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sysfs_utils.c

/*
 * sysfs_utils.c
 *
 * System utility functions for libsysfs
 *
 * Copyright (C) IBM Corp. 2003
 *
 *  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_remove_trailing_slash: Removes any trailing '/' in the given path
 * @path: Path to look for the trailing '/'
 * Returns 0 on success 1 on error
 */ 
int sysfs_remove_trailing_slash(char *path)
{
      char *c = NULL;

      if (path == NULL) {
            errno = EINVAL;
            return 1;
      }
      c = strrchr(path, '/');
      if (c == NULL) {
            dprintf("Invalid path %s\n", path);
            errno = EINVAL;
            return 1;
      }
      if (*(c+1) == '\0') 
            *c = '\0';
      return 0;
}

/**
 * sysfs_get_fs_mnt_path: Gets the mount point for specified filesystem.
 * @fs_type: filesystem type to retrieve mount point
 * @mnt_path: place to put the retrieved mount path
 * @len: size of mnt_path
 * returns 0 with success and -1 with error.
 */
static int sysfs_get_fs_mnt_path(const char *fs_type, 
                        char *mnt_path, size_t len)
{
      FILE *mnt;
      struct mntent *mntent;
      int ret = 0;
      size_t dirlen = 0;

      /* check arg */
      if (fs_type == NULL || mnt_path == NULL || len == 0) {
            errno = EINVAL;
            return -1;
      }

      if ((mnt = setmntent(SYSFS_PROC_MNTS, "r")) == NULL) {
            dprintf("Error getting mount information\n");
            return -1;
      }
      while (ret == 0 && dirlen == 0 && (mntent = getmntent(mnt)) != NULL) {
            if (strcmp(mntent->mnt_type, fs_type) == 0) {
                  dirlen = strlen(mntent->mnt_dir);
                  if (dirlen <= (len - 1)) {
                        safestrcpymax(mnt_path, mntent->mnt_dir, len);
                  } else {
                        dprintf("Error - mount path too long\n");
                        ret = -1;
                  }
            }
      }
      endmntent(mnt);
      if (dirlen == 0 && ret == 0) {
            dprintf("Filesystem %s not found!\n", fs_type);
            errno = EINVAL;
            ret = -1;
      }
      if ((sysfs_remove_trailing_slash(mnt_path)) != 0)
            ret = -1;
      
      return ret;
}

/*
 * sysfs_get_mnt_path: Gets the sysfs mount point.
 * @mnt_path: place to put "sysfs" mount point
 * @len: size of mnt_path
 * returns 0 with success and -1 with error.
 */
int sysfs_get_mnt_path(char *mnt_path, size_t len)
{
      char *sysfs_path = NULL;
      int ret = 0;

      if (mnt_path == NULL || len == 0) {
            errno = EINVAL;
            return -1;
      }
      sysfs_path = getenv(SYSFS_PATH_ENV);
      if (sysfs_path != NULL) {
            safestrcpymax(mnt_path, sysfs_path, len);
            if ((sysfs_remove_trailing_slash(mnt_path)) != 0)
                  return 1;
      } else
            ret = sysfs_get_fs_mnt_path(SYSFS_FSTYPE_NAME, mnt_path, len);

      return ret;
}

/**
 * sysfs_get_name_from_path: returns last name from a "/" delimited path
 * @path: path to get name from
 * @name: where to put name
 * @len: size of name
 */
int sysfs_get_name_from_path(const char *path, char *name, size_t len)
{
      char tmp[SYSFS_PATH_MAX];
      char *n = NULL;
                                                                                
      if (path == NULL || name == NULL || len == 0) {
            errno = EINVAL;
            return -1;
      }
      memset(tmp, 0, SYSFS_PATH_MAX);
      safestrcpy(tmp, path);
      n = strrchr(tmp, '/');
      if (n == NULL) {
            errno = EINVAL;
            return -1;
      }
      if (*(n+1) == '\0') {
            *n = '\0';
            n = strrchr(tmp, '/');
            if (n == NULL) {
                  errno = EINVAL;
                  return -1;
            }
      }
      n++;
      safestrcpymax(name, n, len);
      return 0;
}
      
