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Re: [PATCH 3/3] write_entry: untangle symlink and regular-file cases




Jeff King <peff@xxxxxxxx> writes:

> The write_entry() function switches on the mode of the entry
> we're going to write out. The cases for S_IFLNK and S_IFREG
> are lumped together. In earlier versions of the code, this
> made some sense. They have a shared preamble (which reads
> the blob content), a short type-specific body, and a shared
> conclusion (which writes out the file contents; always for
> S_IFREG and only sometimes for S_IFLNK).
>
> But over time this has grown to make less sense. The preamble
> now has conditional bits for each type, and the S_IFREG body
> has grown a lot more complicated. It's hard to follow the
> logic of which code is running for which mode.

Nicely done and looks correct.  Thanks.

>
> Let's give each mode its own case arm. We will still share
> the conclusion code, which means we now jump to it with a
> goto. Ideally we'd pull that shared code into its own
> function, but it touches so much internal state in the
> write_entry() function that the end result is actually
> harder to follow than the goto.

>
> While we're here, we'll touch up a few bits of whitespace to
> make the beginning and endings of the cases easier to read.
>
> Signed-off-by: Jeff King <peff@xxxxxxxx>
> ---
>  entry.c | 71 +++++++++++++++++++++++++++++++++++++----------------------------
>  1 file changed, 40 insertions(+), 31 deletions(-)
>
> diff --git a/entry.c b/entry.c
> index bec51e37a2..206363fd15 100644
> --- a/entry.c
> +++ b/entry.c
> @@ -260,13 +260,31 @@ static int write_entry(struct cache_entry *ce,
>  	}
>  
>  	switch (ce_mode_s_ifmt) {
> -	case S_IFREG:
>  	case S_IFLNK:
> +		new = read_blob_entry(ce, &size);
> +		if (!new)
> +			return error("unable to read sha1 file of %s (%s)",
> +				     path, oid_to_hex(&ce->oid));
> +
> +		/*
> +		 * We can't make a real symlink; write out a regular file entry
> +		 * with the symlink destination as its contents.
> +		 */
> +		if (!has_symlinks || to_tempfile)
> +			goto write_file_entry;
> +
> +		ret = symlink(new, path);
> +		free(new);
> +		if (ret)
> +			return error_errno("unable to create symlink %s", path);
> +		break;
> +
> +	case S_IFREG:
>  		/*
>  		 * We do not send the blob in case of a retry, so do not
>  		 * bother reading it at all.
>  		 */
> -		if (ce_mode_s_ifmt == S_IFREG && dco && dco->state == CE_RETRY) {
> +		if (dco && dco->state == CE_RETRY) {
>  			new = NULL;
>  			size = 0;
>  		} else {
> @@ -276,42 +294,31 @@ static int write_entry(struct cache_entry *ce,
>  					     path, oid_to_hex(&ce->oid));
>  		}
>  
> -		if (ce_mode_s_ifmt == S_IFLNK && has_symlinks && !to_tempfile) {
> -			ret = symlink(new, path);
> -			free(new);
> -			if (ret)
> -				return error_errno("unable to create symlink %s",
> -						   path);
> -			break;
> -		}
> -
>  		/*
>  		 * Convert from git internal format to working tree format
>  		 */
> -		if (ce_mode_s_ifmt == S_IFREG) {
> -			if (dco && dco->state != CE_NO_DELAY) {
> -				ret = async_convert_to_working_tree(
> -					ce->name, new, size, &buf, dco);
> -				if (ret && string_list_has_string(&dco->paths, ce->name)) {
> -					free(new);
> -					goto delayed;
> -				}
> -			} else
> -				ret = convert_to_working_tree(
> -					ce->name, new, size, &buf);
> -
> -			if (ret) {
> +		if (dco && dco->state != CE_NO_DELAY) {
> +			ret = async_convert_to_working_tree(ce->name, new,
> +							    size, &buf, dco);
> +			if (ret && string_list_has_string(&dco->paths, ce->name)) {
>  				free(new);
> -				new = strbuf_detach(&buf, &newsize);
> -				size = newsize;
> +				goto delayed;
>  			}
> -			/*
> -			 * No "else" here as errors from convert are OK at this
> -			 * point. If the error would have been fatal (e.g.
> -			 * filter is required), then we would have died already.
> -			 */
> +		} else
> +			ret = convert_to_working_tree(ce->name, new, size, &buf);
> +
> +		if (ret) {
> +			free(new);
> +			new = strbuf_detach(&buf, &newsize);
> +			size = newsize;
>  		}
> +		/*
> +		 * No "else" here as errors from convert are OK at this
> +		 * point. If the error would have been fatal (e.g.
> +		 * filter is required), then we would have died already.
> +		 */
>  
> +	write_file_entry:
>  		fd = open_output_fd(path, ce, to_tempfile);
>  		if (fd < 0) {
>  			free(new);
> @@ -326,6 +333,7 @@ static int write_entry(struct cache_entry *ce,
>  		if (wrote != size)
>  			return error("unable to write file %s", path);
>  		break;
> +
>  	case S_IFGITLINK:
>  		if (to_tempfile)
>  			return error("cannot create temporary submodule %s", path);
> @@ -337,6 +345,7 @@ static int write_entry(struct cache_entry *ce,
>  				NULL, oid_to_hex(&ce->oid),
>  				state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
>  		break;
> +
>  	default:
>  		return error("unknown file mode for %s in index", path);
>  	}