Re: [PATCH] Suggestion: new module link

[Bruno Haible]

Hello Eric, Martin,

> > Or print a message and return 77, to skip the test, if the current fs
> > doesn't support links at this point (such as FAT).
> 
> I'd like to do that, but it it not easy to detect this condition. POSIX
> does not specify an error code for it, Linux uses EPERM (which can also
> occur under different circumstances), FreeBSD uses EOPNOTSUPP

Thanks for these detail infos. I implemented Eric's suggestion as follows:

2009-01-19  Bruno Haible  <address@hidden>

        * tests/test-link.c: Include <errno.h>.
        (main): Exit with code 77 when a hard link cannot be created due to
        the file system.
        * tests/test-link.sh: Skip test when a hard link cannot be created due
        to the file system.
        Suggested by Eric Blake.

--- tests/test-link.c.orig      2009-01-20 01:17:22.000000000 +0100
+++ tests/test-link.c   2009-01-20 01:13:52.000000000 +0100
@@ -18,6 +18,7 @@
 
 #include <unistd.h>
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -36,8 +37,20 @@
 int
 main (int argc, char **argv)
 {
+  int ret;
+
   ASSERT (argc == 3);
-  ASSERT (link (argv[1], argv[2]) == 0);
+
+  ret = link (argv[1], argv[2]);
+  if (ret < 0)
+    {
+      /* If the device does not support hard links, errno is
+        EPERM on Linux, EOPNOTSUPP on FreeBSD.  */
+      if (errno == EPERM || errno == EOPNOTSUPP)
+       return 77;
+      perror ("link");
+      return 1;
+    }
 
   return 0;
 }
--- tests/test-link.sh.orig     2009-01-20 01:17:22.000000000 +0100
+++ tests/test-link.sh  2009-01-20 01:17:09.000000000 +0100
@@ -7,7 +7,16 @@
 echo "hello" > test-link-a.txt || exit 1
 
 # Use link() to create a new name for it.
-./test-link${EXEEXT} test-link-a.txt test-link-b.txt || exit 1
+./test-link${EXEEXT} test-link-a.txt test-link-b.txt
+case $? in
+  0) ;;
+  77)
+    echo "Skipping test: hard links are not supported on this file system"
+    rm -fr $tmpfiles
+    exit 77
+    ;;
+  *) exit 1 ;;
+esac
 cmp test-link-a.txt test-link-b.txt || exit 1
 
 # Modify the contents of the first file.