diff options
Diffstat (limited to 'linux-user/path.c')
-rw-r--r-- | linux-user/path.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/linux-user/path.c b/linux-user/path.c new file mode 100644 index 0000000..9e49076 --- /dev/null +++ b/linux-user/path.c @@ -0,0 +1,142 @@ +/* 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 <dirent.h> +#include <unistd.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <stdio.h> +#include "qemu.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); + asprintf(&new->pathname, "%s/%s", root, name); + 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 stabalized (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); +} + +void init_paths(const char *prefix) +{ + if (prefix[0] != '/' || + prefix[0] == '\0' || + !strcmp(prefix, "/")) + return; + + base = new_entry("", NULL, prefix+1); + base = add_dir_maybe(base); + set_parents(base, base); +} + +/* 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; +} + +/* 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[0] != '/') + return name; + + return follow_path(base, name) ?: name; +} |