feat(stdlib): strncpy consistency and add strlcpy (#6204)

12 files changed, 78 insertions, 30 deletions

diff --git a/src/libs/fsdrv/lv_fs_fatfs.c b/src/libs/fsdrv/lv_fs_fatfs.c
index 071f5e2c0..c0fec20ca 100644
--- a/src/libs/fsdrv/lv_fs_fatfs.c
+++ b/src/libs/fsdrv/lv_fs_fatfs.c
@@ -252,6 +252,8 @@ static void * fs_dir_open(lv_fs_drv_t * drv, const char * path)
 static lv_fs_res_t fs_dir_read(lv_fs_drv_t * drv, void * dir_p, char * fn, uint32_t fn_len)
 {
     LV_UNUSED(drv);
+    if(fn_len == 0) return LV_FS_RES_INV_PARAM;
+
     FRESULT res;
     FILINFO fno;
     fn[0] = '\0';
@@ -265,7 +267,7 @@ static lv_fs_res_t fs_dir_read(lv_fs_drv_t * drv, void * dir_p, char * fn, uint3
         if(fno.fattrib & AM_DIR) {
             lv_snprintf(fn, fn_len, "/%s", fno.fname);
         }
-        else lv_strncpy(fn, fno.fname, fn_len);
+        else lv_strlcpy(fn, fno.fname, fn_len);
 
     } while(lv_strcmp(fn, "/.") == 0 || lv_strcmp(fn, "/..") == 0);
 
diff --git a/src/libs/fsdrv/lv_fs_posix.c b/src/libs/fsdrv/lv_fs_posix.c
index d9ba1170c..f583b9a08 100644
--- a/src/libs/fsdrv/lv_fs_posix.c
+++ b/src/libs/fsdrv/lv_fs_posix.c
@@ -287,16 +287,17 @@ static void * fs_dir_open(lv_fs_drv_t * drv, const char * path)
 static lv_fs_res_t fs_dir_read(lv_fs_drv_t * drv, void * dir_p, char * fn, uint32_t fn_len)
 {
     LV_UNUSED(drv);
+    if(fn_len == 0) return LV_FS_RES_INV_PARAM;
 
     struct dirent * entry;
     do {
         entry = readdir(dir_p);
         if(entry) {
             if(entry->d_type == DT_DIR) lv_snprintf(fn, fn_len, "/%s", entry->d_name);
-            else lv_strncpy(fn, entry->d_name, fn_len);
+            else lv_strlcpy(fn, entry->d_name, fn_len);
         }
         else {
-            lv_strncpy(fn, "", fn_len);
+            lv_strlcpy(fn, "", fn_len);
         }
     } while(lv_strcmp(fn, "/.") == 0 || lv_strcmp(fn, "/..") == 0);
 
diff --git a/src/libs/fsdrv/lv_fs_stdio.c b/src/libs/fsdrv/lv_fs_stdio.c
index 4925308c4..1c3849aeb 100644
--- a/src/libs/fsdrv/lv_fs_stdio.c
+++ b/src/libs/fsdrv/lv_fs_stdio.c
@@ -276,6 +276,8 @@ static void * fs_dir_open(lv_fs_drv_t * drv, const char * path)
 static lv_fs_res_t fs_dir_read(lv_fs_drv_t * drv, void * dir_p, char * fn, uint32_t fn_len)
 {
     LV_UNUSED(drv);
+    if(fn_len == 0) return LV_FS_RES_INV_PARAM;
+
     dir_handle_t * handle = (dir_handle_t *)dir_p;
 #ifndef WIN32
     struct dirent * entry;
@@ -284,16 +286,16 @@ static lv_fs_res_t fs_dir_read(lv_fs_drv_t * drv, void * dir_p, char * fn, uint3
         if(entry) {
             /*Note, DT_DIR is not defined in C99*/
             if(entry->d_type == DT_DIR) lv_snprintf(fn, fn_len, "/%s", entry->d_name);
-            else lv_strncpy(fn, entry->d_name, fn_len);
+            else lv_strlcpy(fn, entry->d_name, fn_len);
         }
         else {
-            lv_strncpy(fn, "", fn_len);
+            lv_strlcpy(fn, "", fn_len);
         }
     } while(lv_strcmp(fn, "/.") == 0 || lv_strcmp(fn, "/..") == 0);
 #else
-    lv_strncpy(fn, handle->next_fn, fn_len);
+    lv_strlcpy(fn, handle->next_fn, fn_len);
 
