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authorLaurent Bercot <ska-skaware@skarnet.org>2017-12-03 20:09:22 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2017-12-03 20:09:22 +0000
commit11f210ecaa0e085612058b459523fa2003578aa5 (patch)
treecc19339f86a926a85fc4ea08352a4b693b9b59ee /src/libunixonacid
parent74e6ee2aad79665806facb88fca3185cb664582c (diff)
downloadskalibs-11f210ecaa0e085612058b459523fa2003578aa5.tar.xz
Add atomic_symlink(), prepare for 2.6.3.0
Diffstat (limited to 'src/libunixonacid')
-rw-r--r--src/libunixonacid/atomic_symlink.c41
1 files changed, 41 insertions, 0 deletions
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 ;
+}