sd_id128_to_string

systemd
Developer Lennart Poettering lennart@poettering.net
sd_id128_to_string 3
sd_id128_to_string sd_id128_from_string Format or parse 128-bit IDs as strings

    #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

`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.

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

`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

The `sd_id128_to_string()` and `sd_id128_from_string()` interfaces are available as a shared library, which can be compiled and linked to with the `libsystemd` pkg-config 1 file.

## See Also

systemd 1, sd-id128 3, printf 3