filearch: support gzip/xz-compressed files

Extract them to find out the architecture of the data they hold.
Useful to detect the architecture of e.g. compressed Linux modules.

Provide in the test.iso two samples (compressing existing test data) of
binaries compressed with gzip and xz.

.gitignore

@@ -515,12 +515,14 @@ Makefile.in
 /tests/data/100krandom
 /tests/data/10klines
 /tests/data/abssymlink
+/tests/data/bin-x86_64-dynamic.gz
 /tests/data/blank-disk-*
 /tests/data/blank-disk-*
 /tests/data/hello.b64
 /tests/data/initrd
 /tests/data/initrd-x86_64.img
 /tests/data/initrd-x86_64.img.gz
+/tests/data/lib-i586.so.xz
 /tests/data/test-grep.txt.gz
 /tests/data/test.iso
 /tests/disks/test-qemu-drive-libvirt.xml

generator/actions.ml

@@ -813,6 +813,10 @@ to specify the QEMU interface emulation to use at run time." };
         [["file_architecture"; "/initrd-x86_64.img"]], "x86_64"), [];
       InitISOFS, Always, TestResultString (
         [["file_architecture"; "/initrd-x86_64.img.gz"]], "x86_64"), [];
+      InitISOFS, Always, TestResultString (
+        [["file_architecture"; "/bin-x86_64-dynamic.gz"]], "x86_64"), [];
+      InitISOFS, Always, TestResultString (
+        [["file_architecture"; "/lib-i586.so.xz"]], "i386"), [];
     ];
     shortdesc = "detect the architecture of a binary file";
     longdesc = "\

src/filearch.c

@@ -250,6 +250,66 @@ cpio_arch (guestfs_h *g, const char *file, const char *path)
   return ret;
 }
 
+static char *
+compressed_file_arch (guestfs_h *g, const char *path, const char *method)
+{
+  CLEANUP_FREE char *tmpdir = guestfs_get_tmpdir (g), *dir = NULL;
+  CLEANUP_FREE char *tempfile = NULL, *tempfile_extracted = NULL;
+  CLEANUP_CMD_CLOSE struct command *cmd = guestfs_int_new_command (g);
+  char *ret = NULL;
+  int64_t size;
+  int r;
+  bool matched;
+
+  if (asprintf (&dir, "%s/libguestfsXXXXXX", tmpdir) == -1) {
+    perrorf (g, "asprintf");
+    return NULL;
+  }
+
+  /* Security: Refuse to download file if it is huge. */
+  size = guestfs_filesize (g, path);
+  if (size == -1 || size > 10000000) {
+    error (g, _("size of %s unreasonable (%" PRIi64 " bytes)"),
+           path, size);
+    goto out;
+  }
+
+  if (mkdtemp (dir) == NULL) {
+    perrorf (g, "mkdtemp");
+    goto out;
+  }
+
+  tempfile = safe_asprintf (g, "%s/file", dir);
+  if (guestfs_download (g, path, tempfile) == -1)
+    goto out;
+
+  tempfile_extracted = safe_asprintf (g, "%s/file_extracted", dir);
+
+  /* Construct a command to extract named binaries from the initrd file. */
+  guestfs_int_cmd_add_string_unquoted (cmd, method);
+  guestfs_int_cmd_add_string_unquoted (cmd, " ");
+  guestfs_int_cmd_add_string_quoted (cmd, tempfile);
+  guestfs_int_cmd_add_string_unquoted (cmd, " > ");
+  guestfs_int_cmd_add_string_quoted (cmd, tempfile_extracted);
+
+  r = guestfs_int_cmd_run (cmd);
+  if (r == -1)
+    goto out;
+  if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) {
+    guestfs_int_external_command_failed (g, r, method, path);
+    goto out;
+  }
+
+  ret = magic_for_file (g, tempfile_extracted, NULL, &matched);
+  if (!matched)
+    error (g, "file_architecture: could not determine architecture of compressed file");
+
+ out:
+  guestfs_int_recursive_remove_dir (g, dir);
+
+  return ret;
+}
+
 char *
 guestfs_impl_file_architecture (guestfs_h *g, const char *path)
 {
@@ -272,6 +332,10 @@ guestfs_impl_file_architecture (guestfs_h *g, const char *path)
     ret = safe_strdup (g, "x86_64");
   else if (strstr (file, "cpio archive"))
     ret = cpio_arch (g, file, path);
+  else if (strstr (file, "gzip compressed data"))
+    ret = compressed_file_arch (g, path, "zcat");
+  else if (strstr (file, "XZ compressed data"))
+    ret = compressed_file_arch (g, path, "xzcat");
   else
     error (g, "file_architecture: unknown architecture: %s", path);
 

tests/data/Makefile.am

@@ -76,6 +76,7 @@ images_files_build = \
 	100kallspaces \
 	100krandom \
 	10klines \
+	bin-x86_64-dynamic.gz \
 	blank-disk-1s.raw \
 	blank-disk-1s.qcow2 \
 	blank-disk-1K.raw \
@@ -87,6 +88,7 @@ images_files_build = \
 	initrd \
 	initrd-x86_64.img \
 	initrd-x86_64.img.gz \
+	lib-i586.so.xz \
 	test-grep.txt.gz
 
 check_DATA = $(images_files_build) test.iso
@@ -193,3 +195,13 @@ test-grep.txt.gz: test-grep.txt
 	rm -f $@ $@-t
 	gzip --best -c $< > $@-t
 	mv $@-t $@
+
+bin-x86_64-dynamic.gz: bin-x86_64-dynamic
+	rm -f $@ $@-t
+	gzip --best -c $< > $@-t
+	mv $@-t $@
+
+lib-i586.so.xz: lib-i586.so
+	rm -f $@ $@-t
+	xz -c $< > $@-t
+	mv $@-t $@