From 584b996a1a27870dad30eb422d375bb08b57c64c Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 22 Mar 2012 10:47:24 +1030 Subject: 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 --- lib/replace/test/incoherent_mmap.c | 83 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 lib/replace/test/incoherent_mmap.c (limited to 'lib/replace/test') 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 +#include +#include +#include +#include +#include +#include +#include +#include + +#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); + } +} -- cgit