Re: [PATCH 1/3] test-tool: add pack-deltas helper

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Patrick,

On Fri, 25 Apr 2025, Patrick Steinhardt wrote:

> On Wed, Apr 23, 2025 at 05:40:02PM +0000, Derrick Stolee via GitGitGadget wrote:
> > diff --git a/t/helper/test-pack-deltas.c b/t/helper/test-pack-deltas.c
> > new file mode 100644
> > index 00000000000..db7d1c3cd1f
> > --- /dev/null
> > +++ b/t/helper/test-pack-deltas.c
> > @@ -0,0 +1,140 @@
> [snip]
> > +int cmd__pack_deltas(int argc, const char **argv)
> > +{
> > +	int N;
> > +	struct hashfile *f;
> > +	struct strbuf line = STRBUF_INIT;
> > +
> > +	if (argc != 2) {
> > +		usage(usage_str);
> > +		return -1;
> > +	}
> > +
> > +	N = atoi(argv[1]);
> 
> Is there a reason why we don't use `parse_options()` here? It might make
> this tool easier to use and extend going forward, and we wouldn't have
> to care about invalid arguments. Right now, we silently accept a
> non-integer argument and do the wrong thing.

I think that `parse_options()` would be overkill here because:

- This is a _mandatory_ argument, not an optional one.

- The required data type is `uint32_t`, and `parse_options()` has no
  support for that.

But you do have a good point in that we may want to validate the data type
(even if technically, this is not a user-facing program, it's a test
helper that is used under tight control by Git's own test suite).

Consequently, I would suggest this fixup instead:

-- snipsnap --
Subject: [PATCH] fixup! test-tool: add pack-deltas helper

Let's make the command-line parsing a bit more stringent. We _could_
use `parse_options()`, but that would be overkill for a single,
non-optional argument. Besides, it would not bring any benefit, as the
parsed value needs to fit in the `uint32_t` type, and `parse_options()`
has no provision to ensure that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 t/helper/test-pack-deltas.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/t/helper/test-pack-deltas.c b/t/helper/test-pack-deltas.c
index 4af69bdc05d3..f95d8ee16768 100644
--- a/t/helper/test-pack-deltas.c
+++ b/t/helper/test-pack-deltas.c
@@ -8,11 +8,12 @@
 #include "hex.h"
 #include "pack.h"
 #include "pack-objects.h"
+#include "parse.h"
 #include "setup.h"
 #include "strbuf.h"
 #include "string-list.h"
 
-static const char usage_str[] = "test-tool pack-deltas <n>";
+static const char usage_str[] = "test-tool pack-deltas <nr_entries>";
 
 static unsigned long do_compress(void **pptr, unsigned long size)
 {
@@ -79,7 +80,7 @@ static void write_ref_delta(struct hashfile *f,
 
 int cmd__pack_deltas(int argc, const char **argv)
 {
-	int N;
+	unsigned long n;
 	struct hashfile *f;
 	struct strbuf line = STRBUF_INIT;
 
@@ -88,12 +89,13 @@ int cmd__pack_deltas(int argc, const char **argv)
 		return -1;
 	}
 
-	N = atoi(argv[1]);
+	if (!git_parse_ulong(argv[1], &n) || n != (uint32_t)n)
+		die("invalid number of objects: %s", argv[1]);
 
 	setup_git_directory();
 
 	f = hashfd(1, "<stdout>");
-	write_pack_header(f, N);
+	write_pack_header(f, n);
 
 	/* Read each line from stdin into 'line' */
 	while (strbuf_getline_lf(&line, stdin) != EOF) {
-- 
2.49.0.windows.1