From 11f210ecaa0e085612058b459523fa2003578aa5 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Sun, 3 Dec 2017 20:09:22 +0000
Subject:  Add atomic_symlink(), prepare for 2.6.3.0

---
 NEWS                                     |  6 +++++
 doc/index.html                           |  2 +-
 doc/license.html                         |  2 +-
 doc/upgrade.html                         |  6 +++++
 package/deps.mak                         |  1 +
 package/info                             |  2 +-
 src/include/skalibs/unix-transactional.h |  1 +
 src/libunixonacid/atomic_symlink.c       | 41 ++++++++++++++++++++++++++++++++
 8 files changed, 58 insertions(+), 3 deletions(-)
 create mode 100644 src/libunixonacid/atomic_symlink.c

diff --git a/NEWS b/NEWS
index 70121c6..d22ef48 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,11 @@
 Changelog for skalibs.
 
+In 2.6.3.0
+----------
+
+ - New function: atomic_symlink().
+
+
 In 2.6.2.0
 ----------
 
diff --git a/doc/index.html b/doc/index.html
index 24fe81c..da77c9b 100644
--- a/doc/index.html
+++ b/doc/index.html
@@ -60,7 +60,7 @@ with a standard C development environment </li>
 <h3> Download </h3>
 
 <ul>
- <li> The current released version of skalibs is <a href="skalibs-2.6.2.0.tar.gz">2.6.2.0</a>. </li>
+ <li> The current released version of skalibs is <a href="skalibs-2.6.3.0.tar.gz">2.6.3.0</a>. </li>
  <li> Alternatively, you can checkout a copy of the
 <a href="//git.skarnet.org/cgi-bin/cgit.cgi/skalibs/">skalibs
 git repository</a>:
diff --git a/doc/license.html b/doc/license.html
index 3cd815b..9eb93a0 100644
--- a/doc/license.html
+++ b/doc/license.html
@@ -74,7 +74,7 @@ color, or different text font. </li>
 <p>
  <em>I am aware that the previous restrictions sound completely
 ridiculous while the official skalibs documentation is incomplete.
-As of 2.6.2.0, I'm not going to enforce those restrictions, but if you're
+As of 2.6.3.0, I'm not going to enforce those restrictions, but if you're
 going to provide documentation for skalibs, don't keep it to yourself,
 please send it to me instead. :-) </em>
 </p>
diff --git a/doc/upgrade.html b/doc/upgrade.html
index 536e079..a45131d 100644
--- a/doc/upgrade.html
+++ b/doc/upgrade.html
@@ -16,6 +16,12 @@
 <a href="//skarnet.org/">skarnet.org</a>
 </p>
 
+<h2> in 2.6.3.0 </h2>
+
+<ul>
+ <li> New function: atomic_symlink(). </li>
+</ul>
+
 <h2> in 2.6.2.0 </h2>
 
 <ul>
diff --git a/package/deps.mak b/package/deps.mak
index f5aa076..63dec9f 100644
--- a/package/deps.mak
+++ b/package/deps.mak
@@ -690,6 +690,7 @@ src/libstddjb/xpathexec_run.o src/libstddjb/xpathexec_run.lo: src/libstddjb/xpat
 src/libunixonacid/access_at.o src/libunixonacid/access_at.lo: src/libunixonacid/access_at.c src/include/skalibs/djbunix.h src/include/skalibs/nonposix.h src/include/skalibs/sysdeps.h src/include/skalibs/unix-transactional.h
 src/libunixonacid/atomic_rm_rf.o src/libunixonacid/atomic_rm_rf.lo: src/libunixonacid/atomic_rm_rf.c src/include/skalibs/skamisc.h src/include/skalibs/unix-transactional.h
 src/libunixonacid/atomic_rm_rf_tmp.o src/libunixonacid/atomic_rm_rf_tmp.lo: src/libunixonacid/atomic_rm_rf_tmp.c src/include/skalibs/djbunix.h src/include/skalibs/random.h src/include/skalibs/stralloc.h src/include/skalibs/unix-transactional.h
+src/libunixonacid/atomic_symlink.o src/libunixonacid/atomic_symlink.lo: src/libunixonacid/atomic_symlink.c src/include/skalibs/random.h src/include/skalibs/unix-transactional.h
 src/libunixonacid/bufalloc_timed_flush.o src/libunixonacid/bufalloc_timed_flush.lo: src/libunixonacid/bufalloc_timed_flush.c src/include/skalibs/bufalloc.h src/include/skalibs/functypes.h src/include/skalibs/unix-timed.h
 src/libunixonacid/buffer_timed_fill.o src/libunixonacid/buffer_timed_fill.lo: src/libunixonacid/buffer_timed_fill.c src/include/skalibs/allreadwrite.h src/include/skalibs/buffer.h src/include/skalibs/functypes.h src/include/skalibs/unix-timed.h
 src/libunixonacid/buffer_timed_flush.o src/libunixonacid/buffer_timed_flush.lo: src/libunixonacid/buffer_timed_flush.c src/include/skalibs/buffer.h src/include/skalibs/functypes.h src/include/skalibs/unix-timed.h
diff --git a/package/info b/package/info
index f19446c..404e5b2 100644
--- a/package/info
+++ b/package/info
@@ -1,4 +1,4 @@
 package=skalibs
-version=2.6.2.0
+version=2.6.3.0
 category=prog
 package_macro_name=SKALIBS
diff --git a/src/include/skalibs/unix-transactional.h b/src/include/skalibs/unix-transactional.h
index d548f78..1037e92 100644
--- a/src/include/skalibs/unix-transactional.h
+++ b/src/include/skalibs/unix-transactional.h
@@ -39,6 +39,7 @@ extern size_t openwritevnclose_at (int, char const *, struct iovec const *, unsi
 extern int mkdir_unique (stralloc *, char const *, unsigned int) ;
 extern int atomic_rm_rf (char const *) ;
 extern int atomic_rm_rf_tmp (char const *, stralloc *) ;
+extern int atomic_symlink (char const *, char const *, char const *) ;
 
 
 typedef struct dirdescriptor_s dirdescriptor_t, *dirdescriptor_t_ref ;
diff --git a/src/libunixonacid/atomic_symlink.c b/src/libunixonacid/atomic_symlink.c
new file mode 100644
index 0000000..660e4d3
--- /dev/null
+++ b/src/libunixonacid/atomic_symlink.c
@@ -0,0 +1,41 @@
+/* ISC license. */
+
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+#include <skalibs/random.h>
+#include <skalibs/unix-transactional.h>
+
+int atomic_symlink (char const *target, char const *name, char const *suffix)
+{
+  {
+    int e = errno ;
+    if (symlink(target, name) == 0) return 1 ;
+    if (errno != EEXIST) return 0 ;
+    errno = e ;
+  }
+  {
+    size_t namelen = strlen(name) ;
+    size_t suffixlen = suffix ? strlen(suffix) : 8 ;
+    char tmp[namelen + suffixlen + 2] ;
+    memcpy(tmp, name, namelen) ;
+    tmp[namelen] = ':' ;
+    if (suffix)
+      memcpy(tmp + namelen + 1, suffix, suffixlen + 1) ;
+    else
+    {
+      random_name(tmp + namelen + 1, 8) ;
+      tmp[namelen + 9] = 0 ;
+    }
+    if (symlink(target, tmp) < 0) return 0 ;
+    if (rename(tmp, name) < 0)
+    {
+      int e = errno ;
+      unlink(tmp) ;
+      errno = e ;
+      return 0 ;
+    }
+  }
+  return 1 ;
+}
-- 
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