toybox/lib/dirtree.c
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   1/* dirtree.c - Functions for dealing with directory trees.
   2 *
   3 * Copyright 2007 Rob Landley <rob@landley.net>
   4 */
   5
   6#include "toys.h"
   7
   8int isdotdot(char *name)
   9{
  10  if (name[0]=='.' && (!name[1] || (name[1]=='.' && !name[2]))) return 1;
  11
  12  return 0;
  13}
  14
  15// Default callback, filters out "." and ".." except at top level.
  16
  17int dirtree_notdotdot(struct dirtree *catch)
  18{
  19  // Should we skip "." and ".."?
  20  return (!catch->parent||!isdotdot(catch->name))
  21    *(DIRTREE_SAVE|DIRTREE_RECURSE);
  22}
  23
  24// Create a dirtree node from a path, with stat and symlink info.
  25// (This doesn't open directory filehandles yet so as not to exhaust the
  26// filehandle space on large trees, dirtree_handle_callback() does that.)
  27
  28struct dirtree *dirtree_add_node(struct dirtree *parent, char *name, int flags)
  29{
  30  struct dirtree *dt = NULL;
  31  struct stat st;
  32  int len = 0, linklen = 0;
  33
  34  if (name) {
  35    // open code this because haven't got node to call dirtree_parentfd() on yet
  36    int fd = parent ? parent->dirfd : AT_FDCWD;
  37
  38    if (fstatat(fd, name, &st, AT_SYMLINK_NOFOLLOW*!(flags&DIRTREE_SYMFOLLOW)))
  39      goto error;
  40    if (S_ISLNK(st.st_mode)) {
  41      if (0>(linklen = readlinkat(fd, name, libbuf, 4095))) goto error;
  42      libbuf[linklen++]=0;
  43    }
  44    len = strlen(name);
  45  }
  46  dt = xzalloc((len = sizeof(struct dirtree)+len+1)+linklen);
  47  dt->parent = parent;
  48  if (name) {
  49    memcpy(&(dt->st), &st, sizeof(struct stat));
  50    strcpy(dt->name, name);
  51
  52    if (linklen) dt->symlink = memcpy(len+(char *)dt, libbuf, linklen);
  53  }
  54
  55  return dt;
  56
  57error:
  58  if (!(flags&DIRTREE_SHUTUP) && !isdotdot(name)) {
  59    char *path = parent ? dirtree_path(parent, 0) : "";
  60
  61    perror_msg("%s%s%s", path, parent ? "/" : "", name);
  62    if (parent) free(path);
  63  }
  64  if (parent) parent->symlink = (char *)1;
  65  free(dt);
  66  return 0;
  67}
  68
  69// Return path to this node, assembled recursively.
  70
  71// Initial call can pass in NULL to plen, or point to an int initialized to 0
  72// to return the length of the path, or a value greater than 0 to allocate
  73// extra space if you want to append your own text to the string.
  74
  75char *dirtree_path(struct dirtree *node, int *plen)
  76{
  77  char *path;
  78  int len;
  79
  80  if (!node) {
  81    path = xmalloc(*plen);
  82    *plen = 0;
  83    return path;
  84  }
  85
  86  len = (plen ? *plen : 0)+strlen(node->name)+1;
  87  path = dirtree_path(node->parent, &len);
  88  if (len && path[len-1] != '/') path[len++]='/';
  89  len = (stpcpy(path+len, node->name) - path);
  90  if (plen) *plen = len;
  91
  92  return path;
  93}
  94
  95int dirtree_parentfd(struct dirtree *node)
  96{
  97  return node->parent ? node->parent->dirfd : AT_FDCWD;
  98}
  99
 100// Handle callback for a node in the tree. Returns saved node(s) if
 101// callback returns DIRTREE_SAVE, otherwise frees consumed nodes and
 102// returns NULL. If !callback return top node unchanged.
 103// If !new return DIRTREE_ABORTVAL
 104
 105struct dirtree *dirtree_handle_callback(struct dirtree *new,
 106          int (*callback)(struct dirtree *node))
 107{
 108  int flags;
 109
 110  if (!new) return DIRTREE_ABORTVAL;
 111  if (!callback) return new;
 112  flags = callback(new);
 113
 114  if (S_ISDIR(new->st.st_mode) && (flags & (DIRTREE_RECURSE|DIRTREE_COMEAGAIN)))
 115    flags = dirtree_recurse(new, callback,
 116      openat(dirtree_parentfd(new), new->name, O_CLOEXEC), flags);
 117
 118  // If this had children, it was callback's job to free them already.
 119  if (!(flags & DIRTREE_SAVE)) {
 120    free(new);
 121    new = NULL;
 122  }
 123
 124  return (flags & DIRTREE_ABORT)==DIRTREE_ABORT ? DIRTREE_ABORTVAL : new;
 125}
 126
 127// Recursively read/process children of directory node, filtering through
 128// callback(). Uses and closes supplied ->dirfd.
 129
 130int dirtree_recurse(struct dirtree *node,
 131          int (*callback)(struct dirtree *node), int dirfd, int flags)
 132{
 133  struct dirtree *new, **ddt = &(node->child);
 134  struct dirent *entry;
 135  DIR *dir;
 136
 137  node->dirfd = dirfd;
 138  if (node->dirfd == -1 || !(dir = fdopendir(node->dirfd))) {
 139    if (!(flags & DIRTREE_SHUTUP)) {
 140      char *path = dirtree_path(node, 0);
 141      perror_msg_raw(path);
 142      free(path);
 143    }
 144    close(node->dirfd);
 145
 146    return flags;
 147  }
 148
 149  // according to the fddir() man page, the filehandle in the DIR * can still
 150  // be externally used by things that don't lseek() it.
 151
 152  // The extra parentheses are to shut the stupid compiler up.
 153  while ((entry = readdir(dir))) {
 154    if ((flags&DIRTREE_PROC) && !isdigit(*entry->d_name)) continue;
 155    if (!(new = dirtree_add_node(node, entry->d_name, flags))) continue;
 156    new = dirtree_handle_callback(new, callback);
 157    if (new == DIRTREE_ABORTVAL) break;
 158    if (new) {
 159      *ddt = new;
 160      ddt = &((*ddt)->next);
 161    }
 162  }
 163
 164  if (flags & DIRTREE_COMEAGAIN) {
 165    node->again++;
 166    flags = callback(node);
 167  }
 168
 169  // This closes filehandle as well, so note it
 170  closedir(dir);
 171  node->dirfd = -1;
 172
 173  return flags;
 174}
 175
 176// Create dirtree from path, using callback to filter nodes. If !callback
 177// return just the top node. Use dirtree_notdotdot callback to allocate a
 178// tree of struct dirtree nodes and return pointer to root node for later
 179// processing.
 180// Returns DIRTREE_ABORTVAL if path didn't exist (use DIRTREE_SHUTUP to handle
 181// error message yourself).
 182
 183struct dirtree *dirtree_flagread(char *path, int flags,
 184  int (*callback)(struct dirtree *node))
 185{
 186  return dirtree_handle_callback(dirtree_add_node(0, path, flags), callback);
 187}
 188
 189// Common case
 190struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node))
 191{
 192  return dirtree_flagread(path, 0, callback);
 193}
 194