Re: let git-diff allow patch to delete empty files?

From: Sam Liddicott <sam@liddicott.com>
Date: Nov 5, 2008, 13:07 UTC
Message-ID: <4911B297.2070800@liddicott.com>
In-Reply-To: <49118FEE.30408@liddicott.com>

* Sam Liddicott wrote, On 05/11/08 12:22:

Show 19 quoted lines

> In some cases "patch" cannot apply diff's generated using git-diff, I've
> had a "git diff" output look like this when an empty file was removed as
> the only change:
>
> ..
> However this equivalent pair works by making the file non-empty and then
> deleting it.
>
> diff -Nru 1/here 2/here
> --- 1/here    2008-11-05 09:43:55.000000000 +0000
> +++ 2/here    2008-11-05 09:43:58.000000000 +0000
> @@ -0,0 +1 @@
> +
> diff -Nru 1/here 2/here
> --- 1/here    2008-11-05 09:37:23.000000000 +0000
> +++ 2/here    1970-01-01 01:00:00.000000000 +0100
> @@ -1 +0,0 @@
> -
>

The same problem occurs with new empty files.

Attached is an awk filter which will expand out these git notes into the 2-part unified diff's. It would be nicer if git did it natively. Sam

#! /usr/bin/awk -f

function do_empty() {
  if (diff!="" && deleted!="" && indx!="") {
    printf("Make patch give the file 1 line\n");
    printf("--- %s\n",diff);
    printf("+++ %s\n",diff);
    printf("@@ -0,0 +1 @@\n+\n");
    printf("Make patch delete the 1 line file\n");
    printf("--- %s\t\n",diff);
    printf("+++ /dev/null\t1970-01-01 01:00:00.000000000\n");
    printf("@@ -1 +0,0 @@\n-\n");
  }
  if (diff!="" && created!="" && indx!="") {
    printf("Make patch create the file with 1 line\n");
    printf("--- %s\n",diff);
    printf("+++ %s\n",diff);
    printf("@@ -0,0 +1 @@\n+\n");
    printf("Make patch create delete the line but keep the file\n");
    printf("--- %s\n",diff);
    printf("+++ %s\n",diff);
    printf("@@ -1 +0,0 @@\n-\n");
  }
  no_empty();
}

function no_empty() {
  diff="";
  deleted="";
  created="";
  indx="";
}

{
  if (in_hunk > 0) in_hunk--;
}

/^diff --git / {
  do_empty();
  if (! in_hunk) diff=$3;
}

/^deleted file mode / {
  if (! in_hunk && diff!="") deleted=$0;
}

/^new file mode / {
  if (! in_hunk && diff!="") created=$0;
}

/^index / {
  if (! in_hunk && diff!="") indx=$0;
}

/^--- / {
  no_empty();
}

/^@@ / {
  # read the hunk size
  p=index($2,",");
  if (p==0) c1=1;
  else c1=strtonum(substr($2, p+1));

  p=index($3,",");
  if (p==0) in_hunk=1;
  else in_hunk=strtonum(substr($2, p+1));

  if (c1 > in_hunk) in_hunk=c1;
}

{
  print;
}

END {
  do_empty();
}