sd_bus_path_decode(3) — Linux manual page


SD_BUS_PATH_ENCODE(3)        sd_bus_path_encode        SD_BUS_PATH_ENCODE(3)

NAME         top

       sd_bus_path_encode, sd_bus_path_encode_many, sd_bus_path_decode,
       sd_bus_path_decode_many - Convert an external identifier into an
       object path and back

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       int sd_bus_path_encode(const char *prefix, const char *external_id,
                              char **ret_path);

       int sd_bus_path_encode_many(char **out, const char *path_template,

       int sd_bus_path_decode(const char *path, const char *prefix,
                              char **ret_external_id);

       int sd_bus_path_decode_many(const char *path,
                                   const char *path_template, ...);

DESCRIPTION         top

       sd_bus_path_encode() and sd_bus_path_decode() convert external
       identifier strings into object paths and back. These functions are
       useful to map application-specific string identifiers of any kind
       into bus object paths in a simple, reversible and safe way.

       sd_bus_path_encode() takes a bus path prefix and an external
       identifier string as arguments, plus a place to store the returned
       bus path string. The bus path prefix must be a valid bus path,
       starting with a slash "/", and not ending in one. The external
       identifier string may be in any format, may be the empty string, and
       has no restrictions on the charset — however, it must always be
       NUL-terminated. The returned string will be the concatenation of the
       bus path prefix plus an escaped version of the external identifier
       string. This operation may be reversed with sd_bus_path_decode(). It
       is recommended to only use external identifiers that generally
       require little escaping to be turned into valid bus path identifiers
       (for example, by sticking to a 7-bit ASCII character set), in order
       to ensure the resulting bus path is still short and easily processed.

       sd_bus_path_decode() reverses the operation of sd_bus_path_encode()
       and thus regenerates an external identifier string from a bus path.
       It takes a bus path and a prefix string, plus a place to store the
       returned external identifier string. If the bus path does not start
       with the specified prefix, 0 is returned and the returned string is
       set to NULL. Otherwise, the string following the prefix is unescaped
       and returned in the external identifier string.

       The escaping used will replace all characters which are invalid in a
       bus object path by "_", followed by a hexadecimal value. As a special
       case, the empty string will be replaced by a lone "_".

       sd_bus_path_encode_many() works like its counterpart
       sd_bus_path_encode(), but takes a path template as argument and
       encodes multiple labels according to its embedded directives. For
       each "%" character found in the template, the caller must provide a
       string via varargs, which will be encoded and embedded at the
       position of the "%" character. Any other character in the template is
       copied verbatim into the encoded path.

       sd_bus_path_decode_many() does the reverse of
       sd_bus_path_encode_many(). It decodes the passed object path
       according to the given path template. For each "%" character in the
       template, the caller must provide an output storage ("char **") via
       varargs. The decoded label will be stored there. Each "%" character
       will only match the current label. It will never match across labels.
       Furthermore, only a single directive is allowed per label. If "NULL"
       is passed as output storage, the label is verified but not returned
       to the caller.

RETURN VALUE         top

       On success, sd_bus_path_encode() returns positive or 0, and a valid
       bus path in the return argument. On success, sd_bus_path_decode()
       returns a positive value if the prefixed matched, or 0 if it did not.
       If the prefix matched, the external identifier is returned in the
       return parameter. If it did not match, NULL is returned in the return
       parameter. On failure, a negative errno-style error number is
       returned by either function. The returned strings must be free(3)'d
       by the caller.

NOTES         top

       These APIs are implemented as a shared library, which can be compiled
       and linked to with the libsystemd pkg-config(1) file.

SEE ALSO         top

       systemd(1), sd-bus(3), free(3)

COLOPHON         top

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systemd 247                                            SD_BUS_PATH_ENCODE(3)

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