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5b8bf02930
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 (PR12963). In later versions it 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 being warned 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>
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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