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