aboutsummaryrefslogtreecommitdiff
path: root/lib/dirtree.c
blob: e44df66c69f627cd070d157e5afd4cce5fc65630 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
/* dirtree.c - Functions for dealing with directory trees.
 *
 * Copyright 2007 Rob Landley <rob@landley.net>
 */

#include "toys.h"

int isdotdot(char *name)
{
  if (name[0]=='.' && (!name[1] || (name[1]=='.' && !name[2]))) return 1;

  return 0;
}

// Default callback, filters out "." and ".." except at top level.

int dirtree_notdotdot(struct dirtree *catch)
{
  // Should we skip "." and ".."?
  return (!catch->parent||!isdotdot(catch->name))
    *(DIRTREE_SAVE|DIRTREE_RECURSE);
}

// Create a dirtree node from a path, with stat and symlink info.
// (This doesn't open directory filehandles yet so as not to exhaust the
// filehandle space on large trees, dirtree_handle_callback() does that.)

struct dirtree *dirtree_add_node(struct dirtree *parent, char *name, int flags)
{
  struct dirtree *dt = NULL;
  struct stat st;
  int len = 0, linklen = 0, statless = 0;

  if (name) {
    // open code this because haven't got node to call dirtree_parentfd() on yet
    int fd = parent ? parent->dirfd : AT_FDCWD;

    if (fstatat(fd, name, &st,AT_SYMLINK_NOFOLLOW*!(flags&DIRTREE_SYMFOLLOW))) {
      if ((flags&DIRTREE_STATLESS) && errno == ENOENT) statless++;
      else goto error;
    }
    if (S_ISLNK(st.st_mode)) {
      if (0>(linklen = readlinkat(fd, name, libbuf, 4095))) goto error;
      libbuf[linklen++]=0;
    }
    len = strlen(name);
  }

  // Allocate/populate return structure
  dt = xmalloc((len = sizeof(struct dirtree)+len+1)+linklen);
  memset(dt, 0, statless ? offsetof(struct dirtree, again)
    : offsetof(struct dirtree, st));
  dt->parent = parent;
  dt->again = statless ? 2 : 0;
  if (!statless) memcpy(&dt->st, &st, sizeof(struct stat));
  strcpy(dt->name, name ? name : "");
  if (linklen) dt->symlink = memcpy(len+(char *)dt, libbuf, linklen);

  return dt;

error:
  if (!(flags&DIRTREE_SHUTUP) && !isdotdot(name)) {
    char *path = parent ? dirtree_path(parent, 0) : "";

    perror_msg("%s%s%s", path, parent ? "/" : "", name);
    if (parent) free(path);
  }
  if (parent) parent->symlink = (char *)1;
  free(dt);
  return 0;
}

// Return path to this node, assembled recursively.

// Initial call can pass in NULL to plen, or point to an int initialized to 0
// to return the length of the path, or a value greater than 0 to allocate
// extra space if you want to append your own text to the string.

char *dirtree_path(struct dirtree *node, int *plen)
{
  char *path;
  int len;

  if (!node) {
    path = xmalloc(*plen);
    *plen = 0;
    return path;
  }

  len = (plen ? *plen : 0)+strlen(node->name)+1;
  path = dirtree_path(node->parent, &len);
  if (len && path[len-1] != '/') path[len++]='/';
  len = stpcpy(path+len, node->name) - path;
  if (plen) *plen = len;

  return path;
}

int dirtree_parentfd(struct dirtree *node)
{
  return node->parent ? node->parent->dirfd : AT_FDCWD;
}

// Handle callback for a node in the tree. Returns saved node(s) if
// callback returns DIRTREE_SAVE, otherwise frees consumed nodes and
// returns NULL. If !callback return top node unchanged.
// If !new return DIRTREE_ABORTVAL

struct dirtree *dirtree_handle_callback(struct dirtree *new,
          int (*callback)(struct dirtree *node))
{
  int flags;

  if (!new) return DIRTREE_ABORTVAL;
  if (!callback) return new;
  flags = callback(new);

  if (S_ISDIR(new->st.st_mode) && (flags & (DIRTREE_RECURSE|DIRTREE_COMEAGAIN)))
    flags = dirtree_recurse(new, callback,
      openat(dirtree_parentfd(new), new->name, O_CLOEXEC), flags);

  // If this had children, it was callback's job to free them already.
  if (!(flags & DIRTREE_SAVE)) {
    free(new);
    new = NULL;
  }

  return (flags & DIRTREE_ABORT)==DIRTREE_ABORT ? DIRTREE_ABORTVAL : new;
}

// Recursively read/process children of directory node, filtering through
// callback(). Uses and closes supplied ->dirfd.

int dirtree_recurse(struct dirtree *node,
          int (*callback)(struct dirtree *node), int dirfd, int flags)
{
  struct dirtree *new, **ddt = &(node->child);
  struct dirent *entry;
  DIR *dir;

  node->dirfd = dirfd;
  if (node->dirfd == -1 || !(dir = fdopendir(node->dirfd))) {
    if (!(flags & DIRTREE_SHUTUP)) {
      char *path = dirtree_path(node, 0);
      perror_msg_raw(path);
      free(path);
    }
    close(node->dirfd);

    return flags;
  }

  // according to the fddir() man page, the filehandle in the DIR * can still
  // be externally used by things that don't lseek() it.

  // The extra parentheses are to shut the stupid compiler up.
  while ((entry = readdir(dir))) {
    if ((flags&DIRTREE_PROC) && !isdigit(*entry->d_name)) continue;
    if (!(new = dirtree_add_node(node, entry->d_name, flags))) continue;
    new = dirtree_handle_callback(new, callback);
    if (new == DIRTREE_ABORTVAL) break;
    if (new) {
      *ddt = new;
      ddt = &((*ddt)->next);
    }
  }

  if (flags & DIRTREE_COMEAGAIN) {
    node->again |= 1;
    flags = callback(node);
  }

  // This closes filehandle as well, so note it
  closedir(dir);
  node->dirfd = -1;

  return flags;
}

// Create dirtree from path, using callback to filter nodes. If !callback
// return just the top node. Use dirtree_notdotdot callback to allocate a
// tree of struct dirtree nodes and return pointer to root node for later
// processing.
// Returns DIRTREE_ABORTVAL if path didn't exist (use DIRTREE_SHUTUP to handle
// error message yourself).

struct dirtree *dirtree_flagread(char *path, int flags,
  int (*callback)(struct dirtree *node))
{
  return dirtree_handle_callback(dirtree_add_node(0, path, flags), callback);
}

// Common case
struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node))
{
  return dirtree_flagread(path, 0, callback);
}