unzip: properly use CDF to find compressed files. Closes 9536

function                                             old     new   delta
unzip_main                                          2437    2350     -87

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 165 insertions, 120 deletions

diff --git a/archival/unzip.c b/archival/unzip.c
index c540485ac..edef22f75 100644
--- a/archival/unzip.c
+++ b/archival/unzip.c
@@ -16,7 +16,6 @@
  * TODO
  * Zip64 + other methods
  */
-
 //config:config UNZIP
 //config:       bool "unzip"
 //config:       default y
@@ -24,8 +23,17 @@
 //config:         unzip will list or extract files from a ZIP archive,
 //config:         commonly found on DOS/WIN systems. The default behavior
 //config:         (with no options) is to extract the archive into the
-//config:         current directory. Use the `-d' option to extract to a
-//config:         directory of your choice.
+//config:         current directory.
+//config:
+//config:config FEATURE_UNZIP_CDF
+//config:       bool "Read and use Central Directory data"
+//config:       default y
+//config:       depends on UNZIP
+//config:       help
+//config:         If you know that you only need to deal with simple
+//config:         ZIP files without deleted/updated files, SFX archves etc,
+//config:         you can reduce code size by unselecting this option.
+//config:         To support less trivial ZIPs, say Y.
 
 //applet:IF_UNZIP(APPLET(unzip, BB_DIR_USR_BIN, BB_SUID_DROP))
 //kbuild:lib-$(CONFIG_UNZIP) += unzip.o
@@ -80,30 +88,20 @@ typedef union {
                 uint32_t ucmpsize PACKED;       /* 18-21 */
                 uint16_t filename_len;          /* 22-23 */
                 uint16_t extra_len;             /* 24-25 */
+                /* filename follows (not NUL terminated) */
+                /* extra field follows */
+                /* data follows */
         } formatted PACKED;
 } zip_header_t; /* PACKED - gcc 4.2.1 doesn't like it (spews warning) */
 
-/* Check the offset of the last element, not the length.  This leniency
- * allows for poor packing, whereby the overall struct may be too long,
- * even though the elements are all in the right place.
- */
-struct BUG_zip_header_must_be_26_bytes {
-        char BUG_zip_header_must_be_26_bytes[
-                offsetof(zip_header_t, formatted.extra_len) + 2
-                        == ZIP_HEADER_LEN ? 1 : -1];
-};
-
-#define FIX_ENDIANNESS_ZIP(zip_header) do { \
-        (zip_header).formatted.version      = SWAP_LE16((zip_header).formatted.version     ); \
-        (zip_header).formatted.method       = SWAP_LE16((zip_header).formatted.method      ); \
-        (zip_header).formatted.modtime      = SWAP_LE16((zip_header).formatted.modtime     ); \
-        (zip_header).formatted.moddate      = SWAP_LE16((zip_header).formatted.moddate     ); \
+#define FIX_ENDIANNESS_ZIP(zip_header) \
+do { if (BB_BIG_ENDIAN) { \
         (zip_header).formatted.crc32        = SWAP_LE32((zip_header).formatted.crc32       ); \
         (zip_header).formatted.cmpsize      = SWAP_LE32((zip_header).formatted.cmpsize     ); \
         (zip_header).formatted.ucmpsize     = SWAP_LE32((zip_header).formatted.ucmpsize    ); \
         (zip_header).formatted.filename_len = SWAP_LE16((zip_header).formatted.filename_len); \
         (zip_header).formatted.extra_len    = SWAP_LE16((zip_header).formatted.extra_len   ); \
-} while (0)
+}} while (0)
 
 #define CDF_HEADER_LEN 42
 
@@ -115,8 +113,8 @@ typedef union {
                 uint16_t version_needed;        /* 2-3 */
                 uint16_t cdf_flags;             /* 4-5 */
                 uint16_t method;                /* 6-7 */
-                uint16_t mtime;                 /* 8-9 */
-                uint16_t mdate;                 /* 10-11 */
+                uint16_t modtime;               /* 8-9 */
+                uint16_t moddate;               /* 10-11 */
                 uint32_t crc32;                 /* 12-15 */
                 uint32_t cmpsize;               /* 16-19 */
                 uint32_t ucmpsize;              /* 20-23 */
@@ -127,27 +125,27 @@ typedef union {
                 uint16_t internal_file_attributes; /* 32-33 */
                 uint32_t external_file_attributes PACKED; /* 34-37 */
                 uint32_t relative_offset_of_local_header PACKED; /* 38-41 */
+                /* filename follows (not NUL terminated) */
+                /* extra field follows */
+                /* comment follows */
         } formatted PACKED;
 } cdf_header_t;
 
