Merge remote branch 'kwolf/for-anthony' into HEAD
[qemu.git] / path.c
blob0d2bf149e4eb12f052c67ae38d2a8c264913a909
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");
4 The assumption is that this area does not change.
5 */
6 #include <sys/types.h>
7 #include <sys/param.h>
8 #include <dirent.h>
9 #include <unistd.h>
10 #include <stdlib.h>
11 #include <string.h>
12 #include <errno.h>
13 #include <stdio.h>
14 #include "qemu-common.h"
16 struct pathelem
18 /* Name of this, eg. lib */
19 char *name;
20 /* Full path name, eg. /usr/gnemul/x86-linux/lib. */
21 char *pathname;
22 struct pathelem *parent;
23 /* Children */
24 unsigned int num_entries;
25 struct pathelem *entries[0];
28 static struct pathelem *base;
30 /* First N chars of S1 match S2, and S2 is N chars long. */
31 static int strneq(const char *s1, unsigned int n, const char *s2)
33 unsigned int i;
35 for (i = 0; i < n; i++)
36 if (s1[i] != s2[i])
37 return 0;
38 return s2[i] == 0;
41 static struct pathelem *add_entry(struct pathelem *root, const char *name);
43 static struct pathelem *new_entry(const char *root,
44 struct pathelem *parent,
45 const char *name)
47 struct pathelem *new = malloc(sizeof(*new));
48 new->name = strdup(name);
49 if (asprintf(&new->pathname, "%s/%s", root, name) == -1) {
50 printf("Cannot allocate memory\n");
51 exit(1);
53 new->num_entries = 0;
54 return new;
57 #define streq(a,b) (strcmp((a), (b)) == 0)
59 static struct pathelem *add_dir_maybe(struct pathelem *path)
61 DIR *dir;
63 if ((dir = opendir(path->pathname)) != NULL) {
64 struct dirent *dirent;
66 while ((dirent = readdir(dir)) != NULL) {
67 if (!streq(dirent->d_name,".") && !streq(dirent->d_name,"..")){
68 path = add_entry(path, dirent->d_name);
71 closedir(dir);
73 return path;
76 static struct pathelem *add_entry(struct pathelem *root, const char *name)
78 root->num_entries++;
80 root = realloc(root, sizeof(*root)
81 + sizeof(root->entries[0])*root->num_entries);
83 root->entries[root->num_entries-1] = new_entry(root->pathname, root, name);
84 root->entries[root->num_entries-1]
85 = add_dir_maybe(root->entries[root->num_entries-1]);
86 return root;
89 /* This needs to be done after tree is stabilized (ie. no more reallocs!). */
90 static void set_parents(struct pathelem *child, struct pathelem *parent)
92 unsigned int i;
94 child->parent = parent;
95 for (i = 0; i < child->num_entries; i++)
96 set_parents(child->entries[i], child);
99 /* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */
100 static const char *
101 follow_path(const struct pathelem *cursor, const char *name)
103 unsigned int i, namelen;
105 name += strspn(name, "/");
106 namelen = strcspn(name, "/");
108 if (namelen == 0)
109 return cursor->pathname;
111 if (strneq(name, namelen, ".."))
112 return follow_path(cursor->parent, name + namelen);
114 if (strneq(name, namelen, "."))
115 return follow_path(cursor, name + namelen);
117 for (i = 0; i < cursor->num_entries; i++)
118 if (strneq(name, namelen, cursor->entries[i]->name))
119 return follow_path(cursor->entries[i], name + namelen);
121 /* Not found */
122 return NULL;
125 void init_paths(const char *prefix)
127 char pref_buf[PATH_MAX];
129 if (prefix[0] == '\0' ||
130 !strcmp(prefix, "/"))
131 return;
133 if (prefix[0] != '/') {
134 char *cwd = getcwd(NULL, 0);
135 size_t pref_buf_len = sizeof(pref_buf);
137 if (!cwd)
138 abort();
139 pstrcpy(pref_buf, sizeof(pref_buf), cwd);
140 pstrcat(pref_buf, pref_buf_len, "/");
141 pstrcat(pref_buf, pref_buf_len, prefix);
142 free(cwd);
143 } else
144 pstrcpy(pref_buf, sizeof(pref_buf), prefix + 1);
146 base = new_entry("", NULL, pref_buf);
147 base = add_dir_maybe(base);
148 if (base->num_entries == 0) {
149 free (base);
150 base = NULL;
151 } else {
152 set_parents(base, base);
156 /* Look for path in emulation dir, otherwise return name. */
157 const char *path(const char *name)
159 /* Only do absolute paths: quick and dirty, but should mostly be OK.
160 Could do relative by tracking cwd. */
161 if (!base || !name || name[0] != '/')
162 return name;
164 return follow_path(base, name) ?: name;