src/filebuf.c - third_party/libgit2 - Git at Google

 /*
  * Copyright (C) 2009-2011 the libgit2 contributors
  *
  * This file is part of libgit2, distributed under the GNU GPL v2 with
  * a Linking Exception. For full terms see the included COPYING file.
  */
 #include <stdarg.h>

 #include "common.h"
 #include "filebuf.h"
 #include "fileops.h"

 #define GIT_LOCK_FILE_MODE 0644

 static const size_t WRITE_BUFFER_SIZE = (4096 * 2);

 static int lock_file(git_filebuf *file, int flags)
 {
 	if (git_path_exists(file->path_lock) == 0) {
 		if (flags & GIT_FILEBUF_FORCE)
 			p_unlink(file->path_lock);
 		else
 			return git__throw(GIT_EOSERR, "Failed to lock file");
 	}

 	/* create path to the file buffer is required */
 	if (flags & GIT_FILEBUF_FORCE) {
 		/* XXX: Should dirmode here be configurable? Or is 0777 always fine? */
 		file->fd = git_futils_creat_locked_withpath(file->path_lock, 0777, GIT_LOCK_FILE_MODE);
 	} else {
 		file->fd = git_futils_creat_locked(file->path_lock, GIT_LOCK_FILE_MODE);
 	}

 	if (file->fd < 0)
 		return git__throw(GIT_EOSERR, "Failed to create lock");

 	if ((flags & GIT_FILEBUF_APPEND) && git_path_exists(file->path_original) == 0) {
 		git_file source;
 		char buffer[2048];
 		size_t read_bytes;

 		source = p_open(file->path_original, O_RDONLY);
 		if (source < 0)
 			return git__throw(GIT_EOSERR, "Failed to lock file. Could not open %s", file->path_original);

 		while ((read_bytes = p_read(source, buffer, 2048)) > 0) {
 			p_write(file->fd, buffer, read_bytes);
 			if (file->digest)
 				git_hash_update(file->digest, buffer, read_bytes);
 		}

 		p_close(source);
 	}

 	return GIT_SUCCESS;
 }

 void git_filebuf_cleanup(git_filebuf *file)
 {
 	if (file->fd >= 0)
 		p_close(file->fd);

 	if (file->fd >= 0 && file->path_lock && git_path_exists(file->path_lock) == GIT_SUCCESS)
 		p_unlink(file->path_lock);

 	if (file->digest)
 		git_hash_free_ctx(file->digest);

 	if (file->buffer)
 		git__free(file->buffer);

 	/* use the presence of z_buf to decide if we need to deflateEnd */
 	if (file->z_buf) {
 		git__free(file->z_buf);
 		deflateEnd(&file->zs);
 	}

 	if (file->path_original)
 		git__free(file->path_original);
 	if (file->path_lock)
 		git__free(file->path_lock);

 	memset(file, 0x0, sizeof(git_filebuf));
 	file->fd = -1;
 }

 GIT_INLINE(int) flush_buffer(git_filebuf *file)
 {
 	int result = file->write(file, file->buffer, file->buf_pos);
 	file->buf_pos = 0;
 	return result;
 }

 static int write_normal(git_filebuf *file, void *source, size_t len)
 {
 	int result = 0;

 	if (len > 0) {
 		result = p_write(file->fd, (void *)source, len);
 		if (file->digest)
 			git_hash_update(file->digest, source, len);
 	}

 	return result;
 }

 static int write_deflate(git_filebuf *file, void *source, size_t len)
 {
 	int result = Z_OK;
 	z_stream *zs = &file->zs;

 	if (len > 0 || file->flush_mode == Z_FINISH) {
 		zs->next_in = source;
 		zs->avail_in = (uInt)len;

 		do {
 			size_t have;

 			zs->next_out = file->z_buf;
 			zs->avail_out = (uInt)file->buf_size;

 			result = deflate(zs, file->flush_mode);
 			if (result == Z_STREAM_ERROR)
 				return git__throw(GIT_ERROR, "Failed to deflate input");

 			have = file->buf_size - (size_t)zs->avail_out;

 			if (p_write(file->fd, file->z_buf, have) < GIT_SUCCESS)
 				return git__throw(GIT_EOSERR, "Failed to write to file");

