qmerge: unpack tbz2 file without splitting it first

To save space, and also gain speed, unpack the archive and xpak contents
directly off of the tbz2 file.  This prevents us from having to shell
out to qxpak and to simply spool the relevant part of the tbz2 file to
the decompressor/tar.

Signed-off-by: Fabian Groffen <grobian@gentoo.org>

1 files changed, 59 insertions, 75 deletions

diff --git a/qmerge.c b/qmerge.c
index 103f615..e86ce00 100644
--- a/qmerge.c
+++ b/qmerge.c
@@ -34,6 +34,7 @@
 #include "xasprintf.h"
 #include "xchdir.h"
 #include "xmkdir.h"
+#include "xpak.h"
 #include "xsystem.h"
 
 #ifndef GLOB_BRACE
@@ -137,46 +138,6 @@ prompt(const char *p)
 	}
 }
 
-static int run_applet_l(const char *arg, ...)
-{
-	int (*applet)(int, char **);
-	va_list ap;
-	int ret, optind_saved, argc;
-	char **argv;
-	const char *argv0_saved;
-
-	optind_saved = optind;
-	argv0_saved = argv0;
-
-	applet = lookup_applet(arg);
-	if (!applet)
-		return -1;
-
-	/* This doesn't NULL terminate argv, but you should be using argc */
-	va_start(ap, arg);
-	argc = 0;
-	argv = NULL;
-	while (arg) {
-		argv = xrealloc(argv, sizeof(*argv) * ++argc);
-		argv[argc - 1] = xstrdup(arg);
-		arg = va_arg(ap, const char *);
-	}
-	va_end(ap);
-
-	optind = 0;
-	argv0 = argv[0];
-	ret = applet(argc, argv);
-
-	while (argc--)
-		free(argv[argc]);
-	free(argv);
-
-	optind = optind_saved;
-	argv0 = argv0_saved;
-
-	return ret;
-}
-
 static void
 fetch(const char *destdir, const char *src)
 {
@@ -980,6 +941,32 @@ merge_tree_at(int fd_src, const char *src, int fd_dst, const char *dst,
 	return ret;
 }
 
+static void
+pkg_extract_xpak_cb(
+	void *ctx,
+	char *pathname,
+	int pathname_len,
+	int data_offset,
+	int data_len,
+	char *data)
+{
+	FILE *out;
+	int *destdirfd = (int *)ctx;
+	(void)pathname_len;
+
+	int fd = openat(*destdirfd, pathname,
+			O_WRONLY | O_CLOEXEC | O_CREAT | O_TRUNC, 0644);
+	if (fd < 0)
+		return;
+	out = fdopen(fd, "w");
+	if (!out)
+		return;
+
+	fwrite(data + data_offset, 1, data_len, out);
+
+	fclose(out);
+}
+
 /* oh shit getting into pkg mgt here. FIXME: write a real dep resolver. */
 static void
 pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
@@ -1006,6 +993,7 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 	int cpm_argc;
 	char **cp_argv;
 	char **cpm_argv;
+	int tbz2size;
 
 	if (!install || !pkg || !atom)
 		return;
@@ -1142,24 +1130,23 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 	mkdir("temp", 0755);
 	mkdir_p(portroot, 0755);
 
-	/* XXX: maybe some day we should have this step operate on the
-	 *      tarball directly rather than unpacking it first. */
-
-	/* split the tbz and xpak data */
 	xasprintf(&tbz2, "%s/%s/%s.tbz2", pkgdir, pkg->CATEGORY, pkg->PF);
-	if (run_applet_l("qtbz2", "-s", tbz2, NULL) != 0)
-		err("`qtbz2 -s %s` failed", tbz2);
+	tbz2size = 0;
 
 	mkdir("vdb", 0755);
-	sprintf(tbz2, "%s.xpak", pkg->PF);
-	if (run_applet_l("qxpak", "-d", "vdb", "-x", tbz2, NULL) != 0)
-		err("`qxpak -d vdb -x %s` failed", tbz2);
+	{
+		int vdbfd = open("vdb", O_RDONLY);
+		if (vdbfd == -1)
+			err("failed to open vdb extraction directory");
+		tbz2size = xpak_extract(tbz2, &vdbfd, pkg_extract_xpak_cb);
+	}
+	if (tbz2size <= 0)
+		err("%s appears not to be a valid tbz2 file", tbz2);
 
 	/* figure out if the data is compressed differently from what the
 	 * name suggests, bug #660508, usage of BINPKG_COMPRESS,
 	 * due to the minimal nature of where we run, we cannot rely on file
 	 * or GNU tar, so have to do some laymans MAGIC hunting ourselves */
-	compr = "I brotli"; /* default: brotli; has no magic header */
 	{
 		/* bz2: 3-byte: 'B' 'Z' 'h'              at byte 0
 		 * gz:  2-byte:  1f  8b                  at byte 0
@@ -1173,7 +1160,7 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 		unsigned char magic[257+6];
 		FILE *mfd;
 
