[RFC,WIP,1/3] tag: factor out tag reading from write_tag_body()
diff mbox series

Message ID 20191008184727.14337-2-lucasseikioshiro@gmail.com
State New
Headers show
Series
  • tag: fix --edit and --no-edit flags
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Commit Message

Lucas Oshiro Oct. 8, 2019, 6:47 p.m. UTC
Improve code readability by moving tag reading to a new function called
get_tag_body, which will be used in the implementation of the git tag
--amend functionality.

Add warning in write_tag_body() in case the tag body is not successfully
recovered.

Co-authored-by: Bárbara Fernandes <barbara.dcf@gmail.com>
Signed-off-by: Bárbara Fernandes <barbara.dcf@gmail.com>
Signed-off-by: Lucas Oshiro <lucasseikioshiro@gmail.com>
Helped-by: Matheus Tavares <matheus.bernardino@usp.br>
---
 builtin/tag.c | 42 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 8 deletions(-)

Comments

Matheus Tavares Bernardino Oct. 9, 2019, 1:48 a.m. UTC | #1
On Tue, Oct 8, 2019 at 3:47 PM Lucas Oshiro <lucasseikioshiro@gmail.com> wrote:
>
> Improve code readability by moving tag reading to a new function called
> get_tag_body, which will be used in the implementation of the git tag
> --amend functionality.

This function is also used in your third patch, to fix git-tag's
--no-edit implementation, right? Maybe you could mention this here,
instead of referencing the --amend feature, as the former is already
present in this series.

> Add warning in write_tag_body() in case the tag body is not successfully
> recovered.
>
> Co-authored-by: Bárbara Fernandes <barbara.dcf@gmail.com>
> Signed-off-by: Bárbara Fernandes <barbara.dcf@gmail.com>
> Signed-off-by: Lucas Oshiro <lucasseikioshiro@gmail.com>
> Helped-by: Matheus Tavares <matheus.bernardino@usp.br>

These tags usually come in chronological order. So I think the
Helped-by should come first as I helped you, then you and Bárbara
co-authored the patch and then, lastly, you sent it.

> ---
>  builtin/tag.c | 42 ++++++++++++++++++++++++++++++++++--------
>  1 file changed, 34 insertions(+), 8 deletions(-)
>
> diff --git a/builtin/tag.c b/builtin/tag.c
> index e0a4c25382..e1e3549af9 100644
> --- a/builtin/tag.c
> +++ b/builtin/tag.c
> @@ -170,26 +170,52 @@ static int git_tag_config(const char *var, const char *value, void *cb)
>         return git_color_default_config(var, value, cb);
>  }
>
> -static void write_tag_body(int fd, const struct object_id *oid)
> +/*
> + * Returns the tag body of the given oid or NULL, in case of error. If size is
> + * not NULL it is assigned the body size in bytes (excluding the '\0').
> + */
> +static char *get_tag_body(const struct object_id *oid, size_t *size)
>  {
> -       unsigned long size;
> +       unsigned long buf_size;
>         enum object_type type;
> -       char *buf, *sp;
> +       char *buf, *sp, *tag_body;
> +       size_t tag_body_size, signature_offset;
>
> -       buf = read_object_file(oid, &type, &size);
> +       buf = read_object_file(oid, &type, &buf_size);
>         if (!buf)
> -               return;
> +               return NULL;
>         /* skip header */
>         sp = strstr(buf, "\n\n");
>
> -       if (!sp || !size || type != OBJ_TAG) {
> +       if (!sp || !buf_size || type != OBJ_TAG) {
>                 free(buf);
> -               return;
> +               return NULL;
>         }
>         sp += 2; /* skip the 2 LFs */
> -       write_or_die(fd, sp, parse_signature(sp, buf + size - sp));
> +       signature_offset = parse_signature(sp, buf + buf_size - sp);
> +       sp[signature_offset] = '\0';
>
> +       /* detach sp from buf */
> +       tag_body_size = strlen(sp) + 1;
> +       tag_body = xmalloc(tag_body_size);
> +       xsnprintf(tag_body, tag_body_size, "%s", sp);
>         free(buf);
> +       if (size)
> +               *size = tag_body_size - 1; /* exclude '\0' */
> +       return tag_body;
> +}
> +
> +static void write_tag_body(int fd, const struct object_id *oid)
> +{
> +       size_t size;
> +       const char *tag_body = get_tag_body(oid, &size);
> +
> +       if (!tag_body) {
> +               warning("failed to get tag body for %s", oid->hash);
> +               return;
> +       }
> +       printf("tag_body: <%s>\n", tag_body);

Hm, is this addition right or perhaps was it added in the patch by mistake?

