lib/ukcpio: Clean up & organize code

This change is a minor code cleanup with no significant logic changes,
in preparation for a larger refactoring; it includes:
- improved macros with more logical ordering
- code deduplication
- cleaner structured `read_section` function

Checkpatch-Ignore: COMPLEX_MACRO
Signed-off-by: Andrei Tatar <andrei@unikraft.io>
Reviewed-by: Simon Kuenzer <simon@unikraft.io>
Approved-by: Simon Kuenzer <simon@unikraft.io>
GitHub-Closes: #1181

diff --git a/lib/ukcpio/cpio.c b/lib/ukcpio/cpio.c
index a987f4af8ba79fdf819f3ca4b714c998891e6a6d..4cf03b0438ab62754e3df23c70f200039e7137e6 100644 (file)
--- a/lib/ukcpio/cpio.c
+++ b/lib/ukcpio/cpio.c
@@ -58,18 +58,11 @@
 #define FILE_BITS         0100000
 #define SYMLINK_BITS      0120000
 
-#define ALIGN_4(ptr)      ((void *)ALIGN_UP((uintptr_t)(ptr), 4))
-
 #define IS_FILE_OF_TYPE(mode, bits) (((mode) & (FILE_TYPE_MASK)) == (bits))
 #define IS_FILE(mode) IS_FILE_OF_TYPE((mode), (FILE_BITS))
 #define IS_DIR(mode) IS_FILE_OF_TYPE((mode), (DIRECTORY_BITS))
 #define IS_SYMLINK(mode) IS_FILE_OF_TYPE((mode), (SYMLINK_BITS))
 
-#define S8HEX_TO_U32(buf) ((uint32_t) snhex_to_int((buf), 8))
-#define GET_MODE(hdr)     ((mode_t) S8HEX_TO_U32((hdr)->mode))
-
-#define filename(header) ((const char *)header + sizeof(struct cpio_header))
-
 struct cpio_header {
        char magic[6];
        char inode_num[8];
@@ -127,6 +120,17 @@ snhex_to_int(const char *buf, size_t count)
        return val;
 }
 
+#define ALIGN_4(ptr)      ((void *)ALIGN_UP((uintptr_t)(ptr), 4))
+
+#define CPIO_U32FIELD(buf) \
+       ((uint32_t) snhex_to_int((buf), 8))
+#define CPIO_FILENAME(header) \
+       ((char *)header + sizeof(struct cpio_header))
+#define CPIO_DATA(header, fnlen) \
+       (char *)ALIGN_4((char *)(header) + sizeof(struct cpio_header) + fnlen)
+#define CPIO_NEXT(header, fnlen, fsize) \
+       (struct cpio_header *)ALIGN_4(CPIO_DATA(header, fnlen) + fsize)
+
 /**
  * Create absolute path with prefix.
  *
@@ -203,10 +207,9 @@ read_section(struct cpio_header **header_ptr,
        char *data_location;
        uint32_t bytes_to_write;
        int bytes_written;
-       struct cpio_header *next_header;
        struct utimbuf times;
 
-       if (strcmp(filename(*header_ptr), "TRAILER!!!") == 0) {
+       if (strcmp(CPIO_FILENAME(*header_ptr), "TRAILER!!!") == 0) {
                *header_ptr = NULL;
                return UKCPIO_SUCCESS;
        }
@@ -218,23 +221,33 @@ read_section(struct cpio_header **header_ptr,
                return -UKCPIO_INVALID_HEADER;
        }
 
+       if ((uintptr_t)*header_ptr + sizeof(struct cpio_header) > last) {
+               *header_ptr = NULL;
+               error = -UKCPIO_MALFORMED_INPUT;
+               goto out;
+       }
+
        UK_ASSERT(dest);
 
        header = *header_ptr;
 
-       if (absolute_path(path_from_root, dest, filename(header))) {
-               uk_pr_err("Resulting path too long: %s\n", filename(header));
+       header_mode = CPIO_U32FIELD(header->mode);
+       header_filesize = CPIO_U32FIELD(header->filesize);
+       header_namesize = CPIO_U32FIELD(header->namesize);
+       header_mtime = CPIO_U32FIELD(header->mtime);
+       data_location = CPIO_DATA(header, header_namesize);
+
+       if ((uintptr_t)data_location + header_filesize > last) {
+               uk_pr_err("File exceeds archive bounds: %s\n",
+                         CPIO_FILENAME(header));
                *header_ptr = NULL;
                error = -UKCPIO_MALFORMED_INPUT;
                goto out;
        }
 
-       header_mode = GET_MODE(header);
-       header_filesize = S8HEX_TO_U32(header->filesize);
-       header_namesize = S8HEX_TO_U32(header->namesize);
-       header_mtime = S8HEX_TO_U32(header->mtime);
-
-       if ((uintptr_t)header + sizeof(struct cpio_header) > last) {
+       if (absolute_path(path_from_root, dest, CPIO_FILENAME(header))) {
+               uk_pr_err("Resulting path too long: %s\n",
+                         CPIO_FILENAME(header));
                *header_ptr = NULL;
                error = -UKCPIO_MALFORMED_INPUT;
                goto out;
@@ -253,18 +266,6 @@ read_section(struct cpio_header **header_ptr,
                        goto out;
                }
 
-               data_location = (char *)ALIGN_4(
-                               (char *)(header) + sizeof(struct cpio_header)
-                               + header_namesize);
-
-               if ((uintptr_t)data_location + header_filesize > last) {
-                       uk_pr_err("%s: File exceeds archive bounds\n",
-                                 path_from_root);
-                       *header_ptr = NULL;
-                       error = -UKCPIO_MALFORMED_INPUT;
-                       goto out;
-               }
-
                bytes_to_write = header_filesize;
                bytes_written = 0;
 
@@ -304,7 +305,7 @@ read_section(struct cpio_header **header_ptr,
                }
        } else if (IS_DIR(header_mode)) {
                uk_pr_info("Creating directory %s\n", path_from_root);
-               if (strcmp(".", filename(header)) != 0 &&
+               if (strcmp(".", CPIO_FILENAME(header)) != 0 &&
                    (err = uk_syscall_r_mkdir(path_from_root,
                                              header_mode & 0777)))
                {
@@ -317,18 +318,6 @@ read_section(struct cpio_header **header_ptr,
        } else if (IS_SYMLINK(header_mode)) {
                uk_pr_info("Creating symlink %s\n", path_from_root);
 
-               data_location = (char *)ALIGN_4(
-                               (char *)(header) + sizeof(struct cpio_header)
-                               + header_namesize);
-
-               if ((uintptr_t)data_location + header_filesize > last) {
-                       uk_pr_err("%s: File exceeds archive bounds\n",
-                                 path_from_root);
-                       *header_ptr = NULL;
-                       error = -UKCPIO_MALFORMED_INPUT;
-                       goto out;
-               }
-
                char target[header_filesize + 1];
                memcpy(target, data_location, header_filesize);
                target[header_filesize] = 0;
@@ -346,15 +335,7 @@ read_section(struct cpio_header **header_ptr,
                           path_from_root, header_mode);
        }
 
-       next_header = (struct cpio_header *)ALIGN_4(
-               (char *)header + sizeof(struct cpio_header) + header_namesize
-       );
-
-       next_header = (struct cpio_header *)ALIGN_4(
-               (char *)next_header + header_filesize
-       );
-
-       *header_ptr = next_header;
+       *header_ptr = CPIO_NEXT(header, header_namesize, header_filesize);
 
 out:
        return error;