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Cast 64 bit off_t to 32 bit size_t

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Some systems have sizeof(off_t) == 8 while sizeof(size_t) == 4.
This implies that we are able to access and work on files whose
maximum length is around 2^63-1 bytes, but we can only malloc or
mmap somewhat less than 2^32-1 bytes of memory.

On such a system an implicit conversion of off_t to size_t can cause
the size_t to wrap, resulting in unexpected and exciting behavior.
Right now we are working around all gcc warnings generated by the
-Wshorten-64-to-32 option by passing the off_t through xsize_t().

In the future we should make xsize_t on such problematic platforms
detect the wrapping and die if such a file is accessed.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Shawn O. Pearce
2007-03-06 20:44:37 -05:00
committed by Junio C Hamano
parent 6777a59fcd
commit dc49cd769b
16 changed files with 83 additions and 59 deletions
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7
diffcore-rename.c
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@ -172,7 +172,8 @@ static int estimate_similarity(struct diff_filespec *src,
return 0; /* error but caught downstream */
delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
delta_limit = (unsigned long)
(base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
if (diffcore_count_changes(src->data, src->size,
dst->data, dst->size,
&src->cnt_data, &dst->cnt_data,
@ -186,7 +187,7 @@ static int estimate_similarity(struct diff_filespec *src,
if (!dst->size)
score = 0; /* should not happen */
else
score = src_copied * MAX_SCORE / max_size;
score = (int)(src_copied * MAX_SCORE / max_size);
return score;
}
@ -297,7 +298,7 @@ void diffcore_rename(struct diff_options *options)
struct diff_filespec *one = rename_src[j].one;
if (!is_exact_match(one, two, contents_too))
continue;
record_rename_pair(i, j, MAX_SCORE);
record_rename_pair(i, j, (int)MAX_SCORE);
rename_count++;
break; /* we are done with this entry */
}