/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010-2012 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <string.h> #include <unistd.h> #include <errno.h> #include <stdlib.h> #include <stdio.h> #include <fcntl.h> #include <sys/statvfs.h> #include "macro.h" #include "util.h" #include "log.h" #include "strv.h" #include "path-util.h" #include "missing.h" #include "fileio.h" bool path_is_absolute(const char *p) { return p[0] == '/'; } bool is_path(const char *p) { return !!strchr(p, '/'); } int path_get_parent(const char *path, char **_r) { const char *e, *a = NULL, *b = NULL, *p; char *r; bool slash = false; assert(path); assert(_r); if (!*path) return -EINVAL; for (e = path; *e; e++) { if (!slash && *e == '/') { a = b; b = e; slash = true; } else if (slash && *e != '/') slash = false; } if (*(e-1) == '/') p = a; else p = b; if (!p) return -EINVAL; if (p == path) r = strdup("/"); else r = strndup(path, p-path); if (!r) return -ENOMEM; *_r = r; return 0; } char **path_split_and_make_absolute(const char *p) { char **l; assert(p); l = strv_split(p, ":"); if (!l) return NULL; if (!path_strv_make_absolute_cwd(l)) { strv_free(l); return NULL; } return l; } char *path_make_absolute(const char *p, const char *prefix) { assert(p); /* Makes every item in the list an absolute path by prepending * the prefix, if specified and necessary */ if (path_is_absolute(p) || !prefix) return strdup(p); return strjoin(prefix, "/", p, NULL); } char *path_make_absolute_cwd(const char *p) { _cleanup_free_ char *cwd = NULL; assert(p); /* Similar to path_make_absolute(), but prefixes with the * current working directory. */ if (path_is_absolute(p)) return strdup(p); cwd = get_current_dir_name(); if (!cwd) return NULL; return strjoin(cwd, "/", p, NULL); } int path_make_relative(const char *from_dir, const char *to_path, char **_r) { char *r, *p; unsigned n_parents; assert(from_dir); assert(to_path); assert(_r); /* Strips the common part, and adds ".." elements as necessary. */ if (!path_is_absolute(from_dir)) return -EINVAL; if (!path_is_absolute(to_path)) return -EINVAL; /* Skip the common part. */ for (;;) { size_t a; size_t b; from_dir += strspn(from_dir, "/"); to_path += strspn(to_path, "/"); if (!*from_dir) { if (!*to_path) /* from_dir equals to_path. */ r = strdup("."); else /* from_dir is a parent directory of to_path. */ r = strdup(to_path); if (!r) return -ENOMEM; path_kill_slashes(r); *_r = r; return 0; } if (!*to_path) break; a = strcspn(from_dir, "/"); b = strcspn(to_path, "/"); if (a != b) break; if (memcmp(from_dir, to_path, a) != 0) break; from_dir += a; to_path += b; } /* If we're here, then "from_dir" has one or more elements that need to * be replaced with "..". */ /* Count the number of necessary ".." elements. */ for (n_parents = 0;;) { from_dir += strspn(from_dir, "/"); if (!*from_dir) break; from_dir += strcspn(from_dir, "/"); n_parents++; } r = malloc(n_parents * 3 + strlen(to_path) + 1); if (!r) return -ENOMEM; for (p = r; n_parents > 0; n_parents--, p += 3) memcpy(p, "../", 3); strcpy(p, to_path); path_kill_slashes(r); *_r = r; return 0; } char **path_strv_make_absolute_cwd(char **l) { char **s; /* Goes through every item in the string list and makes it * absolute. This works in place and won't rollback any * changes on failure. */ STRV_FOREACH(s, l) { char *t; t = path_make_absolute_cwd(*s); if (!t) return NULL; free(*s); *s = t; } return l; } char **path_strv_resolve(char **l, const char *prefix) { char **s; unsigned k = 0; bool enomem = false; if (strv_isempty(l)) return l; /* Goes through every item in the string list and canonicalize * the path. This works in place and won't rollback any * changes on failure. */ STRV_FOREACH(s, l) { char *t, *u; _cleanup_free_ char *orig = NULL; if (!path_is_absolute(*s)) { free(*s); continue; } if (prefix) { orig = *s; t = strappend(prefix, orig); if (!t) { enomem = true; continue; } } else t = *s; errno = 0; u = canonicalize_file_name(t); if (!u) { if (errno == ENOENT) { if (prefix) { u = orig; orig = NULL; free(t); } else u = t; } else { free(t); if (errno == ENOMEM || errno == 0) enomem = true; continue; } } else if (prefix) { char *x; free(t); x = path_startswith(u, prefix); if (x) { /* restore the slash if it was lost */ if (!startswith(x, "/")) *(--x) = '/'; t = strdup(x); free(u); if (!t) { enomem = true; continue; } u = t; } else { /* canonicalized path goes outside of * prefix, keep the original path instead */ free(u); u = orig; orig = NULL; } } else free(t); l[k++] = u; } l[k] = NULL; if (enomem) return NULL; return l; } char **path_strv_resolve_uniq(char **l, const char *prefix) { if (strv_isempty(l)) return l; if (!path_strv_resolve(l, prefix)) return NULL; return strv_uniq(l); } char *path_kill_slashes(char *path) { char *f, *t; bool slash = false; /* Removes redundant inner and trailing slashes. Modifies the * passed string in-place. * * ///foo///bar/ becomes /foo/bar */ for (f = path, t = path; *f; f++) { if (*f == '/') { slash = true; continue; } if (slash) { slash = false; *(t++) = '/'; } *(t++) = *f; } /* Special rule, if we are talking of the root directory, a trailing slash is good */ if (t == path && slash) *(t++) = '/'; *t = 0; return path; } char* path_startswith(const char *path, const char *prefix) { assert(path); assert(prefix); if ((path[0] == '/') != (prefix[0] == '/')) return NULL; for (;;) { size_t a, b; path += strspn(path, "/"); prefix += strspn(prefix, "/"); if (*prefix == 0) return (char*) path; if (*path == 0) return NULL; a = strcspn(path, "/"); b = strcspn(prefix, "/"); if (a != b) return NULL; if (memcmp(path, prefix, a) != 0) return NULL; path += a; prefix += b; } } int path_compare(const char *a, const char *b) { int d; assert(a); assert(b); /* A relative path and an abolute path must not compare as equal. * Which one is sorted before the other does not really matter. * Here a relative path is ordered before an absolute path. */ d = (a[0] == '/') - (b[0] == '/'); if (d) return d; for (;;) { size_t j, k; a += strspn(a, "/"); b += strspn(b, "/"); if (*a == 0 && *b == 0) return 0; /* Order prefixes first: "/foo" before "/foo/bar" */ if (*a == 0) return -1; if (*b == 0) return 1; j = strcspn(a, "/"); k = strcspn(b, "/"); /* Alphabetical sort: "/foo/aaa" before "/foo/b" */ d = memcmp(a, b, MIN(j, k)); if (d) return (d > 0) - (d < 0); /* sign of d */ /* Sort "/foo/a" before "/foo/aaa" */ d = (j > k) - (j < k); /* sign of (j - k) */ if (d) return d; a += j; b += k; } } bool path_equal(const char *a, const char *b) { return path_compare(a, b) == 0; } bool path_equal_or_files_same(const char *a, const char *b) { return path_equal(a, b) || files_same(a, b) > 0; } char* path_join(const char *root, const char *path, const char *rest) { assert(path); if (!isempty(root)) return strjoin(root, endswith(root, "/") ? "" : "/", path[0] == '/' ? path+1 : path, rest ? (endswith(path, "/") ? "" : "/") : NULL, rest && rest[0] == '/' ? rest+1 : rest, NULL); else return strjoin(path, rest ? (endswith(path, "/") ? "" : "/") : NULL, rest && rest[0] == '/' ? rest+1 : rest, NULL); } static int fd_fdinfo_mnt_id(int fd, const char *filename, int flags, int *mnt_id) { char path[strlen("/proc/self/fdinfo/") + DECIMAL_STR_MAX(int)]; _cleanup_free_ char *fdinfo = NULL; _cleanup_close_ int subfd = -1; char *p; int r; if ((flags & AT_EMPTY_PATH) && isempty(filename)) xsprintf(path, "/proc/self/fdinfo/%i", fd); else { subfd = openat(fd, filename, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_PATH); if (subfd < 0) return -errno; xsprintf(path, "/proc/self/fdinfo/%i", subfd); } r = read_full_file(path, &fdinfo, NULL); if (r == -ENOENT) /* The fdinfo directory is a relatively new addition */ return -EOPNOTSUPP; if (r < 0) return -errno; p = startswith(fdinfo, "mnt_id:"); if (!p) { p = strstr(fdinfo, "\nmnt_id:"); if (!p) /* The mnt_id field is a relatively new addition */ return -EOPNOTSUPP; p += 8; } p += strspn(p, WHITESPACE); p[strcspn(p, WHITESPACE)] = 0; return safe_atoi(p, mnt_id); } int fd_is_mount_point(int fd, const char *filename, int flags) { union file_handle_union h = FILE_HANDLE_INIT, h_parent = FILE_HANDLE_INIT; int mount_id = -1, mount_id_parent = -1; bool nosupp = false, check_st_dev = true; struct stat a, b; int r; assert(fd >= 0); assert(filename); /* First we will try the name_to_handle_at() syscall, which * tells us the mount id and an opaque file "handle". It is * not supported everywhere though (kernel compile-time * option, not all file systems are hooked up). If it works * the mount id is usually good enough to tell us whether * something is a mount point. * * If that didn't work we will try to read the mount id from * /proc/self/fdinfo/<fd>. This is almost as good as * name_to_handle_at(), however, does not return the * opaque file handle. The opaque file handle is pretty useful * to detect the root directory, which we should always * consider a mount point. Hence we use this only as * fallback. Exporting the mnt_id in fdinfo is a pretty recent * kernel addition. * * As last fallback we do traditional fstat() based st_dev * comparisons. This is how things were traditionally done, * but unionfs breaks breaks this since it exposes file * systems with a variety of st_dev reported. Also, btrfs * subvolumes have different st_dev, even though they aren't * real mounts of their own. */ r = name_to_handle_at(fd, filename, &h.handle, &mount_id, flags); if (r < 0) { if (errno == ENOSYS) /* This kernel does not support name_to_handle_at() * fall back to simpler logic. */ goto fallback_fdinfo; else if (errno == EOPNOTSUPP) /* This kernel or file system does not support * name_to_handle_at(), hence let's see if the * upper fs supports it (in which case it is a * mount point), otherwise fallback to the * traditional stat() logic */ nosupp = true; else return -errno; } r = name_to_handle_at(fd, "", &h_parent.handle, &mount_id_parent, AT_EMPTY_PATH); if (r < 0) { if (errno == EOPNOTSUPP) { if (nosupp) /* Neither parent nor child do name_to_handle_at()? We have no choice but to fall back. */ goto fallback_fdinfo; else /* The parent can't do name_to_handle_at() but the * directory we are interested in can? * If so, it must be a mount point. */ return 1; } else return -errno; } /* The parent can do name_to_handle_at() but the * directory we are interested in can't? If so, it * must be a mount point. */ if (nosupp) return 1; /* If the file handle for the directory we are * interested in and its parent are identical, we * assume this is the root directory, which is a mount * point. */ if (h.handle.handle_bytes == h_parent.handle.handle_bytes && h.handle.handle_type == h_parent.handle.handle_type && memcmp(h.handle.f_handle, h_parent.handle.f_handle, h.handle.handle_bytes) == 0) return 1; return mount_id != mount_id_parent; fallback_fdinfo: r = fd_fdinfo_mnt_id(fd, filename, flags, &mount_id); if (r == -EOPNOTSUPP) goto fallback_fstat; if (r < 0) return r; r = fd_fdinfo_mnt_id(fd, "", AT_EMPTY_PATH, &mount_id_parent); if (r < 0) return r; if (mount_id != mount_id_parent) return 1; /* Hmm, so, the mount ids are the same. This leaves one * special case though for the root file system. For that, * let's see if the parent directory has the same inode as we * are interested in. Hence, let's also do fstat() checks now, * too, but avoid the st_dev comparisons, since they aren't * that useful on unionfs mounts. */ check_st_dev = false; fallback_fstat: /* yay for fstatat() taking a different set of flags than the other * _at() above */ if (flags & AT_SYMLINK_FOLLOW) flags &= ~AT_SYMLINK_FOLLOW; else flags |= AT_SYMLINK_NOFOLLOW; if (fstatat(fd, filename, &a, flags) < 0) return -errno; if (fstatat(fd, "", &b, AT_EMPTY_PATH) < 0) return -errno; /* A directory with same device and inode as its parent? Must * be the root directory */ if (a.st_dev == b.st_dev && a.st_ino == b.st_ino) return 1; return check_st_dev && (a.st_dev != b.st_dev); } /* flags can be AT_SYMLINK_FOLLOW or 0 */ int path_is_mount_point(const char *t, int flags) { _cleanup_close_ int fd = -1; _cleanup_free_ char *canonical = NULL, *parent = NULL; int r; assert(t); if (path_equal(t, "/")) return 1; /* we need to resolve symlinks manually, we can't just rely on * fd_is_mount_point() to do that for us; if we have a structure like * /bin -> /usr/bin/ and /usr is a mount point, then the parent that we * look at needs to be /usr, not /. */ if (flags & AT_SYMLINK_FOLLOW) { canonical = canonicalize_file_name(t); if (!canonical) return -errno; t = canonical; } r = path_get_parent(t, &parent); if (r < 0) return r; fd = openat(AT_FDCWD, parent, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_PATH); if (fd < 0) return -errno; return fd_is_mount_point(fd, basename(t), flags); } int path_is_read_only_fs(const char *path) { struct statvfs st; assert(path); if (statvfs(path, &st) < 0) return -errno; if (st.f_flag & ST_RDONLY) return true; /* On NFS, statvfs() might not reflect whether we can actually * write to the remote share. Let's try again with * access(W_OK) which is more reliable, at least sometimes. */ if (access(path, W_OK) < 0 && errno == EROFS) return true; return false; } int path_is_os_tree(const char *path) { char *p; int r; /* We use /usr/lib/os-release as flag file if something is an OS */ p = strjoina(path, "/usr/lib/os-release"); r = access(p, F_OK); if (r >= 0) return 1; /* Also check for the old location in /etc, just in case. */ p = strjoina(path, "/etc/os-release"); r = access(p, F_OK); return r >= 0; } int find_binary(const char *name, bool local, char **filename) { assert(name); if (is_path(name)) { if (local && access(name, X_OK) < 0) return -errno; if (filename) { char *p; p = path_make_absolute_cwd(name); if (!p) return -ENOMEM; *filename = p; } return 0; } else { const char *path; const char *word, *state; size_t l; /** * Plain getenv, not secure_getenv, because we want * to actually allow the user to pick the binary. */ path = getenv("PATH"); if (!path) path = DEFAULT_PATH; FOREACH_WORD_SEPARATOR(word, l, path, ":", state) { _cleanup_free_ char *p = NULL; if (asprintf(&p, "%.*s/%s", (int) l, word, name) < 0) return -ENOMEM; if (access(p, X_OK) < 0) continue; if (filename) { *filename = path_kill_slashes(p); p = NULL; } return 0; } return -ENOENT; } } bool paths_check_timestamp(const char* const* paths, usec_t *timestamp, bool update) { bool changed = false; const char* const* i; assert(timestamp); if (paths == NULL) return false; STRV_FOREACH(i, paths) { struct stat stats; usec_t u; if (stat(*i, &stats) < 0) continue; u = timespec_load(&stats.st_mtim); /* first check */ if (*timestamp >= u) continue; log_debug("timestamp of '%s' changed", *i); /* update timestamp */ if (update) { *timestamp = u; changed = true; } else return true; } return changed; } int fsck_exists(const char *fstype) { _cleanup_free_ char *p = NULL, *d = NULL; const char *checker; int r; checker = strjoina("fsck.", fstype); r = find_binary(checker, true, &p); if (r < 0) return r; /* An fsck that is linked to /bin/true is a non-existent * fsck */ r = readlink_malloc(p, &d); if (r >= 0 && (path_equal(d, "/bin/true") || path_equal(d, "/usr/bin/true") || path_equal(d, "/dev/null"))) return -ENOENT; return 0; } char *prefix_root(const char *root, const char *path) { char *n, *p; size_t l; /* If root is passed, prefixes path with it. Otherwise returns * it as is. */ assert(path); /* First, drop duplicate prefixing slashes from the path */ while (path[0] == '/' && path[1] == '/') path++; if (isempty(root) || path_equal(root, "/")) return strdup(path); l = strlen(root) + 1 + strlen(path) + 1; n = new(char, l); if (!n) return NULL; p = stpcpy(n, root); while (p > n && p[-1] == '/') p--; if (path[0] != '/') *(p++) = '/'; strcpy(p, path); return n; }