/* * 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_futils_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_futils_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_futils_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) { char tmp_path[GIT_PATH_MAX]; /* Open the file as temporary for locking */ file->fd = git_futils_mktmp(tmp_path, path); if (file->fd < 0) { error = GIT_EOSERR; goto cleanup; } /* No original path */ file->path_original = NULL; file->path_lock = git__strdup(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; }