Add libsimple_bindtemp_un

Signed-off-by: Mattias Andrée <maandree@kth.se>

5 files changed, 110 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index 4a8a324..a66da02 100644
--- a/Makefile
+++ b/Makefile
@@ -39,6 +39,7 @@ SUBHDR =\
 	libsimple/memalloc.h\
 	libsimple/memdup.h\
 	libsimple/memelem.h\
+	libsimple/net.h\
 	libsimple/overflow.h\
 	libsimple/posix_memalign.h\
 	libsimple/posix_memalignz.h\
@@ -86,6 +87,7 @@ OBJ =\
 	asprintf.o\
 	bindex.o\
 	bindex_r.o\
+	bindtemp_un.o\
 	callocn.o\
 	close.o\
 	close_range.o\
diff --git a/README b/README
index 1de7b5c..d7aa9ea 100644
--- a/README
+++ b/README
@@ -5,8 +5,8 @@ values for integer data types.
 
 All functions are namespaced with `libsimple_` and aliased with macro
 definitions to unnamespaced names unless there already is a macro with that
-name. However, some functions are seen as libsimple specific and do not
-have unnamespaced.
+name. However, some functions are seen as libsimple specific and are not
+namespaced.
 
 Programs using this library should define `char *argv0` and set it to
 the 0:th command line argument.
diff --git a/bindtemp_un.c b/bindtemp_un.c
new file mode 100644
index 0000000..0362e47
--- /dev/null
+++ b/bindtemp_un.c
@@ -0,0 +1,89 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#ifndef TEST
+
+
+/**
+ * Fill a buffer with random alphanumerical symbols, and '_' and '-'
+ * 
+ * @param  buf  The buffer to fill
+ * @param  n    The size of the buffer
+ */
+static void
+random_alnum(char *buf, size_t n)
+{
+	size_t i;
+	int rnd;
+	double drnd;
+
+#if defined(__linux__) && defined(GRND_NONBLOCK)
+	ssize_t r = getrandom(buf, n, GRND_NONBLOCK);
+	i = r < 0 ? 0 : (size_t)r;
+#else
+	i = 0;
+#endif
+
+	for (; i < n; i++) {
+		rnd = rand();
+		drnd = (double)rnd / (double)RAND_MAX;
+		drnd *= 63;
+		rnd = (int)drnd;
+		buf[i] = (char)rnd;
+	}
+
+	for (i = 0; i < n; i++)
+		buf[i] = "0123456789_abcdefghijklmnopqrstuvwxyz-ABCDEFGHIJKLMNOPQRSTUVWXYZ"[buf[i] & 63];
+}
+
+
+int
+libsimple_bindtemp_un(int fd, int dir_fd, struct sockaddr_un *addr, socklen_t *addrlen)
+{
+	int len, saved_errno = errno;
+	size_t rem, try_limit = 1000;
+	struct sockaddr_un addr_;
+
+	if (!addr)
+		addr = &addr_;
+	if (addrlen)
+		*addrlen = sizeof(*addr);
+
+	memset(addr, 0, sizeof(*addr));
+	addr->sun_family = AF_UNIX;
+
+	if (dir_fd == AT_FDCWD)
+		len = snprintf(addr->sun_path, sizeof(addr->sun_path), "tmp");
+	else
+		len = snprintf(addr->sun_path, sizeof(addr->sun_path), "/dev/fd/%i/tmp", dir_fd);
+	if (len < 0 || (size_t)len >= sizeof(addr->sun_path) || sizeof(addr->sun_path) - (size_t)len < 6)
+		abort();
+	rem = sizeof(addr->sun_path) - 1 - len;
+	addr->sun_path[sizeof(addr->sun_path) - 1] = 0;
+
+	while (try_limit--) {
+	again:
+		random_alnum(&addr->sun_path[len], rem);
+		if (!bind(fd, (void *)&addr, (socklen_t)sizeof(*addr))) {
+			errno = saved_errno;
+			return 0;
+		} else if (errno == ENAMETOOLONG && rem > 5) {
+			addr->sun_path[len + --rem] = 0;
+			goto again;
+		} else if (errno != EEXIST && errno != EADDRINUSE) {
+			return -1;
+		}
+	}
+	return -1;
+}
+
+
+#else
+#include "test.h"
+
+int
+main(void) /* TODO add test */
+{
+	return 0;
+}
+
+#endif
diff --git a/libsimple.h b/libsimple.h
index bdfc7c7..1d72f46 100644
--- a/libsimple.h
+++ b/libsimple.h
@@ -167,6 +167,7 @@
 #include "libsimple/search.h"
 #include "libsimple/random.h"
 #include "libsimple/abs.h"
+#include "libsimple/net.h"
 
 
 /**
diff --git a/libsimple/net.h b/libsimple/net.h
new file mode 100644
index 0000000..c30020b
--- /dev/null
+++ b/libsimple/net.h
@@ -0,0 +1,16 @@
+/* See LICENSE file for copyright and license details. */
+
+
+/**
+ * Bind a unix(7) socket to a random file name in a specific directory
+ * 
+ * @param   fd           The socket's file descriptor
+ * @param   dir_fd       File descriptor to the directory the socket shall be
+ *                       stored in (may be `AT_FDCWD`)
+ * @param   addr_out     Output parameter for the socket name (may be `NULL`);
+ *                       `&strrchr(addr_out->sun_path, '/')[1]` will be the
+ *                       name of the file the socket will be bound to
+ * @param   addrlen_out  Output parameter for the size of the socket name (may be `NULL`)
+ * @return               0 on success, -1 on failure
+ */
+int libsimple_bindtemp_un(int fd, int dir_fd, struct sockaddr_un *addr_out, socklen_t *addrlen_out); /* TODO man */