, ".."))
                  continue;
            memset(file_path, 0, SYSFS_PATH_MAX);
            safestrcpy(file_path, path);
            safestrcat(file_path, "/");
            safestrcat(file_path, dirent->d_name);
            if ((sysfs_path_is_dir(file_path)) == 0) {
                  if (!dirlist) {
                        dirlist = dlist_new_with_delete
                              (SYSFS_NAME_LEN, sysfs_del_name);
                        if (!dirlist) {
                              dprintf("Error creating list\n");
                              return NULL;
                        }
                  }
                  dir_name = (char *)calloc(1, SYSFS_NAME_LEN);
                  safestrcpymax(dir_name, dirent->d_name, SYSFS_NAME_LEN);
                  dlist_unshift_sorted(dirlist, dir_name, sort_char);
            }
      }
      closedir(dir);
      return dirlist;
}

/**
 * get_attributes_list: build a list of attributes for the given device
 * @dev: devices whose attributes list is required
 * returns dlist of attributes on success and NULL on failure
 */
struct dlist *get_attributes_list(void *dev)
{
      DIR *dir = NULL;
      struct dirent *dirent = NULL;
      struct sysfs_attribute *attr = NULL;
      char file_path[SYSFS_PATH_MAX], path[SYSFS_PATH_MAX];

      if (!dev) {
            errno = EINVAL;
            return NULL;
      }
      memset(path, 0, SYSFS_PATH_MAX);
      safestrcpy(path, ((struct sysfs_device *)dev)->path);
      dir = opendir(path);
      if (!dir) {
            dprintf("Error opening directory %s\n", path);
            return NULL;
      }
      while ((dirent = readdir(dir)) != NULL) {
            if (0 == strcmp(dirent->d_name, "."))
                   continue;
            if (0 == strcmp(dirent->d_name, ".."))
                  continue;
            memset(file_path, 0, SYSFS_PATH_MAX);
            safestrcpy(file_path, path);
            safestrcat(file_path, "/");
            safestrcat(file_path, dirent->d_name);
            if ((sysfs_path_is_file(file_path)) == 0) {
                  if (((struct sysfs_device *)dev)->attrlist) {
                        /* check if attr is already in the list */
                        attr = (struct sysfs_attribute *)
                        dlist_find_custom
                        ((((struct sysfs_device *)dev)->attrlist), 
                        (void *)dirent->d_name, attr_name_equal);
                        if (attr) 
                              continue;
                        else 
                              add_attribute(dev, file_path);
                  } else 
                        attr = add_attribute(dev, file_path);
            }
      }
      closedir(dir);
      return ((struct sysfs_device *)dev)->attrlist;
}

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