-struct BUG_cdf_header_must_be_42_bytes {
-        char BUG_cdf_header_must_be_42_bytes[
-                offsetof(cdf_header_t, formatted.relative_offset_of_local_header) + 4
-                        == CDF_HEADER_LEN ? 1 : -1];
-};
-
-#define FIX_ENDIANNESS_CDF(cdf_header) do { \
+#define FIX_ENDIANNESS_CDF(cdf_header) \
+do { if (BB_BIG_ENDIAN) { \
+        (cdf_header).formatted.version_made_by = SWAP_LE16((cdf_header).formatted.version_made_by); \
+        (cdf_header).formatted.version_needed = SWAP_LE16((cdf_header).formatted.version_needed); \
+        (cdf_header).formatted.method       = SWAP_LE16((cdf_header).formatted.method      ); \
+        (cdf_header).formatted.modtime      = SWAP_LE16((cdf_header).formatted.modtime     ); \
+        (cdf_header).formatted.moddate      = SWAP_LE16((cdf_header).formatted.moddate     ); \
         (cdf_header).formatted.crc32        = SWAP_LE32((cdf_header).formatted.crc32       ); \
         (cdf_header).formatted.cmpsize      = SWAP_LE32((cdf_header).formatted.cmpsize     ); \
         (cdf_header).formatted.ucmpsize     = SWAP_LE32((cdf_header).formatted.ucmpsize    ); \
         (cdf_header).formatted.file_name_length = SWAP_LE16((cdf_header).formatted.file_name_length); \
         (cdf_header).formatted.extra_field_length = SWAP_LE16((cdf_header).formatted.extra_field_length); \
         (cdf_header).formatted.file_comment_length = SWAP_LE16((cdf_header).formatted.file_comment_length); \
-        IF_DESKTOP( \
-        (cdf_header).formatted.version_made_by = SWAP_LE16((cdf_header).formatted.version_made_by); \
         (cdf_header).formatted.external_file_attributes = SWAP_LE32((cdf_header).formatted.external_file_attributes); \
-        ) \
-} while (0)
+}} while (0)
 
 #define CDE_HEADER_LEN 16
 
@@ -166,20 +164,38 @@ typedef union {
         } formatted PACKED;
 } cde_header_t;
 
-struct BUG_cde_header_must_be_16_bytes {
+#define FIX_ENDIANNESS_CDE(cde_header) \
+do { if (BB_BIG_ENDIAN) { \
+        (cde_header).formatted.cdf_offset = SWAP_LE32((cde_header).formatted.cdf_offset); \
+}} while (0)
+
+struct BUG {
+        /* Check the offset of the last element, not the length.  This leniency
+         * allows for poor packing, whereby the overall struct may be too long,
+         * even though the elements are all in the right place.
+         */
+        char BUG_zip_header_must_be_26_bytes[
+                offsetof(zip_header_t, formatted.extra_len) + 2
+                        == ZIP_HEADER_LEN ? 1 : -1];
+        char BUG_cdf_header_must_be_42_bytes[
+                offsetof(cdf_header_t, formatted.relative_offset_of_local_header) + 4
+                        == CDF_HEADER_LEN ? 1 : -1];
         char BUG_cde_header_must_be_16_bytes[
                 sizeof(cde_header_t) == CDE_HEADER_LEN ? 1 : -1];
 };
 
-#define FIX_ENDIANNESS_CDE(cde_header) do { \
-        (cde_header).formatted.cdf_offset = SWAP_LE32((cde_header).formatted.cdf_offset); \
-} while (0)
 
 enum { zip_fd = 3 };
 
 
-#if ENABLE_DESKTOP
+/* This value means that we failed to find CDF */
+#define BAD_CDF_OFFSET ((uint32_t)0xffffffff)
+
+#if !ENABLE_FEATURE_UNZIP_CDF
 