> +       write_or_die(fd, tag_body, size);
>  }
>
>  static int build_tag_object(struct strbuf *buf, int sign, struct object_id *result)
> --
> 2.23.0
>
Junio C Hamano Oct. 10, 2019, 2:42 a.m. UTC | #2
Lucas Oshiro <lucasseikioshiro@gmail.com> writes:

> +/* 
> + * Returns the tag body of the given oid or NULL, in case of error. If size is
> + * not NULL it is assigned the body size in bytes (excluding the '\0').
> + */
> +static char *get_tag_body(const struct object_id *oid, size_t *size) 
>  {
> +	unsigned long buf_size;
>  	enum object_type type;
> +	char *buf, *sp, *tag_body;
> +	size_t tag_body_size, signature_offset;
>  
> +	buf = read_object_file(oid, &type, &buf_size);
>  	if (!buf)
> +		return NULL;
>  	/* skip header */
>  	sp = strstr(buf, "\n\n");
>  
> +	if (!sp || !buf_size || type != OBJ_TAG) {
>  		free(buf);
> +		return NULL;
>  	}

Returning early when !buf_size before even attempting to strstr
would be cleaner to read, i.e.

	buf = read_object_file(...);
	if (!buf || !buf_size) {
		free(buf);
		return NULL;
	}
	body = strstr(buf, "\n\n");

FWIW, the type check that is done after this point could also be a
part of the early return, as there is no point scanning for the end
of object header part if the object is not a tag (e.g. if it were a
blob, there is no "header part" and scanning for a blank line is
meaningless).
	
>  	sp += 2; /* skip the 2 LFs */
> +	signature_offset = parse_signature(sp, buf + buf_size - sp);
> +	sp[signature_offset] = '\0';
>  
> +	/* detach sp from buf */
> +	tag_body_size = strlen(sp) + 1;
> +	tag_body = xmalloc(tag_body_size);
> +	xsnprintf(tag_body, tag_body_size, "%s", sp);

Isn't this essentially

	tag_body = xstrdup(sp);
        tag_body_size = signature_offset;

(my arith may be off by one or two, but does a separate
tag_body_size need to exist?)

>  	free(buf);
> +	if (size)
> +		*size = tag_body_size - 1; /* exclude '\0' */
> +	return tag_body;
> +}
> +
> +static void write_tag_body(int fd, const struct object_id *oid)
> +{
> +	size_t size;
> +	const char *tag_body = get_tag_body(oid, &size);
> +
> +	if (!tag_body) {
> +		warning("failed to get tag body for %s", oid->hash);

I do not think the original gives any such warning.

 - Do we want to be unconditionally noisy this way?
 - Should this be a fatal error?  If not, why?
 - Should the message be translatable?

As an interface, is it sensible to force any and all callers of
get_tag_body() to supply a pointer to &size?  Is the returned value
always a NUL-terminated string?  I suspect that people would find it
a more natural interface if its were like:

	const char *body = get_tag_body(oid);

	if (!body)		
		...;

	if (this caller needs size) {
		size_t body_size = strlen(body);
		... use both body and body_size ...
		write_or_die(fd, body, body_size);
	} else {
		... just use body ...
		printf("%s", body);
	}
	
> +		return;
> +	}
> +	printf("tag_body: <%s>\n", tag_body);
> +	write_or_die(fd, tag_body, size);

WTH is this double writing?

>  }
>  
>  static int build_tag_object(struct strbuf *buf, int sign, struct object_id *result)

Patch
diff mbox series

diff --git a/builtin/tag.c b/builtin/tag.c
index e0a4c25382..e1e3549af9 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -170,26 +170,52 @@  static int git_tag_config(const char *var, const char *value, void *cb)
 	return git_color_default_config(var, value, cb);
 }
 
-static void write_tag_body(int fd, const struct object_id *oid)
+/* 
+ * Returns the tag body of the given oid or NULL, in case of error. If size is
+ * not NULL it is assigned the body size in bytes (excluding the '\0').
+ */
+static char *get_tag_body(const struct object_id *oid, size_t *size) 
 {
-	unsigned long size;
+	unsigned long buf_size;
 	enum object_type type;
-	char *buf, *sp;
+	char *buf, *sp, *tag_body;
+	size_t tag_body_size, signature_offset;
 
-	buf = read_object_file(oid, &type, &size);
+	buf = read_object_file(oid, &type, &buf_size);
 	if (!buf)
-		return;
+		return NULL;
 	/* skip header */
 	sp = strstr(buf, "\n\n");
 
-	if (!sp || !size || type != OBJ_TAG) {
+	if (!sp || !buf_size || type != OBJ_TAG) {
 		free(buf);
-		return;
+		return NULL;
 	}
 	sp += 2; /* skip the 2 LFs */
-	write_or_die(fd, sp, parse_signature(sp, buf + size - sp));
+	signature_offset = parse_signature(sp, buf + buf_size - sp);
+	sp[signature_offset] = '\0';
 
+	/* detach sp from buf */
+	tag_body_size = strlen(sp) + 1;
+	tag_body = xmalloc(tag_body_size);
+	xsnprintf(tag_body, tag_body_size, "%s", sp);
 	free(buf);
+	if (size)
+		*size = tag_body_size - 1; /* exclude '\0' */
+	return tag_body;
+}
+
+static void write_tag_body(int fd, const struct object_id *oid)
+{
+	size_t size;
+	const char *tag_body = get_tag_body(oid, &size);
+
+	if (!tag_body) {
+		warning("failed to get tag body for %s", oid->hash);
+		return;
+	}
+	printf("tag_body: <%s>\n", tag_body);
+	write_or_die(fd, tag_body, size);
 }
 
 static int build_tag_object(struct strbuf *buf, int sign, struct object_id *result)