SD_PATH_LOOKUP(3)

NAME
sd_path_lookup, sd_path_lookup_strv - Query well-known file system paths

SYNOPSIS

#include <systemd/sd-path.h>

enum {
        SD_PATH_TEMPORARY,
        SD_PATH_TEMPORARY_LARGE,
        SD_PATH_SYSTEM_BINARIES,
        SD_PATH_SYSTEM_INCLUDE,
        SD_PATH_SYSTEM_LIBRARY_PRIVATE,
        SD_PATH_SYSTEM_LIBRARY_ARCH,
        SD_PATH_SYSTEM_SHARED,
        SD_PATH_SYSTEM_CONFIGURATION_FACTORY,
        SD_PATH_SYSTEM_STATE_FACTORY,
        SD_PATH_SYSTEM_CONFIGURATION,
        SD_PATH_SYSTEM_RUNTIME,
        SD_PATH_SYSTEM_RUNTIME_LOGS,
        SD_PATH_SYSTEM_STATE_PRIVATE,
        SD_PATH_SYSTEM_STATE_LOGS,
        SD_PATH_SYSTEM_STATE_CACHE,
        SD_PATH_SYSTEM_STATE_SPOOL,
        SD_PATH_USER_BINARIES,
        SD_PATH_USER_LIBRARY_PRIVATE,
        SD_PATH_USER_LIBRARY_ARCH,
        SD_PATH_USER_SHARED,
        SD_PATH_USER_CONFIGURATION,
        SD_PATH_USER_RUNTIME,
        SD_PATH_USER_STATE_PRIVATE,
        SD_PATH_USER_STATE_CACHE,
        SD_PATH_USER,
        SD_PATH_USER_DOCUMENTS,
        SD_PATH_USER_MUSIC,
        SD_PATH_USER_PICTURES,
        SD_PATH_USER_VIDEOS,
        SD_PATH_USER_DOWNLOAD,
        SD_PATH_USER_PUBLIC,
        SD_PATH_USER_TEMPLATES,
        SD_PATH_USER_DESKTOP,
        SD_PATH_SEARCH_BINARIES,
        SD_PATH_SEARCH_BINARIES_DEFAULT,
        SD_PATH_SEARCH_LIBRARY_PRIVATE,
        SD_PATH_SEARCH_LIBRARY_ARCH,
        SD_PATH_SEARCH_SHARED,
        SD_PATH_SEARCH_CONFIGURATION_FACTORY,
        SD_PATH_SEARCH_STATE_FACTORY,
        SD_PATH_SEARCH_CONFIGURATION,
        SD_PATH_SYSTEMD_UTIL,
        SD_PATH_SYSTEMD_SYSTEM_UNIT,
        SD_PATH_SYSTEMD_SYSTEM_PRESET,
        SD_PATH_SYSTEMD_USER_UNIT,
        SD_PATH_SYSTEMD_USER_PRESET,
        SD_PATH_SYSTEMD_SYSTEM_CONF,
        SD_PATH_SYSTEMD_USER_CONF,
        SD_PATH_SYSTEMD_SEARCH_SYSTEM_UNIT,
        SD_PATH_SYSTEMD_SEARCH_USER_UNIT,
        SD_PATH_SYSTEMD_SYSTEM_GENERATOR,
        SD_PATH_SYSTEMD_USER_GENERATOR,
        SD_PATH_SYSTEMD_SEARCH_SYSTEM_GENERATOR,
        SD_PATH_SYSTEMD_SEARCH_USER_GENERATOR,
        SD_PATH_SYSTEMD_SLEEP,
        SD_PATH_SYSTEMD_SHUTDOWN,
        SD_PATH_TMPFILES,
        SD_PATH_SYSUSERS,
        SD_PATH_SYSCTL,
        SD_PATH_BINFMT,
        SD_PATH_MODULES_LOAD,
        SD_PATH_CATALOG,
        SD_PATH_SYSTEMD_SEARCH_NETWORK,
        SD_PATH_SYSTEMD_SYSTEM_ENVIRONMENT_GENERATOR,
        SD_PATH_SYSTEMD_USER_ENVIRONMENT_GENERATOR,
        SD_PATH_SYSTEMD_SEARCH_SYSTEM_ENVIRONMENT_GENERATOR,
        SD_PATH_SYSTEMD_SEARCH_USER_ENVIRONMENT_GENERATOR,
};

int sd_path_lookup(uint64_t type, const char *suffix, char **paths);

int sd_path_lookup_strv(uint64_t type, const char *suffix, char ***paths);

DESCRIPTION

sd_path_lookup() and sd_bus_path_lookup_strv() return a single path or set of file system paths specified by the argument type. In case of sd_path_lookup() a single NUL-terminated string is returned. When type specifies a set of paths, they are concatenated using ":" as a separator (as is traditionally done for e.g. $PATH or $LD_LIBRARY_PATH). In case of sd_path_lookup_strv() a NULL-terminated array of strings is returned (strv). If suffix suffix is given, it is concatenated to each of the paths after a slash ("/"). All returned paths are absolute.

For paths which refer to user directories, the relevant XDG standard is followed, with support for environment variables like $XDG_DOCUMENTS_DIR, $XDG_DESKTOP_DIR, ..., and explicit configuration in /etc/xdg/user-dirs.conf or ${XDG_CONFIG_HOME}/user-dirs.dirs. See XDG Base Directory Specification[1] for details.

systemd-path(1) is a wrapper around sd_path_lookup() and allows the same set of paths to be queried.

RETURN VALUE

On success, sd_path_lookup() and sd_path_lookup_strv() return a non-negative integer. On failure, a negative errno-style error number is returned by either function.

The returned string or string array (strv) must be free(3)'d by the caller.

  Errors

Returned errors may indicate the following problems:

-EOPNOTSUPP
    Unknown identifier type.

-EINVAL
    Output argument is NULL.

-ENXIO
    Query failed because of an undefined environment variable (e.g. for SD_PATH_USER_RUNTIME when $XDG_RUNTIME_DIR is not defined).

-ENOMEM
    Memory allocation failed.

EXAMPLES

  Look up the location of ~/Documents

    /* SPDX-License-Identifier: MIT-0 */
    #include <stdio.h>
    #include <stdlib.h>
    #include <systemd/sd-path.h>
    int main(void) {
      int r;
      char *t;
      r = sd_path_lookup(SD_PATH_USER_DOCUMENTS, NULL, &t);
      if (r < 0)
        return EXIT_FAILURE;
      printf("~/Documents: %s\n", t);
      free(t);
      return EXIT_SUCCESS;
    }

Note that the default answer of $HOME/Documents may be overridden by user-dirs.conf or $XDG_DOCUMENTS_DIR.

NOTES

Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd pkg-config(1) file.

The code described here uses getenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call setenv(3) from a parallel thread. It is recommended to only do calls to setenv() from an early phase of the program when no other threads have been started.

SEE ALSO

systemd-path(1)

NOTES

1.  XDG Base Directory Specification
    https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html