#include "common.h"

#include "filebuf.h"

#include "fileops.h"

static const size_t WRITE_BUFFER_SIZE = (4096 * 2);

enum buferr_t {

};

#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, mode_t mode)

{

if (git_path_exists(file->path_lock) == true) {

if (flags & GIT_FILEBUF_FORCE)

p_unlink(file->path_lock);

else {

giterr_clear(); /* actual OS error code just confuses */

giterr_set(GITERR_OS,

"failed to lock file '%s' for writing", file->path_lock);

return GIT_ELOCKED;

}

}

/* 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, mode);

} else {

file->fd = git_futils_creat_locked(file->path_lock, mode);

}

if (file->fd < 0)

return file->fd;

file->fd_is_open = true;

if ((flags & GIT_FILEBUF_APPEND) && git_path_exists(file->path_original) == true) {

git_file source;

char buffer[FILEIO_BUFSIZE];

ssize_t read_bytes;

int error = 0;

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, sizeof(buffer))) > 0) {

if ((error = p_write(file->fd, buffer, read_bytes)) < 0)

break;

if (file->compute_digest)

git_hash_update(&file->digest, buffer, read_bytes);

}

p_close(source);

if (read_bytes < 0) {

giterr_set(GITERR_OS, "failed to read file '%s'", file->path_original);

return -1;

} else if (error < 0) {

giterr_set(GITERR_OS, "failed to write file '%s'", file->path_lock);

return -1;

}

}

return 0;

}

void git_filebuf_cleanup(git_filebuf *file)

{

if (file->fd_is_open && file->fd >= 0)

p_close(file->fd);

if (file->created_lock && !file->did_rename && file->path_lock && git_path_exists(file->path_lock))

p_unlink(file->path_lock);

if (file->compute_digest) {

git_hash_ctx_cleanup(&file->digest);

file->compute_digest = 0;

}

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;

}

int git_filebuf_flush(git_filebuf *file)

{

return flush_buffer(file);

}

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->compute_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->compute_digest)

git_hash_update(&file->digest, source, len);

}

return 0;

}

#define MAX_SYMLINK_DEPTH 5

static int resolve_symlink(git_buf *out, const char *path)

{

int i, error, root;

ssize_t ret;

struct stat st;

git_buf curpath = GIT_BUF_INIT, target = GIT_BUF_INIT;

if ((error = git_buf_grow(&target, GIT_PATH_MAX + 1)) < 0 ||

(error = git_buf_puts(&curpath, path)) < 0)

return error;

for (i = 0; i < MAX_SYMLINK_DEPTH; i++) {

error = p_lstat(curpath.ptr, &st);

if (error < 0 && errno == ENOENT) {

error = git_buf_puts(out, curpath.ptr);

goto cleanup;

}

if (error < 0) {

giterr_set(GITERR_OS, "failed to stat '%s'", curpath.ptr);

error = -1;

goto cleanup;

}

if (!S_ISLNK(st.st_mode)) {

error = git_buf_puts(out, curpath.ptr);

goto cleanup;

}

ret = p_readlink(curpath.ptr, target.ptr, GIT_PATH_MAX);

if (ret < 0) {

giterr_set(GITERR_OS, "failed to read symlink '%s'", curpath.ptr);

error = -1;

goto cleanup;

}

if (ret == GIT_PATH_MAX) {

giterr_set(GITERR_INVALID, "symlink target too long");

error = -1;

goto cleanup;

}

/* readlink(2) won't NUL-terminate for us */

target.ptr[ret] = '\0';

target.size = ret;

root = git_path_root(target.ptr);

if (root >= 0) {

if ((error = git_buf_sets(&curpath, target.ptr)) < 0)

goto cleanup;

} else {

git_buf dir = GIT_BUF_INIT;

if ((error = git_path_dirname_r(&dir, curpath.ptr)) < 0)

goto cleanup;

git_buf_swap(&curpath, &dir);

git_buf_free(&dir);

if ((error = git_path_apply_relative(&curpath, target.ptr)) < 0)

goto cleanup;

}

}

giterr_set(GITERR_INVALID, "maximum symlink depth reached");

error = -1;

cleanup:

git_buf_free(&curpath);

git_buf_free(&target);

return error;

}

int git_filebuf_open(git_filebuf *file, const char *path, int flags, mode_t mode)

{

return git_filebuf_open_withsize(file, path, flags, mode, WRITE_BUFFER_SIZE);

