Fix handling of ST terminator when parsing OSC-52 reply #2942
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While parsing an OSC-52 reply, we search the input buffer for both BEL and ST. Once one of them has been found, we proceed to copy and base64 decode the payload, and then adding the decoded data to a new paste buffer. The check for ST looks backward in the buffer. I.e. it checks if the *previous* character is ESC, and the *current* character is \. This means, our ‘end’ index points to the *end* of the terminator. This is correct when calculating the length of the entire escape sequence, which is done immediately after having found the terminator. It is however *not* correct when copying out the payload. When an OSC-52 reply is ST terminated, we end up including ESC in the payload. This in turn causes the base64 decode to fail, and no paste buffer is created.
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Nice one, I have applied this now to OpenBSD, it will be in GitHub later. I didn't include the initialization since this is clearly a false positive in whatever compiler you are using, I don't see it in any of the compilers I have here anyway so they may have fixed it already. Thanks! |
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FWIW, I was using gcc-11.1.0.
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While parsing an OSC-52 reply, we search the input buffer for both
BELandST.Once one of them has been found, we proceed to copy and base64 decode the payload, and then adding the decoded data to a new paste buffer.
The check for
STlooks backward in the buffer. I.e. it checks if the previous character isESC, and the current character is\.This means, our ‘end’ index points to the end of the terminator. This is correct when calculating the length of the entire escape sequence, which is done immediately after having found the terminator.
It is however not correct when copying out the payload. When an OSC-52 reply is
STterminated, we end up includingESCin the payload. This in turn causes the base64 decode to fail, and no paste buffer is created.Note: I had to initialize
terminatorto silence a "may be used uninitialized" warning. Not sure why the assignment to*sizea couple of lines up doesn't trigger this warning. In any case, the warning should be a false positive, since we'll either have found a terminator, orend == len(and thus we return before usingterminator).Originally reported here: https://codeberg.org/dnkl/foot/issues/752