1 files changed, 94 insertions, 0 deletions
diff --git a/lib/tar/number.c b/lib/tar/number.c
new file mode 100644
index 0000000..e85866d
--- /dev/null
+++ b/lib/tar/number.c
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "internal.h"
+
+int read_octal(const char *str, int digits, uint64_t *out)
+{
+	uint64_t result = 0;
+
+	while (digits > 0 && isspace(*str)) {
+		++str;
+		--digits;
+	}
+
+	while (digits > 0 && *str >= '0' && *str <= '7') {
+		if (result > 0x1FFFFFFFFFFFFFFFUL) {
+			fputs("numeric overflow parsing tar header\n", stderr);
+			return -1;
+		}
+
+		result = (result << 3) | (*(str++) - '0');
+		--digits;
+	}
+
+	*out = result;
+	return 0;
+}
+
+int read_binary(const char *str, int digits, uint64_t *out)
+{
+	uint64_t x, ov, result = 0;
+	bool first = true;
+
+	while (digits > 0) {
+		x = *((const unsigned char *)str++);
+		--digits;
+
+		if (first) {
+			first = false;
+			if (x == 0xFF) {
+				result = 0xFFFFFFFFFFFFFFFFUL;
+			} else {
+				x &= 0x7F;
+				result = 0;
+				if (digits > 7 && x != 0)
+					goto fail_ov;
+			}
+		}
+
+		ov = (result >> 56) & 0xFF;
+
+		if (ov != 0 && ov != 0xFF)
+			goto fail_ov;
+
+		result = (result << 8) | x;
+	}
+
+	*out = result;
+	return 0;
+fail_ov:
+	fputs("numeric overflow parsing tar header\n", stderr);
+	return -1;
+}
+
+int read_number(const char *str, int digits, uint64_t *out)
+{
+	if (*((unsigned char *)str) & 0x80)
+		return read_binary(str, digits, out);
+
+	return read_octal(str, digits, out);
+}
+
+int pax_read_decimal(const char *str, uint64_t *out)
+{
+	uint64_t result = 0;
+
+	while (*str >= '0' && *str <= '9') {
+		if (result > 0xFFFFFFFFFFFFFFFFUL / 10) {
+			fputs("numeric overflow parsing pax header\n", stderr);
+			return -1;
+		}
+
+		result = (result * 10) + (*(str++) - '0');
+	}
+
+	*out = result;
+	return 0;
+}
+
+void write_octal(char *dst, unsigned int value, int digits)
+{
+	char temp[64];
+
+	sprintf(temp, "%0*o ", digits, value);
+	memcpy(dst, temp, strlen(temp));
+}