Add openMemory method with an example

1 files changed, 159 insertions, 121 deletions

diff --git a/src/cc4group.c b/src/cc4group.c
index 29fe0d5..f3975ee 100644
--- a/src/cc4group.c
+++ b/src/cc4group.c
@@ -75,8 +75,6 @@ typedef struct {
 struct CC4Group_t {
 	uint8_t* uncompressedData;
 	size_t uncompressedSize;
-	const char* path;
-	const char* subPath;
 	C4GroupEntryData root;
 	C4GroupEntryData realRoot;
 
@@ -329,98 +327,45 @@ static void* cc4group_createTmpMemoryAuto(CC4Group* const this, const size_t siz
 
 static CC4Group_TmpMemoryStrategy cc4group_tmpMemoryStrategy = cc4group_createTmpMemoryAuto;
 
-static void cc4group_uncompressGroup(CC4Group* const this)
+static bool cc4group_buildGroupHierarchy(CC4Group* const this)
 {
+	this->root.data = this->uncompressedData;
+	bool ret = buildChildren(this, &this->root, this->uncompressedSize);
+	this->root.core.Directory = 1;
+	this->root.core.FileName[0] = '\0';
+
+	AddCleanupJob(deleteChildren, this->root.children);
+
+	return ret;
+}
+
+static bool cc4group_uncompressGroup(CC4Group* const this, const uint8_t* const compressedData, size_t const size)
+{
+	// only if the group is still empty
+	assert(this->root.children == NULL);
+
 	// declare variables here already for proper cleanup in error cases
-	uint8_t* retData = NULL;
 	C4GroupHeader* header = NULL;
-	uint8_t* mappedFile = MAP_FAILED;
-	void* mapExtra;
-	uint8_t* mappedTmpFile = NULL;
 	bool inflateStarted = false;
+	uint8_t* retData = NULL;
 	size_t currentSize = 0;
 	CC4Group_CleanupJob tmpCleanup;
+	uint8_t* mappedTmpFile = NULL;
 
-	char* path;
-	char* slash = NULL;
-
-	this->path = path = strdup(this->path);
-	AddCleanupJob(free, (void*)this->path);
-
-	int file = -1;
-	for(;;)
-	{
-		file = open(this->path, O_RDONLY | O_BINARY);
-		if(file != -1)
-		{
-			break;
-		}
-
-		if(errno != ENOTDIR)
-		{
-			SET_ERRNO_ERROR("open: Opening group file");
-			goto ret;
-		}
-
-		char* oldSlash = slash;
-
-		slash = strrchr(path, '/');
-
-		if(oldSlash != NULL)
-		{
-			*oldSlash = '/';
-		}
-
-		if(slash != NULL && slash != path)
-		{
-			*slash = '\0';
-			this->subPath = slash + 1;
-		}
-	}
-
-	struct stat st;
-	if(fstat(file, &st) == -1)
-	{
-		SET_ERRNO_ERROR("fstat: on the opened group file");
-		goto ret;
-	}
-
-	if(S_ISDIR(st.st_mode))
-	{
-		SET_MESSAGE_ERROR("The specified group file is a directory");
-		goto ret;
-	}
-
-	off_t size = st.st_size;
-	mappedFile = cc4group_mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, file, 0, &mapExtra);
-
-	if(close(file) == -1)
-	{
-		SET_ERRNO_ERROR("close: Closing the group file");
-		goto ret;
-	}
-
-	if(mappedFile == MAP_FAILED)
-	{
-		SET_ERRNO_ERROR("mmap: Mapping the group file");
-		goto ret;
-	}
+	static uint8_t magic[] = {0x1f, 0x8b};
 
-	if((mappedFile[0] != C4GroupMagic1 && mappedFile[0] != 0x1f) || (mappedFile[1] != C4GroupMagic2 && mappedFile[1] != 0x8b))
+	if((compressedData[0] != C4GroupMagic1 && compressedData[0] != magic[0]) || (compressedData[1] != C4GroupMagic2 && compressedData[1] != magic[1]))
 	{
 		SET_MESSAGE_ERROR("The file is not a valid group file. Magic bytes don't match.");
 		goto ret;
 	}
 
-	mappedFile[0] = 0x1f;
-	mappedFile[1] = 0x8b;
-
 	z_stream strm = {
 		.zalloc = NULL,
 		.zfree = NULL,
 		.opaque = NULL,
-		.next_in = mappedFile,
-		.avail_in = size
+		.next_in = magic,
+		.avail_in = 2
 	};
 
 	int ret = inflateInit2(&strm, 15 + 16); // window size 15 + automatic gzip
@@ -445,7 +390,16 @@ static void cc4group_uncompressGroup(CC4Group* const this)
 	strm.avail_out = currentSize;
 
 	ret = inflate(&strm, Z_SYNC_FLUSH);
+	if(ret != Z_OK && (ret != Z_STREAM_END || strm.avail_in != 0))
+	{
+		SET_ZERROR_ERROR("inflate: inflating the magic", ret);
+		goto ret;
+	}
 
+	strm.next_in = (uint8_t*)compressedData + 2; // I don't know why this must be non-const; anyway a read-only mapped input doesn't segfault. so it seems to be used read-only
+	strm.avail_in = size - 2;
+
+	ret = inflate(&strm, Z_SYNC_FLUSH);
 	if(ret != Z_OK && (ret != Z_STREAM_END || strm.avail_in != 0))
 	{
 		SET_ZERROR_ERROR("inflate: inflating the group header", ret);
@@ -541,14 +495,6 @@ ret:
 		inflateEnd(&strm);
 	}
 
