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[PATCH] gitweb.js: Harden setting blamed commit info in incremental blame

From
Jakub Narebski <jnareb@gmail.com>
Date
Nov 25, 2009, 00:45 UTC
Message-ID
<200911250145.16472.jnareb@gmail.com>
In-Reply-To
<200911211556.52175.jnareb@gmail.com>
On Sat, 21 Nov 2009, Jakub Narebski wrote:
Show 39 quoted lines
> On Sat, 21 Nov 2009, Jakub Narebski wrote:
> 
> > * Testing it with IE8 (Internet Explorer 8.0.6001.18702) page loading stops
> >   at 0%, at the very beginning on startBlame() function
> > 
> >   IE8 shows that it finds the following errors:
> > 
> >   * "firstChild is null or not an object"
> >     line: 565, char:4
> > 
> >       a_sha1.firstChild.data = commit.sha1.substr(0, 8);
> > 
> >     It might be caused by the fact that firstChild for this case should be
> >     text node containing of pure whitespace:
> >        <a href=""> </a>
> >     Perhaps IE8 simplifies it in "compatibility view" mode
> 
> This bug (be it in gitweb.js or in IE8) is fixed by the following patch:
> 
> -- 8< --
> diff --git i/gitweb/gitweb.js w/gitweb/gitweb.js
> index 200ec5a..c1e425c 100644
> --- i/gitweb/gitweb.js
> +++ w/gitweb/gitweb.js
> @@ -562,7 +562,12 @@ function handleLine(commit, group) {
>  			td_sha1.rowSpan = group.numlines;
>  
>  			a_sha1.href = projectUrl + 'a=commit;h=' + commit.sha1;
> -			a_sha1.firstChild.data = commit.sha1.substr(0, 8);
> +			if (a_sha1.firstChild) {
> +				a_sha1.firstChild.data = commit.sha1.substr(0, 8);
> +			} else {
> +				a_sha1.appendChild(
> +					document.createTextNode(commit.sha1.substr(0, 8)));
> +			}
>  			if (group.numlines >= 2) {
>  				var fragment = document.createDocumentFragment();
>  				var br   = document.createElement("br");
> -- >8 --

Below the same patch is in the form of a proper commit; although the title (subject) of this commit could be better...

Show 12 quoted lines
> >  * "Unspecified error" (twice)
> >    line: 777, char:2
> > 
> >      if (xhr.readyState === 3 && xhr.status !== 200) {
> >      	return;
> >      }
> > 
> >    I don't know what might be the source of error here; I suspect that the
> >    error position mentioned by IE8 is bogus.
> 
> But I have no idea how to fix this.  "Unspecified error" isn't very 
> helpful...

Debugging this is serious PITA. After fix below it appears that this bug is some intermittent bug, depending on XMLHttpRequest timing. It more often than not (at least when I tried to debug it using build-in IE8 debugger) works correctly for the folowing files: README, GIT-VERSION-GEN, revision.c (once even it did fail when first running for given file, and then running correctly when reloading from debugger; fun it is not).

It does consistently fail for gitweb/gitweb.perl... but when I tried to debug it IE8 would hang up when trying to use debugger (with around 600MB available RAM). Perhaps somebody else would have more luck...

-- >8 --
Subject: [PATCH] gitweb.js: Harden setting blamed commit info in incremental blame
Internet Explorer 8 stops at beginning of blame filling
with the following bug
  "firstChild is null or not an object"
at this line
  a_sha1.firstChild.data = commit.sha1.substr(0, 8);
It is (probably) caused by the fact that while a_sha1 element,
which looks like this
  <a href=""> </a>
has firstChild which is text node containing only whitespace (single
space character) in other web browsers (Firefox 3.5, Opera 10,
Google Chrome 3.0), IE8 simplifies DOM, removing trailing/leading
whitespace.

Protect against this bug by creating text element if it does not exist.

Found-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
 gitweb/gitweb.js |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/gitweb/gitweb.js b/gitweb/gitweb.js
index 200ec5a..c1e425c 100644
--- a/gitweb/gitweb.js
+++ b/gitweb/gitweb.js
@@ -562,7 +562,12 @@ function handleLine(commit, group) {
 			td_sha1.rowSpan = group.numlines;
 
 			a_sha1.href = projectUrl + 'a=commit;h=' + commit.sha1;
-			a_sha1.firstChild.data = commit.sha1.substr(0, 8);
+			if (a_sha1.firstChild) {
+				a_sha1.firstChild.data = commit.sha1.substr(0, 8);
+			} else {
+				a_sha1.appendChild(
+					document.createTextNode(commit.sha1.substr(0, 8)));
+			}
 			if (group.numlines >= 2) {
 				var fragment = document.createDocumentFragment();
 				var br   = document.createElement("br");
-- 
1.6.5.3
Previous: Jakub NarebskiNext: Nanako Shiraishi
Message 14 of 41 in “jn/gitweb-blame fixes”
  1. 0/2 jn/gitweb-blame fixesStephen Boyd, Nov 19, 2009
  2. 1/2 gitweb.js: fix null object exception in initials calculationStephen Boyd, Nov 19, 2009
  3. Jakub NarebskiNov 19, 2009
  4. Stephen BoydNov 19, 2009
  5. 2/2 gitweb.js: use unicode encoding for nbsp instead of html entityStephen Boyd, Nov 19, 2009
  6. Jakub NarebskiNov 19, 2009
  7. Stephen BoydNov 20, 2009
  8. 2/2 gitweb.js: fix padLeftStr() and its usageStephen Boyd, Nov 25, 2009
  9. Jakub NarebskiNov 19, 2009
  10. Stephen BoydNov 20, 2009
  11. Stephen BoydNov 20, 2009
  12. Jakub NarebskiNov 21, 2009
  13. Jakub NarebskiNov 21, 2009
  14. gitweb.js: Harden setting blamed commit info in incremental blameJakub Narebski, Nov 25, 2009
  15. Nanako ShiraishiNov 25, 2009
  16. Jakub NarebskiNov 25, 2009
  17. Stephen BoydNov 25, 2009
  18. Jakub NarebskiNov 25, 2009
  19. Jakub NarebskiNov 25, 2009
  20. Junio C HamanoNov 25, 2009
  21. Jakub NarebskiNov 25, 2009
  22. Junio C HamanoNov 26, 2009
  23. Jakub NarebskiNov 26, 2009
  24. gitweb: Make linking to actions requiring JavaScript a featureJakub Narebski, Nov 26, 2009
  25. Junio C HamanoNov 26, 2009
  26. Jakub NarebskiNov 26, 2009
  27. Junio C HamanoNov 27, 2009
  28. Jakub NarebskiNov 27, 2009
  29. Junio C HamanoNov 27, 2009
  30. Junio C HamanoDec 1, 2009
  31. Jakub NarebskiDec 1, 2009
  32. 1/2 gitweb: Make linking to actions requiring JavaScript a featureJakub Narebski, Dec 1, 2009
  33. 2/2 gitweb: Add link to other blame implementation in blame viewsJakub Narebski, Dec 1, 2009
  34. Stephen BoydDec 7, 2009
  35. Stephen BoydDec 7, 2009
  36. PATCH/RFC] gitweb.js: Workaround for IE8 bugJakub Narebski, Dec 8, 2009
  37. Stephen BoydDec 8, 2009
  38. Jakub NarebskiDec 8, 2009
  39. Jakub NarebskiDec 8, 2009
  40. Stephen BoydDec 9, 2009
  41. Stephen BoydNov 23, 2009

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