From 73cff35173dd75b0254ae7cf9098c32822859de0 Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Tue, 16 Apr 2019 20:37:01 +0000
Subject:  It builds! Tomorrow: skeletons for stage2, stage3 and runlevel
 scripts.

---
 src/misc/s6-linux-init-umountall.c | 70 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 src/misc/s6-linux-init-umountall.c

(limited to 'src/misc/s6-linux-init-umountall.c')

diff --git a/src/misc/s6-linux-init-umountall.c b/src/misc/s6-linux-init-umountall.c
new file mode 100644
index 0000000..24b22fc
--- /dev/null
+++ b/src/misc/s6-linux-init-umountall.c
@@ -0,0 +1,70 @@
+/* ISC license. */
+
+#include <string.h>
+#include <sys/mount.h>
+
+#include <skalibs/bytestr.h>
+#include <skalibs/buffer.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/skamisc.h>
+
+#define BUFSIZE 4096
+#define MAXLINES 512
+
+int main (int argc, char const *const *argv)
+{
+  stralloc mountpoints[MAXLINES] ;
+  char buf[BUFSIZE] ;
+  buffer b ;
+  stralloc sa = STRALLOC_ZERO ;
+  unsigned int line = 0 ;
+  int e = 0 ;
+  int r ;
+  int fd ;
+
+  PROG = "s6-linux-init-umountall" ;
+
+
+ /*
+    We need to go through /proc/mounts *in reverse order*, because later mounts
+    may depend on earlier mounts.
+    The getmntent() family of functions has obviously not been designed for that
+    use case at all, and it is actually more difficult to use it than to do the
+    /proc/mounts parsing by hand. So, we do it by hand with skalibs functions.
+    That's how you can tell a good API from a terrible one.
+ */
+
+  fd = open_readb("/proc/mounts") ;
+  if (fd < 0) strerr_diefu1sys(111, "open /proc/mounts") ;
+  memset(mountpoints, 0, sizeof(mountpoints)) ;
+  buffer_init(&b, &buffer_read, fd, buf, BUFSIZE) ;
+  for (;;)
+  {
+    size_t n, p ;
+    if (line >= MAXLINES) strerr_dief1x(111, "/proc/mounts too big") ;
+    sa.len = 0 ;
+    r = skagetln(&b, &sa, '\n') ;
+    if (r <= 0) break ;
+    p = byte_chr(sa.s, sa.len, ' ') ;
+    if (p >= sa.len) strerr_dief1x(111, "bad /proc/mounts format") ;
+    p++ ;
+    n = byte_chr(sa.s + p, sa.len - p, ' ') ;
+    if (n == sa.len - p) strerr_dief1x(111, "bad /proc/mounts format") ;
+    if (!stralloc_catb(&mountpoints[line], sa.s + p, n) || !stralloc_0(&mountpoints[line]))
+      strerr_diefu1sys(111, "store mount point") ;
+    line++ ;
+  }
+  fd_close(fd) ;
+  stralloc_free(&sa) ;
+  if (r < 0) strerr_diefu1sys(111, "read /proc/mounts") ;
+
+  while (line--)
+    if (umount(mountpoints[line].s) == -1)
+    {
+      e++ ;
+      strerr_warnwu2sys("umount ", mountpoints[line].s) ;
+    }
+  return e ;
+}
-- 
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