rpm: code shrink. Now uses open_zipped's logic (factored out into setup_unzip_on_fd())

function                                             old     new   delta
setup_unzip_on_fd                                      -      80     +80
open_zipped                                          176     113     -63
rpm_main                                            1672    1355    -317
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/2 up/down: 80/-380)          Total: -300 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/archival/rpm2cpio.c b/archival/rpm2cpio.c
index 5403aee..4ed5b02 100644
--- a/archival/rpm2cpio.c
+++ b/archival/rpm2cpio.c
@@ -8,30 +8,7 @@
  */
 #include "libbb.h"
 #include "unarchive.h"
-
-#define RPM_MAGIC            0xedabeedb
-#define RPM_MAGIC_STR        "\355\253\356\333"
-
-struct rpm_lead {
-	uint32_t magic;
-	uint8_t major, minor;
-	uint16_t type;
-	uint16_t archnum;
-	char name[66];
-	uint16_t osnum;
-	uint16_t signature_type;
-	char reserved[16];
-};
-
-#define RPM_HEADER_MAGICnVER 0x8eade801
-#define RPM_HEADER_MAGIC_STR "\216\255\350"
-
-struct rpm_header {
-	uint32_t magic_and_ver; /* 3 byte magic: 0x8e 0xad 0xe8; 1 byte version */
-	uint32_t reserved; /* 4 bytes reserved */
-	uint32_t entries; /* Number of entries in header (4 bytes) */
-	uint32_t size; /* Size of store (4 bytes) */
-};
+#include "rpm.h"
 
 enum { rpm_fd = STDIN_FILENO };
 
@@ -65,8 +42,6 @@
 {
 	struct rpm_lead lead;
 	unsigned pos;
-	unsigned char magic[2];
-	IF_DESKTOP(long long) int FAST_FUNC (*unpack)(int src_fd, int dst_fd);
 
 	if (argv[1]) {
 		xmove_fd(xopen(argv[1], O_RDONLY), rpm_fd);
@@ -74,33 +49,45 @@
 	xread(rpm_fd, &lead, sizeof(lead));
 
 	/* Just check the magic, the rest is irrelevant */
-	if (lead.magic != htonl(RPM_MAGIC)) {
+	if (lead.magic != htonl(RPM_LEAD_MAGIC)) {
 		bb_error_msg_and_die("invalid RPM magic");
 	}
 
 	/* Skip the signature header, align to 8 bytes */
 	pos = skip_header();
-	seek_by_jump(rpm_fd, (8 - pos) & 7);
+	seek_by_jump(rpm_fd, (-(int)pos) & 7);
 
 	/* Skip the main header */
 	skip_header();
 
-	xread(rpm_fd, &magic, 2);
-	unpack = unpack_gz_stream;
-	if (magic[0] != 0x1f || magic[1] != 0x8b) {
-		if (!ENABLE_FEATURE_SEAMLESS_BZ2
-		 || magic[0] != 'B' || magic[1] != 'Z'
-		) {
-			bb_error_msg_and_die("invalid gzip"
-					IF_FEATURE_SEAMLESS_BZ2("/bzip2")
-					" magic");
-		}
-		unpack = unpack_bz2_stream;
-	}
-
-	if (unpack(rpm_fd, STDOUT_FILENO) < 0) {
+#if 0
+	/* This works, but doesn't report uncompress errors (they happen in child) */
+	setup_unzip_on_fd(rpm_fd /*fail_if_not_detected: 1*/);
+	if (bb_copyfd_eof(rpm_fd, STDOUT_FILENO) < 0)
 		bb_error_msg_and_die("error unpacking");
+#else
+	/* BLOAT */
+	{
+		unsigned char magic[2];
+		IF_DESKTOP(long long) int FAST_FUNC (*unpack)(int src_fd, int dst_fd);
+
+		xread(rpm_fd, &magic, 2);
+		unpack = unpack_gz_stream;
+		if (magic[0] != 0x1f || magic[1] != 0x8b) {
+			if (!ENABLE_FEATURE_SEAMLESS_BZ2
+			 || magic[0] != 'B' || magic[1] != 'Z'
+			) {
+				bb_error_msg_and_die("invalid gzip"
+						IF_FEATURE_SEAMLESS_BZ2("/bzip2")
+						" magic");
+			}
+			unpack = unpack_bz2_stream;
+		}
+
+		if (unpack(rpm_fd, STDOUT_FILENO) < 0)
+			bb_error_msg_and_die("error unpacking");
 	}
+#endif
 
 	if (ENABLE_FEATURE_CLEAN_UP) {
 		close(rpm_fd);