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
isdotdot(char * name)8 int 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
dirtree_notdotdot(struct dirtree * catch)17 int 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
dirtree_add_node(struct dirtree * parent,char * name,int flags)28 struct dirtree *dirtree_add_node(struct dirtree *parent, char *name, int flags)
29 {
30 struct dirtree *dt = 0;
31 struct stat st;
32 int len = 0, linklen = 0, statless = 0;
33
34 if (name) {
35 // open code fd = because haven't got node to call dirtree_parentfd() on yet
36 int fd = parent ? parent->dirfd : AT_FDCWD,
37 sym = AT_SYMLINK_NOFOLLOW*!(flags&DIRTREE_SYMFOLLOW);
38
39 // stat dangling symlinks
40 if (fstatat(fd, name, &st, sym)) {
41 // If we got ENOENT without NOFOLLOW, try again with NOFOLLOW.
42 if (errno!=ENOENT || sym || fstatat(fd, name, &st, AT_SYMLINK_NOFOLLOW)) {
43 if (flags&DIRTREE_STATLESS) statless++;
44 else goto error;
45 }
46 }
47 if (!statless && S_ISLNK(st.st_mode)) {
48 if (0>(linklen = readlinkat(fd, name, libbuf, 4095))) goto error;
49 libbuf[linklen++]=0;
50 }
51 len = strlen(name);
52 }
53
54 // Allocate/populate return structure
55 memset(dt = xmalloc((len = sizeof(struct dirtree)+len+1)+linklen), 0,
56 statless ? sizeof(struct dirtree) : offsetof(struct dirtree, st));
57 dt->parent = parent;
58 dt->again = statless ? 2 : 0;
59 if (!statless) memcpy(&dt->st, &st, sizeof(struct stat));
60 if (name) strcpy(dt->name, name);
61 else *dt->name = 0, dt->st.st_mode = S_IFDIR;
62 if (linklen) dt->symlink = memcpy(len+(char *)dt, libbuf, linklen);
63
64 return dt;
65
66 error:
67 if (!(flags&DIRTREE_SHUTUP) && !isdotdot(name)) {
68 char *path = parent ? dirtree_path(parent, 0) : "";
69
70 perror_msg("%s%s%s", path, parent ? "/" : "", name);
71 if (parent) free(path);
72 }
73 if (parent) parent->symlink = (char *)1;
74 free(dt);
75 return 0;
76 }
77
78 // Return path to this node.
79
80 // Initial call can pass in NULL to plen, or point to an int initialized to 0
81 // to return the length of the path, or a value greater than 0 to allocate
82 // extra space if you want to append your own text to the string.
83
dirtree_path(struct dirtree * node,int * plen)84 char *dirtree_path(struct dirtree *node, int *plen)
85 {
86 struct dirtree *nn;
87 char *path;
88 int ii, ll, len;
89
90 ll = len = plen ? *plen : 0;
91 if (!node->parent)
92 return strcpy(xmalloc(strlen(node->name)+ll+1), node->name);
93 for (nn = node; nn; nn = nn->parent)
94 if ((ii = strlen(nn->name))) len += ii+1-(nn->name[ii-1]=='/');
95 if (plen) *plen = len;
96 path = xmalloc(len)+len-ll;
97 for (nn = node; nn; nn = nn->parent) if ((len = strlen(nn->name))) {
98 *--path = '/'*(nn != node);
99 if (nn->name[len-1]=='/') len--;
100 memcpy(path -= len, nn->name, len);
101 }
102
103 return path;
104 }
105
dirtree_parentfd(struct dirtree * node)106 int dirtree_parentfd(struct dirtree *node)
107 {
108 return node->parent ? node->parent->dirfd : AT_FDCWD;
109 }
110
111 // Handle callback for a node in the tree. Returns saved node(s) if
112 // callback returns DIRTREE_SAVE, otherwise frees consumed nodes and
113 // returns NULL. If !callback return top node unchanged.
