From ec79767e5f2c5fb5d43fae56771c67ac258f827a Mon Sep 17 00:00:00 2001
From: Mike Gelfand <mikedld@mikedld.com>
Date: Sat, 13 Jul 2019 22:53:04 +0300
Subject: [PATCH] Support OFD locks and missing flock

---
 CMakeLists.txt               |  1 +
 libtransmission/file-posix.c | 53 ++++++++++++++++++++++++++++++++++--
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a0f4048e2..2b35962b3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -453,6 +453,7 @@ set(NEEDED_FUNCTIONS
     canonicalize_file_name
     daemon
     fallocate64
+    flock
     getmntent
     getpagesize
     htonll
diff --git a/libtransmission/file-posix.c b/libtransmission/file-posix.c
index 05840e7a5..f481a24c6 100644
--- a/libtransmission/file-posix.c
+++ b/libtransmission/file-posix.c
@@ -11,7 +11,7 @@
 
 #include <dirent.h>
 #include <errno.h>
-#include <fcntl.h> /* O_LARGEFILE, posix_fadvise(), [posix_]fallocate() */
+#include <fcntl.h> /* O_LARGEFILE, posix_fadvise(), [posix_]fallocate(), fcntl() */
 #include <libgen.h> /* basename(), dirname() */
 #include <limits.h> /* PATH_MAX */
 #include <stdio.h>
@@ -985,6 +985,41 @@ bool tr_sys_file_lock(tr_sys_file_t handle, int operation, tr_error** error)
         !!(operation & TR_SYS_FILE_LOCK_UN) == 1);
 
     bool ret;
+
+#if defined(F_OFD_SETLK)
+
+    struct flock fl = {0};
+
+    switch (operation & (TR_SYS_FILE_LOCK_SH | TR_SYS_FILE_LOCK_EX | TR_SYS_FILE_LOCK_UN))
+    {
+    case TR_SYS_FILE_LOCK_SH:
+        fl.l_type = F_RDLCK;
+        break;
+
+    case TR_SYS_FILE_LOCK_EX:
+        fl.l_type = F_WRLCK;
+        break;
+
+    case TR_SYS_FILE_LOCK_UN:
+        fl.l_type = F_UNLCK;
+        break;
+    }
+
+    fl.l_whence = SEEK_SET;
+
+    do
+    {
+        ret = fcntl(handle, (operation & TR_SYS_FILE_LOCK_NB) != 0 ? F_OFD_SETLK : F_OFD_SETLKW, &fl) != -1;
+    }
+    while (!ret && errno == EINTR);
+
+    if (!ret && errno == EAGAIN)
+    {
+        errno = EWOULDBLOCK;
+    }
+
+#elif defined(HAVE_FLOCK)
+
     int native_operation = 0;
 
     if ((operation & TR_SYS_FILE_LOCK_SH) != 0)
@@ -1007,7 +1042,21 @@ bool tr_sys_file_lock(tr_sys_file_t handle, int operation, tr_error** error)
         native_operation |= LOCK_UN;
     }
 
-    ret = flock(handle, native_operation) != -1;
+    do
+    {
+        ret = flock(handle, native_operation) != -1;
+    }
+    while (!ret && errno == EINTR);
+
+#else
+
+    (void)handle;
+    (void)operation;
+
+    errno = ENOSYS;
+    ret = false;
+
+#endif
 
     if (!ret)
     {