amigaos4: implement flock() emulation

Beware: not an exact implementation, the locks follow the OS level
filehandle not the process.

3 files changed, 100 insertions, 0 deletions

diff --git a/README.amiga b/README.amiga
index 0e6358d225..934b037a49 100644
--- a/README.amiga
+++ b/README.amiga
@@ -178,6 +178,9 @@ This will build the default setup that installs under SDK:local/newlib/lib/
 
 =item Fix issue with newlib's unlink, which could cause infinite loops.
 
+=item Add flock() emulation using IDOS->LockRecord thanks to Tony Cook
+for the suggestion.
+
 =back
 
 =item B<27th November 2013>
diff --git a/amigaos4/amigaos.c b/amigaos4/amigaos.c
index 8e26064f08..f79943079f 100644
--- a/amigaos4/amigaos.c
+++ b/amigaos4/amigaos.c
@@ -1078,3 +1078,89 @@ BPTR amigaos_get_file(int fd)
         }
         return fh;
 }
+
+/*########################################################################*/
+
+#define LOCK_START 0xFFFFFFFFFFFFFFFELL
+#define LOCK_LENGTH 1LL
+
+// No wait forever option so lets wait for a loooong time.
+#define TIMEOUT 0x7FFFFFFF
+
+int amigaos_flock(int fd, int oper)
+{
+        BPTR fh;
+        int32 success = -1;
+
+        if (!(fh = amigaos_get_file(fd)))
+        {
+                errno = EBADF;
+                return -1;
+        }
+
+        switch (oper)
+        {
+        case LOCK_SH:
+        {
+                if (IDOS->LockRecord(fh, LOCK_START, LOCK_LENGTH,
+                                     REC_SHARED | RECF_DOS_METHOD_ONLY,
+                                     TIMEOUT))
+                {
+                        success = 0;
+                }
+                break;
+        }
+        case LOCK_EX:
+        {
+                if (IDOS->LockRecord(fh, LOCK_START, LOCK_LENGTH,
+                                     REC_EXCLUSIVE | RECF_DOS_METHOD_ONLY,
+                                     TIMEOUT))
+                {
+                        success = 0;
+                }
+                break;
+        }
+        case LOCK_SH | LOCK_NB:
+        {
+                if (IDOS->LockRecord(fh, LOCK_START, LOCK_LENGTH,
+                                     REC_SHARED_IMMED | RECF_DOS_METHOD_ONLY,
+                                     TIMEOUT))
+                {
+                        success = 0;
+                }
+                else
+                {
+                        errno = EWOULDBLOCK;
+                }
+                break;
+        }
+        case LOCK_EX | LOCK_NB:
+        {
+                if (IDOS->LockRecord(fh, LOCK_START, LOCK_LENGTH,
+                                     REC_EXCLUSIVE_IMMED | RECF_DOS_METHOD_ONLY,
+                                     TIMEOUT))
+                {
+                        success = 0;
+                }
+                else
+                {
+                        errno = EWOULDBLOCK;
+                }
+                break;
+        }
+        case LOCK_UN:
+        {
+                if (IDOS->UnLockRecord(fh, LOCK_START, LOCK_LENGTH))
+                {
+                        success = 0;
+                }
+                break;
+        }
+        default:
+        {
+                errno = EINVAL;
+                return -1;
+        }
+        }
+        return success;
+}
diff --git a/amigaos4/amigaos.h b/amigaos4/amigaos.h
index 96f521d59b..2f6d4b2d49 100644
--- a/amigaos4/amigaos.h
+++ b/amigaos4/amigaos.h
@@ -52,4 +52,15 @@ long amigaos_get_file(int fd);
 
 // BOOL constructed;
 
+/* emulated flock stuff */
+
+#define LOCK_SH 1 /* Shared lock.  */
+#define LOCK_EX 2 /* Exclusive lock.  */
+#define LOCK_UN 8 /* Unlock.  */
+#define LOCK_NB 4 /* Don't block when locking.  */
+
+extern int flock(int fd, int operation);
+
+#define flock(a, b) amigaos_flock((a), (b))
+
 #endif