-    lv_strncpy(handle->next_fn, "", fn_len);
+    lv_strcpy(handle->next_fn, "");
     WIN32_FIND_DATAA fdata;
 
     if(FindNextFileA(handle->dir_p, &fdata) == false) return LV_FS_RES_OK;
diff --git a/src/libs/fsdrv/lv_fs_win32.c b/src/libs/fsdrv/lv_fs_win32.c
index 26d50614b..fd90f279f 100644
--- a/src/libs/fsdrv/lv_fs_win32.c
+++ b/src/libs/fsdrv/lv_fs_win32.c
@@ -413,9 +413,10 @@ static void * fs_dir_open(lv_fs_drv_t * drv, const char * path)
 static lv_fs_res_t fs_dir_read(lv_fs_drv_t * drv, void * dir_p, char * fn, uint32_t fn_len)
 {
     LV_UNUSED(drv);
-    LV_UNUSED(fn_len);
+    if(fn_len == 0) return LV_FS_RES_INV_PARAM;
+
     dir_handle_t * handle = (dir_handle_t *)dir_p;
-    lv_strcpy(fn, handle->next_fn);
+    lv_strlcpy(fn, handle->next_fn, fn_len);
     lv_fs_res_t current_error = handle->next_error;
     lv_strcpy(handle->next_fn, "");
 
diff --git a/src/others/file_explorer/lv_file_explorer.c b/src/others/file_explorer/lv_file_explorer.c
index 40a7a383c..ac68078be 100644
--- a/src/others/file_explorer/lv_file_explorer.c
+++ b/src/others/file_explorer/lv_file_explorer.c
@@ -598,8 +598,7 @@ static void show_dir(lv_obj_t * obj, const char * path)
     /*Move the table to the top*/
     lv_obj_scroll_to_y(explorer->file_table, 0, LV_ANIM_OFF);
 
-    lv_memzero(explorer->current_path, sizeof(explorer->current_path));
-    lv_strncpy(explorer->current_path, path, sizeof(explorer->current_path) - 1);
+    lv_strlcpy(explorer->current_path, path, sizeof(explorer->current_path));
     lv_label_set_text_fmt(explorer->path_label, LV_SYMBOL_EYE_OPEN" %s", path);
 
     size_t current_path_len = lv_strlen(explorer->current_path);
diff --git a/src/others/observer/lv_observer.c b/src/others/observer/lv_observer.c
index 0b6e94a36..b13291498 100644
--- a/src/others/observer/lv_observer.c
+++ b/src/others/observer/lv_observer.c
@@ -116,8 +116,8 @@ int32_t lv_subject_get_previous_int(lv_subject_t * subject)
 void lv_subject_init_string(lv_subject_t * subject, char * buf, char * prev_buf, size_t size, const char * value)
 {
     lv_memzero(subject, sizeof(lv_subject_t));
-    lv_strncpy(buf, value, size);
-    if(prev_buf) lv_strncpy(prev_buf, value, size);
+    lv_strlcpy(buf, value, size);
+    if(prev_buf) lv_strlcpy(prev_buf, value, size);
 
     subject->type = LV_SUBJECT_TYPE_STRING;
     subject->size = size;
@@ -136,10 +136,10 @@ void lv_subject_copy_string(lv_subject_t * subject, const char * buf)
 
     if(subject->size < 1) return;
     if(subject->prev_value.pointer) {
-        lv_strncpy((char *)subject->prev_value.pointer, subject->value.pointer, subject->size - 1);
+        lv_strlcpy((char *)subject->prev_value.pointer, subject->value.pointer, subject->size);
     }
 
