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3f790003a3
On 32-bit architectures with 64-bit file offsets, gcc 4.3 and earlier produce the following warning: CC vcs-svn/sliding_window.o vcs-svn/sliding_window.c: In function `check_overflow': vcs-svn/sliding_window.c:36: warning: comparison is always false \ due to limited range of data type The warning appears even when gcc is run without any warning flags (this is gcc bug 12963). In later versions the same warning can be reproduced with -Wtype-limits, which is implied by -Wextra. On 64-bit architectures it really is possible for a size_t not to be representable as an off_t so the check this is warning about is not actually redundant. But even false positives are distracting. Avoid the warning by making the "len" argument to check_overflow a uintmax_t; no functional change intended. Reported-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
80 lines
2 KiB
C
80 lines
2 KiB
C
/*
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* Licensed under a two-clause BSD-style license.
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* See LICENSE for details.
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*/
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#include "git-compat-util.h"
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#include "sliding_window.h"
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#include "line_buffer.h"
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#include "strbuf.h"
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static int input_error(struct line_buffer *file)
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{
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if (!buffer_ferror(file))
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return error("delta preimage ends early");
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return error("cannot read delta preimage: %s", strerror(errno));
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}
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static int skip_or_whine(struct line_buffer *file, off_t gap)
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{
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if (buffer_skip_bytes(file, gap) != gap)
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return input_error(file);
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return 0;
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}
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static int read_to_fill_or_whine(struct line_buffer *file,
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struct strbuf *buf, size_t width)
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{
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buffer_read_binary(file, buf, width - buf->len);
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if (buf->len != width)
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return input_error(file);
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return 0;
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}
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static int check_offset_overflow(off_t offset, uintmax_t len)
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{
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if (len > maximum_signed_value_of_type(off_t))
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return error("unrepresentable length in delta: "
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"%"PRIuMAX" > OFF_MAX", len);
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if (signed_add_overflows(offset, (off_t) len))
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return error("unrepresentable offset in delta: "
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"%"PRIuMAX" + %"PRIuMAX" > OFF_MAX",
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(uintmax_t) offset, len);
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return 0;
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}
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int move_window(struct sliding_view *view, off_t off, size_t width)
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{
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off_t file_offset;
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assert(view);
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assert(view->width <= view->buf.len);
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assert(!check_offset_overflow(view->off, view->buf.len));
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if (check_offset_overflow(off, width))
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return -1;
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if (off < view->off || off + width < view->off + view->width)
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return error("invalid delta: window slides left");
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if (view->max_off >= 0 && view->max_off < off + width)
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return error("delta preimage ends early");
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file_offset = view->off + view->buf.len;
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if (off < file_offset) {
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/* Move the overlapping region into place. */
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strbuf_remove(&view->buf, 0, off - view->off);
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} else {
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/* Seek ahead to skip the gap. */
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if (skip_or_whine(view->file, off - file_offset))
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return -1;
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strbuf_setlen(&view->buf, 0);
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}
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if (view->buf.len > width)
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; /* Already read. */
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else if (read_to_fill_or_whine(view->file, &view->buf, width))
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return -1;
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view->off = off;
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view->width = width;
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return 0;
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}
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