From 5d0b180f798ca53cc04be4cec82c7c56b6c25d97 Mon Sep 17 00:00:00 2001 From: Mathias Kresin Date: Tue, 9 Aug 2016 08:22:24 +0200 Subject: [PATCH] tools: flock: add NFSv4 compatibility This patch fixes the LEDE build on mounted NFSv4 shares. The lock file cannot be opened in read-write mode by default, because then we cannot use flock(1) to lock executable files. The read-write mode for lock files is necessary on NFSv4 where flock(2) is emulated by by fcntl() -- this situation is possible to detect by flock(2) EBADF error. The patch consist of the following util-linux/flock commits http://git.kernel.org/cgit/utils/util-linux/util-linux.git/commit/?id=eb742a1f66d5e3a7c5b43efce741c113f51bef3b http://git.kernel.org/cgit/utils/util-linux/util-linux.git/commit/?id=caf1ba11a367ad702fb774653daf9ebdcca49d7b without including the pre kernel 3.4 support. Signed-off-by: Mathias Kresin Signed-off-by: Felix Fietkau [minor cleanup] --- tools/flock/src/flock.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/tools/flock/src/flock.c b/tools/flock/src/flock.c index 3ac3a4bebc..37ab0ea72d 100644 --- a/tools/flock/src/flock.c +++ b/tools/flock/src/flock.c @@ -133,6 +133,7 @@ int main(int argc, char *argv[]) int do_close = 0; int err; int status; + int open_flags = 0; char *eon; char **cmd_argv = NULL, *sh_c_argv[4]; const char *filename = NULL; @@ -266,6 +267,21 @@ int main(int argc, char *argv[]) if ( timeout_expired ) exit(1); /* -w option set and failed to lock */ continue; /* otherwise try again */ + case EBADF: /* since Linux 3.4 (commit 55725513) */ + /* Probably NFSv4 where flock() is emulated by fcntl(). + * Let's try to reopen in read-write mode. + */ + if (!(open_flags & O_RDWR) && + type != LOCK_SH && + filename && + access(filename, R_OK | W_OK) == 0) { + + close(fd); + open_flags = O_RDWR; + fd = open(filename, open_flags); + break; + } + /* go through */ default: /* Other errors */ if ( filename ) fprintf(stderr, "%s: %s: %s\n", program, filename, strerror(err));