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From: "René Scharfe" <l.s.r@web.de>
To: Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org
Cc: Matheus Tavares <matheus.bernardino@usp.br>,
	Eric Sunshine <sunshine@sunshineco.com>,
	Elijah Newren <newren@gmail.com>
Subject: Re: [PATCH v2 1/3] mem-pool: add convenience functions for xstrdup and xstrndup
Date: Fri, 14 Aug 2020 10:21:22 +0200	[thread overview]
Message-ID: <e7ef099b-5d96-ff67-5d4e-b6fa306adb38@web.de> (raw)
In-Reply-To: <6d679c5b46541208f5fa714174555ff0dc756b9a.1597384820.git.gitgitgadget@gmail.com>

Am 14.08.20 um 08:00 schrieb Elijah Newren via GitGitGadget:
> From: Elijah Newren <newren@gmail.com>
>
> fast-import had a special mem_pool_xstrdup() convenience function that I
> want to be able to use from the new merge algorithm I am writing.  Move
> it from fast-import to mem-pool, and also add a mem_pool_xstrndup()
> while at it that I also want to use.
>
> Signed-off-by: Elijah Newren <newren@gmail.com>
> ---
>  fast-import.c | 12 ++----------
>  mem-pool.c    | 23 +++++++++++++++++++++++
>  mem-pool.h    |  6 ++++++
>  3 files changed, 31 insertions(+), 10 deletions(-)
>
> diff --git a/fast-import.c b/fast-import.c
> index ce47794db6..dd5b563950 100644
> --- a/fast-import.c
> +++ b/fast-import.c
> @@ -526,14 +526,6 @@ static unsigned int hc_str(const char *s, size_t len)
>  	return r;
>  }
>
> -static char *pool_strdup(const char *s)
> -{
> -	size_t len = strlen(s) + 1;
> -	char *r = mem_pool_alloc(&fi_mem_pool, len);
> -	memcpy(r, s, len);
> -	return r;
> -}

Note: No "x" in the name and it doesn't handle mem_pool_alloc()
returning NULL.

> -
>  static void insert_mark(struct mark_set *s, uintmax_t idnum, struct object_entry *oe)
>  {
>  	while ((idnum >> s->shift) >= 1024) {
> @@ -615,7 +607,7 @@ static struct branch *new_branch(const char *name)
>  		die("Branch name doesn't conform to GIT standards: %s", name);
>
>  	b = mem_pool_calloc(&fi_mem_pool, 1, sizeof(struct branch));
> -	b->name = pool_strdup(name);
> +	b->name = mem_pool_xstrdup(&fi_mem_pool, name);
>  	b->table_next_branch = branch_table[hc];
>  	b->branch_tree.versions[0].mode = S_IFDIR;
>  	b->branch_tree.versions[1].mode = S_IFDIR;
> @@ -2806,7 +2798,7 @@ static void parse_new_tag(const char *arg)
>
>  	t = mem_pool_alloc(&fi_mem_pool, sizeof(struct tag));
>  	memset(t, 0, sizeof(struct tag));
> -	t->name = pool_strdup(arg);
> +	t->name = mem_pool_xstrdup(&fi_mem_pool, arg);
>  	if (last_tag)
>  		last_tag->next_tag = t;
>  	else
> diff --git a/mem-pool.c b/mem-pool.c
> index a2841a4a9a..33fda1c411 100644
> --- a/mem-pool.c
> +++ b/mem-pool.c
> @@ -102,6 +102,29 @@ void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
>  	return r;
>  }
>
> +char *mem_pool_xstrdup(struct mem_pool *pool, const char *str)
> +{
> +	size_t len = strlen(str) + 1;
> +	char *ret = mem_pool_alloc(pool, len);
> +
> +	if (!ret)
> +		die(_("mem_pool_xstrdup: out of memory"));

Can mem_pool_alloc() actually return NULL?  It will rather die because
it uses xmalloc(), right?  So that check is unnecessary.

And since "mem_pool_" already implies that these functions won't return
if an allocation fails, no extra "x" is needed in their name.

