diff options
Diffstat (limited to 'vcs-svn')
| -rw-r--r-- | vcs-svn/LICENSE | 2 | ||||
| -rw-r--r-- | vcs-svn/sliding_window.c | 77 | ||||
| -rw-r--r-- | vcs-svn/sliding_window.h | 17 |
3 files changed, 96 insertions, 0 deletions
diff --git a/vcs-svn/LICENSE b/vcs-svn/LICENSE index 0a5e3c43a0..805882c838 100644 --- a/vcs-svn/LICENSE +++ b/vcs-svn/LICENSE @@ -1,6 +1,8 @@ Copyright (C) 2010 David Barr <david.barr@cordelta.com>. All rights reserved. +Copyright (C) 2010 Jonathan Nieder <jrnieder@gmail.com>. + Copyright (C) 2008 Jason Evans <jasone@canonware.com>. All rights reserved. diff --git a/vcs-svn/sliding_window.c b/vcs-svn/sliding_window.c new file mode 100644 index 0000000000..1b8d9875ed --- /dev/null +++ b/vcs-svn/sliding_window.c @@ -0,0 +1,77 @@ +/* + * Licensed under a two-clause BSD-style license. + * See LICENSE for details. + */ + +#include "git-compat-util.h" +#include "sliding_window.h" +#include "line_buffer.h" +#include "strbuf.h" + +static int input_error(struct line_buffer *file) +{ + if (!buffer_ferror(file)) + return error("delta preimage ends early"); + return error("cannot read delta preimage: %s", strerror(errno)); +} + +static int skip_or_whine(struct line_buffer *file, off_t gap) +{ + if (buffer_skip_bytes(file, gap) != gap) + return input_error(file); + return 0; +} + +static int read_to_fill_or_whine(struct line_buffer *file, + struct strbuf *buf, size_t width) +{ + buffer_read_binary(file, buf, width - buf->len); + if (buf->len != width) + return input_error(file); + return 0; +} + +static int check_overflow(off_t a, size_t b) +{ + if (b > maximum_signed_value_of_type(off_t)) + return error("unrepresentable length in delta: " + "%"PRIuMAX" > OFF_MAX", (uintmax_t) b); + if (signed_add_overflows(a, (off_t) b)) + return error("unrepresentable offset in delta: " + "%"PRIuMAX" + %"PRIuMAX" > OFF_MAX", + (uintmax_t) a, (uintmax_t) b); + return 0; +} + +int move_window(struct sliding_view *view, off_t off, size_t width) +{ + off_t file_offset; + assert(view); + assert(view->width <= view->buf.len); + assert(!check_overflow(view->off, view->buf.len)); + + if (check_overflow(off, width)) + return -1; + if (off < view->off || off + width < view->off + view->width) + return error("invalid delta: window slides left"); + + file_offset = view->off + view->buf.len; + if (off < file_offset) { + /* Move the overlapping region into place. */ + strbuf_remove(&view->buf, 0, off - view->off); + } else { + /* Seek ahead to skip the gap. */ + if (skip_or_whine(view->file, off - file_offset)) + return -1; + strbuf_setlen(&view->buf, 0); + } + + if (view->buf.len > width) + ; /* Already read. */ + else if (read_to_fill_or_whine(view->file, &view->buf, width)) + return -1; + + view->off = off; + view->width = width; + return 0; +} diff --git a/vcs-svn/sliding_window.h b/vcs-svn/sliding_window.h new file mode 100644 index 0000000000..ed0bfdd65c --- /dev/null +++ b/vcs-svn/sliding_window.h @@ -0,0 +1,17 @@ +#ifndef SLIDING_WINDOW_H_ +#define SLIDING_WINDOW_H_ + +#include "strbuf.h" + +struct sliding_view { + struct line_buffer *file; + off_t off; + size_t width; + struct strbuf buf; +}; + +#define SLIDING_VIEW_INIT(input) { (input), 0, 0, STRBUF_INIT } + +extern int move_window(struct sliding_view *view, off_t off, size_t width); + +#endif |