114 // If !new return DIRTREE_ABORTVAL
115
dirtree_handle_callback(struct dirtree * new,int (* callback)(struct dirtree * node))116 static struct dirtree *dirtree_handle_callback(struct dirtree *new,
117 int (*callback)(struct dirtree *node))
118 {
119 int flags;
120
121 if (!new) return DIRTREE_ABORTVAL;
122 if (!callback) return new;
123 flags = callback(new);
124
125 if (S_ISDIR(new->st.st_mode) && (flags & (DIRTREE_RECURSE|DIRTREE_COMEAGAIN)))
126 flags = dirtree_recurse(new, callback, !*new->name ? AT_FDCWD :
127 openat(dirtree_parentfd(new), new->name, O_CLOEXEC), flags);
128
129 // Free node that didn't request saving and has no saved children.
130 if (!new->child && !(flags & DIRTREE_SAVE)) {
131 free(new);
132 new = 0;
133 }
134
135 return (flags & DIRTREE_ABORT)==DIRTREE_ABORT ? DIRTREE_ABORTVAL : new;
136 }
137
138 // Recursively read/process children of directory node, filtering through
139 // callback(). Uses and closes supplied ->dirfd.
140
dirtree_recurse(struct dirtree * node,int (* callback)(struct dirtree * node),int dirfd,int flags)141 int dirtree_recurse(struct dirtree *node,
142 int (*callback)(struct dirtree *node), int dirfd, int flags)
143 {
144 struct dirtree *new, **ddt = &(node->child);
145 struct dirent *entry;
146 DIR *dir = 0;
147
148 // Why doesn't fdopendir() support AT_FDCWD?
149 if (AT_FDCWD == (node->dirfd = dirfd)) dir = opendir(".");
150 else if (node->dirfd != -1) dir = fdopendir(node->dirfd);
151 if (!dir) {
152 if (!(flags & DIRTREE_SHUTUP)) {
153 char *path = dirtree_path(node, 0);
154 perror_msg_raw(path);
155 free(path);
156 }
157 close(node->dirfd);
158
159 return flags;
160 }
161
162 // according to the fddir() man page, the filehandle in the DIR * can still
163 // be externally used by things that don't lseek() it.
164
165 // The extra parentheses are to shut the stupid compiler up.
166 while ((entry = readdir(dir))) {
167 if ((flags&DIRTREE_PROC) && !isdigit(*entry->d_name)) continue;
168 if (!(new = dirtree_add_node(node, entry->d_name, flags))) continue;
169 if (!new->st.st_blksize && !new->st.st_mode)
170 new->st.st_mode = entry->d_type<<12;
171 new = dirtree_handle_callback(new, callback);
172 if (new == DIRTREE_ABORTVAL) break;
173 if (new) {
174 *ddt = new;
175 ddt = &((*ddt)->next);
176 }
177 }
178
179 if (flags & DIRTREE_COMEAGAIN) {
180 node->again |= 1;
181 flags = callback(node);
182 }
183
184 // This closes filehandle as well, so note it
185 closedir(dir);
186 node->dirfd = -1;
187
188 return flags;
189 }
190
191 // Create dirtree from path, using callback to filter nodes. If !callback
192 // return just the top node. Use dirtree_notdotdot callback to allocate a
193 // tree of struct dirtree nodes and return pointer to root node for later
194 // processing.
195 // Returns DIRTREE_ABORTVAL if path didn't exist (use DIRTREE_SHUTUP to handle
196 // error message yourself).
197
dirtree_flagread(char * path,int flags,int (* callback)(struct dirtree * node))198 struct dirtree *dirtree_flagread(char *path, int flags,
199 int (*callback)(struct dirtree *node))
200 {
201 return dirtree_handle_callback(dirtree_add_node(0, path, flags), callback);
202 }
203
204 // Common case
dirtree_read(char * path,int (* callback)(struct dirtree * node))205 struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node))
206 {
207 return dirtree_flagread(path, 0, callback);
208 }
209