-    lv_strncpy((char *)subject->value.pointer, buf, subject->size - 1);
+    lv_strlcpy((char *)subject->value.pointer, buf, subject->size);
 
     lv_subject_notify(subject);
 
diff --git a/src/stdlib/builtin/lv_string_builtin.c b/src/stdlib/builtin/lv_string_builtin.c
index bc4551bbb..071e2d97b 100644
--- a/src/stdlib/builtin/lv_string_builtin.c
+++ b/src/stdlib/builtin/lv_string_builtin.c
@@ -191,13 +191,28 @@ size_t lv_strlen(const char * str)
     return i;
 }
 
+size_t lv_strlcpy(char * dst, const char * src, size_t dst_size)
+{
+    size_t i = 0;
+    if(dst_size > 0) {
+        for(; i < dst_size - 1 && src[i]; i++) {
+            dst[i] = src[i];
+        }
+        dst[i] = '\0';
+    }
+    while(src[i]) i++;
+    return i;
+}
+
 char * lv_strncpy(char * dst, const char * src, size_t dst_size)
 {
     size_t i;
-    for(i = 0; i < dst_size - 1 && src[i]; i++) {
+    for(i = 0; i < dst_size && src[i]; i++) {
         dst[i] = src[i];
     }
-    dst[i] = '\0';
+    for(; i < dst_size; i++) {
+        dst[i] = '\0';
+    }
     return dst;
 }
 
diff --git a/src/stdlib/clib/lv_string_clib.c b/src/stdlib/clib/lv_string_clib.c
index bec286e7a..2f1015187 100644
--- a/src/stdlib/clib/lv_string_clib.c
+++ b/src/stdlib/clib/lv_string_clib.c
@@ -60,14 +60,20 @@ size_t lv_strlen(const char * str)
     return strlen(str);
 }
 
-char * lv_strncpy(char * dst, const char * src, size_t dest_size)
+size_t lv_strlcpy(char * dst, const char * src, size_t dst_size)
 {
-    if(dest_size > 0) {
-        dst[0] = '\0';
-        strncat(dst, src, dest_size - 1);
+    size_t src_len = strlen(src);
+    if(dst_size > 0) {
+        size_t copy_size = src_len < dst_size ? src_len : dst_size - 1;
+        memcpy(dst, src, copy_size);
+        dst[copy_size] = '\0';
     }
+    return src_len;
+}
 
-    return dst;
+char * lv_strncpy(char * dst, const char * src, size_t dest_size)
+{
+    return strncpy(dst, src, dest_size);
 }
 
 char * lv_strcpy(char * dst, const char * src)
diff --git a/src/stdlib/lv_string.h b/src/stdlib/lv_string.h
index a7dcc7c30..b3da79fe0 100644
--- a/src/stdlib/lv_string.h
+++ b/src/stdlib/lv_string.h
@@ -83,11 +83,22 @@ static inline void lv_memzero(void * dst, size_t len)
 size_t lv_strlen(const char * str);
 
 /**
- * @brief Copies up to dest_size characters from the string pointed to by src to the character array pointed to by dst.
+ * @brief Copies up to dst_size-1 (non-null) characters from src to dst. A null terminator is always added.
  * @param dst Pointer to the destination array where the content is to be copied.
  * @param src Pointer to the source of data to be copied.
- * @param dest_size Maximum number of characters to be copied to dst, including the null character.
+ * @param dst_size Maximum number of characters to be copied to dst, including the null character.
+ * @return The length of src. The return value is equivalent to the value returned by lv_strlen(src)
+ */
+size_t lv_strlcpy(char * dst, const char * src, size_t dst_size);
+
+/**
+ * @brief Copies up to dest_size characters from the string pointed to by src to the character array pointed to by dst
+ *        and fills the remaining length with null bytes.
+ * @param dst Pointer to the destination array where the content is to be copied.
+ * @param src Pointer to the source of data to be copied.
+ * @param dest_size Maximum number of characters to be copied to dst.
  * @return A pointer to the destination array, which is dst.
+ * @note dst will not be null terminated if dest_size bytes were copied from src before the end of src was reached.
  */
 char * lv_strncpy(char * dst, const char * src, size_t dest_size);
 
