diff options
Diffstat (limited to 'util/path.c')
| -rw-r--r-- | util/path.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/util/path.c b/util/path.c new file mode 100644 index 0000000000..4c5b0f6296 --- /dev/null +++ b/util/path.c @@ -0,0 +1,182 @@ +/* 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, + unsigned char type); + +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) + +/* Not all systems provide this feature */ +#if defined(DT_DIR) && defined(DT_UNKNOWN) && defined(DT_LNK) +# define dirent_type(dirent) ((dirent)->d_type) +# define is_dir_maybe(type) \ + ((type) == DT_DIR || (type) == DT_UNKNOWN || (type) == DT_LNK) +#else +# define dirent_type(dirent) (1) +# define is_dir_maybe(type) (type) +#endif + +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, dirent_type(dirent)); + } + } + closedir(dir); + } + return path; +} + +static struct pathelem *add_entry(struct pathelem *root, const char *name, + unsigned char type) +{ + struct pathelem **e; + + root->num_entries++; + + root = realloc(root, sizeof(*root) + + sizeof(root->entries[0])*root->num_entries); + e = &root->entries[root->num_entries-1]; + + *e = new_entry(root->pathname, root, name); + if (is_dir_maybe(type)) { + *e = add_dir_maybe(*e); + } + + 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; +} |