 		} while (zs->avail_out == 0);

 		assert(zs->avail_in == 0);

 		if (file->digest)
 			git_hash_update(file->digest, source, len);
 	}

 	return GIT_SUCCESS;
 }

 int git_filebuf_open(git_filebuf *file, const char *path, int flags)
 {
 	int error, compression;
 	size_t path_len;

 	assert(file && path);

 	if (file->buffer)
 		return git__throw(GIT_EINVALIDARGS, "Tried to reopen an open filebuf");

 	memset(file, 0x0, sizeof(git_filebuf));

 	file->buf_size = WRITE_BUFFER_SIZE;
 	file->buf_pos = 0;
 	file->fd = -1;

 	/* Allocate the main cache buffer */
 	file->buffer = git__malloc(file->buf_size);
 	if (file->buffer == NULL){
 		error = GIT_ENOMEM;
 		goto cleanup;
 	}

 	/* If we are hashing on-write, allocate a new hash context */
 	if (flags & GIT_FILEBUF_HASH_CONTENTS) {
 		if ((file->digest = git_hash_new_ctx()) == NULL) {
 			error = GIT_ENOMEM;
 			goto cleanup;
 		}
 	}

 	compression = flags >> GIT_FILEBUF_DEFLATE_SHIFT;

 	/* If we are deflating on-write, */
 	if (compression != 0) {
 		/* Initialize the ZLib stream */
 		if (deflateInit(&file->zs, compression) != Z_OK) {
 			error = git__throw(GIT_EZLIB, "Failed to initialize zlib");
 			goto cleanup;
 		}

 		/* Allocate the Zlib cache buffer */
 		file->z_buf = git__malloc(file->buf_size);
 		if (file->z_buf == NULL){
 			error = GIT_ENOMEM;
 			goto cleanup;
 		}

 		/* Never flush */
 		file->flush_mode = Z_NO_FLUSH;
 		file->write = &write_deflate;
 	} else {
 		file->write = &write_normal;
 	}

 	/* If we are writing to a temp file */
 	if (flags & GIT_FILEBUF_TEMPORARY) {
 		git_buf tmp_path = GIT_BUF_INIT;

 		/* Open the file as temporary for locking */
 		file->fd = git_futils_mktmp(&tmp_path, path);
 		if (file->fd < 0) {
 			git_buf_free(&tmp_path);
 			error = GIT_EOSERR;
 			goto cleanup;
 		}

 		/* No original path */
 		file->path_original = NULL;
 		file->path_lock = git_buf_detach(&tmp_path);

 		if (file->path_lock == NULL) {
 			error = GIT_ENOMEM;
 			goto cleanup;
 		}
 	} else {
 		path_len = strlen(path);

 		/* Save the original path of the file */
 		file->path_original = git__strdup(path);
 		if (file->path_original == NULL) {
 			error = GIT_ENOMEM;
 			goto cleanup;
 		}

 		/* create the locking path by appending ".lock" to the original */
 		file->path_lock = git__malloc(path_len + GIT_FILELOCK_EXTLENGTH);
 		if (file->path_lock == NULL) {
 			error = GIT_ENOMEM;
 			goto cleanup;
 		}

 		memcpy(file->path_lock, file->path_original, path_len);
 		memcpy(file->path_lock + path_len, GIT_FILELOCK_EXTENSION, GIT_FILELOCK_EXTLENGTH);

