From: Drew Northup <n1xim.email@gmail.com>
To: git@vger.kernel.org
Cc: David Aguilar <davvid@gmail.com>,
Junio C Hamano <gitster@pobox.com>, Johannes Sixt <j6t@kdbg.org>,
Jonas Fonseca <fonseca@diku.dk>,
Drew Northup <n1xim.email@gmail.com>
Subject: [PATCH] TIG: Implement mkstemps() work-around for platforms lacking it
Date: Tue, 9 Jul 2013 11:33:12 -0400 [thread overview]
Message-ID: <1373383992-4298-1-git-send-email-n1xim.email@gmail.com> (raw)
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.
*/
--
1.8.0
next reply other threads:[~2013-07-09 15:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-09 15:33 Drew Northup [this message]
2013-07-18 4:45 ` [PATCH] TIG: Implement mkstemps() work-around for platforms lacking it Drew Northup
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