In Xfree86-4.0.2-9, I found that the function MoveLine in lib/Xaw/TextAction.c sometimes attempts to read uninitialized memory when I hit ctrl-N in a Text widget to move to the next line. This occurs because the call to XawTextSourceRead returns a text block whos "length" field is set to "-1". I couldn't figure out whether this indicates a bug in the ReadText function in lib/Xaw/AsciiSrc.c. It was occurring there because of the line near the end "count = piece->used - (pos - start)"; in this case, piece->used was 703, pos was 704, and start was 0, thus causing "count" and thus subsequently text->length to be set to -1. Like I said, I don't know whether this is a bug in AsciiSrc.c, so I instead fixed it in TextAction.c -- I changed the line after "XawTextSourceRead" so that instead of reading "if (block.length)" it reads "if (block.length > 0)".
Does this problem still exist if you try XFree86 4.0.3-3 from: ftp://people.redhat.com/mharris
Yes, this is still a problem in 4.0.3-3. You can duplicate it by running under Purify or Checker or something (so that you'll catch the uninitialized memory reference), bringing up a Text widget, typing a single line of Text in the widget with a newline at the end of it (i.e., such that the newline is the last character in the widget), going to the end of that line and typing ctrl-n. I'll attach a patch for 4.0.3-3.
Created attachment 13684 [details] Patch to fix this in 4.0.3-3.
Applied in 4.0.3-4 in rawhide. Thanks for supplying all the patches you've been sending in. Very much appreciated.
Sorry to cause you trouble :-), but I've concluded that the patch I submitted is not the correct way to fix this problem. The bug isn't in MoveLine, it's in ReadText. I'm attaching a new patch, which does the following: 1) Fix the ReadText functions in AsciiSrc.c and MultiSrc.c so that they return correct information when they were unable to read any data (i.e., they were asked to read data from the end of the source). 2) Fix the comments above the ReadText functions so that they correctly document their return values. 3) Fix the documentation in xc/doc/specs/Xaw so that it correctly documents what text source read functions are supposed to return. The patch I sent you doesn't do any harm, but it's also unnecessary once this new, corrected patch is applied, so you might as well back it out.
Created attachment 13804 [details] New patch for this problem
Old patch replaced with new patch. I'm going to clean up my tree and build the 4.0.3-4 release now. Thanks.