 		/* open the file for locking */
 		if ((error = lock_file(file, flags)) < GIT_SUCCESS)
 			goto cleanup;
 	}

 	return GIT_SUCCESS;

 cleanup:
 	git_filebuf_cleanup(file);
 	return git__rethrow(error, "Failed to open file buffer for '%s'", path);
 }

 int git_filebuf_hash(git_oid *oid, git_filebuf *file)
 {
 	int error;

 	assert(oid && file && file->digest);

 	if ((error = flush_buffer(file)) < GIT_SUCCESS)
 		return git__rethrow(error, "Failed to get hash for file");

 	git_hash_final(oid, file->digest);
 	git_hash_free_ctx(file->digest);
 	file->digest = NULL;

 	return GIT_SUCCESS;
 }

 int git_filebuf_commit_at(git_filebuf *file, const char *path, mode_t mode)
 {
 	git__free(file->path_original);
 	file->path_original = git__strdup(path);
 	if (file->path_original == NULL)
 		return GIT_ENOMEM;

 	return git_filebuf_commit(file, mode);
 }

 int git_filebuf_commit(git_filebuf *file, mode_t mode)
 {
 	int error;

 	/* temporary files cannot be committed */
 	assert(file && file->path_original);

 	file->flush_mode = Z_FINISH;
 	if ((error = flush_buffer(file)) < GIT_SUCCESS)
 		goto cleanup;

 	p_close(file->fd);
 	file->fd = -1;

 	if (p_chmod(file->path_lock, mode)) {
 		error = git__throw(GIT_EOSERR, "Failed to chmod locked file before committing");
 		goto cleanup;
 	}

 	error = p_rename(file->path_lock, file->path_original);

 cleanup:
 	git_filebuf_cleanup(file);
 	if (error < GIT_SUCCESS)
 		return git__rethrow(error, "Failed to commit locked file from buffer");
 	return GIT_SUCCESS;
 }

 GIT_INLINE(void) add_to_cache(git_filebuf *file, const void *buf, size_t len)
 {
 	memcpy(file->buffer + file->buf_pos, buf, len);
 	file->buf_pos += len;
 }

 int git_filebuf_write(git_filebuf *file, const void *buff, size_t len)
 {
 	int error;
 	const unsigned char *buf = buff;

 	for (;;) {
 		size_t space_left = file->buf_size - file->buf_pos;

 		/* cache if it's small */
 		if (space_left > len) {
 			add_to_cache(file, buf, len);
 			return GIT_SUCCESS;
 		}

 		add_to_cache(file, buf, space_left);

 		if ((error = flush_buffer(file)) < GIT_SUCCESS)
 			return git__rethrow(error, "Failed to write to buffer");

 		len -= space_left;
 		buf += space_left;
 	}
 }

 int git_filebuf_reserve(git_filebuf *file, void **buffer, size_t len)
 {
 	int error;
 	size_t space_left = file->buf_size - file->buf_pos;

 	*buffer = NULL;

 	if (len > file->buf_size)
 		return GIT_ENOMEM;

 	if (space_left <= len) {
 		if ((error = flush_buffer(file)) < GIT_SUCCESS)
 			return git__rethrow(error, "Failed to reserve buffer");
 	}

 	*buffer = (file->buffer + file->buf_pos);
 	file->buf_pos += len;

 	return GIT_SUCCESS;
 }

 int git_filebuf_printf(git_filebuf *file, const char *format, ...)
 {
 	va_list arglist;
 	size_t space_left;
 	int len, error;
 	char *tmp_buffer;

 	space_left = file->buf_size - file->buf_pos;

 	do {
 		va_start(arglist, format);
 		len = p_vsnprintf((char *)file->buffer + file->buf_pos, space_left, format, arglist);
 		va_end(arglist);

 		if (len < 0)
 			return git__throw(GIT_EOSERR, "Failed to format string");

 		if ((size_t)len + 1 <= space_left) {
 			file->buf_pos += len;
 			return GIT_SUCCESS;
 		}

 		if ((error = flush_buffer(file)) < GIT_SUCCESS)
 			return git__rethrow(error, "Failed to output to buffer");

 		space_left = file->buf_size - file->buf_pos;

