xref: /openbmc/qemu/util/path.c (revision c4107e82)
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 #include "qemu/osdep.h"
7 #include <sys/param.h>
8 #include <dirent.h>
9 #include "qemu/cutils.h"
10 #include "qemu/path.h"
11 #include "qemu/thread.h"
12 
13 static const char *base;
14 static GHashTable *hash;
15 static QemuMutex lock;
16 
init_paths(const char * prefix)17 void init_paths(const char *prefix)
18 {
19     if (prefix[0] == '\0' || !strcmp(prefix, "/")) {
20         return;
21     }
22 
23     if (prefix[0] == '/') {
24         base = g_strdup(prefix);
25     } else {
26         char *cwd = g_get_current_dir();
27         base = g_build_filename(cwd, prefix, NULL);
28         g_free(cwd);
29     }
30 
31     hash = g_hash_table_new(g_str_hash, g_str_equal);
32     qemu_mutex_init(&lock);
33 }
34 
35 /* Look for path in emulation dir, otherwise return name. */
path(const char * name)36 const char *path(const char *name)
37 {
38     gpointer key, value;
39     const char *ret;
40 
41     /* Only do absolute paths: quick and dirty, but should mostly be OK.  */
42     if (!base || !name || name[0] != '/') {
43         return name;
44     }
45 
46     qemu_mutex_lock(&lock);
47 
48     /* Have we looked up this file before?  */
49     if (g_hash_table_lookup_extended(hash, name, &key, &value)) {
50         ret = value ? value : name;
51     } else {
52         char *save = g_strdup(name);
53         char *full = g_build_filename(base, name, NULL);
54 
55         /* Look for the path; record the result, pass or fail.  */
56         if (access(full, F_OK) == 0) {
57             /* Exists.  */
58             g_hash_table_insert(hash, save, full);
59             ret = full;
60         } else {
61             /* Does not exist.  */
62             g_free(full);
63             g_hash_table_insert(hash, save, NULL);
64             ret = name;
65         }
66     }
67 
68     qemu_mutex_unlock(&lock);
69     return ret;
70 }
71