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/*
* Copyright (C) 2009-2012 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);
enum buferr_t {
BUFERR_OK = 0,
BUFERR_WRITE,
BUFERR_ZLIB,
BUFERR_MEM
};
#define ENSURE_BUF_OK(buf) if ((buf)->last_error != BUFERR_OK) { return -1; }
static int verify_last_error(git_filebuf *file)
{
switch (file->last_error) {
case BUFERR_WRITE:
giterr_set(GITERR_OS, "Failed to write out file");
return -1;
case BUFERR_MEM:
giterr_set_oom();
return -1;
case BUFERR_ZLIB:
giterr_set(GITERR_ZLIB,
"Buffer error when writing out ZLib data");
return -1;
default:
return 0;
}
}
static int lock_file(git_filebuf *file, int flags)
{
if (git_path_exists(file->path_lock) == true) {
if (flags & GIT_FILEBUF_FORCE)
p_unlink(file->path_lock);
else {
giterr_set(GITERR_OS,
"Failed to lock file '%s' for writing", file->path_lock);
return -1;
}
}
/* 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 -1;
file->fd_is_open = true;
if ((flags & GIT_FILEBUF_APPEND) && git_path_exists(file->path_original) == true) {
git_file source;
char buffer[2048];
size_t read_bytes;
source = p_open(file->path_original, O_RDONLY);
if (source < 0) {
giterr_set(GITERR_OS,
"Failed to open file '%s' for reading",
file->path_original);
return -1;
}
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 0;
}
void git_filebuf_cleanup(git_filebuf *file)
{
if (file->fd_is_open && file->fd >= 0)
p_close(file->fd);
if (file->fd_is_open && file->path_lock && git_path_exists(file->path_lock))
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)
{
if (len > 0) {
if (p_write(file->fd, (void *)source, len) < 0) {
file->last_error = BUFERR_WRITE;
return -1;
}
if (file->digest)
git_hash_update(file->digest, source, len);
}
return 0;
}
static int write_deflate(git_filebuf *file, void *source, size_t len)
{
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;
if (deflate(zs, file->flush_mode) == Z_STREAM_ERROR) {
file->last_error = BUFERR_ZLIB;
return -1;
}
have = file->buf_size - (size_t)zs->avail_out;
if (p_write(file->fd, file->z_buf, have) < 0) {
file->last_error = BUFERR_WRITE;
return -1;
}
} while (zs->avail_out == 0);
assert(zs->avail_in == 0);
if (file->digest)
git_hash_update(file->digest, source, len);
}
return 0;
}
int git_filebuf_open(git_filebuf *file, const char *path, int flags)
{
int compression;
size_t path_len;
/* opening an already open buffer is a programming error;
* assert that this never happens instead of returning
* an error code */
assert(file && path && file->buffer == NULL);
memset(file, 0x0, sizeof(git_filebuf));
file->buf_size = WRITE_BUFFER_SIZE;
file->buf_pos = 0;
file->fd = -1;
file->last_error = BUFERR_OK;
/* Allocate the main cache buffer */
file->buffer = git__malloc(file->buf_size);
GITERR_CHECK_ALLOC(file->buffer);
/* If we are hashing on-write, allocate a new hash context */
if (flags & GIT_FILEBUF_HASH_CONTENTS) {
file->digest = git_hash_new_ctx();
GITERR_CHECK_ALLOC(file->digest);
}
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) {
giterr_set(GITERR_ZLIB, "Failed to initialize zlib");
goto cleanup;
}
/* Allocate the Zlib cache buffer */
file->z_buf = git__malloc(file->buf_size);
GITERR_CHECK_ALLOC(file->z_buf);
/* 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);
goto cleanup;
}
file->fd_is_open = true;
/* No original path */
file->path_original = NULL;
file->path_lock = git_buf_detach(&tmp_path);
GITERR_CHECK_ALLOC(file->path_lock);
} else {
path_len = strlen(path);
/* Save the original path of the file */
file->path_original = git__strdup(path);
GITERR_CHECK_ALLOC(file->path_original);
/* create the locking path by appending ".lock" to the original */
file->path_lock = git__malloc(path_len + GIT_FILELOCK_EXTLENGTH);
GITERR_CHECK_ALLOC(file->path_lock);
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 (lock_file(file, flags) < 0)
goto cleanup;
}
return 0;
cleanup:
git_filebuf_cleanup(file);
return -1;
}
int git_filebuf_hash(git_oid *oid, git_filebuf *file)
{
assert(oid && file && file->digest);
flush_buffer(file);
if (verify_last_error(file) < 0)
return -1;
git_hash_final(oid, file->digest);
git_hash_free_ctx(file->digest);
file->digest = NULL;
return 0;
}
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);
GITERR_CHECK_ALLOC(file->path_original);
return git_filebuf_commit(file, mode);
}
int git_filebuf_commit(git_filebuf *file, mode_t mode)
{
/* temporary files cannot be committed */
assert(file && file->path_original);
file->flush_mode = Z_FINISH;
flush_buffer(file);
if (verify_last_error(file) < 0)
goto on_error;
p_close(file->fd);
file->fd = -1;
file->fd_is_open = false;
if (p_chmod(file->path_lock, mode)) {
giterr_set(GITERR_OS, "Failed to set attributes for file at '%s'", file->path_lock);
goto on_error;
}
p_unlink(file->path_original);
if (p_rename(file->path_lock, file->path_original) < 0) {
giterr_set(GITERR_OS, "Failed to rename lockfile to '%s'", file->path_original);
goto on_error;
}
git_filebuf_cleanup(file);
return 0;
on_error:
git_filebuf_cleanup(file);
return -1;
}
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)
{
const unsigned char *buf = buff;
ENSURE_BUF_OK(file);
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 0;
}
add_to_cache(file, buf, space_left);
if (flush_buffer(file) < 0)
return -1;
len -= space_left;
buf += space_left;
}
}
int git_filebuf_reserve(git_filebuf *file, void **buffer, size_t len)
{
size_t space_left = file->buf_size - file->buf_pos;
*buffer = NULL;
ENSURE_BUF_OK(file);
if (len > file->buf_size) {
file->last_error = BUFERR_MEM;
return -1;
}
if (space_left <= len) {
if (flush_buffer(file) < 0)
return -1;
}
*buffer = (file->buffer + file->buf_pos);
file->buf_pos += len;
return 0;
}
int git_filebuf_printf(git_filebuf *file, const char *format, ...)
{
va_list arglist;
size_t space_left;
int len, res;
char *tmp_buffer;
ENSURE_BUF_OK(file);
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) {
file->last_error = BUFERR_MEM;
return -1;
}
if ((size_t)len + 1 <= space_left) {
file->buf_pos += len;
return 0;
}
if (flush_buffer(file) < 0)
return -1;
space_left = file->buf_size - file->buf_pos;
} while ((size_t)len + 1 <= space_left);
tmp_buffer = git__malloc(len + 1);
if (!tmp_buffer) {
file->last_error = BUFERR_MEM;
return -1;
}
va_start(arglist, format);
len = p_vsnprintf(tmp_buffer, len + 1, format, arglist);
va_end(arglist);
if (len < 0) {
git__free(tmp_buffer);
file->last_error = BUFERR_MEM;
return -1;
}
res = git_filebuf_write(file, tmp_buffer, len);
git__free(tmp_buffer);
return res;
}
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