}

int git_filebuf_open_withsize(git_filebuf *file, const char *path, int flags, mode_t mode, size_t size)

{

int compression, error = -1;

size_t path_len, alloc_len;

/* opening an already open buffer is a programming error;

assert(file && path && file->buffer == NULL);

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

if (flags & GIT_FILEBUF_DO_NOT_BUFFER)

file->do_not_buffer = true;

if (flags & GIT_FILEBUF_FSYNC)

file->do_fsync = true;

file->buf_size = size;

file->buf_pos = 0;

file->fd = -1;

file->last_error = BUFERR_OK;

/* Allocate the main cache buffer */

if (!file->do_not_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->compute_digest = 1;

if (git_hash_ctx_init(&file->digest) < 0)

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) {

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, mode);

if (file->fd < 0) {

git_buf_free(&tmp_path);

goto cleanup;

}

file->fd_is_open = true;

file->created_lock = true;

/* No original path */

file->path_original = NULL;

file->path_lock = git_buf_detach(&tmp_path);

GITERR_CHECK_ALLOC(file->path_lock);

} else {

git_buf resolved_path = GIT_BUF_INIT;

if ((error = resolve_symlink(&resolved_path, path)) < 0)

goto cleanup;

/* Save the original path of the file */

path_len = resolved_path.size;

file->path_original = git_buf_detach(&resolved_path);

/* create the locking path by appending ".lock" to the original */

GITERR_CHECK_ALLOC_ADD(&alloc_len, path_len, GIT_FILELOCK_EXTLENGTH);

file->path_lock = git__malloc(alloc_len);

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);

if (git_path_isdir(file->path_original)) {

giterr_set(GITERR_FILESYSTEM, "path '%s' is a directory", file->path_original);

error = GIT_EDIRECTORY;

goto cleanup;

}

/* open the file for locking */

if ((error = lock_file(file, flags, mode)) < 0)

goto cleanup;

file->created_lock = true;

}

return 0;

cleanup:

git_filebuf_cleanup(file);

return error;

}

int git_filebuf_hash(git_oid *oid, git_filebuf *file)

{

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

flush_buffer(file);

if (verify_last_error(file) < 0)

return -1;

git_hash_final(oid, &file->digest);

git_hash_ctx_cleanup(&file->digest);

file->compute_digest = 0;

return 0;

}

int git_filebuf_commit_at(git_filebuf *file, const char *path)

{

git__free(file->path_original);

file->path_original = git__strdup(path);

GITERR_CHECK_ALLOC(file->path_original);

return git_filebuf_commit(file);

}

int git_filebuf_commit(git_filebuf *file)

{

/* 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;

file->fd_is_open = false;

if (file->do_fsync && p_fsync(file->fd) < 0) {

giterr_set(GITERR_OS, "failed to fsync '%s'", file->path_lock);

goto on_error;

}

if (p_close(file->fd) < 0) {

giterr_set(GITERR_OS, "failed to close file at '%s'", file->path_lock);

goto on_error;

}

file->fd = -1;

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;

}

if (file->do_fsync && git_futils_fsync_parent(file->path_original) < 0)

goto on_error;

file->did_rename = true;

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);

if (file->do_not_buffer)

return file->write(file, (void *)buff, len);

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, len, alloclen;

int written, res;

char *tmp_buffer;

ENSURE_BUF_OK(file);

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

do {

va_start(arglist, format);

written = p_vsnprintf((char *)file->buffer + file->buf_pos, space_left, format, arglist);

va_end(arglist);

if (written < 0) {

file->last_error = BUFERR_MEM;

return -1;

}

len = written;

if (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 (len + 1 <= space_left);

if (GIT_ADD_SIZET_OVERFLOW(&alloclen, len, 1) ||

!(tmp_buffer = git__malloc(alloclen))) {

file->last_error = BUFERR_MEM;

return -1;

}

va_start(arglist, format);

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

va_end(arglist);

if (written < 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;

}

int git_filebuf_stats(time_t *mtime, size_t *size, git_filebuf *file)

{

int res;

struct stat st;

if (file->fd_is_open)

res = p_fstat(file->fd, &st);

else

res = p_stat(file->path_original, &st);

if (res < 0) {

giterr_set(GITERR_OS, "could not get stat info for '%s'",

file->path_original);

return res;

}

if (mtime)

*mtime = st.st_mtime;

if (size)

*size = (size_t)st.st_size;

return 0;

}