diff --git a/src/stdlib/rtthread/lv_string_rtthread.c b/src/stdlib/rtthread/lv_string_rtthread.c
index c2a12a117..6077db609 100644
--- a/src/stdlib/rtthread/lv_string_rtthread.c
+++ b/src/stdlib/rtthread/lv_string_rtthread.c
@@ -60,6 +60,17 @@ int32_t lv_memcmp(const void * p1, const void * p2, size_t len)
     return rt_memcmp(p1, p2, len);
 }
 
+size_t lv_strlcpy(char * dst, const char * src, size_t dst_size)
+{
+    size_t src_len = lv_strlen(src);
+    if(dst_size > 0) {
+        size_t copy_size = src_len < dst_size ? src_len : dst_size - 1;
+        lv_memcpy(dst, src, copy_size);
+        dst[copy_size] = '\0';
+    }
+    return src_len;
+}
+
 char * lv_strncpy(char * dst, const char * src, size_t dest_size)
 {
     return rt_strncpy(dst, src, dest_size);
diff --git a/tests/src/test_cases/test_observer.c b/tests/src/test_cases/test_observer.c
index 7122a4126..fa94ea1dc 100644
--- a/tests/src/test_cases/test_observer.c
+++ b/tests/src/test_cases/test_observer.c
@@ -95,26 +95,26 @@ void test_observer_string(void)
 
     /*Clip long text*/
     lv_subject_copy_string(&subject, "text to be clipped to 32 chars.this should be clipped");
-    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars", lv_subject_get_string(&subject));
+    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars.", lv_subject_get_string(&subject));
     TEST_ASSERT_EQUAL_STRING("how are you?", lv_subject_get_previous_string(&subject));
 
     /*Check if the previous string is clipped correctly*/
     lv_subject_copy_string(&subject, "a");
     TEST_ASSERT_EQUAL_STRING("a", lv_subject_get_string(&subject));
-    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars", lv_subject_get_previous_string(&subject));
+    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars.", lv_subject_get_previous_string(&subject));
 
     /*Ignore incorrect types*/
     lv_subject_set_pointer(&subject, NULL);
     TEST_ASSERT_EQUAL_STRING("a", lv_subject_get_string(&subject));
-    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars", lv_subject_get_previous_string(&subject));
+    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars.", lv_subject_get_previous_string(&subject));
 
     lv_subject_set_color(&subject, lv_color_black());
     TEST_ASSERT_EQUAL_STRING("a", lv_subject_get_string(&subject));
-    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars", lv_subject_get_previous_string(&subject));
+    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars.", lv_subject_get_previous_string(&subject));
 
     lv_subject_set_int(&subject, 10);
     TEST_ASSERT_EQUAL_STRING("a", lv_subject_get_string(&subject));
-    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars", lv_subject_get_previous_string(&subject));
+    TEST_ASSERT_EQUAL_STRING("text to be clipped to 32 chars.", lv_subject_get_previous_string(&subject));
 }
 
 void test_observer_pointer(void)
diff --git a/tests/unity/unity_support.c b/tests/unity/unity_support.c
index a2a563977..4907b978a 100644
--- a/tests/unity/unity_support.c
+++ b/tests/unity/unity_support.c
@@ -198,7 +198,7 @@ static bool screenhot_compare(const char * fn_ref, const char * mode, uint8_t to
 
     if(err) {
         char fn_ref_no_ext[128];
-        strcpy(fn_ref_no_ext, fn_ref);
+        lv_strlcpy(fn_ref_no_ext, fn_ref, sizeof(fn_ref_no_ext));
         fn_ref_no_ext[strlen(fn_ref_no_ext) - 4] = '\0';
 
         char fn_err_full[256];