diff options
Diffstat (limited to 'src/libsystemd-basic/src/path-util.c')
-rw-r--r-- | src/libsystemd-basic/src/path-util.c | 816 |
1 files changed, 816 insertions, 0 deletions
diff --git a/src/libsystemd-basic/src/path-util.c b/src/libsystemd-basic/src/path-util.c new file mode 100644 index 0000000000..603c93f948 --- /dev/null +++ b/src/libsystemd-basic/src/path-util.c @@ -0,0 +1,816 @@ +/*** + 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 <errno.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/stat.h> +#include <unistd.h> + +/* When we include libgen.h because we need dirname() we immediately + * undefine basename() since libgen.h defines it as a macro to the + * POSIX version which is really broken. We prefer GNU basename(). */ +#include <libgen.h> +#undef basename + +#include "systemd-basic/alloc-util.h" +#include "systemd-basic/extract-word.h" +#include "systemd-basic/fs-util.h" +#include "systemd-basic/log.h" +#include "systemd-basic/macro.h" +#include "systemd-basic/missing.h" +#include "systemd-basic/path-util.h" +#include "systemd-basic/stat-util.h" +#include "systemd-basic/string-util.h" +#include "systemd-basic/strv.h" +#include "systemd-basic/time-util.h" + +bool path_is_absolute(const char *p) { + return p[0] == '/'; +} + +bool is_path(const char *p) { + return !!strchr(p, '/'); +} + +int path_split_and_make_absolute(const char *p, char ***ret) { + char **l; + int r; + + assert(p); + assert(ret); + + l = strv_split(p, ":"); + if (!l) + return -ENOMEM; + + r = path_strv_make_absolute_cwd(l); + if (r < 0) { + strv_free(l); + return r; + } + + *ret = l; + return r; +} + +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); +} + +int path_make_absolute_cwd(const char *p, char **ret) { + char *c; + + assert(p); + assert(ret); + + /* Similar to path_make_absolute(), but prefixes with the + * current working directory. */ + + if (path_is_absolute(p)) + c = strdup(p); + else { + _cleanup_free_ char *cwd = NULL; + + cwd = get_current_dir_name(); + if (!cwd) + return negative_errno(); + + c = strjoin(cwd, "/", p, NULL); + } + if (!c) + return -ENOMEM; + + *ret = c; + return 0; +} + +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; +} + +int path_strv_make_absolute_cwd(char **l) { + char **s; + int r; + + /* 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; + + r = path_make_absolute_cwd(*s, &t); + if (r < 0) + return r; + + free(*s); + *s = t; + } + + return 0; +} + +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 != 0) + 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 != 0) + 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 != 0) + 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); +} + +int find_binary(const char *name, char **ret) { + int last_error, r; + const char *p; + + assert(name); + + if (is_path(name)) { + if (access(name, X_OK) < 0) + return -errno; + + if (ret) { + r = path_make_absolute_cwd(name, ret); + if (r < 0) + return r; + } + + return 0; + } + + /** + * Plain getenv, not secure_getenv, because we want + * to actually allow the user to pick the binary. + */ + p = getenv("PATH"); + if (!p) + p = DEFAULT_PATH; + + last_error = -ENOENT; + + for (;;) { + _cleanup_free_ char *j = NULL, *element = NULL; + + r = extract_first_word(&p, &element, ":", EXTRACT_RELAX|EXTRACT_DONT_COALESCE_SEPARATORS); + if (r < 0) + return r; + if (r == 0) + break; + + if (!path_is_absolute(element)) + continue; + + j = strjoin(element, "/", name, NULL); + if (!j) + return -ENOMEM; + + if (access(j, X_OK) >= 0) { + /* Found it! */ + + if (ret) { + *ret = path_kill_slashes(j); + j = NULL; + } + + return 0; + } + + last_error = -errno; + } + + return last_error; +} + +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; +} + +static int binary_is_good(const char *binary) { + _cleanup_free_ char *p = NULL, *d = NULL; + int r; + + r = find_binary(binary, &p); + if (r == -ENOENT) + return 0; + 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 == -EINVAL) /* not a symlink */ + return 1; + if (r < 0) + return r; + + return !PATH_IN_SET(d, "true" + "/bin/true", + "/usr/bin/true", + "/dev/null"); +} + +int fsck_exists(const char *fstype) { + const char *checker; + + assert(fstype); + + if (streq(fstype, "auto")) + return -EINVAL; + + checker = strjoina("fsck.", fstype); + return