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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 17:04:52 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 17:04:52 +0000
commit5e03c718f4e7ff13cb6834eda737c269ebed02ad (patch)
treebfad3f5be123f000fdb03e26400050dece33d72f /lib/flock.c
parentInitial commit. (diff)
downloadwget-5e03c718f4e7ff13cb6834eda737c269ebed02ad.tar.xz
wget-5e03c718f4e7ff13cb6834eda737c269ebed02ad.zip
Adding upstream version 1.21.3.upstream/1.21.3upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/flock.c')
-rw-r--r--lib/flock.c224
1 files changed, 224 insertions, 0 deletions
diff --git a/lib/flock.c b/lib/flock.c
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+/* Emulate flock on platforms that lack it, primarily Windows and MinGW.
+
+ This is derived from sqlite3 sources.
+ https://www.sqlite.org/src/finfo?name=src/os_win.c
+ https://www.sqlite.org/copyright.html
+
+ Written by Richard W.M. Jones <rjones.at.redhat.com>
+
+ Copyright (C) 2008-2022 Free Software Foundation, Inc.
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include <sys/file.h>
+
+#if defined _WIN32 && ! defined __CYGWIN__
+
+/* LockFileEx */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+
+# include <errno.h>
+
+/* _get_osfhandle */
+# if GNULIB_MSVC_NOTHROW
+# include "msvc-nothrow.h"
+# else
+# include <io.h>
+# endif
+
+/* Determine the current size of a file. Because the other braindead
+ * APIs we'll call need lower/upper 32 bit pairs, keep the file size
+ * like that too.
+ */
+static BOOL
+file_size (HANDLE h, DWORD * lower, DWORD * upper)
+{
+ *lower = GetFileSize (h, upper);
+ return 1;
+}
+
+/* LOCKFILE_FAIL_IMMEDIATELY is undefined on some Windows systems. */
+# ifndef LOCKFILE_FAIL_IMMEDIATELY
+# define LOCKFILE_FAIL_IMMEDIATELY 1
+# endif
+
+/* Acquire a lock. */
+static BOOL
+do_lock (HANDLE h, int non_blocking, int exclusive)
+{
+ BOOL res;
+ DWORD size_lower, size_upper;
+ OVERLAPPED ovlp;
+ int flags = 0;
+
+ /* We're going to lock the whole file, so get the file size. */
+ res = file_size (h, &size_lower, &size_upper);
+ if (!res)
+ return 0;
+
+ /* Start offset is 0, and also zero the remaining members of this struct. */
+ memset (&ovlp, 0, sizeof ovlp);
+
+ if (non_blocking)
+ flags |= LOCKFILE_FAIL_IMMEDIATELY;
+ if (exclusive)
+ flags |= LOCKFILE_EXCLUSIVE_LOCK;
+
+ return LockFileEx (h, flags, 0, size_lower, size_upper, &ovlp);
+}
+
+/* Unlock reader or exclusive lock. */
+static BOOL
+do_unlock (HANDLE h)
+{
+ int res;
+ DWORD size_lower, size_upper;
+
+ res = file_size (h, &size_lower, &size_upper);
+ if (!res)
+ return 0;
+
+ return UnlockFile (h, 0, 0, size_lower, size_upper);
+}
+
+/* Now our BSD-like flock operation. */
+int
+flock (int fd, int operation)
+{
+ HANDLE h = (HANDLE) _get_osfhandle (fd);
+ DWORD res;
+ int non_blocking;
+
+ if (h == INVALID_HANDLE_VALUE)
+ {
+ errno = EBADF;
+ return -1;
+ }
+
+ non_blocking = operation & LOCK_NB;
+ operation &= ~LOCK_NB;
+
+ switch (operation)
+ {
+ case LOCK_SH:
+ res = do_lock (h, non_blocking, 0);
+ break;
+ case LOCK_EX:
+ res = do_lock (h, non_blocking, 1);
+ break;
+ case LOCK_UN:
+ res = do_unlock (h);
+ break;
+ default:
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* Map Windows errors into Unix errnos. As usual MSDN fails to
+ * document the permissible error codes.
+ */
+ if (!res)
+ {
+ DWORD err = GetLastError ();
+ switch (err)
+ {
+ /* This means someone else is holding a lock. */
+ case ERROR_LOCK_VIOLATION:
+ errno = EAGAIN;
+ break;
+
+ /* Out of memory. */
+ case ERROR_NOT_ENOUGH_MEMORY:
+ errno = ENOMEM;
+ break;
+
+ case ERROR_BAD_COMMAND:
+ errno = EINVAL;
+ break;
+
+ /* Unlikely to be other errors, but at least don't lose the
+ * error code.
+ */
+ default:
+ errno = err;
+ }
+
+ return -1;
+ }
+
+ return 0;
+}
+
+#else /* !Windows */
+
+# ifdef HAVE_STRUCT_FLOCK_L_TYPE
+/* We know how to implement flock in terms of fcntl. */
+
+# include <fcntl.h>
+
+# ifdef HAVE_UNISTD_H
+# include <unistd.h>
+# endif
+
+# include <errno.h>
+# include <string.h>
+
+int
+flock (int fd, int operation)
+{
+ int cmd, r;
+ struct flock fl;
+
+ if (operation & LOCK_NB)
+ cmd = F_SETLK;
+ else
+ cmd = F_SETLKW;
+ operation &= ~LOCK_NB;
+
+ memset (&fl, 0, sizeof fl);
+ fl.l_whence = SEEK_SET;
+ /* l_start & l_len are 0, which as a special case means "whole file". */
+
+ switch (operation)
+ {
+ case LOCK_SH:
+ fl.l_type = F_RDLCK;
+ break;
+ case LOCK_EX:
+ fl.l_type = F_WRLCK;
+ break;
+ case LOCK_UN:
+ fl.l_type = F_UNLCK;
+ break;
+ default:
+ errno = EINVAL;
+ return -1;
+ }
+
+ r = fcntl (fd, cmd, &fl);
+ if (r == -1 && errno == EACCES)
+ errno = EAGAIN;
+
+ return r;
+}
+
+# else /* !HAVE_STRUCT_FLOCK_L_TYPE */
+
+# error "This platform lacks flock function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib."
+
+# endif /* !HAVE_STRUCT_FLOCK_L_TYPE */
+
+#endif /* !Windows */