1 /* Code to mangle pathnames into those matching a given prefix.
2 eg. open("/lib/foo.so") => open("/usr/gnemul/i386-linux/lib/foo.so");
3
4 The assumption is that this area does not change.
5 */
6 #ifdef __linux__
7 #define _GNU_SOURCE 1
8 #endif
9 #include <sys/types.h>
10 #include <sys/param.h>
11 #include <dirent.h>
12 #include <unistd.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <errno.h>
16 #include <stdio.h>
17 #include "qemu-common.h"
18
19 struct pathelem
20 {
21 /* Name of this, eg. lib */
22 char *name;
23 /* Full path name, eg. /usr/gnemul/x86-linux/lib. */
24 char *pathname;
25 struct pathelem *parent;
26 /* Children */
27 unsigned int num_entries;
28 struct pathelem *entries[0];
29 };
30
31 static struct pathelem *base;
32
33 /* First N chars of S1 match S2, and S2 is N chars long. */
strneq(const char * s1,unsigned int n,const char * s2)34 static int strneq(const char *s1, unsigned int n, const char *s2)
35 {
36 unsigned int i;
37
38 for (i = 0; i < n; i++)
39 if (s1[i] != s2[i])
40 return 0;
41 return s2[i] == 0;
42 }
43
44 static struct pathelem *add_entry(struct pathelem *root, const char *name,
45 unsigned type);
46
new_entry(const char * root,struct pathelem * parent,const char * name)47 static struct pathelem *new_entry(const char *root,
48 struct pathelem *parent,
49 const char *name)
50 {
51 struct pathelem *new = malloc(sizeof(*new));
52 new->name = strdup(name);
53 new->pathname = g_strdup_printf("%s/%s", root, name);
54 new->num_entries = 0;
55 return new;
56 }
57
58 #define streq(a,b) (strcmp((a), (b)) == 0)
59
60 /* Not all systems provide this feature */
61 #if defined(DT_DIR) && defined(DT_UNKNOWN) && defined(DT_LNK)
62 # define dirent_type(dirent) ((dirent)->d_type)
63 # define is_dir_maybe(type) \
64 ((type) == DT_DIR || (type) == DT_UNKNOWN || (type) == DT_LNK)
65 #else
66 # define dirent_type(dirent) (1)
67 # define is_dir_maybe(type) (type)
68 #endif
69
add_dir_maybe(struct pathelem * path)70 static struct pathelem *add_dir_maybe(struct pathelem *path)
71 {
72 DIR *dir;
73
74 if ((dir = opendir(path->pathname)) != NULL) {
75 struct dirent *dirent;
76
77 while ((dirent = readdir(dir)) != NULL) {
78 if (!streq(dirent->d_name,".") && !streq(dirent->d_name,"..")){
79 path = add_entry(path, dirent->d_name, dirent_type(dirent));
80 }
81 }
82 closedir(dir);
83 }
84 return path;
85 }
86
add_entry(struct pathelem * root,const char * name,unsigned type)87 static struct pathelem *add_entry(struct pathelem *root, const char *name,
88 unsigned type)
89 {
90 struct pathelem **e;
91
92 root->num_entries++;
93
94 root = realloc(root, sizeof(*root)
95 + sizeof(root->entries[0])*root->num_entries);
96 e = &root->entries[root->num_entries-1];
97
98 *e = new_entry(root->pathname, root, name);
99 if (is_dir_maybe(type)) {
100 *e = add_dir_maybe(*e);
101 }
102
103 return root;
104 }
105
106 /* This needs to be done after tree is stabilized (ie. no more reallocs!). */
set_parents(struct pathelem * child,struct pathelem * parent)107 static void set_parents(struct pathelem *child, struct pathelem *parent)
108 {
109 unsigned int i;
110
111 child->parent = parent;
112 for (i = 0; i < child->num_entries; i++)
113 set_parents(child->entries[i], child);
114 }
115
116 /* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */
117 static const char *
follow_path(const struct pathelem * cursor,const char * name)118 follow_path(const struct pathelem *cursor, const char *name)
119 {
120 unsigned int i, namelen;
121
122 name += strspn(name, "/");
123 namelen = strcspn(name, "/");
124
125 if (namelen == 0)
126 return cursor->pathname;
127
128 if (strneq(name, namelen, ".."))
129 return follow_path(cursor->parent, name + namelen);
130
131 if (strneq(name, namelen, "."))
132 return follow_path(cursor, name + namelen);
133
134 for (i = 0; i < cursor->num_entries; i++)
135 if (strneq(name, namelen, cursor->entries[i]->name))
136 return follow_path(cursor->entries[i], name + namelen);
137
138 /* Not found */
139 return NULL;
140 }
141
init_paths(const char * prefix)142 void init_paths(const char *prefix)
143 {
144 char pref_buf[PATH_MAX];
145
146 if (prefix[0] == '\0' ||
147 !strcmp(prefix, "/"))
148 return;
149
150 if (prefix[0] != '/') {
151 char *cwd = getcwd(NULL, 0);
152 size_t pref_buf_len = sizeof(pref_buf);
153
154 if (!cwd)
155 abort();
156 pstrcpy(pref_buf, sizeof(pref_buf), cwd);
157 pstrcat(pref_buf, pref_buf_len, "/");
158 pstrcat(pref_buf, pref_buf_len, prefix);
159 free(cwd);
160 } else
161 pstrcpy(pref_buf, sizeof(pref_buf), prefix + 1);
162
163 base = new_entry("", NULL, pref_buf);
164 base = add_dir_maybe(base);
165 if (base->num_entries == 0) {
166 free (base);
167 base = NULL;
168 } else {
169 set_parents(base, base);
170 }
171 }
172
173 /* Look for path in emulation dir, otherwise return name. */
path(const char * name)174 const char *path(const char *name)
175 {
176 /* Only do absolute paths: quick and dirty, but should mostly be OK.
177 Could do relative by tracking cwd. */
178 if (!base || !name || name[0] != '/')
179 return name;
180
181 return follow_path(base, name) ?: name;
182 }
183