 	} while ((size_t)len + 1 <= space_left);

 	tmp_buffer = git__malloc(len + 1);
 	if (!tmp_buffer)
 		return GIT_ENOMEM;

 	va_start(arglist, format);
 	len = p_vsnprintf(tmp_buffer, len + 1, format, arglist);
 	va_end(arglist);

 	if (len < 0) {
 		git__free(tmp_buffer);
 		return git__throw(GIT_EOSERR, "Failed to format string");
 	}

 	error = git_filebuf_write(file, tmp_buffer, len);
 	git__free(tmp_buffer);

 	return error;
 }
	/*
	* Copyright (C) 2009-2011 the libgit2 contributors
	*
	* This file is part of libgit2, distributed under the GNU GPL v2 with
	* a Linking Exception. For full terms see the included COPYING file.
	*/
	#include <stdarg.h>

	#include "common.h"
	#include "filebuf.h"
	#include "fileops.h"

	#define GIT_LOCK_FILE_MODE 0644

	static const size_t WRITE_BUFFER_SIZE = (4096 * 2);

	static int lock_file(git_filebuf *file, int flags)
	{
	if (git_path_exists(file->path_lock) == 0) {
	if (flags & GIT_FILEBUF_FORCE)
	p_unlink(file->path_lock);
	else
	return git__throw(GIT_EOSERR, "Failed to lock file");
	}

	/* create path to the file buffer is required */
	if (flags & GIT_FILEBUF_FORCE) {
	/* XXX: Should dirmode here be configurable? Or is 0777 always fine? */
	file->fd = git_futils_creat_locked_withpath(file->path_lock, 0777, GIT_LOCK_FILE_MODE);
	} else {
	file->fd = git_futils_creat_locked(file->path_lock, GIT_LOCK_FILE_MODE);
	}

	if (file->fd < 0)
	return git__throw(GIT_EOSERR, "Failed to create lock");

	if ((flags & GIT_FILEBUF_APPEND) && git_path_exists(file->path_original) == 0) {
	git_file source;
	char buffer[2048];
	size_t read_bytes;

	source = p_open(file->path_original, O_RDONLY);
	if (source < 0)
	return git__throw(GIT_EOSERR, "Failed to lock file. Could not open %s", file->path_original);

	while ((read_bytes = p_read(source, buffer, 2048)) > 0) {
	p_write(file->fd, buffer, read_bytes);
	if (file->digest)
	git_hash_update(file->digest, buffer, read_bytes);
	}

	p_close(source);
	}

	return GIT_SUCCESS;
	}

	void git_filebuf_cleanup(git_filebuf *file)
	{
	if (file->fd >= 0)
	p_close(file->fd);

	if (file->fd >= 0 && file->path_lock && git_path_exists(file->path_lock) == GIT_SUCCESS)
	p_unlink(file->path_lock);

	if (file->digest)
	git_hash_free_ctx(file->digest);

	if (file->buffer)
	git__free(file->buffer);

	/* use the presence of z_buf to decide if we need to deflateEnd */
	if (file->z_buf) {
	git__free(file->z_buf);
	deflateEnd(&file->zs);
	}

	if (file->path_original)
	git__free(file->path_original);
	if (file->path_lock)
	git__free(file->path_lock);

	memset(file, 0x0, sizeof(git_filebuf));
	file->fd = -1;
	}

	GIT_INLINE(int) flush_buffer(git_filebuf *file)
	{
	int result = file->write(file, file->buffer, file->buf_pos);
	file->buf_pos = 0;
	return result;
	}

	static int write_normal(git_filebuf file, void source, size_t len)
	{
	int result = 0;

	if (len > 0) {
	result = p_write(file->fd, (void *)source, len);
	if (file->digest)
	git_hash_update(file->digest, source, len);
	}

	return result;
	}

	static int write_deflate(git_filebuf file, void source, size_t len)
	{
	int result = Z_OK;
	z_stream *zs = &file->zs;

	if (len > 0 \|\| file->flush_mode == Z_FINISH) {
	zs->next_in = source;
	zs->avail_in = (uInt)len;

	do {
	size_t have;

	zs->next_out = file->z_buf;
	zs->avail_out = (uInt)file->buf_size;

	result = deflate(zs, file->flush_mode);
	if (result == Z_STREAM_ERROR)
	return git__throw(GIT_ERROR, "Failed to deflate input");

	have = file->buf_size - (size_t)zs->avail_out;

	if (p_write(file->fd, file->z_buf, have) < GIT_SUCCESS)
	return git__throw(GIT_EOSERR, "Failed to write to file");

