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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 
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 = 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 
57 error:
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 
dirtree_path(struct dirtree * node,int * plen)75 char *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 
dirtree_parentfd(struct dirtree * node)95 int 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 
dirtree_handle_callback(struct dirtree * new,int (* callback)(struct dirtree * node))105 struct 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 
dirtree_recurse(struct dirtree * node,int (* callback)(struct dirtree * node),int dirfd,int flags)130 int 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("No %s", 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 
dirtree_flagread(char * path,int flags,int (* callback)(struct dirtree * node))183 struct 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
dirtree_read(char * path,int (* callback)(struct dirtree * node))190 struct dirtree *dirtree_read(char *path, int (*callback)(struct dirtree *node))
191 {
192   return dirtree_flagread(path, 0, callback);
193 }
194