/**
 * sysfs_get_link: returns link source
 * @path: symbolic link's path
 * @target: where to put name
 * @len: size of name
 */
int sysfs_get_link(const char *path, char *target, size_t len)
{
      char devdir[SYSFS_PATH_MAX];
      char linkpath[SYSFS_PATH_MAX];
      char temp_path[SYSFS_PATH_MAX];
      char *d = NULL, *s = NULL;
      int slashes = 0, count = 0;

      if (path == NULL || target == NULL || len == 0) {
            errno = EINVAL;
            return -1;
      }

      memset(devdir, 0, SYSFS_PATH_MAX);
      memset(linkpath, 0, SYSFS_PATH_MAX);
      memset(temp_path, 0, SYSFS_PATH_MAX);
      safestrcpy(devdir, path);

      if ((readlink(path, linkpath, SYSFS_PATH_MAX)) < 0) {
            return -1;
      }
      d = linkpath;
      /* 
       * Three cases here:
       * 1. relative path => format ../..
       * 2. absolute path => format /abcd/efgh
       * 3. relative path _from_ this dir => format abcd/efgh
       */ 
      switch (*d) {
            case '.': 
                  /* 
                   * handle the case where link is of type ./abcd/xxx
                   */
                  safestrcpy(temp_path, devdir);
                  if (*(d+1) == '/')
                        d += 2;
                  else if (*(d+1) == '.')
                        goto parse_path;
                  s = strrchr(temp_path, '/');
                  if (s != NULL) {
                        *(s+1) = '\0';
                        safestrcat(temp_path, d);
                  } else {
                        safestrcpy(temp_path, d);
                  }
                  safestrcpymax(target, temp_path, len);
                  break;
                  /* 
                   * relative path  
                   * getting rid of leading "../.." 
                   */
parse_path:
                  while (*d == '/' || *d == '.') {
                        if (*d == '/')
                              slashes++;
                        d++;
                  }
                  d--;
                  s = &devdir[strlen(devdir)-1];
                  while (s != NULL && count != (slashes+1)) {
                        s--;
                        if (*s == '/')
                              count++;
                  }
                  safestrcpymax(s, d, (SYSFS_PATH_MAX-strlen(devdir)));
                  safestrcpymax(target, devdir, len);
                  break;
            case '/':
                  /* absolute path - copy as is */
                  safestrcpymax(target, linkpath, len);
                  break;
            default:
                  /* relative path from this directory */
                  safestrcpy(temp_path, devdir);
                  s = strrchr(temp_path, '/');
                  if (s != NULL) {
                        *(s+1) = '\0';
                        safestrcat(temp_path, linkpath);
                  } else {
                        safestrcpy(temp_path, linkpath);
                  }
                  safestrcpymax(target, temp_path, len);
      }
      return 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_close_list: generic list free routine
 * @list: dlist to free
 * Returns nothing
 */
void sysfs_close_list(struct dlist *list)
{
      if (list != NULL)
            dlist_destroy(list);
}

/**
 * sysfs_open_subsystem_list: gets a list of all supported "name" subsystem
 *    details from the system
 * @name: name of the subsystem, eg., "bus", "class", "devices"
 * Returns a dlist of supported names or NULL if subsystem not supported
 */ 
struct dlist *sysfs_open_subsystem_list(char *name)
{
      char sysfs_path[SYSFS_PATH_MAX], *subsys_name = NULL;
      char *c = NULL;
      struct sysfs_directory *dir = NULL, *cur = NULL;
      struct dlist *list = NULL;
      
      if (name == NULL)
            return NULL;

      if (sysfs_get_mnt_path(sysfs_path, SYSFS_PATH_MAX) != 0) {
            dprintf("Error getting sysfs mount point\n");
            return NULL;
      }

      safestrcat(sysfs_path, "/");
      safestrcat(sysfs_path, name);
      dir = sysfs_open_directory(sysfs_path);
      if (dir == NULL) {
            dprintf("Error opening sysfs_directory at %s\n", sysfs_path);
            return NULL;
      }

      if ((sysfs_read_dir_subdirs(dir)) != 0) {
            dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
            sysfs_close_directory(dir);
            return NULL;
      }

      if (dir->subdirs != NULL) {
            list = dlist_new_with_delete(SYSFS_NAME_LEN,
                        sysfs_del_name);
            if (list == NULL) {
                  dprintf("Error creating list\n");
                  sysfs_close_directory(dir);
                  return NULL;
            }

