1 files changed, 125 insertions, 0 deletions
diff --git a/src/lib/file-copy.c b/src/lib/file-copy.c
new file mode 100644
index 0000000..c9b8e3e
--- /dev/null
+++ b/src/lib/file-copy.c
@@ -0,0 +1,125 @@
+/* Copyright (c) 2006-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "istream.h"
+#include "ostream.h"
+#include "file-copy.h"
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+static int file_copy_to_tmp(const char *srcpath, const char *tmppath,
+			    bool try_hardlink)
+{
+	struct istream *input;
+	struct ostream *output;
+	struct stat st;
+	mode_t old_umask;
+	int fd_in, fd_out;
+	int ret = -1;
+
+	if (try_hardlink) {
+		/* see if hardlinking works */
+		if (link(srcpath, tmppath) == 0)
+			return 1;
+		if (errno == EEXIST) {
+			if (i_unlink_if_exists(tmppath) < 0)
+				return -1;
+			if (link(srcpath, tmppath) == 0)
+				return 1;
+		}
+		if (errno == ENOENT)
+			return 0;
+		if (!ECANTLINK(errno)) {
+			i_error("link(%s, %s) failed: %m", srcpath, tmppath);
+			return -1;
+		}
+
+		/* fallback to manual copying */
+	}
+
+	fd_in = open(srcpath, O_RDONLY);
+	if (fd_in == -1) {
+		if (errno == ENOENT)
+			return 0;
+		i_error("open(%s) failed: %m", srcpath);
+		return -1;
+	}
+
+	if (fstat(fd_in, &st) < 0) {
+		i_error("fstat(%s) failed: %m", srcpath);
+		i_close_fd(&fd_in);
+		return -1;
+	}
+
+	old_umask = umask(0);
+	fd_out = open(tmppath, O_WRONLY | O_CREAT | O_TRUNC, st.st_mode);
+	umask(old_umask);
+	if (fd_out == -1) {
+		i_error("open(%s, O_CREAT) failed: %m", tmppath);
+		i_close_fd(&fd_in);
+		return -1;
+	}
+
+	/* try to change the group, don't really care if it fails */
+	if (fchown(fd_out, (uid_t)-1, st.st_gid) < 0 && errno != EPERM)
+		i_error("fchown(%s) failed: %m", tmppath);
+
+	input = i_stream_create_fd(fd_in, IO_BLOCK_SIZE);
+	output = o_stream_create_fd_file(fd_out, 0, FALSE);
+
+	switch (o_stream_send_istream(output, input)) {
+	case OSTREAM_SEND_ISTREAM_RESULT_FINISHED:
+		ret = 0;
+		break;
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_INPUT:
+	case OSTREAM_SEND_ISTREAM_RESULT_WAIT_OUTPUT:
+		i_unreached();
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_INPUT:
+		i_error("read(%s) failed: %s", srcpath,
+			i_stream_get_error(input));
+		break;
+	case OSTREAM_SEND_ISTREAM_RESULT_ERROR_OUTPUT:
+		i_error("write(%s) failed: %s", tmppath,
+			o_stream_get_error(output));
+		break;
+	}
+
+	i_stream_destroy(&input);
+	o_stream_destroy(&output);
+
+	if (close(fd_in) < 0) {
+		i_error("close(%s) failed: %m", srcpath);
+		ret = -1;
+	}
+	if (close(fd_out) < 0) {
+		i_error("close(%s) failed: %m", tmppath);
+		ret = -1;
+	}
+	return ret < 0 ? -1 : 1;
+}
+
+int file_copy(const char *srcpath, const char *destpath, bool try_hardlink)
+{
+	int ret;
+
+	T_BEGIN {
+		const char *tmppath;
+
+		tmppath = t_strconcat(destpath, ".tmp", NULL);
+
+		ret = file_copy_to_tmp(srcpath, tmppath, try_hardlink);
+		if (ret > 0) {
+			if (rename(tmppath, destpath) < 0) {
+				i_error("rename(%s, %s) failed: %m",
+					tmppath, destpath);
+				ret = -1;
+			}
+		}
+		if (ret < 0)
+			i_unlink(tmppath);
+	} T_END;
+	return ret;
+}