Merge branch 'master' into modify_1400

.github/workflows/main.yml

@@ -47,6 +47,15 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
+      # This allows SSH access to the GitHub Actions VM to debug things that
+      # only happen on CI. Comment out unless needed. WARNING: tmate.io has
+      # access to unencrypted SSH traffic.
+      # See: https://github.com/marketplace/actions/debugging-with-tmate
+      #- name: set up tmate session
+      #  uses: mxschmitt/action-tmate@v3
+      #  with:
+      #    detached: true
+
       - name: early setup & validation
         run: |
           [[ -n $CH_TEST_BUILDER ]]

VERSION

@@ -1 +1 @@
-0.37~pre
+0.38~pre

bin/Makefile.am

@@ -13,7 +13,8 @@ if HAVE_LIBSQUASHFUSE
 ch_run_SOURCES += ch_fuse.h ch_fuse.c
 endif
 
-ch_run_CFLAGS = $(CFLAGS) $(PTHREAD_CFLAGS)
+# additional build flags for ch-run
+ch_run_CFLAGS = $(PTHREAD_CFLAGS)
 ch_run_LDADD = $(CH_RUN_LIBS)
 
 

bin/ch-image.py.in

@@ -431,6 +431,8 @@ if (__name__ == "__main__"):
          for (opt, arg) in zip(sys.argv[1:], sys.argv[2:] + [None]):
             (opt, _, arg_eq) = opt.partition("=")
             if (opt == "--break"):
+               if (not sys.stdin.isatty()):
+                  ch.FATAL("--break: standard input must be a terminal")
                if (arg_eq != ""):
                   arg = arg_eq
                try:

bin/ch-run.c

@@ -446,6 +446,12 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state)
          exit(0);
 #else
          exit(ERR_CHRUN);
+#endif
+      } else if (!strcmp(arg, "overlayfs")) {
+#ifdef HAVE_OVERLAYFS
+         exit(0);
+#else
+         exit(1);
 #endif
       } else if (!strcmp(arg, "seccomp")) {
 #ifdef HAVE_SECCOMP
@@ -458,6 +464,12 @@ static error_t parse_opt(int key, char *arg, struct argp_state *state)
          exit(0);
 #else
          exit(ERR_CHRUN);
+#endif
+      } else if (!strcmp(arg, "tmpfs-xattrs")) {
+#ifdef HAVE_TMPFS_XATTRS
+         exit(0);
+#else
+         exit(1);
 #endif
       }
       else

bin/ch_core.c

@@ -41,10 +41,27 @@
 /* Timeout in seconds for waiting for join semaphore. */
 #define JOIN_TIMEOUT 30
 
-/* Maximum length of paths we're willing to deal with. (Note that
+/* Maximum length of paths we’re willing to deal with. (Note that
    system-defined PATH_MAX isn't reliable.) */
 #define PATH_CHARS 4096
 
+/* Mount point for the tmpfs used by -W. We want this to be (a) always
+   available [1], (b) short, (c) not used by anything else we care about
+   during container setup, and (d) not wildly confusing if users see it in an
+   error message. Must be a string literal because we use C’s literal
+   concatenation feature. Options considered (all of these required by FHS):
+
+      /boot       Not present if host is booted in some strange way?
+      /etc        Likely very reliable but seems risky
+      /mnt        Used for images on GitHub Actions and causes CI failures
+      /opt        Seems very omittable
+      /srv        I’ve never actually seen it used; reliable?
+      /var        Too aggressive?
+      /var/spool  Long; omittable for lightweight hosts?
+
+   [1]: https://www.pathname.com/fhs/pub/fhs-2.3.pdf */
+#define WF_MNT "/srv"
+
 
