Re: [Quilt-dev] handling empty new files

[Joe Green]

> Joe Green wrote:
>
> > The problem is that quilt forces the "-E" option when it invokes 
> > patch.  If this option is not specified, patch can determine the 
> > difference between an empty file and a removed or added file by 
> > looking at the patch file names (/dev/null "to" file means removed, 
> > on "from" file means added) or the file timestamps (epoch means 
> > removed/added).
> >
> > I've attached a sample patch to remove this option.  Warning:  I've 
> > just updated this to 0.42; I haven't tested it yet, but it's fairly 
> > straightforward.
OK, now that I've done the testing, it's not quite that straightforward. :)

The attached patch shows the changes that are needed.  This gets it 
working the way I've used it before:  you can remove all the lines from 
a file in a patch, and patch knows the difference between this and 
removing a file.

However, it doesn't look like diff or patch will support creating an 
empty file in one step.  Diff won't generate the output for an empty 
file, and patch won't accept it if I cobble it up by hand, using what I 
think would be the correct syntax.  It seems a bit odd that patch would 
only implement part of the solution, but I wasn't able to find a way to 
make it work.

So, with this patch applied you could have empty files by having one 
patch add the file with some dummy content, and then have a subsequent 
patch remove that content, but that's pretty gross.  In practice, it's 
probably best to just avoid empty files as Jean Devere originally 
suggested.  Sorry for the unnecessary runaround.

--
Joe Green <address@hidden>
MontaVista Software, Inc.

Source: MontaVista Software, Inc <address@hidden>
Type: Enhancement

Don't assume empty files are the same as removed files.  Allow patch
to recognize the difference.

Index: quilt-0.42/quilt/diff.in
===================================================================
--- quilt-0.42.orig/quilt/diff.in
+++ quilt-0.42/quilt/diff.in
@@ -114,8 +114,8 @@ do_diff()
        
        if [ -n "$opt_diff" ]
        then
-               [ -s "$old_file" ] || old_file=/dev/null
-               [ -s "$new_file" ] || new_file=/dev/null
+               [ -r "$old_file" ] || old_file=/dev/null
+               [ -r "$new_file" ] || new_file=/dev/null
                if ! @DIFF@ -qN $old_file $new_file >/dev/null
                then
                        export LANG=$ORIGINAL_LANG
@@ -353,7 +353,7 @@ then
        then
                if ! cat_file $patch_file \
                     | @PATCH@ -d $workdir $QUILT_PATCH_OPTS $patch_args \
-                              --no-backup-if-mismatch -Ef \
+                              --no-backup-if-mismatch -f \
                               >/dev/null 2>/dev/null
                then
                        # Generating a relative diff for a subset of files in
Index: quilt-0.42/quilt/fold.in
===================================================================
--- quilt-0.42.orig/quilt/fold.in
+++ quilt-0.42/quilt/fold.in
@@ -83,7 +83,7 @@ fi
 trap "failed=1" SIGINT
 
 workdir=$(gen_tempfile -d $PWD)
address@hidden@ $QUILT_PATCH_OPTS -p$opt_strip_level $silent --backup 
--prefix="$workdir/" -E \
address@hidden@ $QUILT_PATCH_OPTS -p$opt_strip_level $silent --backup 
--prefix="$workdir/" \
 || failed=1
 
 if [ -z "$failed" ]
Index: quilt-0.42/quilt/pop.in
===================================================================
--- quilt-0.42.orig/quilt/pop.in
+++ quilt-0.42/quilt/pop.in
@@ -130,7 +130,7 @@ check_for_pending_changes()
                if ! cat_file $patch_file \
                     | @PATCH@ -d $workdir $QUILT_PATCH_OPTS \
                               $(patch_args $patch) \
-                              --no-backup-if-mismatch -E \
+                              --no-backup-if-mismatch \
                               >/dev/null 2>/dev/null
                then
                        if ! [ -e $QUILT_PC/$patch ]
Index: quilt-0.42/quilt/push.in
===================================================================
--- quilt-0.42.orig/quilt/push.in
+++ quilt-0.42/quilt/push.in
@@ -99,19 +99,19 @@ apply_patch()
                | @PATCH@ $QUILT_PATCH_OPTS $(patch_args $patch) \
                        --backup --prefix="$QUILT_PC/$patch/" \
                        $no_reject_files \
-                       -E $silent $force_apply 2>&1
+                       $silent $force_apply 2>&1
        elif [ "${patch_file:(-4)}" = ".bz2" ]
        then
                bzip2 -cd $patch_file \
                | @PATCH@ $QUILT_PATCH_OPTS $(patch_args $patch) \
                        --backup --prefix="$QUILT_PC/$patch/" \
                        $no_reject_files \
-                       -E $silent $force_apply 2>&1
+                       $silent $force_apply 2>&1
        else
                @PATCH@ $QUILT_PATCH_OPTS $(patch_args $patch) \
                        --backup --prefix="$QUILT_PC/$patch/" \
                        $no_reject_files \
-                       -E $silent $force_apply -i $patch_file 2>&1
+                       $silent $force_apply -i $patch_file 2>&1
        fi
 }
 
Index: quilt-0.42/scripts/patchfns.in
===================================================================
--- quilt-0.42.orig/scripts/patchfns.in
+++ quilt-0.42/scripts/patchfns.in
@@ -534,7 +534,7 @@ diff_file()
        fi
        index=$new_hdr
        
-       if ! [ -s "$old_file" ]
+       if ! [ -r "$old_file" ]
        then
                old_file=/dev/null
                old_hdr=/dev/null
@@ -545,7 +545,7 @@ diff_file()
                || old_date=$'\t'$(date +'%Y-%m-%d %H:%M:%S.%N %z' \
                                        -r "$old_file")
        fi
-       if ! [ -s "$new_file" ]
+       if ! [ -r "$new_file" ]
        then
                new_file=/dev/null
                new_hdr=/dev/null
Index: quilt-0.42/lib/backup-files.c
===================================================================
--- quilt-0.42.orig/lib/backup-files.c
+++ quilt-0.42/lib/backup-files.c
@@ -263,7 +263,7 @@ process_file(const char *file)
                        perror(backup);
                        return 1;
                }
-               if (st.st_size == 0) {
+               if (!(st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO))) {
                        if (unlink(file) == 0 || errno == ENOENT) {
                                if (!opt_silent)
                                        printf("Removing %s\n", file);