binary_is_good(checker); +} + +int mkfs_exists(const char *fstype) { + const char *mkfs; + + assert(fstype); + + if (streq(fstype, "auto")) + return -EINVAL; + + mkfs = strjoina("mkfs.", fstype); + return binary_is_good(mkfs); +} + +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; +} + +int parse_path_argument_and_warn(const char *path, bool suppress_root, char **arg) { + char *p; + int r; + + /* + * This function is intended to be used in command line + * parsers, to handle paths that are passed in. It makes the + * path absolute, and reduces it to NULL if omitted or + * root (the latter optionally). + * + * NOTE THAT THIS WILL FREE THE PREVIOUS ARGUMENT POINTER ON + * SUCCESS! Hence, do not pass in uninitialized pointers. + */ + + if (isempty(path)) { + *arg = mfree(*arg); + return 0; + } + + r = path_make_absolute_cwd(path, &p); + if (r < 0) + return log_error_errno(r, "Failed to parse path \"%s\" and make it absolute: %m", path); + + path_kill_slashes(p); + if (suppress_root && path_equal(p, "/")) + p = mfree(p); + + free(*arg); + *arg = p; + return 0; +} + +char* dirname_malloc(const char *path) { + char *d, *dir, *dir2; + + assert(path); + + d = strdup(path); + if (!d) + return NULL; + + dir = dirname(d); + assert(dir); + + if (dir == d) + return d; + + dir2 = strdup(dir); + free(d); + + return dir2; +} + +bool filename_is_valid(const char *p) { + const char *e; + + if (isempty(p)) + return false; + + if (streq(p, ".")) + return false; + + if (streq(p, "..")) + return false; + + e = strchrnul(p, '/'); + if (*e != 0) + return false; + + if (e - p > FILENAME_MAX) + return false; + + return true; +} + +bool path_is_safe(const char *p) { + + if (isempty(p)) + return false; + + if (streq(p, "..") || startswith(p, "../") || endswith(p, "/..") || strstr(p, "/../")) + return false; + + if (strlen(p)+1 > PATH_MAX) + return false; + + /* The following two checks are not really dangerous, but hey, they still are confusing */ + if (streq(p, ".") || startswith(p, "./") || endswith(p, "/.") || strstr(p, "/./")) + return false; + + if (strstr(p, "//")) + return false; + + return true; +} + +char *file_in_same_dir(const char *path, const char *filename) { + char *e, *ret; + size_t k; + + assert(path); + assert(filename); + + /* This removes the last component of path and appends + * filename, unless the latter is absolute anyway or the + * former isn't */ + + if (path_is_absolute(filename)) + return strdup(filename); + + e = strrchr(path, '/'); + if (!e) + return strdup(filename); + + k = strlen(filename); + ret = new(char, (e + 1 - path) + k + 1); + if (!ret) + return NULL; + + memcpy(mempcpy(ret, path, e + 1 - path), filename, k + 1); + return ret; +} + +bool hidden_or_backup_file(const char *filename) { + const char *p; + + assert(filename); + + if (filename[0] == '.' || + streq(filename, "lost+found") || + streq(filename, "aquota.user") || + streq(filename, "aquota.group") || + endswith(filename, "~")) + return true; + + p = strrchr(filename, '.'); + if (!p) + return false; + + /* Please, let's not add more entries to the list below. If external projects think it's a good idea to come up + * with always new suffixes and that everybody else should just adjust to that, then it really should be on + * them. Hence, in future, let's not add any more entries. Instead, let's ask those packages to instead adopt + * one of the generic suffixes/prefixes for hidden files or backups, possibly augmented with an additional + * string. Specifically: there's now: + * + * The generic suffixes "~" and ".bak" for backup files + * The generic prefix "." for hidden files + * + * Thus, if a new package manager "foopkg" wants its own set of ".foopkg-new", ".foopkg-old", ".foopkg-dist" + * or so registered, let's refuse that and ask them to use ".foopkg.new", ".foopkg.old" or ".foopkg~" instead. + */ + + return STR_IN_SET(p + 1, + "rpmnew", + "rpmsave", + "rpmorig", + "dpkg-old", + "dpkg-new", + "dpkg-tmp", + "dpkg-dist", + "dpkg-bak", + "dpkg-backup", + "dpkg-remove", + "ucf-new", + "ucf-old", + "ucf-dist", + "swp", + "bak", + "old", + "new"); +} + +bool is_device_path(const char *path) { + + /* Returns true on paths that refer to a device, either in + * sysfs or in /dev */ + + return + path_startswith(path, "/dev/") || + path_startswith(path, "/sys/"); +} |