libkmod: Move zstd-related functions to separate file

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

Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/58
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>

Makefile.am

@@ -84,6 +84,10 @@ if ENABLE_ZLIB
 libkmod_libkmod_la_SOURCES += libkmod/libkmod-file-zlib.c
 endif
 
+if ENABLE_ZSTD
+libkmod_libkmod_la_SOURCES += libkmod/libkmod-file-zstd.c
+endif
+
 EXTRA_DIST += libkmod/libkmod.sym
 EXTRA_DIST += libkmod/README \
 	libkmod/COPYING testsuite/COPYING tools/COPYING COPYING

configure.ac

@@ -125,6 +125,7 @@ AS_IF([test "x$with_zstd" != "xno"], [
 	AC_MSG_NOTICE([Zstandard support not requested])
 ])
 CC_FEATURE_APPEND([with_features], [with_zstd], [ZSTD])
+AM_CONDITIONAL([ENABLE_ZSTD], [test "x$with_zstd" != "xno"])
 
 AC_ARG_WITH([xz],
 	AS_HELP_STRING([--with-xz], [handle Xz-compressed modules @<:@default=disabled@:>@]),

libkmod/libkmod-file-zstd.c

@@ -0,0 +1,147 @@
+// 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 <zstd.h>
+
+#include <shared/util.h>
+
+#include "libkmod.h"
+#include "libkmod-internal.h"
+#include "libkmod-internal-file.h"
+
+static int zstd_read_block(struct kmod_file *file, size_t block_size,
+			   ZSTD_inBuffer *input, size_t *input_capacity)
+{
+	ssize_t rdret;
+	int ret;
+
+	if (*input_capacity < block_size) {
+		free((void *)input->src);
+		input->src = malloc(block_size);
+		if (input->src == NULL) {
+			ret = -errno;
+			ERR(file->ctx, "zstd: %m\n");
+			return ret;
+		}
+		*input_capacity = block_size;
+	}
+
+	rdret = read(file->fd, (void *)input->src, block_size);
+	if (rdret < 0) {
+		ret = -errno;
+		ERR(file->ctx, "zstd: %m\n");
+		return ret;
+	}
+
+	input->pos = 0;
+	input->size = rdret;
+	return 0;
+}
+
+static int zstd_ensure_outbuffer_space(ZSTD_outBuffer *buffer, size_t min_free)
+{
+	uint8_t *old_buffer = buffer->dst;
+	int ret = 0;
+
+	if (buffer->size - buffer->pos >= min_free)
+		return 0;
+
+	if (buffer->size < min_free)
+		buffer->size = min_free;
+	else
+		buffer->size *= 2;
+
+	buffer->size += min_free;
+	buffer->dst = realloc(buffer->dst, buffer->size);
+	if (buffer->dst == NULL) {
+		ret = -errno;
+		free(old_buffer);
+	}
+
+	return ret;
+}
+
+static int zstd_decompress_block(struct kmod_file *file, ZSTD_DStream *dstr,
+				 ZSTD_inBuffer *input, ZSTD_outBuffer *output,
+				 size_t *next_block_size)
+{
+	size_t out_buf_min_size = ZSTD_DStreamOutSize();
+	int ret = 0;
+
+	do {
+		ssize_t dsret;
+
+		ret = zstd_ensure_outbuffer_space(output, out_buf_min_size);
+		if (ret) {
+			ERR(file->ctx, "zstd: %s\n", strerror(-ret));
+			break;
+		}
+
+		dsret = ZSTD_decompressStream(dstr, output, input);
+		if (ZSTD_isError(dsret)) {
+			ret = -EINVAL;
+			ERR(file->ctx, "zstd: %s\n", ZSTD_getErrorName(dsret));
+			break;
+		}
+		if (dsret > 0)
+			*next_block_size = (size_t)dsret;
+	} while (input->pos < input->size
+		 || output->pos > output->size
+		 || output->size - output->pos < out_buf_min_size);
+
+	return ret;
+}
+
+int kmod_file_load_zstd(struct kmod_file *file)
+{
+	ZSTD_DStream *dstr;
+	size_t next_block_size;
+	size_t zst_inb_capacity = 0;
+	ZSTD_inBuffer zst_inb = { 0 };
+	ZSTD_outBuffer zst_outb = { 0 };
+	int ret;
+
+	dstr = ZSTD_createDStream();
+	if (dstr == NULL) {
+		ret = -EINVAL;
+		ERR(file->ctx, "zstd: Failed to create decompression stream\n");
+		goto out;
+	}
+
+	next_block_size = ZSTD_initDStream(dstr);
+
+	while (true) {
+		ret = zstd_read_block(file, next_block_size, &zst_inb,
+				      &zst_inb_capacity);
+		if (ret != 0)
+			goto out;
+		if (zst_inb.size == 0) /* EOF */
+			break;
+
+		ret = zstd_decompress_block(file, dstr, &zst_inb, &zst_outb,
+					    &next_block_size);
+		if (ret != 0)
+			goto out;
+	}
+
+	ZSTD_freeDStream(dstr);
+	free((void *)zst_inb.src);
+	file->memory = zst_outb.dst;
+	file->size = zst_outb.pos;
+	return 0;
+out:
+	if (dstr != NULL)
+		ZSTD_freeDStream(dstr);
+	free((void *)zst_inb.src);
+	free((void *)zst_outb.dst);
+	return ret;
+}

libkmod/libkmod-file.c

@@ -26,9 +26,6 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
-#ifdef ENABLE_ZSTD
-#include <zstd.h>
-#endif
 