	} while (zs->avail_out == 0);

	assert(zs->avail_in == 0);

	if (file->digest)
	git_hash_update(file->digest, source, len);
	}

	return GIT_SUCCESS;
	}

	int git_filebuf_open(git_filebuf file, const char path, int flags)
	{
	int error, compression;
	size_t path_len;

	assert(file && path);

	if (file->buffer)
	return git__throw(GIT_EINVALIDARGS, "Tried to reopen an open filebuf");

	memset(file, 0x0, sizeof(git_filebuf));

	file->buf_size = WRITE_BUFFER_SIZE;
	file->buf_pos = 0;
	file->fd = -1;

	/* Allocate the main cache buffer */
	file->buffer = git__malloc(file->buf_size);
	if (file->buffer == NULL){
	error = GIT_ENOMEM;
	goto cleanup;
	}

	/* If we are hashing on-write, allocate a new hash context */
	if (flags & GIT_FILEBUF_HASH_CONTENTS) {
	if ((file->digest = git_hash_new_ctx()) == NULL) {
	error = GIT_ENOMEM;
	goto cleanup;
	}
	}

	compression = flags >> GIT_FILEBUF_DEFLATE_SHIFT;

	/* If we are deflating on-write, */
	if (compression != 0) {
	/* Initialize the ZLib stream */
	if (deflateInit(&file->zs, compression) != Z_OK) {
	error = git__throw(GIT_EZLIB, "Failed to initialize zlib");
	goto cleanup;
	}

	/* Allocate the Zlib cache buffer */
	file->z_buf = git__malloc(file->buf_size);
	if (file->z_buf == NULL){
	error = GIT_ENOMEM;
	goto cleanup;
	}

	/* Never flush */
	file->flush_mode = Z_NO_FLUSH;
	file->write = &write_deflate;
	} else {
	file->write = &write_normal;
	}

	/* If we are writing to a temp file */
	if (flags & GIT_FILEBUF_TEMPORARY) {
	git_buf tmp_path = GIT_BUF_INIT;

	/* Open the file as temporary for locking */
	file->fd = git_futils_mktmp(&tmp_path, path);
	if (file->fd < 0) {
	git_buf_free(&tmp_path);
	error = GIT_EOSERR;
	goto cleanup;
	}

	/* No original path */
	file->path_original = NULL;
	file->path_lock = git_buf_detach(&tmp_path);

	if (file->path_lock == NULL) {
	error = GIT_ENOMEM;
	goto cleanup;
	}
	} else {
	path_len = strlen(path);

	/* Save the original path of the file */
	file->path_original = git__strdup(path);
	if (file->path_original == NULL) {
	error = GIT_ENOMEM;
	goto cleanup;
	}

	/* create the locking path by appending ".lock" to the original */
	file->path_lock = git__malloc(path_len + GIT_FILELOCK_EXTLENGTH);
	if (file->path_lock == NULL) {
	error = GIT_ENOMEM;
	goto cleanup;
	}

	memcpy(file->path_lock, file->path_original, path_len);
	memcpy(file->path_lock + path_len, GIT_FILELOCK_EXTENSION, GIT_FILELOCK_EXTLENGTH);