> +
> +	return memcpy(ret, str, len);
> +}
> +
> +char *mem_pool_xstrndup(struct mem_pool *pool, const char *str, size_t len)
> +{
> +	size_t minlen = strnlen(str, len);

Hmm, this would be our first caller of strnlen().  wrapper.c::xstrndup()
uses memchr() instead.  It was added in 2008, and strnlen() is in
POSIX.1-2008, so back then it made sense.  Perhaps there are still
systems out there without one?

> +	char *ret = mem_pool_alloc(pool, minlen+1);
> +
> +	if (!ret)
> +		die(_("mem_pool_xstrndup: out of memory"));

The same comments as on mem_pool_xstrdup() apply here.

> +
> +	ret[minlen] = '\0';
> +	return memcpy(ret, str, minlen);
> +}
> +
>  int mem_pool_contains(struct mem_pool *mem_pool, void *mem)
>  {
>  	struct mp_block *p;
> diff --git a/mem-pool.h b/mem-pool.h
> index 999d3c3a52..fcaa2d462b 100644
> --- a/mem-pool.h
> +++ b/mem-pool.h
> @@ -41,6 +41,12 @@ void *mem_pool_alloc(struct mem_pool *pool, size_t len);
>   */
>  void *mem_pool_calloc(struct mem_pool *pool, size_t count, size_t size);
>
> +/*
> + * Allocate memory from the memory pool and copy str into it.
> + */
> +char *mem_pool_xstrdup(struct mem_pool *pool, const char *str);
> +char *mem_pool_xstrndup(struct mem_pool *pool, const char *str, size_t len);
> +
>  /*
>   * Move the memory associated with the 'src' pool to the 'dst' pool. The 'src'
>   * pool will be empty and not contain any memory. It still needs to be free'd
>


  reply	other threads:[~2020-08-14  8:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-14  3:02 [PATCH 0/3] Extend and add a little more generalization to the mem_pool API Elijah Newren via GitGitGadget
2020-08-14  3:02 ` [PATCH 1/3] mem-pool: add convenience functions for xstrdup and xstrndup Elijah Newren via GitGitGadget
2020-08-14  4:42   ` Eric Sunshine
2020-08-14  3:02 ` [PATCH 2/3] mem-pool: use more standard initialization and finalization Elijah Newren via GitGitGadget
2020-08-14  4:38   ` Junio C Hamano
2020-08-14  3:02 ` [PATCH 3/3] mem-pool: use consistent pool variable name Elijah Newren via GitGitGadget
2020-08-14  3:51 ` [PATCH 0/3] Extend and add a little more generalization to the mem_pool API Matheus Tavares Bernardino
2020-08-14  6:00 ` [PATCH v2 " Elijah Newren via GitGitGadget
2020-08-14  6:00   ` [PATCH v2 1/3] mem-pool: add convenience functions for xstrdup and xstrndup Elijah Newren via GitGitGadget
2020-08-14  8:21     ` René Scharfe [this message]
2020-08-14  6:00   ` [PATCH v2 2/3] mem-pool: use more standard initialization and finalization Elijah Newren via GitGitGadget
2020-08-14  6:00   ` [PATCH v2 3/3] mem-pool: use consistent pool variable name Elijah Newren via GitGitGadget
2020-08-15 17:37   ` [PATCH v3 0/3] Extend and add a little more generalization to the mem_pool API Elijah Newren via GitGitGadget
2020-08-15 17:37     ` [PATCH v3 1/3] mem-pool: add convenience functions for strdup and strndup Elijah Newren via GitGitGadget
2020-08-15 17:37     ` [PATCH v3 2/3] mem-pool: use more standard initialization and finalization Elijah Newren via GitGitGadget
2020-08-15 17:37     ` [PATCH v3 3/3] mem-pool: use consistent pool variable name Elijah Newren via GitGitGadget
2020-08-18 19:27     ` [PATCH v3 0/3] Extend and add a little more generalization to the mem_pool API Junio C Hamano

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