Two followups.
First, though not the problem I'm seeing, as I understand
it, mkstemp isn't guaranteed to work on NFS v2 mounted
drives. Thus I suggest including the hostname; there's
already tmp_string() which is perfect. Patch below.
Second, I'm still not sure of the cause, but if I count
bytes copied, and fail if zero bytes are moved this works
around the issue. Patch below, but this not be the right
solution. I thought of calling stat() after the copy, and
fail if the size doesn't match what stat says, alas
compression makes that difficult.
One thing I wonder is the unlink() before the rename. I
presume that is needed to prevent permission issues, but I
wonder if it contributes to the race involving
host1:unlink(), host1:rename(), host2:unlink(),
host2:rename(), host3:open().
-Wilson
diff --git a/util.c b/util.c
index ae48cf0..df522f1 100644
--- a/util.c
+++ b/util.c
@@ -128,7 +128,7 @@ int copy_file(const char *src, const char *dest, int
compress_dest)
mode_t mask;
struct stat st;
- x_asprintf(&tmp_name, "%s.XXXXXX", dest);
+ x_asprintf(&tmp_name, "%s.%s.XXXXXX", dest, tmp_string());
/* open source file */
fd_in = open(src, O_RDONLY);
diff --git a/util.c b/util.c
index ae48cf0..df522f1 100644
--- a/util.c
+++ b/util.c
@@ -177,7 +177,9 @@ int copy_file(const char *src, const char *dest, int
compress_dest)
}
}
+ int bytecnt = 0;
while ((n = gzread(gz_in, buf, sizeof(buf))) > 0) {
+ bytecnt += n;
if (compress_dest) {
ret = gzwrite(gz_out, buf, n);
} else {
@@ -212,14 +214,25 @@ int copy_file(const char *src, const char *dest, int
compress_dest)
return -1;
}
+ /* Empty objects are bad - created by race in NFS between 2 writers and
1+ readers */
+ if (bytecnt == 0) {
+ unlink(tmp_name);
+ free(tmp_name);
+ cc_log("Refusing to copy zero sized file %s", src);
+ return -1;
+ }
+
unlink(dest);
if (rename(tmp_name, dest) == -1) {
unlink(tmp_name);
free(tmp_name);
+ cc_log("Rename failed");
return -1;
}
+ cc_log("Copied %d bytes from %s via %s to %s", bytecnt, src, tmp_name,
dest);
+
free(tmp_name);
return 0;
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