path.c (1809B)
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 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. */ 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 }