zip: Avoid magic numbers

Provide preprocessor macros for two recurring magic numbers in the zip
support code: the length of the local file header (30 bytes) and the
maximum allowable size for Mac metadata (4 MiB).

diff --git a/libarchive/archive_read_support_format_zip.c b/libarchive/archive_read_support_format_zip.c
index 9abd55709e3fca645163150bb6b54a68db752655..27ba6348bfdc8fe677d9c0a57ce5845c702c66b6 100644 (file)
--- a/libarchive/archive_read_support_format_zip.c
+++ b/libarchive/archive_read_support_format_zip.c
@@ -78,6 +78,12 @@
 #include "archive_crc32.h"
 #endif
 
+/* length of local file header, not including filename and extra */
+#define ZIP_LOCHDR_LEN         30U
+
+/* maximum length of Mac metadata in MiB */
+#define ZIP_MAX_METADATA       4U
+
 struct zip_entry {
        struct archive_rb_node  node;
        struct zip_entry        *next;
@@ -933,7 +939,7 @@ zip_read_local_file_header(struct archive_read *a, struct archive_entry *entry,
                zip->init_default_conversion = 1;
        }
 
-       if ((p = __archive_read_ahead(a, 30, NULL)) == NULL) {
+       if ((p = __archive_read_ahead(a, ZIP_LOCHDR_LEN, NULL)) == NULL) {
                archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
                    "Truncated ZIP file header");
                return (ARCHIVE_FATAL);
@@ -969,7 +975,7 @@ zip_read_local_file_header(struct archive_read *a, struct archive_entry *entry,
        filename_length = archive_le16dec(p + 26);
        extra_length = archive_le16dec(p + 28);
 
-       __archive_read_consume(a, 30);
+       __archive_read_consume(a, ZIP_LOCHDR_LEN);
 
        /* Read the filename. */
        if ((h = __archive_read_ahead(a, filename_length, NULL)) == NULL) {
@@ -3637,7 +3643,7 @@ read_eocd(struct zip *zip, const char *p, int64_t current_offset)
 {
        uint16_t disk_num;
        uint32_t cd_size, cd_offset;
-       
+
        disk_num = archive_le16dec(p + 4);
        cd_size = archive_le32dec(p + 12);
        cd_offset = archive_le32dec(p + 16);
@@ -4097,7 +4103,7 @@ zip_get_local_file_header_size(struct archive_read *a, size_t extra)
        const char *p;
        ssize_t filename_length, extra_length;
 
-       if ((p = __archive_read_ahead(a, extra + 30, NULL)) == NULL) {
+       if ((p = __archive_read_ahead(a, extra + ZIP_LOCHDR_LEN, NULL)) == NULL) {
                archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
                    "Truncated ZIP file header");
                return (ARCHIVE_WARN);
@@ -4111,7 +4117,7 @@ zip_get_local_file_header_size(struct archive_read *a, size_t extra)
        filename_length = archive_le16dec(p + 26);
        extra_length = archive_le16dec(p + 28);
 
-       return (30 + filename_length + extra_length);
+       return (ZIP_LOCHDR_LEN + filename_length + extra_length);
 }
 
 static int
@@ -4148,16 +4154,16 @@ zip_read_mac_metadata(struct archive_read *a, struct archive_entry *entry,
                return (ARCHIVE_WARN);
        }
 
-       if (rsrc->uncompressed_size > (4 * 1024 * 1024)) {
+       if (rsrc->uncompressed_size > ZIP_MAX_METADATA * 1048576U) {
                archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
-                   "Mac metadata is too large: %jd > 4M bytes",
-                   (intmax_t)rsrc->uncompressed_size);
+                   "Mac metadata is too large: %jd > %u MiB",
+                   (intmax_t)rsrc->uncompressed_size, ZIP_MAX_METADATA);
                return (ARCHIVE_WARN);
        }
-       if (rsrc->compressed_size > (4 * 1024 * 1024)) {
+       if (rsrc->compressed_size > ZIP_MAX_METADATA * 1048576U) {
                archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,
-                   "Mac metadata is too large: %jd > 4M bytes",
-                   (intmax_t)rsrc->compressed_size);
+                   "Mac metadata is too large: %jd > %u MiB",
+                   (intmax_t)rsrc->compressed_size, ZIP_MAX_METADATA);
                return (ARCHIVE_WARN);
        }