+# define find_cdf_offset() BAD_CDF_OFFSET
+
+#else
 /* Seen in the wild:
  * Self-extracting PRO2K3XP_32.exe contains 19078464 byte zip archive,
  * where CDE was nearly 48 kbytes before EOF.
@@ -188,25 +204,26 @@ enum { zip_fd = 3 };
  * To make extraction work, bumped PEEK_FROM_END from 16k to 64k.
  */
 #define PEEK_FROM_END (64*1024)
-
-/* This value means that we failed to find CDF */
-#define BAD_CDF_OFFSET ((uint32_t)0xffffffff)
-
 /* NB: does not preserve file position! */
 static uint32_t find_cdf_offset(void)
 {
         cde_header_t cde_header;
+        unsigned char *buf;
         unsigned char *p;
         off_t end;
-        unsigned char *buf = xzalloc(PEEK_FROM_END);
         uint32_t found;
 
-        end = xlseek(zip_fd, 0, SEEK_END);
+        end = lseek(zip_fd, 0, SEEK_END);
+        if (end == (off_t) -1)
+                return BAD_CDF_OFFSET;
+
         end -= PEEK_FROM_END;
         if (end < 0)
                 end = 0;
+
         dbg("Looking for cdf_offset starting from 0x%"OFF_FMT"x", end);
         xlseek(zip_fd, end, SEEK_SET);
+        buf = xzalloc(PEEK_FROM_END);
         full_read(zip_fd, buf, PEEK_FROM_END);
 
         found = BAD_CDF_OFFSET;
@@ -252,30 +269,36 @@ static uint32_t find_cdf_offset(void)
 static uint32_t read_next_cdf(uint32_t cdf_offset, cdf_header_t *cdf_ptr)
 {
         off_t org;
+        uint32_t magic;
 
-        org = xlseek(zip_fd, 0, SEEK_CUR);
+        if (cdf_offset == BAD_CDF_OFFSET)
+                return cdf_offset;
 
-        if (!cdf_offset)
-                cdf_offset = find_cdf_offset();
-
-        if (cdf_offset != BAD_CDF_OFFSET) {
-                dbg("Reading CDF at 0x%x", (unsigned)cdf_offset);
-                xlseek(zip_fd, cdf_offset + 4, SEEK_SET);
-                xread(zip_fd, cdf_ptr->raw, CDF_HEADER_LEN);
-                FIX_ENDIANNESS_CDF(*cdf_ptr);
-                dbg("  file_name_length:%u extra_field_length:%u file_comment_length:%u",
-                        (unsigned)cdf_ptr->formatted.file_name_length,
-                        (unsigned)cdf_ptr->formatted.extra_field_length,
-                        (unsigned)cdf_ptr->formatted.file_comment_length
-                );
-                cdf_offset += 4 + CDF_HEADER_LEN
-                        + cdf_ptr->formatted.file_name_length
-                        + cdf_ptr->formatted.extra_field_length
-                        + cdf_ptr->formatted.file_comment_length;
+        org = xlseek(zip_fd, 0, SEEK_CUR);
+        dbg("Reading CDF at 0x%x", (unsigned)cdf_offset);
+        xlseek(zip_fd, cdf_offset, SEEK_SET);
+        xread(zip_fd, &magic, 4);
+        /* Central Directory End? */
+        if (magic == ZIP_CDE_MAGIC) {
+                dbg("got ZIP_CDE_MAGIC");
+                return 0; /* EOF */
         }
+        xread(zip_fd, cdf_ptr->raw, CDF_HEADER_LEN);
+        /* Caller doesn't need this: */
+        /* dbg("Returning file position to 0x%"OFF_FMT"x", org); */
+        /* xlseek(zip_fd, org, SEEK_SET); */
+
+        FIX_ENDIANNESS_CDF(*cdf_ptr);
+        dbg("  file_name_length:%u extra_field_length:%u file_comment_length:%u",
+                (unsigned)cdf_ptr->formatted.file_name_length,
+                (unsigned)cdf_ptr->formatted.extra_field_length,
+                (unsigned)cdf_ptr->formatted.file_comment_length
+        );
+        cdf_offset += 4 + CDF_HEADER_LEN
+                + cdf_ptr->formatted.file_name_length
+                + cdf_ptr->formatted.extra_field_length
+                + cdf_ptr->formatted.file_comment_length;
 
-        dbg("Returning file position to 0x%"OFF_FMT"x", org);
-        xlseek(zip_fd, org, SEEK_SET);
         return cdf_offset;
 };
 #endif
@@ -324,6 +347,7 @@ static void unzip_extract(zip_header_t *zip_header, int dst_fd)
                         bb_error_msg("bad length");
                 }
         }
+        /* TODO? method 12: bzip2, method 14: LZMA */
 }
 
 static void my_fgets80(char *buf80)
@@ -339,15 +363,12 @@ int unzip_main(int argc, char **argv)
 {
         enum { O_PROMPT, O_NEVER, O_ALWAYS };
 