	/* open the file for locking */
	if ((error = lock_file(file, flags)) < GIT_SUCCESS)
	goto cleanup;
	}

	return GIT_SUCCESS;

	cleanup:
	git_filebuf_cleanup(file);
	return git__rethrow(error, "Failed to open file buffer for '%s'", path);
	}

	int git_filebuf_hash(git_oid oid, git_filebuf file)
	{
	int error;

	assert(oid && file && file->digest);

	if ((error = flush_buffer(file)) < GIT_SUCCESS)
	return git__rethrow(error, "Failed to get hash for file");

	git_hash_final(oid, file->digest);
	git_hash_free_ctx(file->digest);
	file->digest = NULL;

	return GIT_SUCCESS;
	}

	int git_filebuf_commit_at(git_filebuf file, const char path, mode_t mode)
	{
	git__free(file->path_original);
	file->path_original = git__strdup(path);
	if (file->path_original == NULL)
	return GIT_ENOMEM;

	return git_filebuf_commit(file, mode);
	}

	int git_filebuf_commit(git_filebuf *file, mode_t mode)
	{
	int error;

	/* temporary files cannot be committed */
	assert(file && file->path_original);

	file->flush_mode = Z_FINISH;
	if ((error = flush_buffer(file)) < GIT_SUCCESS)
	goto cleanup;

	p_close(file->fd);
	file->fd = -1;

	if (p_chmod(file->path_lock, mode)) {
	error = git__throw(GIT_EOSERR, "Failed to chmod locked file before committing");
	goto cleanup;
	}

	error = p_rename(file->path_lock, file->path_original);

	cleanup:
	git_filebuf_cleanup(file);
	if (error < GIT_SUCCESS)
	return git__rethrow(error, "Failed to commit locked file from buffer");
	return GIT_SUCCESS;
	}

	GIT_INLINE(void) add_to_cache(git_filebuf file, const void buf, size_t len)
	{
	memcpy(file->buffer + file->buf_pos, buf, len);
	file->buf_pos += len;
	}

	int git_filebuf_write(git_filebuf file, const void buff, size_t len)
	{
	int error;
	const unsigned char *buf = buff;

	for (;;) {
	size_t space_left = file->buf_size - file->buf_pos;

	/* cache if it's small */
	if (space_left > len) {
	add_to_cache(file, buf, len);
	return GIT_SUCCESS;
	}

	add_to_cache(file, buf, space_left);

	if ((error = flush_buffer(file)) < GIT_SUCCESS)
	return git__rethrow(error, "Failed to write to buffer");

	len -= space_left;
	buf += space_left;
	}
	}

	int git_filebuf_reserve(git_filebuf file, void *buffer, size_t len)
	{
	int error;
	size_t space_left = file->buf_size - file->buf_pos;

	*buffer = NULL;

	if (len > file->buf_size)
	return GIT_ENOMEM;

	if (space_left <= len) {
	if ((error = flush_buffer(file)) < GIT_SUCCESS)
	return git__rethrow(error, "Failed to reserve buffer");
	}

	*buffer = (file->buffer + file->buf_pos);
	file->buf_pos += len;

	return GIT_SUCCESS;
	}

	int git_filebuf_printf(git_filebuf file, const char format, ...)
	{
	va_list arglist;
	size_t space_left;
	int len, error;
	char *tmp_buffer;

	space_left = file->buf_size - file->buf_pos;

	do {
	va_start(arglist, format);
	len = p_vsnprintf((char *)file->buffer + file->buf_pos, space_left, format, arglist);
	va_end(arglist);

	if (len < 0)
	return git__throw(GIT_EOSERR, "Failed to format string");

	if ((size_t)len + 1 <= space_left) {
	file->buf_pos += len;
	return GIT_SUCCESS;
	}

	if ((error = flush_buffer(file)) < GIT_SUCCESS)
	return git__rethrow(error, "Failed to output to buffer");

	space_left = file->buf_size - file->buf_pos;

	} while ((size_t)len + 1 <= space_left);

	tmp_buffer = git__malloc(len + 1);
	if (!tmp_buffer)
	return GIT_ENOMEM;

	va_start(arglist, format);
	len = p_vsnprintf(tmp_buffer, len + 1, format, arglist);
	va_end(arglist);

	if (len < 0) {
	git__free(tmp_buffer);
	return git__throw(GIT_EOSERR, "Failed to format string");
	}

	error = git_filebuf_write(file, tmp_buffer, len);
	git__free(tmp_buffer);

	return error;
	}