/* Code to mangle pathnames into those matching a given prefix. eg. open("/lib/foo.so") => open("/usr/gnemul/i386-linux/lib/foo.so"); The assumption is that this area does not change. */ #include <sys/types.h> #include <sys/param.h> #include <dirent.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <stdio.h> #include "qemu-common.h" struct pathelem { /* Name of this, eg. lib */ char *name; /* Full path name, eg. /usr/gnemul/x86-linux/lib. */ char *pathname; struct pathelem *parent; /* Children */ unsigned int num_entries; struct pathelem *entries[0]; }; static struct pathelem *base; /* First N chars of S1 match S2, and S2 is N chars long. */ static int strneq(const char *s1, unsigned int n, const char *s2) { unsigned int i; for (i = 0; i < n; i++) if (s1[i] != s2[i]) return 0; return s2[i] == 0; } static struct pathelem *add_entry(struct pathelem *root, const char *name); static struct pathelem *new_entry(const char *root, struct pathelem *parent, const char *name) { struct pathelem *new = malloc(sizeof(*new)); new->name = strdup(name); if (asprintf(&new->pathname, "%s/%s", root, name) == -1) { printf("Cannot allocate memory\n"); exit(1); } new->num_entries = 0; return new; } #define streq(a,b) (strcmp((a), (b)) == 0) static struct pathelem *add_dir_maybe(struct pathelem *path) { DIR *dir; if ((dir = opendir(path->pathname)) != NULL) { struct dirent *dirent; while ((dirent = readdir(dir)) != NULL) { if (!streq(dirent->d_name,".") && !streq(dirent->d_name,"..")){ path = add_entry(path, dirent->d_name); } } closedir(dir); } return path; } static struct pathelem *add_entry(struct pathelem *root, const char *name) { root->num_entries++; root = realloc(root, sizeof(*root) + sizeof(root->entries[0])*root->num_entries); root->entries[root->num_entries-1] = new_entry(root->pathname, root, name); root->entries[root->num_entries-1] = add_dir_maybe(root->entries[root->num_entries-1]); return root; } /* This needs to be done after tree is stabilized (ie. no more reallocs!). */ static void set_parents(struct pathelem *child, struct pathelem *parent) { unsigned int i; child->parent = parent; for (i = 0; i < child->num_entries; i++) set_parents(child->entries[i], child); } /* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */ static const char * follow_path(const struct pathelem *cursor, const char *name) { unsigned int i, namelen; name += strspn(name, "/"); namelen = strcspn(name, "/"); if (namelen == 0) return cursor->pathname; if (strneq(name, namelen, "..")) return follow_path(cursor->parent, name + namelen); if (strneq(name, namelen, ".")) return follow_path(cursor, name + namelen); for (i = 0; i < cursor->num_entries; i++) if (strneq(name, namelen, cursor->entries[i]->name)) return follow_path(cursor->entries[i], name + namelen); /* Not found */ return NULL; } void init_paths(const char *prefix) { char pref_buf[PATH_MAX]; if (prefix[0] == '\0' || !strcmp(prefix, "/")) return; if (prefix[0] != '/') { char *cwd = getcwd(NULL, 0); size_t pref_buf_len = sizeof(pref_buf); if (!cwd) abort(); pstrcpy(pref_buf, sizeof(pref_buf), cwd); pstrcat(pref_buf, pref_buf_len, "/"); pstrcat(pref_buf, pref_buf_len, prefix); free(cwd); } else pstrcpy(pref_buf, sizeof(pref_buf), prefix + 1); base = new_entry("", NULL, pref_buf); base = add_dir_maybe(base); if (base->num_entries == 0) { free (base); base = NULL; } else { set_parents(base, base); } } /* Look for path in emulation dir, otherwise return name. */ const char *path(const char *name) { /* Only do absolute paths: quick and dirty, but should mostly be OK. Could do relative by tracking cwd. */ if (!base || !name || name[0] != '/') return name; return follow_path(base, name) ?: name; }