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From: Junio C Hamano <gitster@pobox.com>
To: Pierre Habouzit <madcoder@debian.org>
Cc: git@vger.kernel.org
Subject: Re: [PATCH] Rework strbuf API and semantics.
Date: Thu, 06 Sep 2007 03:03:57 -0700	[thread overview]
Message-ID: <7vtzq89kky.fsf@gitster.siamese.dyndns.org> (raw)
In-Reply-To: <11890199232110-git-send-email-madcoder@debian.org> (Pierre Habouzit's message of "Wed, 5 Sep 2007 21:18:36 +0200")

Pierre Habouzit <madcoder@debian.org> writes:

> diff --git a/strbuf.c b/strbuf.c
> ...
> +void strbuf_addvf(struct strbuf *sb, const char *fmt, va_list ap)
> +{
> +	size_t len;
> +	va_list ap2;
> +
> +	va_copy(ap2, ap);
> +
> +	len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap);
> +	if (len < 0) {
> +		len = 0;
> +	}
> +	if (len >= sb->alloc - sb->len) {
> +		strbuf_grow(sb, len);
> +		len = vsnprintf(sb->buf + sb->len, sb->alloc - sb->len, fmt, ap2);
> +		if (len >= sb->alloc - sb->len) {
> +			len = sb->alloc - sb->len - 1;
> +		}
> +	}
> +	sb->len = sb->len + len;
> +	sb->buf[sb->len] = '\0';
>  }

Hmmmmm...  Didn't we recently had a patch that used va_copy()
which was not available somewhere and was shot down?

Instead of that nice inline strbuf_addf(), you may have to do
something like:

	strbuf_addf(..., fmt, ...) {
                va_list ap;

                va_start(ap, fmt);
                len = vsnprintf(...);
                va_end(ap);
                if (len >= sb_avail(sb)) {
                        strbuf_grow(sb, len);
                        va_start(ap, fmt);
                        len = vsnprintf(...);
                        va_end(ap);
                        if (len >= sb_avail(sb))
                                gaah();
                }
		sb->len += len;
                sb->buf[sb->len] = '\0';
	}


> +ssize_t strbuf_read(struct strbuf *sb, int fd)
> +{
> +	size_t oldlen = sb->len;
> +
> +	for (;;) {
> +		ssize_t cnt;
> +
> +		strbuf_grow(sb, 8192);
> +		cnt = xread(fd, sb->buf + sb->len, sb->alloc - sb->len - 1);
> +		if (cnt < 0) {
> +			sb->buf[sb->len = oldlen] = '\0';

Assignment inside array subscript is very hard to read.
Besides, what's the error semantics?  On error, this behaves as
if no bytes are read (i.e. partial read results in the initial
round is lost forever)?