-	if(mappedFile != MAP_FAILED)
-	{
-		if(cc4group_munmap(mappedFile, size, mapExtra) == -1)
-		{
-			fprintf(stderr, "WARNING: munmap: Unmapping the group file failed: %s\n", strerror(errno));
-		}
-	}
-
 	if(retData == NULL && mappedTmpFile != NULL)
 	{
 		tmpCleanup.func(tmpCleanup.data);
@@ -560,18 +506,137 @@ ret:
 
 	this->uncompressedData = retData;
 	this->uncompressedSize = currentSize;
+
+	if(retData == NULL)
+	{
+		return false;
+	}
+	return cc4group_buildGroupHierarchy(this);
 }
 
-static bool cc4group_buildGroupHierarchy(CC4Group* const this)
+static bool cc4group_openMemory(CC4Group* const this, const uint8_t* const compressedData, size_t const size)
 {
-	this->root.data = this->uncompressedData;
-	bool ret = buildChildren(this, &this->root, this->uncompressedSize);
-	this->root.core.Directory = 1;
-	this->root.core.FileName[0] = '\0';
+	assert(this);
+	assert(compressedData);
+	assert(size);
 
-	AddCleanupJob(deleteChildren, this->root.children);
+	return cc4group_uncompressGroup(this, compressedData, size);
+}
 
-	return ret;
+static bool cc4group_setSubRoot(CC4Group* const this, const char* const subPath)
+{
+	if(subPath != NULL && *subPath != '\0')
+	{
+		this->realRoot = this->root;
+
+		const C4GroupEntryData* subRoot = cc4group_getDirectoryByPath(this, subPath);
+
+		if(subRoot == NULL)
+		{
+			return false;
+		}
+
+		this->root = *subRoot;
+	}
+
+	return true;
+}
+
+static bool cc4group_uncompressGroupFromFile(CC4Group* const this, const char* const path)
+{
+	uint8_t* mappedFile = MAP_FAILED;
+	void* mapExtra;
+	bool success = false;
+
+	char* slash = NULL;
+	char* tmpPath = strdup(path);
+
+	if(tmpPath == NULL)
+	{
+		SET_ERRNO_ERROR("strdup: duplicating the path");
+		return false;
+	}
+
+	char* subPath = NULL;
+
+	int file = -1;
+	for(;;)
+	{
+		file = open(tmpPath, O_RDONLY | O_BINARY);
+		if(file != -1)
+		{
+			break;
+		}
+
+		if(errno != ENOTDIR)
+		{
+			SET_ERRNO_ERROR("open: Opening group file");
+			goto ret;
+		}
+
+		char* oldSlash = slash;
+
+		slash = strrchr(tmpPath, '/');
+
+		if(oldSlash != NULL)
+		{
+			*oldSlash = '/';
+		}
+
+		if(slash != NULL && slash != tmpPath)
+		{
+			*slash = '\0';
+			subPath = slash + 1;
+		}
+	}
+
+	struct stat st;
+	if(fstat(file, &st) == -1)
+	{
+		SET_ERRNO_ERROR("fstat: on the opened group file");
+		goto ret;
+	}
+
+	if(S_ISDIR(st.st_mode))
+	{
+		SET_MESSAGE_ERROR("The specified group file is a directory");
+		goto ret;
+	}
+
+	off_t size = st.st_size;
+	mappedFile = cc4group_mmap(NULL, size, PROT_READ, MAP_PRIVATE, file, 0, &mapExtra);
+
+	if(close(file) == -1)
+	{
+		SET_ERRNO_ERROR("close: Closing the group file");
+		goto ret;
+	}
+
+	if(mappedFile == MAP_FAILED)
+	{
+		SET_ERRNO_ERROR("mmap: Mapping the group file");
+		goto ret;
+	}
+
+	success = cc4group_uncompressGroup(this, mappedFile, size);
+
+ret:
+	if(mappedFile != MAP_FAILED)
+	{
+		if(cc4group_munmap(mappedFile, size, mapExtra) == -1)
+		{
+			fprintf(stderr, "WARNING: munmap: Unmapping the group file failed: %s\n", strerror(errno));
+		}
+	}
+
+	if(success)
+	{
+		success = cc4group_setSubRoot(this, subPath);
+	}
+
+	free(tmpPath);
+
+	return success;
 }
 
 static void cc4group_init(CC4Group* const this)
@@ -580,8 +645,6 @@ static void cc4group_init(CC4Group* const this)
 
 	this->uncompressedData = NULL;
 	this->uncompressedSize = 0;
-	this->path = "";
-	this->subPath = "";
 
 	this->root.data = NULL;
 	this->root.freeData = false;
@@ -767,33 +830,7 @@ static bool cc4group_openExisting(CC4Group* const this, const char* const path)
 {
 	assert(this);
 
-	// only if the group is still empty
-	assert(this->root.children == NULL);
-
-	this->path = path;
-	cc4group_uncompressGroup(this);
-	if(this->uncompressedData == NULL)
-	{
-		return false;
-	}
-
-	cc4group_buildGroupHierarchy(this);
-
-	if(*this->subPath != '\0')
-	{
-		this->realRoot = this->root;
-
-		const C4GroupEntryData* subRoot = cc4group_getDirectoryByPath(this, this->subPath);
-
-		if(subRoot == NULL)
-		{
-			return false;
-		}
-
-		this->root = *subRoot;
-	}
-
-	return true;
+	return cc4group_uncompressGroupFromFile(this, path);
 }
 
 static void cc4group_delete(CC4Group* const this)
@@ -1650,6 +1687,7 @@ CC4Group_API cc4group = {
 	.create = cc4group_create,
 	.delete = cc4group_delete,
 	.openExisting = cc4group_openExisting,
+	.openMemory = cc4group_openMemory,
 	.save = cc4group_save,
 	.saveOverwrite = cc4group_saveOverwrite,
 	.extractAll = cc4group_extractAll,