 /** Constants **/
 
@@ -306,26 +323,30 @@ void enter_udss(struct container *c)
    // https://www.kernel.org/doc/html/v5.11/filesystems/tmpfs.html
    // https://www.kernel.org/doc/html/v5.11/filesystems/overlayfs.html
    if (c->overlay_size != NULL) {
-      VERBOSE("overlaying tmpfs for --write-fake (%s)", c->overlay_size);
       char *options;
+      struct stat st;
+      VERBOSE("overlaying tmpfs for --write-fake (%s)", c->overlay_size);
       T_ (1 <= asprintf(&options, "size=%s", c->overlay_size));
-      Zf (mount(NULL, "/mnt", "tmpfs", 0, options),  // host should have /mnt
+      Zf (mount(NULL, WF_MNT, "tmpfs", 0, options),
           "cannot mount tmpfs for overlay");
       free(options);
-      Z_ (mkdir("/mnt/upper", 0700));
-      Z_ (mkdir("/mnt/work", 0700));
-      Z_ (mkdir("/mnt/merged", 0700));
-      mkdir_scratch = "/mnt/mkdir_overmount";
+      Z_ (mkdir(WF_MNT "/upper", 0700));
+      Z_ (mkdir(WF_MNT "/work", 0700));
+      Z_ (mkdir(WF_MNT "/merged", 0700));
+      mkdir_scratch = WF_MNT "/mkdir_overmount";
       Z_ (mkdir(mkdir_scratch, 0700));
-      T_ (1 <= asprintf(&options, "lowerdir=%s,upperdir=%s,workdir=%s,"
-                                  "index=on,userxattr,volatile",
-                                  c->newroot, "/mnt/upper", "/mnt/work"));
+      T_ (1 <= asprintf(&options, ("lowerdir=%s,upperdir=%s,workdir=%s,"
+                                   "index=on,userxattr,volatile"),
+                        c->newroot, WF_MNT "/upper", WF_MNT "/work"));
       // update newroot
-      c->newroot = "/mnt/merged";
+      Zf (stat(c->newroot, &st),
+          "can't stat new root; overmounted by tmpfs for -W?: %s", c->newroot);
+      c->newroot = WF_MNT "/merged";
       free(nr_parent);
       free(nr_base);
       path_split(c->newroot, &nr_parent, &nr_base);
-      Zf (mount(NULL, c->newroot, "overlay", 0, options), "can't overlay");
+      Zf (mount(NULL, c->newroot, "overlay", 0, options),
+          "can't overlay: %s, %s", c->newroot, options);
       VERBOSE("newroot updated: %s", c->newroot);
       free(options);
    }

bin/ch_fuse.c

@@ -27,6 +27,11 @@
 // SquashFUSE redefines __le16 unless HAVE_LINUX_TYPES_LE16 is defined. We are
 // assuming it is defined in <linux/types.h> on your machine.
 #define HAVE_LINUX_TYPES_LE16
+// The forget operation in libfuse3 takes uint64_t as third parameter,
+// while SquashFUSE defaults to unsigned long as used in libfuse2.
+// This causes a mess on arches with different size of these types,
+// so explicitly switch to the libfuse3 variant.
+#define HAVE_FUSE_LL_FORGET_OP_64T
 // Now we can include ll.h.
 #include <squashfuse/ll.h>
 

configure.ac

@@ -63,12 +63,6 @@ MKDIR_P=${MKDIR_P:-install -d -m 0755}
 
 AM_INIT_AUTOMAKE([1.13 -Wall -Werror foreign subdir-objects])
 