-        zip_header_t zip_header;
         smallint quiet = 0;
-        IF_NOT_DESKTOP(const) smallint verbose = 0;
+        IF_NOT_FEATURE_UNZIP_CDF(const) smallint verbose = 0;
         smallint listing = 0;
         smallint overwrite = O_PROMPT;
         smallint x_opt_seen;
-#if ENABLE_DESKTOP
         uint32_t cdf_offset;
-#endif
         unsigned long total_usize;
         unsigned long total_size;
         unsigned total_entries;
@@ -430,7 +451,7 @@ int unzip_main(int argc, char **argv)
                         break;
 
                 case 'v': /* Verbose list */
-                        IF_DESKTOP(verbose++;)
+                        IF_FEATURE_UNZIP_CDF(verbose++;)
                         listing = 1;
                         break;
 
@@ -545,78 +566,102 @@ int unzip_main(int argc, char **argv)
         total_usize = 0;
         total_size = 0;
         total_entries = 0;
-#if ENABLE_DESKTOP
-        cdf_offset = 0;
-#endif
+        cdf_offset = find_cdf_offset(); /* try to seek to the end, find CDE and CDF start */
         while (1) {
-                uint32_t magic;
+                zip_header_t zip_header;
                 mode_t dir_mode = 0777;
-#if ENABLE_DESKTOP
+#if ENABLE_FEATURE_UNZIP_CDF
                 mode_t file_mode = 0666;
 #endif
 
-                /* Check magic number */
-                xread(zip_fd, &magic, 4);
-                /* Central directory? It's at the end, so exit */
-                if (magic == ZIP_CDF_MAGIC) {
-                        dbg("got ZIP_CDF_MAGIC");
-                        break;
-                }
-#if ENABLE_DESKTOP
-                /* Data descriptor? It was a streaming file, go on */
-                if (magic == ZIP_DD_MAGIC) {
-                        dbg("got ZIP_DD_MAGIC");
-                        /* skip over duplicate crc32, cmpsize and ucmpsize */
-                        unzip_skip(3 * 4);
-                        continue;
-                }
-#endif
-                if (magic != ZIP_FILEHEADER_MAGIC)
-                        bb_error_msg_and_die("invalid zip magic %08X", (int)magic);
-                dbg("got ZIP_FILEHEADER_MAGIC");
-
-                /* Read the file header */
-                xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);
-                FIX_ENDIANNESS_ZIP(zip_header);
-                if ((zip_header.formatted.method != 0) && (zip_header.formatted.method != 8)) {
-                        bb_error_msg_and_die("unsupported method %d", zip_header.formatted.method);
-                }
-#if !ENABLE_DESKTOP
-                if (zip_header.formatted.zip_flags & SWAP_LE16(0x0009)) {
-                        bb_error_msg_and_die("zip flags 1 and 8 are not supported");
-                }
-#else
-                if (zip_header.formatted.zip_flags & SWAP_LE16(0x0001)) {
-                        /* 0x0001 - encrypted */
-                        bb_error_msg_and_die("zip flag 1 (encryption) is not supported");
-                }
+                if (!ENABLE_FEATURE_UNZIP_CDF || cdf_offset == BAD_CDF_OFFSET) {
+                        /* Normally happens when input is unseekable.
+                         *
+                         * Valid ZIP file has Central Directory at the end
+                         * with central directory file headers (CDFs).
+                         * After it, there is a Central Directory End structure.
+                         * CDFs identify what files are in the ZIP and where
+                         * they are located. This allows ZIP readers to load
+                         * the list of files without reading the entire ZIP archive.
+                         * ZIP files may be appended to, only files specified in
+                         * the CD are valid. Scanning for local file headers is
+                         * not a correct algorithm.
+                         *
+                         * We try to do the above, and resort to "linear" reading
+                         * of ZIP file only if seek failed or CDE wasn't found.
+                         */
+                        uint32_t magic;
 
