From: Drew Northup <n1xim.email@gmail.com>
To: Drew Northup <n1xim.email@gmail.com>
Cc: git@vger.kernel.org, David Aguilar <davvid@gmail.com>,
Junio C Hamano <gitster@pobox.com>, Johannes Sixt <j6t@kdbg.org>,
Jonas Fonseca <fonseca@diku.dk>
Subject: Re: [PATCH] TIG: Implement mkstemps() work-around for platforms lacking it
Date: Thu, 18 Jul 2013 00:45:23 -0400 [thread overview]
Message-ID: <51E772E3.20008@gmail.com> (raw)
In-Reply-To: <1373383992-4298-1-git-send-email-n1xim.email@gmail.com>
Giving this one last kick to make absolutely sure that nobody disagrees
with allowing this code to be included into tig, which does not limit
to a specific version of the GPL (version 2 in the case of git, any
version equal to or newer than 2 in the case of tig), pursuant to
paragraph 9 of said license.
On 07/09/2013 11:33 AM, Drew Northup wrote:
> The function mkstemps() isn't available in all libc implementations. In
> glibc it first became available in 2.11, so platforms such as RHEL 5&
> Slackware 13 lack it. This is likely true of many non-LINUX platforms
> as well.
>
> This fixes breakage that was introduced with a0fdac29 "Create temporary
> file with name as suffix."
>
> Signed-off-by: Drew Northup<n1xim.email@gmail.com>
> ---
>
> This work-around is taken from Git and was inspired by code in libiberty.
> It is presumed that this isn't a problem due to compatible license terms.
>
> A (virtually identical) version of this available in
> https://github.com/n1xim/tig/tree/mkstemps_wkarnd (differences only in
> the commit message).
>
> configure.ac | 4 ++++
> io.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> io.h | 14 +++++++++++
> 3 files changed, 95 insertions(+)
>
> diff --git a/configure.ac b/configure.ac
> index 8dd2508..40e1f85 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -21,6 +21,10 @@ AC_SUBST(CURSES_LIB)
>
> AM_ICONV
>
> +dnl Not all platforms have mkstemps
> +AC_CHECK_FUNC([mkstemps], [AC_DEFINE([HAVE_MKSTEMPS], [1],
> + [Define if mkstemps is available.])])
> +
> AC_PROG_CC
>
> AC_CHECK_PROGS(ASCIIDOC, [asciidoc], [false])
> diff --git a/io.c b/io.c
> index 3ff1d1c..f1b6fbc 100644
> --- a/io.c
> +++ b/io.c
> @@ -237,6 +237,83 @@ encoding_convert(struct encoding *encoding, char *line)
> }
>
> /*
> + * Compatibility: no mkstemps()
> + */
> +
> +/* Adapted from libiberty's mkstemp.c via Git's wrapper.c. */
> +
> +#undef TMP_MAX
> +#define TMP_MAX 16384
> +
> +int tig_mkstemps_mode(char *pattern, int suffix_len, int mode)
> +{
> + static const char letters[] =
> + "abcdefghijklmnopqrstuvwxyz"
> + "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
> + "0123456789";
> + static const int num_letters = 62;
> + uint64_t value;
> + struct timeval tv;
> + char *template;
> + size_t len;
> + int fd, count;
> +
> + len = strlen(pattern);
> +
> + if (len< 6 + suffix_len) {
> + errno = EINVAL;
> + return -1;
> + }
> +
> + if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
> + errno = EINVAL;
> + return -1;
> + }
> +
> + /*
> + * Replace pattern's XXXXXX characters with randomness.
> + * Try TMP_MAX different filenames.
> + */
> + gettimeofday(&tv, NULL);
> + value = ((size_t)(tv.tv_usec<< 16)) ^ tv.tv_sec ^ getpid();
> + template =&pattern[len - 6 - suffix_len];
> + for (count = 0; count< TMP_MAX; ++count) {
> + uint64_t v = value;
> + /* Fill in the random bits. */
> + template[0] = letters[v % num_letters]; v /= num_letters;
> + template[1] = letters[v % num_letters]; v /= num_letters;
> + template[2] = letters[v % num_letters]; v /= num_letters;
> + template[3] = letters[v % num_letters]; v /= num_letters;
> + template[4] = letters[v % num_letters]; v /= num_letters;
> + template[5] = letters[v % num_letters]; v /= num_letters;
> +
> + fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);
> + if (fd> 0)
> + return fd;
> + /*
> + * Fatal error (EPERM, ENOSPC etc).
> + * It doesn't make sense to loop.
> + */
> + if (errno != EEXIST)
> + break;
> + /*
> + * This is a random value. It is only necessary that
> + * the next TMP_MAX values generated by adding 7777 to
> + * VALUE are different with (module 2^32).
> + */
> + value += 7777;
> + }
> + /* We return the null string if we can't find a unique file name. */
> + pattern[0] = '\0';
> + return -1;
> +}
> +
> +int tigmkstemps(char *pattern, int suffix_len)
> +{
> + return tig_mkstemps_mode(pattern, suffix_len, 0600);
> +}
> +
> +/*
> * Executing external commands.
> */
>
> diff --git a/io.h b/io.h
> index 646989d..8f43216 100644
> --- a/io.h
> +++ b/io.h
> @@ -16,6 +16,9 @@
>
> #include "tig.h"
>
> +/* Needed for mkstemps workaround */
> +#include<stdint.h>
> +
> /*
> * Argument array helpers.
> */
> @@ -41,6 +44,17 @@ struct encoding *encoding_open(const char *fromcode);
> char *encoding_convert(struct encoding *encoding, char *line);
>
> /*
> + * Compatibility: no mkstemps()
> + */
> +
> +#ifndef HAVE_MKSTEMPS
> +#define mkstemps tigmkstemps
> +#endif
> +
> +int tigmkstemps(char *, int);
> +int tig_mkstemps_mode(char *pattern, int suffix_len, int mode);
> +
> +/*
> * Executing external commands.
> */
>
prev parent reply other threads:[~2013-07-18 4:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-09 15:33 [PATCH] TIG: Implement mkstemps() work-around for platforms lacking it Drew Northup
2013-07-18 4:45 ` Drew Northup [this message]
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