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> With that license, linking to an unmodified library in proprietary software is fine. Was it linked dynamically? Static linking to an LGPL library from a prop

> With that license, linking to an unmodified library in proprietary software is fine. Was it linked dynamically? Static linking to an LGPL library from a proprietary application is also possible, but way trickier.

skissane 2y ago
> Was it linked dynamically? Static linking to an LGPL library from a proprietary application is also possible, but way trickier. For a "shared source" app (i.e. source available but under restrictive non-open source terms), static linking is generally a non-issue, provided you give people permission to recompile the app from source with a modified library version, and you actually built the binaries you ship from the source you provide them (as opposed to some separate internal repo containing changes missing in the source you provide to your customers or the public). So, WinAmp currently would not be infringing even if it were statically linking modified LGPL libraries (assuming their source repo includes the source to the modifications) – although this may be evidence of past non-compliance. Static linking is really only a big problem for proprietary apps where you don't give people the source code. Even there, so long as you ship them object files so they can relink it with an updated LGPL library version, you are fine. Once upon a time, linking at the customer site was not an uncommon strategy for enterprise software, in fact last time I worked with Oracle RDBMS (7+ years ago) it was still using that strategy for a standard install. For LGPL 2.1, you don't even need to ship the object files or offer them for download – you just need to make an offer, valid for at least 3 years, [0] to supply them on request. LGPL 3.0 removed that provision, with LGPL 3.0 you have to either ship them or offer them as a separate download. [0] I believe the "3 years" is from the date you ship each individual copy of the software. So if you released version 1.0 in 2001, and it contained a "valid for 3 years offer", if you are still offering version 1.0 for download from your website in 2024, that offer is valid until 2027 for someone who downloads it today. But if you removed version 1.0 from your website in 2005, and since then have not given anyone a copy, then the offer would have expired in 2008.

skissane 2y ago

> Was it linked dynamically? Static linking to an LGPL library from a proprietary application is also possible, but way trickier. For a "shared source" app (i.e. source available but under restrictive non-open source terms), static linking is generally a non-issue, provided you give people permission to recompile the app from source with a modified library version, and you actually built the binaries you ship from the source you provide them (as opposed to some separate internal repo containing changes missing in the source you provide to your customers or the public). So, WinAmp currently would not be infringing even if it were statically linking modified LGPL libraries (assuming their source repo includes the source to the modifications) – although this may be evidence of past non-compliance. Static linking is really only a big problem for proprietary apps where you don't give people the source code. Even there, so long as you ship them object files so they can relink it with an updated LGPL library version, you are fine. Once upon a time, linking at the customer site was not an uncommon strategy for enterprise software, in fact last time I worked with Oracle RDBMS (7+ years ago) it was still using that strategy for a standard install. For LGPL 2.1, you don't even need to ship the object files or offer them for download – you just need to make an offer, valid for at least 3 years, [0] to supply them on request. LGPL 3.0 removed that provision, with LGPL 3.0 you have to either ship them or offer them as a separate download. [0] I believe the "3 years" is from the date you ship each individual copy of the software. So if you released version 1.0 in 2001, and it contained a "valid for 3 years offer", if you are still offering version 1.0 for download from your website in 2024, that offer is valid until 2027 for someone who downloads it today. But if you removed version 1.0 from your website in 2005, and since then have not given anyone a copy, then the offer would have expired in 2008.