From: Junio C Hamano <gitster@pobox•com>
To: Yiannis Marangos <yiannis.marangos@gmail•com>
Cc: git@vger•kernel.org
Subject: Re: [PATCH v7 1/2] Add xpread() and xpwrite()
Date: Thu, 10 Apr 2014 11:35:42 -0700 [thread overview]
Message-ID: <xmqq7g6xxcap.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <1397154681-31803-1-git-send-email-yiannis.marangos@gmail.com> (Yiannis Marangos's message of "Thu, 10 Apr 2014 21:31:20 +0300")
Yiannis Marangos <yiannis.marangos@gmail•com> writes:
> xpread() and xpwrite() pay attention to EAGAIN/EINTR, so they will resume
> automatically on interrupted call.
We do not even use pwrite(); please don't add anything unnecessary
and unexercised, like xpwrite(), as potential bugs in it will go
unnoticed long after its introduction until it first gets used.
> diff --git a/builtin/index-pack.c b/builtin/index-pack.c
> index b9f6e12..1bac0f5 100644
> --- a/builtin/index-pack.c
> +++ b/builtin/index-pack.c
> @@ -542,7 +542,7 @@ static void *unpack_data(struct object_entry *obj,
>
> do {
> ssize_t n = (len < 64*1024) ? len : 64*1024;
> - n = pread(pack_fd, inbuf, n, from);
> + n = xpread(pack_fd, inbuf, n, from);
> if (n < 0)
> die_errno(_("cannot pread pack file"));
> if (!n)
OK.
> diff --git a/compat/mmap.c b/compat/mmap.c
> index c9d46d1..7f662fe 100644
> --- a/compat/mmap.c
> +++ b/compat/mmap.c
> @@ -14,7 +14,7 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of
> }
>
> while (n < length) {
> - ssize_t count = pread(fd, (char *)start + n, length - n, offset + n);
> + ssize_t count = xpread(fd, (char *)start + n, length - n, offset + n);
>
> if (count == 0) {
> memset((char *)start+n, 0, length-n);
> @@ -22,8 +22,6 @@ void *git_mmap(void *start, size_t length, int prot, int flags, int fd, off_t of
> }
>
> if (count < 0) {
> - if (errno == EAGAIN || errno == EINTR)
> - continue;
> free(start);
> errno = EACCES;
> return MAP_FAILED;
OK.
> diff --git a/wrapper.c b/wrapper.c
> index 0cc5636..25b7419 100644
> --- a/wrapper.c
> +++ b/wrapper.c
> @@ -174,6 +174,42 @@ ssize_t xwrite(int fd, const void *buf, size_t len)
> }
> }
>
> +/*
> + * xpread() is the same as pread(), but it automatically restarts pread()
> + * operations with a recoverable error (EAGAIN and EINTR). xpread() DOES
> + * NOT GUARANTEE that "len" bytes is read even if the data is available.
> + */
> +ssize_t xpread(int fd, void *buf, size_t len, off_t offset)
> +{
> + ssize_t nr;
> + if (len > MAX_IO_SIZE)
> + len = MAX_IO_SIZE;
> + while (1) {
> + nr = pread(fd, buf, len, offset);
> + if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
> + continue;
> + return nr;
> + }
> +}
OK.
Thanks.
next prev parent reply other threads:[~2014-04-10 18:35 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-09 22:06 [PATCH] Verify index file before we opportunistically update it Yiannis Marangos
2014-04-09 22:06 ` Yiannis Marangos
2014-04-09 22:34 ` [PATCH v2] " Yiannis Marangos
2014-04-09 23:05 ` Junio C Hamano
2014-04-09 22:52 ` [PATCH v3] " Yiannis Marangos
2014-04-10 5:22 ` [PATCH v4] " Yiannis Marangos
2014-04-10 5:34 ` [PATCH v5] " Yiannis Marangos
2014-04-10 10:40 ` Duy Nguyen
2014-04-10 11:57 ` Yiannis Marangos
2014-04-10 16:57 ` Junio C Hamano
2014-04-10 13:11 ` [PATCH v6] " Yiannis Marangos
2014-04-10 18:31 ` [PATCH v7 1/2] Add xpread() and xpwrite() Yiannis Marangos
2014-04-10 18:31 ` [PATCH v7 2/2] Verify index file before we opportunistically update it Yiannis Marangos
2014-04-10 19:28 ` Junio C Hamano
2014-04-11 2:57 ` Duy Nguyen
2014-04-11 19:24 ` Junio C Hamano
2014-04-11 20:43 ` Junio C Hamano
2014-04-11 23:30 ` Yiannis Marangos
2014-04-12 0:10 ` Duy Nguyen
2014-04-12 4:19 ` Junio C Hamano
2014-04-12 7:05 ` Junio C Hamano
2014-04-12 10:13 ` Duy Nguyen
2014-04-14 18:50 ` Junio C Hamano
2014-04-11 7:47 ` Torsten Bögershausen
2014-04-11 15:58 ` Yiannis Marangos
2014-04-11 10:36 ` Duy Nguyen
2014-04-10 18:35 ` Junio C Hamano [this message]
2014-04-10 18:44 ` [PATCH v7 1/2] Add xpread() and xpwrite() Yiannis Marangos
2014-04-10 18:54 ` [PATCH v8 1/2] Add xpread() Yiannis Marangos
2014-04-10 19:12 ` Johannes Sixt
2014-04-10 19:20 ` Junio C Hamano
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