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
notdotdot(char * name)8 static int notdotdot(char *name)
9 {
10 if (name[0]=='.' && (!name[1] || (name[1]=='.' && !name[2]))) return 0;
11
12 return 1;
13 }
14
15 // Default callback, filters out "." and "..".
16
dirtree_notdotdot(struct dirtree * catch)17 int dirtree_notdotdot(struct dirtree *catch)
18 {
19 // Should we skip "." and ".."?
20 return notdotdot(catch->name) ? DIRTREE_SAVE|DIRTREE_RECURSE : 0;
21 }
22
23 // Create a dirtree node from a path, with stat and symlink info.
24 // (This doesn't open directory filehandles yet so as not to exhaust the
25 // filehandle space on large trees, dirtree_handle_callback() does that.)
26
dirtree_add_node(struct dirtree * parent,char * name,int flags)27 struct dirtree *dirtree_add_node(struct dirtree *parent, char *name, int flags)
28 {
29 struct dirtree *dt = NULL;
30 struct stat st;
31 int len = 0, linklen = 0;
32
33 if (name) {
34 // open code this because haven't got node to call dirtree_parentfd() on yet
35 int fd = parent ? parent->dirfd : AT_FDCWD;
36
37 if (fstatat(fd, name, &st, AT_SYMLINK_NOFOLLOW*!(flags&DIRTREE_SYMFOLLOW)))
38 goto error;
39 if (S_ISLNK(st.st_mode)) {
40 if (0>(linklen = readlinkat(fd, name, libbuf, 4095))) goto error;
41 libbuf[linklen++]=0;
42 }
43 len = strlen(name);
44 }
45 dt = xzalloc((len = sizeof(struct dirtree)+len+1)+linklen);
46 dt->parent = parent;
47 if (name) {
48 memcpy(&(dt->st), &st, sizeof(struct stat));
49 strcpy(dt->name, name);
50
51 if (linklen) dt->symlink = memcpy(len+(char *)dt, libbuf, linklen);
52 }
53
54 return dt;
55
56 error:
57 if (!(flags&DIRTREE_SHUTUP) && notdotdot(name)) {
58 char *path = parent ? dirtree_path(parent, 0) : "";
59
60 perror_msg("%s%s%s", path, parent ? "/" : "", name);
61 if (parent) free(path);
62 }
63 if (parent) parent->symlink = (char *)1;
64 free(dt);
65 return 0;
66 }
67
68 // Return path to this node, assembled recursively.
69
70 // Initial call can pass in NULL to plen, or point to an int initialized to 0
71 // to return the length of the path, or a value greater than 0 to allocate
72 // extra space if you want to append your own text to the string.
73
dirtree_path(struct dirtree * node,int * plen)74 char *dirtree_path(struct dirtree *node, int *plen)
75 {
76 char *path;
77 int len;
78
79 if (!node) {
80 path = xmalloc(*plen);
81 *plen = 0;
82 return path;
83 }
84
85 len = (plen ? *plen : 0)+strlen(node->name)+1;
86 path = dirtree_path(node->parent, &len);
87 if (len && path[len-1] != '/') path[len++]='/';
88 len = (stpcpy(path+len, node->name) - path);
89 if (plen) *plen = len;
90
91 return path;
92 }
93
dirtree_parentfd(struct dirtree * node)94 int dirtree_parentfd(struct dirtree *node)
95 {
96 return node->parent ? node->parent->dirfd : AT_FDCWD;
97 }
98
99 // Handle callback for a node in the tree. Returns saved node(s) or NULL.
100 //
101 // By default, allocates a tree of struct dirtree, not following symlinks
102 // If callback==NULL, or callback always returns 0, allocate tree of struct
103 // dirtree and return root of tree. Otherwise call callback(node) on each
104 // hit, free structures after use, and return NULL.
105 //
106
dirtree_handle_callback(struct dirtree * new,int (* callback)(struct dirtree * node))107 struct dirtree *dirtree_handle_callback(struct dirtree *new,
108 int (*callback)(struct dirtree *node))
109 {
110 int flags;
111
112 if (!new) return 0;
113 if (!callback) callback = dirtree_notdotdot;
114 flags = callback(new);
115
116 if (S_ISDIR(new->st.st_mode)) {
117 if (flags & (DIRTREE_RECURSE|DIRTREE_COMEAGAIN)) {
118 new->dirfd = openat(dirtree_parentfd(new), new->name, O_CLOEXEC);
119 flags = dirtree_recurse(new, callback, flags);
120 }
121 }
122
123 // If this had children, it was callback's job to free them already.
124 if (!(flags & DIRTREE_SAVE)) {
125 free(new);
126 new = NULL;
127 }
128
129 return (flags & DIRTREE_ABORT)==DIRTREE_ABORT ? DIRTREE_ABORTVAL : new;
130 }
131
132 // Recursively read/process children of directory node, filtering through
133 // callback(). Uses and closes supplied ->dirfd.
134
dirtree_recurse(struct dirtree * node,int (* callback)(struct dirtree * node),int flags)135 int dirtree_recurse(struct dirtree *node,
136 int (*callback)(struct dirtree *node), int flags)
137 {
138 struct dirtree *new, **ddt = &(node->child);
139 struct dirent *entry;
140 DIR *dir;
141
142 if (node->dirfd == -1 || !(dir = fdopendir(node->dirfd))) {
143 if (!(flags & DIRTREE_SHUTUP)) {
144 char *path = dirtree_path(node, 0);
145 perror_msg("No %s", path);
146 free(path);
147 }
148 close(node->dirfd);
149
150 return flags;
151 }
152
153 // according to the fddir() man page, the filehandle in the DIR * can still
154 // be externally used by things that don't lseek() it.
155
156 // The extra parentheses are to shut the stupid compiler up.
157 while ((entry = readdir(dir))) {
158 if (!(new = dirtree_add_node(node, entry->d_name, flags))) continue;
159 new = dirtree_handle_callback(new, callback);
160 if (new == DIRTREE_ABORTVAL) break;
161 if (new) {
162 *ddt = new;
163 ddt = &((*ddt)->next);
164 }
165 }
166
167 if (flags & DIRTREE_COMEAGAIN) {
168 node->again++;
169 flags = callback(node);
170 }
171
172 // This closes filehandle as well, so note it
173 closedir(dir);
174 node->dirfd = -1;
175
176 return flags;
177 }
178
179 // Create dirtree root
dirtree_start(char * name,int symfollow)180 struct dirtree *dirtree_start(char *name, int symfollow)
181 {
182 return dirtree_add_node(0, name, DIRTREE_SYMFOLLOW*!!symfollow);
183 }
184
185 // Create dirtree from path, using callback to filter nodes.
186 // If callback == NULL allocate a tree of struct dirtree nodes and return
187 // pointer to root node.
188
dirtree_read(char * path,int (* callback)(struct dirtree * node))189 struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node))
190 {
191 struct dirtree *root = dirtree_start(path, 0);
192
193 return root ? dirtree_handle_callback(root, callback) : DIRTREE_ABORTVAL;
194 }
195