1 files changed, 127 insertions, 0 deletions
diff --git a/lib/iolog/iolog_open.c b/lib/iolog/iolog_open.c
new file mode 100644
index 0000000..c2556a7
--- /dev/null
+++ b/lib/iolog/iolog_open.c
@@ -0,0 +1,127 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2009-2021 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 <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_STDBOOL_H
+# include <stdbool.h>
+#else
+# include "compat/stdbool.h"
+#endif
+#include <errno.h>
+#include <fcntl.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "sudo_compat.h"
+#include "sudo_debug.h"
+#include "sudo_iolog.h"
+#include "sudo_util.h"
+
+static unsigned char const gzip_magic[2] = {0x1f, 0x8b};
+
+/*
+ * Open the specified I/O log file and store in iol.
+ * Stores the open file handle which has the close-on-exec flag set.
+ */
+bool
+iolog_open(struct iolog_file *iol, int dfd, int iofd, const char *mode)
+{
+    int flags;
+    const char *file;
+    unsigned char magic[2];
+    const uid_t iolog_uid = iolog_get_uid();
+    const gid_t iolog_gid = iolog_get_gid();
+    debug_decl(iolog_open, SUDO_DEBUG_UTIL);
+
+    if (mode[0] == 'r') {
+	flags = mode[1] == '+' ? O_RDWR : O_RDONLY;
+    } else if (mode[0] == 'w') {
+	flags = O_CREAT|O_TRUNC;
+	flags |= mode[1] == '+' ? O_RDWR : O_WRONLY;
+    } else {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: invalid I/O mode %s", __func__, mode);
+	debug_return_bool(false);
+    }
+    if ((file = iolog_fd_to_name(iofd)) == NULL) {
+	sudo_debug_printf(SUDO_DEBUG_ERROR,
+	    "%s: invalid iofd %d", __func__, iofd);
+	debug_return_bool(false);
+    }
+
+    iol->writable = false;
+    iol->compressed = false;
+    if (iol->enabled) {
+	int fd = iolog_openat(dfd, file, flags);
+	if (fd != -1) {
+	    if (*mode == 'w') {
+		if (fchown(fd, iolog_uid, iolog_gid) != 0) {
+		    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+			"%s: unable to fchown %d:%d %s", __func__,
+			(int)iolog_uid, (int)iolog_gid, file);
+		}
+		iol->compressed = iolog_get_compress();
+	    } else {
+		/* check for gzip magic number */
+		if (pread(fd, magic, sizeof(magic), 0) == ssizeof(magic)) {
+		    if (magic[0] == gzip_magic[0] && magic[1] == gzip_magic[1])
+			iol->compressed = true;
+		}
+	    }
+	    if (fcntl(fd, F_SETFD, FD_CLOEXEC) != -1) {
+#ifdef HAVE_ZLIB_H
+		if (iol->compressed)
+		    iol->fd.g = gzdopen(fd, mode);
+		else
+#endif
+		    iol->fd.f = fdopen(fd, mode);
+	    }
+	    if (iol->fd.v != NULL) {
+		switch ((flags & O_ACCMODE)) {
+		case O_WRONLY:
+		case O_RDWR:
+		    iol->writable = true;
+		    break;
+		}
+	    } else {
+		int save_errno = errno;
+		close(fd);
+		errno = save_errno;
+		fd = -1;
+	    }
+	}
+	if (fd == -1) {
+	    iol->enabled = false;
+	    debug_return_bool(false);
+	}
+    } else {
+	if (*mode == 'w') {
+	    /* Remove old log file in case we recycled sequence numbers. */
+	    (void)unlinkat(dfd, file, 0);
+	}
+    }
+    debug_return_bool(true);
+}