Merge pull request #10 from vanbako/c_strmem

Added c string functions

xzre.h

@@ -3905,6 +3905,42 @@ extern BOOL sshd_find_sensitive_data(
 	imported_funcs_t *funcs,
 	global_context_t *ctx);
 
+
+/**
+ * @brief returns length of c string
+ * 
+ * @param str pointer to c string
+ * @return ssize_t length of c string
+ */
+extern ssize_t c_strlen(
+	char *str
+);
+
+/**
+ * @brief returns length of c string with a maximum length
+ * 
+ * @param str pointer to c string
+ * @param max_len maximum length of c string
+ * @return ssize_t length of c string
+ */
+extern ssize_t c_strnlen(
+	char *str,
+	size_t max_len
+);
+
+/**
+ * @brief copies memory
+ * 
+ * @param dest destination buffer
+ * @param src source buffer
+ * @param cnt number of bytes to copy
+ */
+extern void c_memmove(
+	char *dest,
+	char *src,
+	size_t cnt
+);
+
 /**
  * @brief counts the number of times the IFUNC resolver is called
  * 

xzre.lds.in

@@ -43,7 +43,7 @@ SECTIONS_BEGIN()
 	/* 0000000000001870 */ DEFSYM(elf_symbol_get, .text.crc_inia)
 	DEFSYM_START(.text.crc64_generia)
 		/* 0000000000001AF0 */ DEFSYM2(elf_symbol_get_addr, 0)
-		/* 0000000000001B20 */ DEFSYM2(c_memmove, 0x1B20 - 0x1AF0) // FIXME: prototype
+		/* 0000000000001B20 */ DEFSYM2(c_memmove, 0x1B20 - 0x1AF0)
 	DEFSYM_END(.text.crc64_generia)
 	/* 0000000000001B70 */ DEFSYM(fake_lzma_alloc, .text.init_pric_tabla)
 	/* 0000000000001B80 */ DEFSYM(elf_find_rela_reloc, .text.stream_encoder_updata) // FIXME: prototype
@@ -106,8 +106,8 @@ SECTIONS_BEGIN()
 	/* 0000000000005820 */ DEFSYM(backdoor_setup, .text.microlzma_encoder_inia)
 	/* 0000000000006F20 */ DEFSYM(backdoor_init_stage2, .text.lzma_validate_chaia)
 	DEFSYM_START(.text.parse_optiona)
-		/* 0000000000007020 */ DEFSYM2(c_strlen, 0) // FIXME: prototype
-		/* 0000000000007040 */ DEFSYM2(c_strnlen, 0x7040 - 0x7020) // FIXME: prototype
+		/* 0000000000007020 */ DEFSYM2(c_strlen, 0)
+		/* 0000000000007040 */ DEFSYM2(c_strnlen, 0x7040 - 0x7020)
 	DEFSYM_END(.text.parse_optiona)
 	/* 0000000000007070 */ DEFSYM(fd_read, .text.auto_decoder_inia)
 	DEFSYM_START(.text.bt_find_funa)

xzre_code/CMakeLists.txt

@@ -1,5 +1,8 @@
 add_library(xzre_code
 	backdoor_entry.c
+  c_memmove.c
+	c_strlen.c
+	c_strnlen.c
 	chacha_decrypt.c
 	count_bits.c
 	count_pointers.c

xzre_code/c_memmove.c

@@ -0,0 +1,26 @@
+/**
+ * Copyright (C) 2024 Koen Van Bastelaere <[email protected]>
+ **/
+#include "xzre.h"
+
+void c_memmove(char *dest, char *src, size_t cnt) {
+    if ((src < dest) && (dest < (src + cnt))) {
+        size_t curr = cnt - 1;
+        if (cnt != 0) {
+            do {
+                *(dest + curr) = *(src + curr);
+                --curr;
+            } while (curr != -1);
+            return;
+        }
+    } else {
+        if (cnt == 0)
+            return;
+        size_t curr = 0;
+        do {
+            *(dest + curr) = *(src + curr);
+            ++curr;
+        } while (cnt != curr);
+    }
+    return;
+}

xzre_code/c_strlen.c

@@ -0,0 +1,15 @@
+/**
+ * Copyright (C) 2024 Koen Van Bastelaere <[email protected]>
+ **/
+#include "xzre.h"
+
+ssize_t c_strlen(char *str) {
+    if (*str != '\0') {
+        ssize_t len = 0;
+        do {
+            ++len;
+        } while (*(str + len) != '\0');
+        return len;
+    }
+    return 0;
+}

xzre_code/c_strnlen.c

@@ -0,0 +1,16 @@
+/**
+ * Copyright (C) 2024 Koen Van Bastelaere <[email protected]>
+ **/
+#include "xzre.h"
+
+ssize_t c_strnlen(char *str, size_t max_len) {
+    ssize_t len = 0;
+    if (max_len == 0)
+        return max_len;
+    do {
+        if (*(str + len) == '\0')
+            return len;
+        ++len;
+    } while (max_len != len);
+    return max_len;
+}