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