Automatic verification is designed to fail for stdin

[stefanrueger]

Problem. Currently, automatic verification is instigated during option parsing of -U through

avrdude/src/main.c

Lines 528 to 532 in affe4cb

	if (verify && upd->op == DEVICE_WRITE) {
	upd = dup_update(upd);
	upd->op = DEVICE_VERIFY;
	ladd(updates, upd);
	}

So, each -U memory:w:file:... will see a verification request -U memory:v:file:... inserted into the update action list after the write request (unless -V was specified before the -U). This is designed to fail if file is stdin - as the file is read twice.

Proposed solution. I would make verify a global variable, remove above lines and change the code for writing to memory that it checks against the already read file (so that does not need to be read twice).

(Making verify global also helps the micronucleus programmer print a warning that it needs to switch off verify because the micronucleus bootloader cannot read flash.)

[stefanrueger]

The following should give a verification error

yes "The quick brown fox jumps over the lazy dog" | avrdude -c ... -p ... -U eeprom:w:-:r

[MCUdude]

Thanks for reporting! Would be great if a solution to this would be something #1036 could benefit from.

yes "The quick brown fox jumps over the lazy dog" | avrdude -c ... -p ... -U eeprom:w:-:r

Ooh, this could be very useful!

[mcuee]

Indeed this is an issue. Verfication after writing will fail even though the writing itself is good.

$ yes "The quick brown fox jumps over the lazy dog" | ./avrdude -c usbasp -qqp m328p 
-U eeprom:w:-:r
avrdude.exe: verification error, first mismatch at byte 0x0000
             0x54 != 0x6f
avrdude.exe: verification error; content mismatch

$ yes "The quick brown fox jumps over the lazy dog" | ./avrdude -c usbasp -qqp m328p 
-U eeprom:v:-:r && echo OK
OK

$ yes "The quick brown fox jumps over the lazy dog" | ./avrdude -c usbasp -qqp m328p 
-V -U eeprom:w:-:r && echo OK
OK

[dl8dtl]

I'm not a big fan of global variables … but we certainly ought to do something, I agree.

[mcuee]

The simplest fix is probably documentation fix to mention this limitation of the current implementation -- and then provide the workaround of using -V before -U.

[mcuee]

Related issue.

• [bug #50087] option parse error: after -U flash:w:program_to_upload.hex, subsequent -V ignored #441

[stefanrueger]

Fixed by PR #1053