-                if (cdf_offset != BAD_CDF_OFFSET) {
+                        /* Check magic number */
+                        xread(zip_fd, &magic, 4);
+                        /* Central directory? It's at the end, so exit */
+                        if (magic == ZIP_CDF_MAGIC) {
+                                dbg("got ZIP_CDF_MAGIC");
+                                break;
+                        }
+                        /* Data descriptor? It was a streaming file, go on */
+                        if (magic == ZIP_DD_MAGIC) {
+                                dbg("got ZIP_DD_MAGIC");
+                                /* skip over duplicate crc32, cmpsize and ucmpsize */
+                                unzip_skip(3 * 4);
+                                continue;
+                        }
+                        if (magic != ZIP_FILEHEADER_MAGIC)
+                                bb_error_msg_and_die("invalid zip magic %08X", (int)magic);
+                        dbg("got ZIP_FILEHEADER_MAGIC");
+
+                        xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);
+                        FIX_ENDIANNESS_ZIP(zip_header);
+                        if ((zip_header.formatted.method != 0)
+                         && (zip_header.formatted.method != 8)
+                        ) {
+                                /* TODO? method 12: bzip2, method 14: LZMA */
+                                bb_error_msg_and_die("unsupported method %d", zip_header.formatted.method);
+                        }
+                        if (zip_header.formatted.zip_flags & SWAP_LE16(0x0009)) {
+                                bb_error_msg_and_die("zip flags 1 and 8 are not supported");
+                        }
+                }
+#if ENABLE_FEATURE_UNZIP_CDF
+                else {
+                        /* cdf_offset is valid (and we know the file is seekable) */
                         cdf_header_t cdf_header;
                         cdf_offset = read_next_cdf(cdf_offset, &cdf_header);
-                        /*
-                         * Note: cdf_offset can become BAD_CDF_OFFSET after the above call.
-                         */
+                        if (cdf_offset == 0) /* EOF? */
+                                break;
+# if 0
+                        xlseek(zip_fd,
+                                SWAP_LE32(cdf_header.formatted.relative_offset_of_local_header) + 4,
+                                SEEK_SET);
+                        xread(zip_fd, zip_header.raw, ZIP_HEADER_LEN);
+                        FIX_ENDIANNESS_ZIP(zip_header);
                         if (zip_header.formatted.zip_flags & SWAP_LE16(0x0008)) {
                                 /* 0x0008 - streaming. [u]cmpsize can be reliably gotten
-                                 * only from Central Directory. See unzip_doc.txt
+                                 * only from Central Directory.
                                  */
                                 zip_header.formatted.crc32    = cdf_header.formatted.crc32;
                                 zip_header.formatted.cmpsize  = cdf_header.formatted.cmpsize;
                                 zip_header.formatted.ucmpsize = cdf_header.formatted.ucmpsize;
                         }
+# else
+                        /* CDF has the same data as local header, no need to read the latter */
+                        memcpy(&zip_header.formatted.version,
+                                &cdf_header.formatted.version_needed, ZIP_HEADER_LEN);
+                        xlseek(zip_fd,
+                                SWAP_LE32(cdf_header.formatted.relative_offset_of_local_header) + 4 + ZIP_HEADER_LEN,
+                                SEEK_SET);
+# endif
                         if ((cdf_header.formatted.version_made_by >> 8) == 3) {
                                 /* This archive is created on Unix */
                                 dir_mode = file_mode = (cdf_header.formatted.external_file_attributes >> 16);
                         }
                 }
-                if (cdf_offset == BAD_CDF_OFFSET
-                 && (zip_header.formatted.zip_flags & SWAP_LE16(0x0008))
-                ) {
-                        /* If it's a streaming zip, we _require_ CDF */
-                        bb_error_msg_and_die("can't find file table");
-                }
 #endif
+
+                if (zip_header.formatted.zip_flags & SWAP_LE16(0x0001)) {
+                        /* 0x0001 - encrypted */
+                        bb_error_msg_and_die("zip flag 1 (encryption) is not supported");
+                }
                 dbg("File cmpsize:0x%x extra_len:0x%x ucmpsize:0x%x",
                         (unsigned)zip_header.formatted.cmpsize,
                         (unsigned)zip_header.formatted.extra_len,
@@ -751,7 +796,7 @@ int unzip_main(int argc, char **argv)
                         overwrite = O_ALWAYS;
                 case 'y': /* Open file and fall into unzip */
                         unzip_create_leading_dirs(dst_fn);
-#if ENABLE_DESKTOP
+#if ENABLE_FEATURE_UNZIP_CDF
                         dst_fd = xopen3(dst_fn, O_WRONLY | O_CREAT | O_TRUNC, file_mode);
 #else
                         dst_fd = xopen(dst_fn, O_WRONLY | O_CREAT | O_TRUNC);