 #include <shared/util.h>
 
@@ -36,140 +33,6 @@
 #include "libkmod-internal.h"
 #include "libkmod-internal-file.h"
 
-#ifdef ENABLE_ZSTD
-static int zstd_read_block(struct kmod_file *file, size_t block_size,
-			   ZSTD_inBuffer *input, size_t *input_capacity)
-{
-	ssize_t rdret;
-	int ret;
-
-	if (*input_capacity < block_size) {
-		free((void *)input->src);
-		input->src = malloc(block_size);
-		if (input->src == NULL) {
-			ret = -errno;
-			ERR(file->ctx, "zstd: %m\n");
-			return ret;
-		}
-		*input_capacity = block_size;
-	}
-
-	rdret = read(file->fd, (void *)input->src, block_size);
-	if (rdret < 0) {
-		ret = -errno;
-		ERR(file->ctx, "zstd: %m\n");
-		return ret;
-	}
-
-	input->pos = 0;
-	input->size = rdret;
-	return 0;
-}
-
-static int zstd_ensure_outbuffer_space(ZSTD_outBuffer *buffer, size_t min_free)
-{
-	uint8_t *old_buffer = buffer->dst;
-	int ret = 0;
-
-	if (buffer->size - buffer->pos >= min_free)
-		return 0;
-
-	if (buffer->size < min_free)
-		buffer->size = min_free;
-	else
-		buffer->size *= 2;
-
-	buffer->dst = realloc(buffer->dst, buffer->size);
-	if (buffer->dst == NULL) {
-		ret = -errno;
-		free(old_buffer);
-	}
-
-	return ret;
-}
-
-static int zstd_decompress_block(struct kmod_file *file, ZSTD_DStream *dstr,
-				 ZSTD_inBuffer *input, ZSTD_outBuffer *output,
-				 size_t *next_block_size)
-{
-	size_t out_buf_min_size = ZSTD_DStreamOutSize();
-	int ret = 0;
-
-	do {
-		ssize_t dsret;
-
-		ret = zstd_ensure_outbuffer_space(output, out_buf_min_size);
-		if (ret) {
-			ERR(file->ctx, "zstd: %s\n", strerror(-ret));
-			break;
-		}
-
-		dsret = ZSTD_decompressStream(dstr, output, input);
-		if (ZSTD_isError(dsret)) {
-			ret = -EINVAL;
-			ERR(file->ctx, "zstd: %s\n", ZSTD_getErrorName(dsret));
-			break;
-		}
-		if (dsret > 0)
-			*next_block_size = (size_t)dsret;
-	} while (input->pos < input->size
-		 || output->pos > output->size
-		 || output->size - output->pos < out_buf_min_size);
-
-	return ret;
-}
-
-static int load_zstd(struct kmod_file *file)
-{
-	ZSTD_DStream *dstr;
-	size_t next_block_size;
-	size_t zst_inb_capacity = 0;
-	ZSTD_inBuffer zst_inb = { 0 };
-	ZSTD_outBuffer zst_outb = { 0 };
-	int ret;
-
-	dstr = ZSTD_createDStream();
-	if (dstr == NULL) {
-		ret = -EINVAL;
-		ERR(file->ctx, "zstd: Failed to create decompression stream\n");
-		goto out;
-	}
-
-	next_block_size = ZSTD_initDStream(dstr);
-
-	while (true) {
-		ret = zstd_read_block(file, next_block_size, &zst_inb,
-				      &zst_inb_capacity);
-		if (ret != 0)
-			goto out;
-		if (zst_inb.size == 0) /* EOF */
-			break;
-
-		ret = zstd_decompress_block(file, dstr, &zst_inb, &zst_outb,
-					    &next_block_size);
-		if (ret != 0)
-			goto out;
-	}
-
-	ZSTD_freeDStream(dstr);
-	free((void *)zst_inb.src);
-	file->memory = zst_outb.dst;
-	file->size = zst_outb.pos;
-	return 0;
-out:
-	if (dstr != NULL)
-		ZSTD_freeDStream(dstr);
-	free((void *)zst_inb.src);
-	free((void *)zst_outb.dst);
-	return ret;
-}
-#else
-static int load_zstd(struct kmod_file *file)
-{
-	return -ENOSYS;
-}
-#endif
-
 static const char magic_zstd[] = {0x28, 0xB5, 0x2F, 0xFD};
 static const char magic_xz[] = {0xfd, '7', 'z', 'X', 'Z', 0};
 static const char magic_zlib[] = {0x1f, 0x8b};
@@ -198,7 +61,7 @@ static const struct comp_type {
 	const char *magic_bytes;
 	int (*load)(struct kmod_file *file);
 } comp_types[] = {
-	{sizeof(magic_zstd),	KMOD_FILE_COMPRESSION_ZSTD, magic_zstd, load_zstd},
+	{sizeof(magic_zstd),	KMOD_FILE_COMPRESSION_ZSTD, magic_zstd, kmod_file_load_zstd},
 	{sizeof(magic_xz),	KMOD_FILE_COMPRESSION_XZ, magic_xz, kmod_file_load_xz},
 	{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

@@ -32,3 +32,8 @@ int kmod_file_load_zlib(struct kmod_file *file);
 static inline int kmod_file_load_zlib(struct kmod_file *file) { return -ENOSYS; }
 #endif
 
+#ifdef ENABLE_ZSTD
+int kmod_file_load_zstd(struct kmod_file *file);
+#else
+static inline int kmod_file_load_zstd(struct kmod_file *file) { return -ENOSYS; }
+#endif