diff options
| -rw-r--r-- | converter/pbm/pbmtonokia.c | 15 | ||||
| -rw-r--r-- | doc/HISTORY | 2 |
2 files changed, 16 insertions, 1 deletions
diff --git a/converter/pbm/pbmtonokia.c b/converter/pbm/pbmtonokia.c index 0e479d67..4604064a 100644 --- a/converter/pbm/pbmtonokia.c +++ b/converter/pbm/pbmtonokia.c @@ -415,13 +415,26 @@ convertToNpm(bit ** const image, now, where the text field starts in the 7th byte. */ + /* The code below that deliberately avoids using 'text' as an argument to + memcpy when 'text' is null looks like it should have no practical + effect, because with a zero length memcpy, it shouldn't matter what the + from and to arguments are. But it's logically correct - a null pointer + just doesn't point anywhere. And believe it or not, it has a practical + effect - a truly bizarre one. This code used to be simpler and just + pass that null pointer to memcpy, with length 0, and as reported in May + 2020, a new optimizing compiler caused header[3] to contain random + values. That's right: 3. Skipping that presumed no-op memcpy stopped + the behavior. + */ + header[ 0] = 'N'; header[ 1] = 'P'; header[ 2] = 'M'; header[ 3] = 0; header[ 4] = textLen; header[ 5] = 0; - memcpy(&header[6], text, textLen); + if (text) /* see above */ + memcpy(&header[6], text, textLen); header[ 6 + textLen] = cols; header[ 7 + textLen] = rows; header[ 8 + textLen] = 1; diff --git a/doc/HISTORY b/doc/HISTORY index 7a2aa143..d04c27d2 100644 --- a/doc/HISTORY +++ b/doc/HISTORY @@ -8,6 +8,8 @@ not yet BJH Release 10.91.00 pbmtonokia: Fix incorrect output with -txt option. + pbmtonokia: Fix incorrect output with newer compiler. + pnmtorle: Fix incorrect command and filename in header. Broken in Netpbm 10.88 (September 2019). |