1 files changed, 48 insertions, 0 deletions
diff --git a/lib/util/pread.c b/lib/util/pread.c
new file mode 100644
index 0000000..a8a4774
--- /dev/null
+++ b/lib/util/pread.c
@@ -0,0 +1,48 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <errno.h>
+#include <unistd.h>
+
+#include <sudo_compat.h>
+
+#if !defined(HAVE_PREAD) && !defined(HAVE_PREAD64)
+ssize_t
+sudo_pread(int fd, void *buf, size_t nbytes, off_t offset)
+{
+    ssize_t nread;
+    off_t old_offset;
+
+    old_offset = lseek(fd, (off_t)0, SEEK_CUR);
+    if (old_offset == -1 || lseek(fd, offset, SEEK_SET) == -1)
+	return -1;
+
+    nread = read(fd, buf, nbytes);
+    if (lseek(fd, old_offset, SEEK_SET) == -1)
+	return -1;
+
+    return nread;
+}
+#endif /* !HAVE_PREAD && !HAVE_PREAD64 */