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authorLaurent Bercot <ska-skaware@skarnet.org>2014-09-19 02:53:32 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2014-09-19 02:53:32 +0000
commitbea0037dbdd979603fb0b5be8b43f5478c1f6fec (patch)
tree5776ae3af5a3e83d41c7087f70713952b6360988 /src/skaembutils/s6-ln.c
downloads6-portable-utils-bea0037dbdd979603fb0b5be8b43f5478c1f6fec.tar.xz
initial commit
Diffstat (limited to 'src/skaembutils/s6-ln.c')
-rw-r--r--src/skaembutils/s6-ln.c145
1 files changed, 145 insertions, 0 deletions
diff --git a/src/skaembutils/s6-ln.c b/src/skaembutils/s6-ln.c
new file mode 100644
index 0000000..7f6f7b6
--- /dev/null
+++ b/src/skaembutils/s6-ln.c
@@ -0,0 +1,145 @@
+/* ISC license. */
+
+#include <skalibs/sysdeps.h>
+
+#ifdef SKALIBS_HASLINKAT
+#include <skalibs/nonposix.h>
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/random.h>
+#include <skalibs/skamisc.h>
+
+#define USAGE "s6-ln [ -s ] [ -f ] [ -L ] [ -P ] src... dest"
+
+typedef int linkfunc_t (char const *, char const *) ;
+typedef linkfunc_t *linkfunc_t_ref ;
+
+typedef void ln_t (char const *, char const *, linkfunc_t_ref) ;
+typedef ln_t *ln_t_ref ;
+
+#ifdef SKALIBS_HASLINKAT
+
+static int linknoderef (char const *old, char const *new)
+{
+ return linkat(AT_FDCWD, old, AT_FDCWD, new, 0) ;
+}
+
+static int linkderef (char const *old, char const *new)
+{
+ return linkat(AT_FDCWD, old, AT_FDCWD, new, AT_SYMLINK_FOLLOW) ;
+}
+
+#else /* can't implement SUSv4, default to link */
+
+# define linknoderef link
+# define linkderef link
+
+#endif
+
+static void force (char const *old, char const *new, linkfunc_t_ref doit)
+{
+ if ((*doit)(old, new) == -1)
+ {
+ unsigned int base = satmp.len ;
+ if (errno != EEXIST)
+ strerr_diefu5sys(111, "make a link", " from ", new, " to ", old) ;
+ if (!stralloc_catb(&satmp, new, str_len(new))
+ || (random_sauniquename(&satmp, 8) == -1)
+ || !stralloc_0(&satmp))
+ strerr_diefu2sys(111, "make a unique name for ", old) ;
+ if ((*doit)(old, satmp.s + base) == -1)
+ strerr_diefu3sys(111, "make a link", " to ", old) ;
+ if (rename(satmp.s + base, new) == -1)
+ {
+ unlink(satmp.s + base) ;
+ strerr_diefu2sys(111, "atomically replace ", new) ;
+ }
+ satmp.len = base ;
+ }
+}
+
+static void noforce (char const *old, char const *new, linkfunc_t_ref doit)
+{
+ if ((*doit)(old, new) == -1)
+ strerr_diefu5sys(111, "make a link", " from ", new, " to ", old) ;
+}
+
+int main (int argc, char const *const *argv)
+{
+ linkfunc_t_ref mylink = &link ; /* default to system behaviour */
+ ln_t_ref f = &noforce ;
+ PROG = "s6-ln" ;
+ {
+ subgetopt_t l = SUBGETOPT_ZERO ;
+ for (;;)
+ {
+ register int opt = subgetopt_r(argc, argv, "sfLP", &l) ;
+ if (opt == -1) break ;
+ switch (opt)
+ {
+ case 's': mylink = &symlink ; break ;
+ case 'f': f = &force ; break ;
+ case 'L': if (mylink != &symlink) mylink = &linkderef ; break ;
+ case 'P': if (mylink != &symlink) mylink = &linknoderef ; break ;
+ default : strerr_dieusage(100, USAGE) ;
+ }
+ }
+ argc -= l.ind ; argv += l.ind ;
+ }
+ if (argc < 2) strerr_dieusage(100, USAGE) ;
+ if (argc > 2)
+ {
+ stralloc sa = STRALLOC_ZERO ;
+ unsigned int i = 0 ;
+ unsigned int base ;
+ if (!stralloc_cats(&sa, argv[argc-1]) || !stralloc_catb(&sa, "/", 1))
+ strerr_diefu1sys(111, "stralloc_cats") ;
+ base = sa.len ;
+ for (; i < (unsigned int)(argc-1) ; i++)
+ {
+ sa.len = base ;
+ if (!sabasename(&sa, argv[i], str_len(argv[i])))
+ strerr_diefu1sys(111, "sabasename") ;
+ if (!stralloc_0(&sa)) strerr_diefu1sys(111, "stralloc_0") ;
+ (*f)(argv[i], sa.s, mylink) ;
+ }
+ return 0 ;
+ }
+
+ {
+ struct stat st ;
+ if (stat(argv[1], &st) < 0)
+ {
+ if (errno != ENOENT) strerr_diefu2sys(111, "stat ", argv[1]) ;
+ (*f)(argv[0], argv[1], mylink) ;
+ return 0 ;
+ }
+ if (!S_ISDIR(st.st_mode))
+ {
+ (*f)(argv[0], argv[1], mylink) ;
+ return 0 ;
+ }
+ }
+
+ {
+ stralloc sa = STRALLOC_ZERO ;
+ if (!stralloc_cats(&sa, argv[1])
+ || !stralloc_catb(&sa, "/", 1)
+ || !sabasename(&sa, argv[0], str_len(argv[0]))
+ || !stralloc_0(&sa))
+ strerr_diefu1sys(111, "stralloc_catb") ;
+ (*f)(argv[0], sa.s, mylink) ;
+ }
+ return 0 ;
+}