-		sprintf(tbz2, "%s.tar.bz2", pkg->PF);
+		compr = "brotli -dc"; /* default: brotli; has no magic header */
 		mfd = fopen(tbz2, "r");
 		if (mfd != NULL) {
 			size_t mlen = fread(magic, 1, sizeof(magic), mfd);
@@ -1182,16 +1169,16 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 			if (mlen >= 3 && magic[0] == 'B' && magic[1] == 'Z' &&
 					magic[2] == 'h')
 			{
-				compr = "j";
+				compr = "bzip2 -dc";
 			} else if (mlen >= 2 &&
 					magic[0] == 037 && magic[1] == 0213)
 			{
-				compr = "z";
+				compr = "gzip -dc";
 			} else if (mlen >= 5 &&
 					magic[1] == '7' && magic[2] == 'z' &&
 					magic[3] == 'X' && magic[4] == 'Z')
 			{
-				compr = "J";
+				compr = "xz -dc";
 			} else if (mlen == 257+6 &&
 					magic[257] == 'u' && magic[258] == 's' &&
 					magic[259] == 't' && magic[260] == 'a' &&
@@ -1202,7 +1189,7 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 					magic[0] == 0x04 && magic[1] == 0x22 &&
 					magic[2] == 0x4D && magic[3] == 0x18)
 			{
-				compr = "I lz4";
+				compr = "lz4 -dc";
 			} else if (mlen >= 4 &&
 					magic[0] >= 0x22 && magic[0] <= 0x28 &&
 					magic[1] == 0xB5 && magic[2] == 0x2F &&
@@ -1214,7 +1201,7 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 				 * that not more memory is allocated than what is really
 				 * needed to decompress the file. See
 				 * https://bugs.gentoo.org/show_bug.cgi?id=634980 */
-				compr = "I zstd --long=31";
+				compr = "zstd --long=31 -dc";
 				/* If really tar -I would be used we would have to quote:
 				 * compr = "I \"zstd --long=31\"";
 				 * But actually we use a pipe (see below) */
@@ -1222,7 +1209,7 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 					magic[0] == 'L' && magic[1] == 'Z' &&
 					magic[2] == 'I' && magic[3] == 'P')
 			{
-				compr = "I lzip";
+				compr = "lzip -dc";
 			} else if (mlen >= 9 &&
 					magic[0] == 0x89 && magic[1] == 'L' &&
 					magic[2] == 'Z' && magic[3] == 'O' &&
@@ -1230,30 +1217,27 @@ pkg_merge(int level, const depend_atom *atom, const struct pkg_t *pkg)
 					magic[6] == 0x0A && magic[7] == 0x1A &&
 					magic[8] == 0x0A)
 			{
-				compr = "I lzop";
+				compr = "lzop -dc";
 			}
+			fclose(mfd);
 		}
 	}
 
-	free(tbz2);
-
 	/* extract the binary package data */
 	mkdir("image", 0755);
-	if (compr[0] != 'I') {
-		snprintf(buf, sizeof(buf),
-			BUSYBOX " tar -x%s%s -f %s.tar.bz2 -C image/",
-			((verbose > 1) ? "v" : ""), compr, pkg->PF);
-	} else {
-		/* busybox's tar has no -I option. Thus, although we possibly
-		 * use busybox's shell and tar, we thus pipe, expecting the
-		 * corresponding (de)compression tool to be in PATH; if not,
-		 * a failure will occur.
-		 * Since some tools (e.g. zstd) complain about the .bz2
-		 * extension, we feed the tool by input redirection. */
-		snprintf(buf, sizeof(buf),
-			BUSYBOX " sh -c '%s -dc <%s.tar.bz2 | tar -x%sf - -C image/'",
-			compr + 2, pkg->PF, ((verbose > 1) ? "v" : ""));
-	}
+	/* busybox's tar has no -I option. Thus, although we possibly
+	 * use busybox's shell and tar, we thus pipe, expecting the
+	 * corresponding (de)compression tool to be in PATH; if not,
+	 * a failure will occur.
+	 * Since some tools (e.g. zstd) complain about the .bz2
+	 * extension, we feed the tool by input redirection. */
+	snprintf(buf, sizeof(buf),
+		BUSYBOX " sh -c 'dd status=none if=%s bs=1 count=%d %s%s | "
+		"tar -x%sf - -C image/'",
+		tbz2, tbz2size, compr[0] == '\0' ? "" : "| ", compr,
+		((verbose > 1) ? "v" : ""));
+
+	free(tbz2);
 	xsystem(buf);
 	fflush(stdout);