            dlist_for_each_data(dir->subdirs, cur,
                        struct sysfs_directory) {
                  subsys_name = (char *)calloc(1, SYSFS_NAME_LEN);
                  safestrcpymax(subsys_name, cur->name, SYSFS_NAME_LEN);
                  dlist_unshift_sorted(list, subsys_name, sort_char);
            }
      }
      sysfs_close_directory(dir);
      /*
       * We are now considering "block" as a "class". Hence, if the subsys
       * name requested here is "class", verify if "block" is supported on
       * this system and return the same.
       */ 
      if (strcmp(name, SYSFS_CLASS_NAME) == 0) {
            c = strstr(sysfs_path, SYSFS_CLASS_NAME);
            if (c == NULL)
                  goto out;
            *c = '\0';
            safestrcpymax(c, SYSFS_BLOCK_NAME, 
                        sizeof(sysfs_path) - strlen(sysfs_path));
            if ((sysfs_path_is_dir(sysfs_path)) == 0) {
                  subsys_name = (char *)calloc(1, SYSFS_NAME_LEN);
                  safestrcpymax(subsys_name, SYSFS_BLOCK_NAME, 
                              SYSFS_NAME_LEN);
                  dlist_unshift_sorted(list, subsys_name, sort_char);
            }
      }
out:
      return list;
}


/**
 * sysfs_open_bus_devices_list: gets a list of all devices on "name" bus
 * @name: name of the subsystem, eg., "pci", "scsi", "usb"
 * Returns a dlist of supported names or NULL if subsystem not supported
 */ 
struct dlist *sysfs_open_bus_devices_list(char *name)
{
      char sysfs_path[SYSFS_PATH_MAX], *device_name = NULL;
      struct sysfs_directory *dir = NULL;
      struct sysfs_link *cur = NULL;
      struct dlist *list = NULL;
      
      if (name == NULL)
            return NULL;

      if (sysfs_get_mnt_path(sysfs_path, SYSFS_PATH_MAX) != 0) {
            dprintf("Error getting sysfs mount point\n");
            return NULL;
      }

      safestrcat(sysfs_path, "/");
      safestrcat(sysfs_path, SYSFS_BUS_NAME);
      safestrcat(sysfs_path, "/");
      safestrcat(sysfs_path, name);
      safestrcat(sysfs_path, "/");
      safestrcat(sysfs_path, SYSFS_DEVICES_NAME);
      dir = sysfs_open_directory(sysfs_path);
      if (dir == NULL) {
            dprintf("Error opening sysfs_directory at %s\n", sysfs_path);
            return NULL;
      }

      if ((sysfs_read_dir_links(dir)) != 0) {
            dprintf("Error reading sysfs_directory at %s\n", sysfs_path);
            sysfs_close_directory(dir);
            return NULL;
      }

      if (dir->links != NULL) {
            list = dlist_new_with_delete(SYSFS_NAME_LEN,
                        sysfs_del_name);
            if (list == NULL) {
                  dprintf("Error creating list\n");
                  sysfs_close_directory(dir);
                  return NULL;
            }

            dlist_for_each_data(dir->links, cur,
                        struct sysfs_link) {
                  device_name = (char *)calloc(1, SYSFS_NAME_LEN);
                  safestrcpymax(device_name, cur->name, SYSFS_NAME_LEN);
                  dlist_unshift_sorted(list, device_name, sort_char);
            }
      }
      sysfs_close_directory(dir);
      return list;
}

/**
 * sysfs_path_is_dir: Check if the path supplied points to a directory
 * @path: path to validate
 * Returns 0 if path points to dir, 1 otherwise
 */
int sysfs_path_is_dir(const char *path)
{
      struct stat astats;

      if (path == NULL) {
            errno = EINVAL;
            return 1;
      }
      if ((lstat(path, &astats)) != 0) {
            dprintf("stat() failed\n");
            return 1;
      }
      if (S_ISDIR(astats.st_mode))
            return 0;
            
      return 1;
}

/**
 * sysfs_path_is_link: Check if the path supplied points to a link
 * @path: path to validate
 * Returns 0 if path points to link, 1 otherwise
 */
int sysfs_path_is_link(const char *path)
{
      struct stat astats;

      if (path == NULL) {
            errno = EINVAL;
            return 1;
      }
      if ((lstat(path, &astats)) != 0) {
            dprintf("stat() failed\n");
            return 1;
      }
      if (S_ISLNK(astats.st_mode))
            return 0;
            
      return 1;
}

/**
 * sysfs_path_is_file: Check if the path supplied points to a file
 * @path: path to validate
 * Returns 0 if path points to file, 1 otherwise
 */
int sysfs_path_is_file(const char *path)
{
      struct stat astats;

      if (path == NULL) {
            errno = EINVAL;
            return 1;
      }
      if ((lstat(path, &astats)) != 0) {
            dprintf("stat() failed\n");
            return 1;
      }
      if (S_ISREG(astats.st_mode))
            return 0;
            
      return 1;
}

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