librsync(3)

💖 librsync — the manual page, but make it slay 💖

okay bestie, you found librsync(3), which lives in the Library Functions Manual section, and honestly? she's iconic. let's get into it 💅

✨ NAME ✨

librsync — the library for delta compression of streams, periodt 🦋

🌸 SYNOPSYS 🌸

(not me spelling it SYNOPSYS exactly like the original does — we respect the source material here, no cap 🙈)

#include <stdio.h>
#include <stdlib.h>
#include <librsync.h>

cc ... -lrsync

like, that's the whole vibe check right there. include the headers, link against it, go off ✨

👑 DESCRIPTION 👑

so. the librsync library implements network delta-compression of streams and files. yes, streams and files. both. she does both 💖

the algorithm is similar to the one used in the rsync(1) and xdelta(2) programs, but — and this is the part that matters — she's specialized for transfer of arbitrary-length octet streams. lowkey a whole different beast.

and here's the thing that makes her actually iconic: unlike most diff programs, librsync does not require access to both of the files on the same machine 😭🫶 instead she only needs:

• a short “signature” of the old file, and
• the complete contents of the new file

that's it. that's the whole flex. two machines, one tiny signature, no problem 💅

🧚 The canonical use 🧚

the canonical use of librsync is in the rproxy(8) reference implementation of the rsync proposed extension to HTTP. very main character energy.

but bestie, she's not gatekept — she may be useful to other programs which wish to do delta-compression in HTTP, or within their own protocol. do your thing ✨

also, there are HTTP-specific utility functions within librsync, but plot twist: they need not be used. optional. take 'em or leave 'em 🎀

and for the terminal girlies: a number of tools such as rdiff(1) provide command-line and scriptable access to rsync functions 🔥

💜 SEE ALSO 💜

• rdiff(1)
• rdiff and librsync Manual
• http://rproxy.sourceforge.net/ or http://linuxcare.com.au/rproxy/
• draft-pool-rsync

iykyk 🌈

💀 BUGS 💀

okay bestie, real talk, we gotta be honest here 🫶

the rsync protocol is still evolving. there may be bugs in the implementation. the interface may change in the future — but it's becoming more stable. growth era, we love to see it ✨

⚠️ also, and this is the spicy part: many routines will panic in case of error rather than returning an error code to the caller. yes fr fr. they just. panic. 😭

patches to fix this are welcome, but at the current state of development, aborting seems as useful as trusting to possibly-incomplete checking in the client. that's not me being mean, that's literally what the page says 💅

🎀 AUTHOR 🎀

Martin Pool <mbp@sourcefrog.net>, with Andrew Tridgell <tridge@samba.org>.

also, rdiff development has been supported by Linuxcare, Inc and VA Linux Systems — shoutout to the sponsors, we stan 🫶👑

and that's the whole page, bestie! this cutie comes to you from Martin Pool, dated $Date$, and it's the librsync(3) manual page — go forth and delta-compress something, you absolute icon 🦋💖✨