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authorRusty Russell <rusty@rustcorp.com.au>2012-03-22 10:47:24 +1030
committerRusty Russell <rusty@rustcorp.com.au>2012-03-22 01:57:37 +0100
commit584b996a1a27870dad30eb422d375bb08b57c64c (patch)
treeea15ee6020b25f0ff46060043aa7a62b3f767bf6
parentb3a6ffd7b269f7a34334d24b54591c225da773a5 (diff)
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lib/replace: test for incoherent mmap.
We test for other mmap features here, and both tdb1 and tdb2 want this check. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--lib/replace/libreplace.m47
-rw-r--r--lib/replace/test/incoherent_mmap.c83
-rw-r--r--lib/replace/wscript7
3 files changed, 97 insertions, 0 deletions
diff --git a/lib/replace/libreplace.m4 b/lib/replace/libreplace.m4
index ca0c6846ab..e14fadabf1 100644
--- a/lib/replace/libreplace.m4
+++ b/lib/replace/libreplace.m4
@@ -107,6 +107,13 @@ if test x"$libreplace_cv_HAVE_MREMAP" = x"yes"; then
AC_DEFINE(HAVE_MREMAP,1,[Whether mremap works])
fi
+AC_CACHE_CHECK([for incoherent mmap],libreplace_cv_HAVE_INCOHERENT_MMAP,[
+AC_TRY_RUN([#include "$libreplacedir/test/incoherent_mmap.c"],
+ libreplace_cv_HAVE_INCOHERENT_MMAP=yes,libreplace_cv_HAVE_INCOHERENT_MMAP=no,libreplace_cv_HAVE_INCOHERENT_MMAP=cross)])
+if test x"$libreplace_cv_HAVE_INCOHERENT_MMAP" = x"yes"; then
+ AC_DEFINE(HAVE_INCOHERENT_MMAP,1,[Whether mmap is incoherent against write])
+fi
+
AC_CHECK_HEADERS(sys/syslog.h syslog.h)
AC_CHECK_HEADERS(sys/time.h time.h)
diff --git a/lib/replace/test/incoherent_mmap.c b/lib/replace/test/incoherent_mmap.c
new file mode 100644
index 0000000000..ee288fd806
--- /dev/null
+++ b/lib/replace/test/incoherent_mmap.c
@@ -0,0 +1,83 @@
+/* In OpenBSD, if you write to a file, another process doesn't see it
+ * in its mmap. Returns with exit status 0 if that is the case, 1 if
+ * it's coherent, and other if there's a problem. */
+#include <err.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#define DATA "coherent.mmap"
+
+int main(int argc, char *argv[])
+{
+ int tochild[2], toparent[2];
+ int fd;
+ volatile unsigned char *map;
+ unsigned char *page;
+ const char *fname = argv[1];
+ char c = 0;
+
+ if (pipe(tochild) != 0 || pipe(toparent) != 0)
+ err(2, "Creating pipe");
+
+ if (!fname)
+ fname = DATA;
+
+ fd = open(fname, O_RDWR|O_CREAT|O_TRUNC, 0600);
+ if (fd < 0)
+ err(2, "opening %s", fname);
+ unlink(fname);
+
+ switch (fork()) {
+ case -1:
+ err(2, "Fork");
+ case 0:
+ close(tochild[1]);
+ close(toparent[0]);
+
+ /* Wait for parent to create file. */
+ if (read(tochild[0], &c, 1) != 1)
+ err(2, "reading from parent");
+
+ /* Alter first byte. */
+ pwrite(fd, &c, 1, 0);
+
+ if (write(toparent[1], &c, 1) != 1)
+ err(2, "writing to parent");
+ exit(0);
+
+ default:
+ close(tochild[0]);
+ close(toparent[1]);
+
+ /* Create a file and mmap it. */
+ page = malloc(getpagesize());
+ memset(page, 0x42, getpagesize());
+ if (write(fd, page, getpagesize()) != getpagesize())
+ err(2, "writing first page");
+ map = mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE,
+ MAP_SHARED, fd, 0);
+ if (map == MAP_FAILED)
+ err(2, "mapping file");
+
+ if (*map != 0x42)
+ errx(2, "first byte isn't 0x42!");
+
+ /* Tell child to alter file. */
+ if (write(tochild[1], &c, 1) != 1)
+ err(2, "writing to child");
+
+ if (read(toparent[0], &c, 1) != 1)
+ err(2, "reading from child");
+
+ if (*map)
+ errx(0, "mmap incoherent: first byte isn't 0.");
+
+ exit(1);
+ }
+}
diff --git a/lib/replace/wscript b/lib/replace/wscript
index 36c2f0f3e1..63944c3800 100644
--- a/lib/replace/wscript
+++ b/lib/replace/wscript
@@ -299,6 +299,13 @@ def configure(conf):
addmain=False,
msg="Checking for C99 vsnprintf")
+ # OpenBSD (and I've heard HPUX) doesn't sync between mmap and write.
+ # FIXME: Anything other than a 0 or 1 exit code should abort configure!
+ conf.CHECK_CODE('#include "test/incoherent_mmap.c"',
+ addmain=False, add_headers=False, execute=True,
+ define='HAVE_INCOHERENT_MMAP',
+ msg="Checking for HAVE_INCOHERENT_MMAP")
+
conf.SAMBA_BUILD_ENV()
conf.CHECK_CODE('''