From: Michael Tremer <michael.tremer@ipfire.org>
Date: Wed, 17 Mar 2021 11:33:12 +0000 (+0000)
Subject: compress: Add write support for XZ
X-Git-Tag: 0.9.28~1285^2~518
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0bed1e1da805459f25fc5b61b540b03e330ae414;p=pakfire.git

compress: Add write support for XZ

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/libpakfire/compress.c b/src/libpakfire/compress.c
index 0f0bd2ba2..726b57dd6 100644
--- a/src/libpakfire/compress.c
+++ b/src/libpakfire/compress.c
@@ -32,6 +32,9 @@
 // Compression/Decompression buffer size
 #define BUFFER_SIZE			64 * 1024
 
+// Settings for XZ
+#define XZ_COMPRESSION_LEVEL	6
+
 const struct compressor {
 	char magic[MAX_MAGIC_LENGTH];
 	size_t magic_length;
@@ -109,7 +112,6 @@ struct xz_cookie {
 	uint8_t buffer[BUFFER_SIZE];
 };
 
-
 static ssize_t xz_read(void* data, char* buffer, size_t size) {
 	struct xz_cookie* cookie = (struct xz_cookie*)data;
 	if (!cookie)
@@ -169,6 +171,45 @@ static ssize_t xz_read(void* data, char* buffer, size_t size) {
 	}
 }
 
+static ssize_t xz_write(void* data, const char* buffer, size_t size) {
+	struct xz_cookie* cookie = (struct xz_cookie*)data;
+	if (!cookie)
+		return -1;
+
+	// Do not write when mode is "r"
+	if (cookie->mode == 'r')
+		return 0;
+
+	// Return nothing when there is no input
+	if (size == 0)
+		return 0;
+
+	// Set input to allocated buffer
+	cookie->stream.next_out  = (uint8_t *)buffer;
+	cookie->stream.avail_out = size;
+
+	while (1) {
+		cookie->stream.next_out  = cookie->buffer;
+		cookie->stream.avail_out = sizeof(cookie->buffer);
+
+		lzma_ret ret = lzma_code(&cookie->stream, LZMA_RUN);
+		if (ret != LZMA_OK)
+			return -1;
+
+		size_t bytes_to_write = sizeof(cookie->buffer) - cookie->stream.avail_out;
+		if (bytes_to_write) {
+			size_t bytes_written = fwrite(cookie->buffer, 1, bytes_to_write, cookie->f);
+
+			if (bytes_written != bytes_to_write)
+				return -1;
+		}
+
+		// Report that all data has been written
+		if (cookie->stream.avail_in == 0)
+			return size;
+	}
+}
+
 static int xz_close(void* data) {
 	struct xz_cookie* cookie = (struct xz_cookie*)data;
 
@@ -199,14 +240,29 @@ FILE* pakfire_xzfopen(FILE* f, const char* mode) {
 		.done = 0,
 	};
 
-	// Initialise the decoder
-	lzma_ret ret = lzma_stream_decoder(&cookie.stream, UINT64_MAX, 0);
+	lzma_ret ret;
+
+	// Initialise the encoder/decoder
+	switch (cookie.mode) {
+		case 'r':
+			ret = lzma_stream_decoder(&cookie.stream, UINT64_MAX, 0);
+			break;
+
+		case 'w':
+			ret = lzma_easy_encoder(&cookie.stream, XZ_COMPRESSION_LEVEL, LZMA_CHECK_SHA256);
+			break;
+
+		default:
+			errno = ENOTSUP;
+			return NULL;
+	}
+
 	if (ret != LZMA_OK)
 		return NULL;
 
 	cookie_io_functions_t functions = {
 		.read  = xz_read,
-		.write = NULL,
+		.write = xz_write,
 		.seek  = NULL,
 		.close = xz_close,
 	};