  parent reply	other threads:[~2007-09-06 10:04 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-02 22:42 strbuf API Pierre Habouzit
2007-09-03  5:43 ` Johan Herland
2007-09-03  8:46   ` Pierre Habouzit
2007-09-04  1:52     ` Miles Bader
2007-09-04  8:47       ` strbuf new semantics, let's give it a try Pierre Habouzit
2007-09-04  8:47       ` [PATCH] Rework strbuf API and semantics Pierre Habouzit
2007-09-04 11:11         ` Johannes Schindelin
2007-09-04 11:53           ` Pierre Habouzit
2007-09-04 13:34             ` Andreas Ericsson
2007-09-04 14:01             ` Pierre Habouzit
2007-09-04 15:44               ` Johannes Schindelin
2007-09-04 16:18                 ` Pierre Habouzit
2007-09-04 17:18                   ` Wincent Colaiuta
2007-09-04 14:01             ` [PATCH] Simplify strbuf uses in fast-import.c using the proper functions Pierre Habouzit
2007-09-04 23:46               ` René Scharfe
2007-09-04 23:46               ` René Scharfe
2007-09-05  7:48                 ` Pierre Habouzit
2007-09-05  8:05                   ` Junio C Hamano
2007-09-05  8:57                     ` Pierre Habouzit
2007-09-05 19:18                       ` [PATCH] Rework strbuf API and semantics Pierre Habouzit
2007-09-05 19:18                         ` [PATCH] Simplify strbuf uses in archive-tar.c using the proper functions Pierre Habouzit
2007-09-05 19:18                           ` [PATCH] Simplify strbuf uses in fast-import.c " Pierre Habouzit
2007-09-05 19:18                             ` [PATCH] Use proper strbuf API, and also simplify cmd_data code Pierre Habouzit
2007-09-05 19:18                               ` [PATCH] Simplify write_tree using strbuf's Pierre Habouzit
2007-09-05 19:18                                 ` [PATCH] Further strbuf re-engineering Pierre Habouzit
2007-09-05 19:18                                   ` [PATCH] Eradicate yet-another-buffer implementation in buitin-rerere.c Pierre Habouzit
2007-09-05 19:18                                     ` [PATCH] More strbuf uses in cache-tree.c Pierre Habouzit
2007-09-19  8:05                                   ` [PATCH] Further strbuf re-engineering Junio C Hamano
2007-09-05 19:21                             ` [PATCH] Simplify strbuf uses in fast-import.c using the proper functions Pierre Habouzit
2007-09-19  8:06                           ` [PATCH] Simplify strbuf uses in archive-tar.c " Junio C Hamano
2007-09-19  8:36                             ` Pierre Habouzit
2007-09-06  9:31                         ` [PATCH] Rework strbuf API and semantics Junio C Hamano
2007-09-06  9:49                           ` Pierre Habouzit
2007-09-06 10:03                         ` Junio C Hamano [this message]
2007-09-06 10:22                           ` Pierre Habouzit
2007-09-04 14:01             ` [PATCH] Use proper strbuf API, and also simplify cmd_data code Pierre Habouzit
2007-09-05  4:44             ` [PATCH] Rework strbuf API and semantics Miles Bader
2007-09-04  8:48       ` [PATCH] Add strbuf_fread, use it in fast-import.c Pierre Habouzit
2007-09-03  8:32 ` strbuf API Matthieu Moy
2007-09-03  8:49   ` Pierre Habouzit
2007-09-03  9:02     ` Matthieu Moy
2007-09-03  9:18     ` Junio C Hamano
2007-09-03 11:53       ` Pierre Habouzit
2007-09-03 12:29       ` Johannes Schindelin
2007-09-06 11:20 ` strbuf new API, take 2 for inclusion Pierre Habouzit
2007-09-06 11:20   ` [PATCH 1/7] Rework strbuf API and semantics Pierre Habouzit
2007-09-06 11:20     ` [PATCH 2/7] Simplify strbuf uses in archive-tar.c using the proper functions Pierre Habouzit
2007-09-06 11:20       ` [PATCH 3/7] Use proper strbuf API, and also simplify cmd_data code Pierre Habouzit
2007-09-06 11:20         ` [PATCH 4/7] Simplify write_tree using strbuf's Pierre Habouzit
2007-09-06 11:20           ` [PATCH 5/7] Further strbuf re-engineering Pierre Habouzit
2007-09-06 11:20             ` [PATCH 6/7] Eradicate yet-another-buffer implementation in buitin-rerere.c Pierre Habouzit
2007-09-06 11:20               ` [PATCH 7/7] More strbuf uses in cache-tree.c Pierre Habouzit
2007-09-06 14:05               ` [PATCH 6/7] Eradicate yet-another-buffer implementation in buitin-rerere.c Johannes Schindelin
2007-09-06 17:17                 ` Pierre Habouzit
2007-09-06 20:16                   ` David Kastrup
2007-09-06 20:54                     ` Pierre Habouzit
2007-09-07  8:03                   ` Junio C Hamano
2007-09-07  9:02                     ` Pierre Habouzit
2007-09-06 17:59       ` [PATCH 2/7] Simplify strbuf uses in archive-tar.c using the proper functions Kristian Høgsberg
2007-09-06 18:08         ` Pierre Habouzit
2007-09-06 18:18           ` Kristian Høgsberg
2007-09-06 18:27             ` Pierre Habouzit
2007-09-06 22:54               ` René Scharfe
2007-09-06 14:09     ` [PATCH 1/7] Rework strbuf API and semantics Johannes Schindelin
2007-09-06 14:21       ` Jeff King
2007-09-06 14:44         ` David Kastrup
2007-09-06 14:50           ` Jeff King
2007-09-06 15:06             ` David Kastrup
2007-09-06 15:36               ` Jeff King
2007-09-06 15:53                 ` David Kastrup
2007-09-06 15:45               ` Johannes Sixt
2007-09-06 14:43       ` David Kastrup
2007-09-06 14:52         ` Jeff King
2007-09-06 17:49     ` Kristian Høgsberg
2007-09-06 12:58   ` strbuf new API, take 2 for inclusion Jeff King
2007-09-06 17:15     ` Pierre Habouzit
2007-09-06 17:16       ` Jeff King
2007-09-06 17:19         ` Pierre Habouzit
2007-09-08 11:53 ` Use strbufs in commit.c (pretty printing) Pierre Habouzit
2007-09-08 11:53   ` [PATCH 1/3] Add strbuf_rtrim (to remove trailing spaces) Pierre Habouzit
2007-09-08 11:53     ` [PATCH 2/3] Change semantics of interpolate to work like snprintf Pierre Habouzit
2007-09-08 11:53       ` [PATCH 3/3] Rework pretty_print_commit to use strbufs instead of custom buffers Pierre Habouzit
2007-09-08 11:59         ` David Kastrup
2007-09-08 12:17           ` Pierre Habouzit
2007-09-08 12:28           ` Pierre Habouzit
2007-09-08 18:40         ` René Scharfe
2007-09-08 18:49           ` Pierre Habouzit
2007-09-08 16:18     ` [PATCH 1/3] Add strbuf_rtrim (to remove trailing spaces) René Scharfe
2007-09-08 22:53       ` Pierre Habouzit
2007-09-08 23:44         ` Pierre Habouzit

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