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 <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" 15 16 struct pathelem 17 { 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]; 26 }; 27 28 static struct pathelem *base; 29 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) 32 { 33 unsigned int i; 34 35 for (i = 0; i < n; i++) 36 if (s1[i] != s2[i]) 37 return 0; 38 return s2[i] == 0; 39 } 40 41 static struct pathelem *add_entry(struct pathelem *root, const char *name, 42 unsigned type); 43 44 static struct pathelem *new_entry(const char *root, 45 struct pathelem *parent, 46 const char *name) 47 { 48 struct pathelem *new = malloc(sizeof(*new)); 49 new->name = strdup(name); 50 new->pathname = g_strdup_printf("%s/%s", root, name); 51 new->num_entries = 0; 52 return new; 53 } 54 55 #define streq(a,b) (strcmp((a), (b)) == 0) 56 57 /* Not all systems provide this feature */ 58 #if defined(DT_DIR) && defined(DT_UNKNOWN) && defined(DT_LNK) 59 # define dirent_type(dirent) ((dirent)->d_type) 60 # define is_dir_maybe(type) \ 61 ((type) == DT_DIR || (type) == DT_UNKNOWN || (type) == DT_LNK) 62 #else 63 # define dirent_type(dirent) (1) 64 # define is_dir_maybe(type) (type) 65 #endif 66 67 static struct pathelem *add_dir_maybe(struct pathelem *path) 68 { 69 DIR *dir; 70 71 if ((dir = opendir(path->pathname)) != NULL) { 72 struct dirent *dirent; 73 74 while ((dirent = readdir(dir)) != NULL) { 75 if (!streq(dirent->d_name,".") && !streq(dirent->d_name,"..")){ 76 path = add_entry(path, dirent->d_name, dirent_type(dirent)); 77 } 78 } 79 closedir(dir); 80 } 81 return path; 82 } 83 84 static struct pathelem *add_entry(struct pathelem *root, const char *name, 85 unsigned type) 86 { 87 struct pathelem **e; 88 89 root->num_entries++; 90 91 root = realloc(root, sizeof(*root) 92 + sizeof(root->entries[0])*root->num_entries); 93 e = &root->entries[root->num_entries-1]; 94 95 *e = new_entry(root->pathname, root, name); 96 if (is_dir_maybe(type)) { 97 *e = add_dir_maybe(*e); 98 } 99 100 return root; 101 } 102 103 /* This needs to be done after tree is stabilized (ie. no more reallocs!). */ 104 static void set_parents(struct pathelem *child, struct pathelem *parent) 105 { 106 unsigned int i; 107 108 child->parent = parent; 109 for (i = 0; i < child->num_entries; i++) 110 set_parents(child->entries[i], child); 111 } 112 113 /* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */ 114 static const char * 115 follow_path(const struct pathelem *cursor, const char *name) 116 { 117 unsigned int i, namelen; 118 119 name += strspn(name, "/"); 120 namelen = strcspn(name, "/"); 121 122 if (namelen == 0) 123 return cursor->pathname; 124 125 if (strneq(name, namelen, "..")) 126 return follow_path(cursor->parent, name + namelen); 127 128 if (strneq(name, namelen, ".")) 129 return follow_path(cursor, name + namelen); 130 131 for (i = 0; i < cursor->num_entries; i++) 132 if (strneq(name, namelen, cursor->entries[i]->name)) 133 return follow_path(cursor->entries[i], name + namelen); 134 135 /* Not found */ 136 return NULL; 137 } 138 139 void init_paths(const char *prefix) 140 { 141 char pref_buf[PATH_MAX]; 142 143 if (prefix[0] == '\0' || 144 !strcmp(prefix, "/")) 145 return; 146 147 if (prefix[0] != '/') { 148 char *cwd = getcwd(NULL, 0); 149 size_t pref_buf_len = sizeof(pref_buf); 150 151 if (!cwd) 152 abort(); 153 pstrcpy(pref_buf, sizeof(pref_buf), cwd); 154 pstrcat(pref_buf, pref_buf_len, "/"); 155 pstrcat(pref_buf, pref_buf_len, prefix); 156 free(cwd); 157 } else 158 pstrcpy(pref_buf, sizeof(pref_buf), prefix + 1); 159 160 base = new_entry("", NULL, pref_buf); 161 base = add_dir_maybe(base); 162 if (base->num_entries == 0) { 163 free (base); 164 base = NULL; 165 } else { 166 set_parents(base, base); 167 } 168 } 169 170 /* Look for path in emulation dir, otherwise return name. */ 171 const char *path(const char *name) 172 { 173 /* Only do absolute paths: quick and dirty, but should mostly be OK. 174 Could do relative by tracking cwd. */ 175 if (!base || !name || name[0] != '/') 176 return name; 177 178 return follow_path(base, name) ?: name; 179 } 180