libkmod: Move zlib-related functions to separate file

Move zlib-related function to a separate file so it's easier to isolate
the dependency on each decompression library.

Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>

Makefile.am

@@ -79,6 +79,10 @@ if ENABLE_XZ
 libkmod_libkmod_la_SOURCES += libkmod/libkmod-file-xz.c
 endif
 
+if ENABLE_ZLIB
+libkmod_libkmod_la_SOURCES += libkmod/libkmod-file-zlib.c
+endif
+
 EXTRA_DIST += libkmod/libkmod.sym
 EXTRA_DIST += libkmod/README \
 	libkmod/COPYING testsuite/COPYING tools/COPYING COPYING

configure.ac

@@ -150,6 +150,7 @@ AS_IF([test "x$with_zlib" != "xno"], [
 	AC_MSG_NOTICE([zlib support not requested])
 ])
 CC_FEATURE_APPEND([with_features], [with_zlib], [ZLIB])
+AM_CONDITIONAL([ENABLE_ZLIB], [test "x$with_zlib" != "xno"])
 
 AC_ARG_WITH([openssl],
 	AS_HELP_STRING([--with-openssl], [handle PKCS7 signatures @<:@default=disabled@:>@]),

libkmod/libkmod-file-zlib.c

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <zlib.h>
+
+#include <shared/util.h>
+
+#include "libkmod.h"
+#include "libkmod-internal.h"
+#include "libkmod-internal-file.h"
+
+#define READ_STEP (4 * 1024 * 1024)
+
+int kmod_file_load_zlib(struct kmod_file *file)
+{
+	int err = 0;
+	off_t did = 0, total = 0;
+	_cleanup_free_ unsigned char *p = NULL;
+	gzFile gzf;
+	int gzfd;
+
+	errno = 0;
+	gzfd = fcntl(file->fd, F_DUPFD_CLOEXEC, 3);
+	if (gzfd < 0)
+		return -errno;
+
+	gzf = gzdopen(gzfd, "rb"); /* takes ownership of the fd */
+	if (gzf == NULL) {
+		close(gzfd);
+		return -errno;
+	}
+
+	for (;;) {
+		int r;
+
+		if (did == total) {
+			void *tmp = realloc(p, total + READ_STEP);
+			if (tmp == NULL) {
+				err = -errno;
+				goto error;
+			}
+			total += READ_STEP;
+			p = tmp;
+		}
+
+		r = gzread(gzf, p + did, total - did);
+		if (r == 0)
+			break;
+		else if (r < 0) {
+			int gzerr;
+			const char *gz_errmsg = gzerror(gzf, &gzerr);
+
+			ERR(file->ctx, "gzip: %s\n", gz_errmsg);
+
+			/* gzip might not set errno here */
+			err = gzerr == Z_ERRNO ? -errno : -EINVAL;
+			goto error;
+		}
+		did += r;
+	}
+
+	file->memory = p;
+	file->size = did;
+	p = NULL;
+	gzclose(gzf);
+	return 0;
+
+error:
+	gzclose(gzf); /* closes the gzfd */
+	return err;
+}
+

libkmod/libkmod-file.c

@@ -29,9 +29,6 @@
 #ifdef ENABLE_ZSTD
 #include <zstd.h>
 #endif
-#ifdef ENABLE_ZLIB
-#include <zlib.h>
-#endif
 
 #include <shared/util.h>
 
@@ -175,74 +172,6 @@ static int load_zstd(struct kmod_file *file)
 
 static const char magic_zstd[] = {0x28, 0xB5, 0x2F, 0xFD};
 static const char magic_xz[] = {0xfd, '7', 'z', 'X', 'Z', 0};
-
-#ifdef ENABLE_ZLIB
-#define READ_STEP (4 * 1024 * 1024)
-static int load_zlib(struct kmod_file *file)
-{
-	int err = 0;
-	off_t did = 0, total = 0;
-	_cleanup_free_ unsigned char *p = NULL;
-	gzFile gzf;
-	int gzfd;
-
-	errno = 0;
-	gzfd = fcntl(file->fd, F_DUPFD_CLOEXEC, 3);
-	if (gzfd < 0)
-		return -errno;
-
-	gzf = gzdopen(gzfd, "rb"); /* takes ownership of the fd */
-	if (gzf == NULL) {
-		close(gzfd);
-		return -errno;
-	}
-
-	for (;;) {
-		int r;
-
-		if (did == total) {
-			void *tmp = realloc(p, total + READ_STEP);
-			if (tmp == NULL) {
-				err = -errno;
-				goto error;
-			}
-			total += READ_STEP;
-			p = tmp;
-		}
-
-		r = gzread(gzf, p + did, total - did);
-		if (r == 0)
-			break;
-		else if (r < 0) {
-			int gzerr;
-			const char *gz_errmsg = gzerror(gzf, &gzerr);
-
-			ERR(file->ctx, "gzip: %s\n", gz_errmsg);
-
-			/* gzip might not set errno here */
-			err = gzerr == Z_ERRNO ? -errno : -EINVAL;
-			goto error;
-		}
-		did += r;
-	}
-
-	file->memory = p;
-	file->size = did;
-	p = NULL;
-	gzclose(gzf);
-	return 0;
-
-error:
-	gzclose(gzf); /* closes the gzfd */
-	return err;
-}
-#else
-static int load_zlib(struct kmod_file *file)
-{
-	return -ENOSYS;
-}
-#endif
-
 static const char magic_zlib[] = {0x1f, 0x8b};
 
 static int load_reg(struct kmod_file *file)
@@ -271,7 +200,7 @@ static const struct comp_type {
 } comp_types[] = {
 	{sizeof(magic_zstd),	KMOD_FILE_COMPRESSION_ZSTD, magic_zstd, load_zstd},
 	{sizeof(magic_xz),	KMOD_FILE_COMPRESSION_XZ, magic_xz, kmod_file_load_xz},
-	{sizeof(magic_zlib),	KMOD_FILE_COMPRESSION_ZLIB, magic_zlib, load_zlib},
+	{sizeof(magic_zlib),	KMOD_FILE_COMPRESSION_ZLIB, magic_zlib, kmod_file_load_zlib},
 	{0,			KMOD_FILE_COMPRESSION_NONE, NULL, load_reg}
 };
 

libkmod/libkmod-internal-file.h

@@ -25,3 +25,10 @@ int kmod_file_load_xz(struct kmod_file *file);
 #else
 static inline int kmod_file_load_xz(struct kmod_file *file) { return -ENOSYS; }
 #endif
+
+#if ENABLE_ZLIB
+int kmod_file_load_zlib(struct kmod_file *file);
+#else
+static inline int kmod_file_load_zlib(struct kmod_file *file) { return -ENOSYS; }
+#endif
+