5 files changed, 127 insertions, 1 deletions
diff --git a/include/util.h b/include/util.h
new file mode 100644
index 0000000..16f3162
--- /dev/null
+++ b/include/util.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#ifndef UTIL_H
+#define UTIL_H
+
+#include <sys/types.h>
+
+int canonicalize_name(char *filename);
+
+ssize_t write_retry(int fd, void *data, size_t size);
+
+ssize_t read_retry(int fd, void *buffer, size_t size);
+
+#endif /* UTIL_H */
diff --git a/lib/Makemodule.am b/lib/Makemodule.am
index 89ec538..67804d8 100644
--- a/lib/Makemodule.am
+++ b/lib/Makemodule.am
@@ -6,6 +6,9 @@ libcompress_a_SOURCES = lib/comp/compressor.c lib/comp/internal.h
 libcompress_a_CFLAGS = $(AM_CFLAGS)
 libcompress_a_CPPFLAGS = $(AM_CPPFLAGS)
 
+libutil_a_SOURCES = lib/util/canonicalize_name.c lib/util/write_retry.c
+libutil_a_SOURCES += lib/util/read_retry.c include/util.h
+
 if WITH_ZLIB
 libcompress_a_SOURCES += lib/comp/zlib.c
 
@@ -20,4 +23,4 @@ libcompress_a_CFLAGS += $(XZ_CFLAGS)
 libcompress_a_CPPFLAGS += -DWITH_LZMA
 endif
 
-noinst_LIBRARIES += libfstree.a libcompress.a
+noinst_LIBRARIES += libfstree.a libcompress.a libutil.a
diff --git a/lib/util/canonicalize_name.c b/lib/util/canonicalize_name.c
new file mode 100644
index 0000000..6703b66
--- /dev/null
+++ b/lib/util/canonicalize_name.c
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <string.h>
+
+#include "util.h"
+
+int canonicalize_name(char *filename)
+{
+	char *ptr = filename;
+	int i;
+
+	while (*ptr == '/')
+		++ptr;
+
+	if (ptr != filename) {
+		memmove(filename, ptr, strlen(ptr) + 1);
+		ptr = filename;
+	}
+
+	while (*ptr != '\0') {
+		if (*ptr == '/') {
+			for (i = 0; ptr[i] == '/'; ++i)
+				;
+
+			if (i > 1)
+				memmove(ptr + 1, ptr + i, strlen(ptr + i) + 1);
+		}
+
+		if (ptr[0] == '/' && ptr[1] == '\0') {
+			*ptr = '\0';
+			break;
+		}
+
+		++ptr;
+	}
+
+	ptr = filename;
+
+	while (*ptr != '\0') {
+		if (ptr[0] == '.') {
+			if (ptr[1] == '/' || ptr[1] == '\0')
+				return -1;
+
+			if (ptr[1] == '.' &&
+			    (ptr[2] == '/' || ptr[2] == '\0')) {
+				return -1;
+			}
+		}
+
+		while (*ptr != '\0' && *ptr != '/')
+			++ptr;
+		if (*ptr == '/')
+			++ptr;
+	}
+
+	return 0;
+}
diff --git a/lib/util/read_retry.c b/lib/util/read_retry.c
new file mode 100644
index 0000000..eb113c4
--- /dev/null
+++ b/lib/util/read_retry.c
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <unistd.h>
+#include <errno.h>
+
+#include "util.h"
+
+ssize_t read_retry(int fd, void *buffer, size_t size)
+{
+	ssize_t ret, total = 0;
+
+	while (size > 0) {
+		ret = read(fd, buffer, size);
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			return -1;
+		}
+		if (ret == 0)
+			break;
+
+		total += ret;
+		size -= ret;
+		buffer = (char *)buffer + ret;
+	}
+
+	return total;
+}
diff --git a/lib/util/write_retry.c b/lib/util/write_retry.c
new file mode 100644
index 0000000..637b5d2
--- /dev/null
+++ b/lib/util/write_retry.c
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <unistd.h>
+#include <errno.h>
+
+#include "util.h"
+
+ssize_t write_retry(int fd, void *data, size_t size)
+{
+	ssize_t ret, total = 0;
+
+	while (size > 0) {
+		ret = write(fd, data, size);
+		if (ret == 0)
+			break;
+		if (ret < 0) {
+			if (errno == EINTR)
+				continue;
+			return -1;
+		}
+
+		data = (char *)data + ret;
+		size -= ret;
+		total += ret;
+	}
+
+	return total;
+}