7zip: add SFX boundary tests

Add PE and ELF SFX fixtures for the SFX scanner boundary cases.

The PE fixture places an empty 7z archive at the final exact
32-byte scan window. The ELF fixture places ".data\0" at the final
valid section string-table position.

Register the fixtures for autotools distcheck.

Makefile.am

@@ -893,6 +893,8 @@ libarchive_test_EXTRA_DIST=\
 	libarchive/test/test_read_format_7zip_malformed_numfiles_oom.7z.uu \
 	libarchive/test/test_read_format_7zip_packinfo_digests.7z.uu \
 	libarchive/test/test_read_format_7zip_ppmd.7z.uu \
+	libarchive/test/test_read_format_7zip_sfx_boundary_elf.elf.uu \
+	libarchive/test/test_read_format_7zip_sfx_boundary_pe.exe.uu \
 	libarchive/test/test_read_format_7zip_sfx_elf.elf.uu \
 	libarchive/test/test_read_format_7zip_sfx_elf64trunc.elf.uu \
 	libarchive/test/test_read_format_7zip_sfx_modified_pe.exe.uu \

libarchive/test/test_read_format_7zip.c

@@ -1383,6 +1383,47 @@ DEFINE_TEST(test_read_format_7zip_sfx_elf)
 	assertEqualInt(ARCHIVE_OK, archive_read_free(a));
 }
 
+static void
+test_sfx_boundary_empty_7z(const char *refname)
+{
+	struct archive_entry *ae = NULL;
+	struct archive *a;
+	const int bs = 10240;
+
+	extract_reference_file(refname);
+
+	assert((a = archive_read_new()) != NULL);
+	assertEqualIntA(a, ARCHIVE_OK, archive_read_support_filter_all(a));
+	assertEqualIntA(a, ARCHIVE_OK, archive_read_support_format_all(a));
+	assertEqualIntA(a, ARCHIVE_OK,
+	    archive_read_open_filename(a, refname, bs));
+	assertEqualIntA(a, ARCHIVE_EOF, archive_read_next_header(a, &ae));
+	assertEqualInt(0, archive_file_count(a));
+	assertEqualIntA(a, ARCHIVE_FORMAT_7ZIP, archive_format(a));
+	assertEqualIntA(a, ARCHIVE_OK, archive_read_close(a));
+	assertEqualInt(ARCHIVE_OK, archive_read_free(a));
+}
+
+DEFINE_TEST(test_read_format_7zip_sfx_boundary_pe)
+{
+	/*
+	 * The embedded empty 7z archive starts at the final exact
+	 * 32-byte scan window after the PE overlay offset.
+	 */
+	test_sfx_boundary_empty_7z(
+	    "test_read_format_7zip_sfx_boundary_pe.exe");
+}
+
+DEFINE_TEST(test_read_format_7zip_sfx_boundary_elf)
+{
+	/*
+	 * The ELF section string table contains "\0.data\0", so
+	 * ".data\0" starts at the final valid string-table position.
+	 */
+	test_sfx_boundary_empty_7z(
+	    "test_read_format_7zip_sfx_boundary_elf.elf");
+}
+
 /*
  * A truncated ELF 64-bit MSB file.
  */

libarchive/test/test_read_format_7zip_sfx_boundary_elf.elf.uu

@@ -0,0 +1,22 @@
+begin 644 test_read_format_7zip_sfx_boundary_elf.elf
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+end

libarchive/test/test_read_format_7zip_sfx_boundary_pe.exe.uu

@@ -0,0 +1,22 @@
+begin 644 test_read_format_7zip_sfx_boundary_pe.exe
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+end