diff options
Diffstat (limited to 'src/util/filebuf.c')
| -rw-r--r-- | src/util/filebuf.c | 595 |
1 files changed, 595 insertions, 0 deletions
diff --git a/src/util/filebuf.c b/src/util/filebuf.c new file mode 100644 index 000000000..e014d43b2 --- /dev/null +++ b/src/util/filebuf.c @@ -0,0 +1,595 @@ +/* + * Copyright (C) the libgit2 contributors. All rights reserved. + * + * 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 "filebuf.h" + +#include "futils.h" + +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: + git_error_set(GIT_ERROR_OS, "failed to write out file"); + return -1; + + case BUFERR_MEM: + git_error_set_oom(); + return -1; + + case BUFERR_ZLIB: + git_error_set(GIT_ERROR_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_fs_path_exists(file->path_lock) == true) { + git_error_clear(); /* actual OS error code just confuses */ + git_error_set(GIT_ERROR_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_CREATE_LEADING_DIRS) { + /* 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_fs_path_exists(file->path_original) == true) { + git_file source; + char buffer[GIT_BUFSIZE_FILEIO]; + ssize_t read_bytes; + int error = 0; + + source = p_open(file->path_original, O_RDONLY); + if (source < 0) { + git_error_set(GIT_ERROR_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) { + git_error_set(GIT_ERROR_OS, "failed to read file '%s'", file->path_original); + return -1; + } else if (error < 0) { + git_error_set(GIT_ERROR_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_fs_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); + + GIT_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_str *out, const char *path) +{ + int i, error, root; + ssize_t ret; + struct stat st; + git_str curpath = GIT_STR_INIT, target = GIT_STR_INIT; + + if ((error = git_str_grow(&target, GIT_PATH_MAX + 1)) < 0 || + (error = git_str_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_str_puts(out, curpath.ptr); + goto cleanup; + } + + if (error < 0) { + git_error_set(GIT_ERROR_OS, "failed to stat '%s'", curpath.ptr); + error = -1; + goto cleanup; + } + + if (!S_ISLNK(st.st_mode)) { + error = git_str_puts(out, curpath.ptr); + goto cleanup; + } + + ret = p_readlink(curpath.ptr, target.ptr, GIT_PATH_MAX); + if (ret < 0) { + git_error_set(GIT_ERROR_OS, "failed to read symlink '%s'", curpath.ptr); + error = -1; + goto cleanup; + } + + if (ret == GIT_PATH_MAX) { + git_error_set(GIT_ERROR_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_fs_path_root(target.ptr); + if (root >= 0) { + if ((error = git_str_sets(&curpath, target.ptr)) < 0) + goto cleanup; + } else { + git_str dir = GIT_STR_INIT; + + if ((error = git_fs_path_dirname_r(&dir, curpath.ptr)) < 0) + goto cleanup; + + git_str_swap(&curpath, &dir); + git_str_dispose(&dir); + + if ((error = git_fs_path_apply_relative(&curpath, target.ptr)) < 0) + goto cleanup; + } + } + + git_error_set(GIT_ERROR_INVALID, "maximum symlink depth reached"); + error = -1; + +cleanup: + git_str_dispose(&curpath); + git_str_dispose(&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; + + GIT_ASSERT_ARG(file); + GIT_ASSERT_ARG(path); + GIT_ASSERT(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); + GIT_ERROR_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, GIT_HASH_ALGORITHM_SHA1) < 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) { + git_error_set(GIT_ERROR_ZLIB, "failed to initialize zlib"); + goto cleanup; + } + + /* Allocate the Zlib cache buffer */ + file->z_buf = git__malloc(file->buf_size); + GIT_ERROR_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_str tmp_path = GIT_STR_INIT; + + /* Open the file as temporary for locking */ + file->fd = git_futils_mktmp(&tmp_path, path, mode); + + if (file->fd < 0) { + git_str_dispose(&tmp_path); + goto cleanup; + } + file->fd_is_open = true; + file->created_lock = true; + + /* No original path */ + file->path_original = NULL; + file->path_lock = git_str_detach(&tmp_path); + GIT_ERROR_CHECK_ALLOC(file->path_lock); + } else { + git_str resolved_path = GIT_STR_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_str_detach(&resolved_path); + + /* create the locking path by appending ".lock" to the original */ + GIT_ERROR_CHECK_ALLOC_ADD(&alloc_len, path_len, GIT_FILELOCK_EXTLENGTH); + file->path_lock = git__malloc(alloc_len); + GIT_ERROR_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_fs_path_isdir(file->path_original)) { + git_error_set(GIT_ERROR_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(unsigned char *out, git_filebuf *file) +{ + GIT_ASSERT_ARG(out); + GIT_ASSERT_ARG(file); + GIT_ASSERT_ARG(file->compute_digest); + + flush_buffer(file); + + if (verify_last_error(file) < 0) + return -1; + + git_hash_final(out, &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); + GIT_ERROR_CHECK_ALLOC(file->path_original); + + return git_filebuf_commit(file); +} + +int git_filebuf_commit(git_filebuf *file) +{ + /* temporary files cannot be committed */ + GIT_ASSERT_ARG(file); + GIT_ASSERT(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) { + git_error_set(GIT_ERROR_OS, "failed to fsync '%s'", file->path_lock); + goto on_error; + } + + if (p_close(file->fd) < 0) { + git_error_set(GIT_ERROR_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) { + git_error_set(GIT_ERROR_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) { + git_error_set(GIT_ERROR_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; +} |