On Wed, Jan 6, 2016 at 8:34 AM, Tobias Klauser
<tobias.klauser@xxxxxxxxxx> wrote:
> Add a command line option --in-place to support in-place editing akin to
> sed -i. This allows to write commands like the following:
>
> git interpret-trailers --trailer "X: Y" a.txt > b.txt && mv b.txt a.txt
>
> in a more concise way:
>
> git interpret-trailers --trailer "X: Y" --in-place a.txt
>
> Also add the corresponding documentation and tests.
In addition to Matthieu's comments...
> Signed-off-by: Tobias Klauser <tklauser@xxxxxxxxxx>
> ---
> diff --git a/trailer.c b/trailer.c
> @@ -856,19 +858,28 @@ void process_trailers(const char *file, int trim_empty, struct string_list *trai
>
> lines = read_input_file(file);
>
> + if (in_place) {
> + fp = fopen(file, "w");
> + if (!fp)
> + die_errno(_("could not open file '%s' for writing"), file);
> + }
The input file should be considered precious, but this implementation
plays too loosely with it. If the user interrupts the program or a
die() somewhere within the "trailers" code aborts the program before
the output file is written, then the original file will be
irrecoverably lost. Users won't be happy about that.
Instead, this code should go through the standard dance of writing the
output to a new file (with some unique temporary name) and then, only
once the output has been successfully written in full, rename the new
file atop the old.
> /* Print the lines before the trailers */
> - trailer_end = process_input_file(lines, &in_tok_first, &in_tok_last);
> + trailer_end = process_input_file(fp, lines, &in_tok_first, &in_tok_last);
>
> arg_tok_first = process_command_line_args(trailers);
>
> process_trailers_lists(&in_tok_first, &in_tok_last, &arg_tok_first);
>
> - print_all(in_tok_first, trim_empty);
> + print_all(fp, in_tok_first, trim_empty);
>
> free_all(&in_tok_first);
>
> /* Print the lines after the trailers as is */
> - print_lines(lines, trailer_end, INT_MAX);
> + print_lines(fp, lines, trailer_end, INT_MAX);
> +
> + if (in_place)
> + fclose(fp);
>
> strbuf_list_free(lines);
> }
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