sd_id128_to_string(3) — Linux manual page


SD_ID128_TO_STRING(3)        sd_id128_to_string        SD_ID128_TO_STRING(3)

NAME         top

       sd_id128_to_string, sd_id128_from_string - Format or parse 128-bit
       IDs as strings

SYNOPSIS         top

       #include <systemd/sd-id128.h>

       char *sd_id128_to_string(sd_id128_t id, char s[33]);

       int sd_id128_from_string(const char *s, sd_id128_t *ret);

DESCRIPTION         top

       sd_id128_to_string() formats a 128-bit ID as a character string. It
       expects the ID and a string array capable of storing 33 characters.
       The ID will be formatted as 32 lowercase hexadecimal digits and be
       terminated by a NUL byte.

       sd_id128_from_string() implements the reverse operation: it takes a
       33 character string with 32 hexadecimal digits (either lowercase or
       uppercase, terminated by NUL) and parses them back into a 128-bit ID
       returned in ret. Alternatively, this call can also parse a
       37-character string with a 128-bit ID formatted as RFC UUID. If ret
       is passed as NULL the function will validate the passed ID string,
       but not actually return it in parsed form.

       For more information about the "sd_id128_t" type see sd-id128(3).
       Note that these calls operate the same way on all architectures, i.e.
       the results do not depend on endianness.

       When formatting a 128-bit ID into a string, it is often easier to use
       a format string for printf(3). This is easily done using the
       SD_ID128_FORMAT_STR and SD_ID128_FORMAT_VAL() macros. For more
       information see sd-id128(3).

RETURN VALUE         top

       sd_id128_to_string() always succeeds and returns a pointer to the
       string array passed in.  sd_id128_from_string returns 0 on success,
       in which case ret is filled in, or a negative errno-style error code.

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-id128(3), printf(3)

COLOPHON         top

       This page is part of the systemd (systemd system and service manager)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug
       report for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-08-13.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-11.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
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       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

systemd 246                                            SD_ID128_TO_STRING(3)

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