-# Check for “pkg-config”. It’s here because we use PKG_CHECK_MODULES
-# conditionally later and we want to make sure this always happens [1, §3.4].
-#
-# [1]: https://autotools.info/pkgconfig/pkg_check_modules.html
-PKG_PROG_PKG_CONFIG
-
 AC_CONFIG_HEADERS([bin/config.h])
 AC_CONFIG_FILES([Makefile
                  bin/Makefile
@@ -349,6 +343,7 @@ AC_MSG_RESULT($have_userns)
 AC_DEFUN([CH_OVERLAY_C], [[
   #define _GNU_SOURCE
   #include <errno.h>
+  #include <fcntl.h>
   #include <sched.h>
   #include <stdio.h>
   #include <stdlib.h>
@@ -491,17 +486,22 @@ have_libfuse3=n/a
 have_libsquashfuse_ll=n/a
 have_ll_h=n/a
 AS_IF([test $want_libsquashfuse = yes], [
-  # libfuse3. Must use pkg-config because as of version 0.5.0 SquashFUSE’s
-  # ll.h won’t build without an appropriate -I [1]. This macro defines some
-  # variables that we use here; see this third-party documentation [2]. (I
-  # could not find first-party docs for it.)
+  # libfuse3. As of version 0.5.0, SquashFUSE’s ll.h won’t build without an
+  # appropriate -I [1]. Presently we use pkg-config to find it, but see #1844.
+  #
+  # We avoid PKG_CHECK_MODULES because it introduces a dependency on
+  # pkg-config at autogen.sh time, with impressively incomprehensible error
+  # messages if it’s not met [2]. The approach below also seems simpler [3]?
   #
   # [1]: https://github.com/vasi/squashfuse/commit/eca5764
-  # [2]: https://autotools.info/pkgconfig/pkg_check_modules.html
-  PKG_CHECK_MODULES([fuse3], [fuse3], [
-    # libfuse3 found
+  # [2]: https://ae1020.github.io/undefined-macro-pkg-config/
+  # [3]: https://tirania.org/blog/archive/2012/Oct-20.html
+  AC_CHECK_PROG(have_pkg_config, pkg-config, yes, no)
+  AS_IF([test $have_pkg_config != yes],
+        [AC_MSG_ERROR([need pkg-config to find libfuse3; try --with-libsquashfuse=no or see issue @%:@1844])])
+  AS_IF([pkg-config --exists fuse3], [
     have_libfuse3=yes
-    CFLAGS="$CFLAGS $fuse3_CFLAGS"
+    CFLAGS="$CFLAGS $(pkg-config --cflags fuse3)"
     # libsquashfuse?
     AC_CHECK_LIB([squashfuse_ll], [sqfs_ll_mount],
       [have_libsquashfuse_ll=yes],
@@ -787,6 +787,10 @@ AC_SUBST([CH_RUN_LIBS])
 AC_SUBST([PYTHON_SHEBANG])
 AC_SUBST([SPHINX])
 
+AS_IF([test $have_overlayfs = yes],
+      [AC_DEFINE([HAVE_OVERLAYFS], [1], [unprivileged overlayfs])])
+AS_IF([test $have_tmpfs_xattrs = yes],
+      [AC_DEFINE([HAVE_TMPFS_XATTRS], [1], [tmpfs user xattrs])])
 AS_IF([test $have_fnm_extmatch = yes],
       [AC_DEFINE([HAVE_FNM_EXTMATCH], [1], [extended globs supported])])
 AS_IF([test $have_seccomp = yes],
@@ -942,7 +946,7 @@ Building Charliecloud
     test suite ... ${enable_test}
 
   required:
-    C99 compiler ... ${CC} ${CC_VERSION}
+    C99 compiler ... ${CC} ${CFLAGS}
 
   optional:
     extended glob patterns in --unset-env ... ${have_fnm_extmatch}

doc/_loc.rst

@@ -1,24 +1,24 @@
 .. Do not edit this file — it’s auto-generated.
 
 We pride ourselves on keeping Charliecloud lightweight and simple. The lines
-of code as of version 0.36 is:
+of code as of version 0.37 is:
 
 .. list-table::
 
    * - Program itself
-     - 8924
+     - 9079
    * - Test suite & examples
-     - 11941
+     - 12019
    * - Documentation
-     - 6311
+     - 6416
    * - Build system
-     - 1289
+     - 1294
    * - Packaging
-     - 628
+     - 629
    * - Miscellaneous
      - 506
    * - Total
-     - 29599
+     - 29943
 
 These include code only, excluding blank lines and comments. They were counted
 using `cloc <https://github.com/AlDanial/cloc>`_ version 1.96.