1 files changed, 51 insertions, 0 deletions
diff --git a/src/libs6/s6_dtally_read.c b/src/libs6/s6_dtally_read.c
new file mode 100644
index 0000000..3906b93
--- /dev/null
+++ b/src/libs6/s6_dtally_read.c
@@ -0,0 +1,51 @@
+/* ISC license. */
+
+#include <sys/stat.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/tai.h>
+#include <skalibs/djbunix.h>
+#include <s6/s6-supervise.h>
+
+static int truncit (char const *s)
+{
+  int fd = open_trunc(s) ;
+  if (fd < 0) return -1 ;
+  fd_close(fd) ;
+  return 0 ;
+}
+
+ssize_t s6_dtally_read (char const *sv, s6_dtally_t *tab, size_t max)
+{
+  size_t len = strlen(sv) ;
+  size_t n ;
+  int fd ;
+  struct stat st ;
+  char fn[len + sizeof(S6_DTALLY_FILENAME) + 1] ;
+  memcpy(fn, sv, len) ;
+  memcpy(fn + len, "/" S6_DTALLY_FILENAME, sizeof(S6_DTALLY_FILENAME) + 1) ;
+  fd = open_read(fn) ;
+  if (fd < 0) return errno == ENOENT ? truncit(fn) : -1 ;
+  if (fstat(fd, &st) < 0) goto err ;
+  if (st.st_size % S6_DTALLY_PACK)
+  {
+    fd_close(fd) ;
+    return truncit(fn) ;
+  }
+  n = st.st_size / S6_DTALLY_PACK ;
+  if (n > max) n = max ;
+  {
+    char tmp[n ? S6_DTALLY_PACK * n : 1] ;
+    if (lseek(fd, -(off_t)(n * S6_DTALLY_PACK), SEEK_END) < 0) goto err ;
+    if (allread(fd, tmp, n * S6_DTALLY_PACK) < n * S6_DTALLY_PACK) goto err ;
+    fd_close(fd) ;
+    for (size_t i = 0 ; i < n ; i++) s6_dtally_unpack(tmp + i * S6_DTALLY_PACK, tab + i) ;
+  }
+  return n ;
+
+ err:
+  fd_close(fd) ;
+  return -1 ;
+}