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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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28
config.c
View File

@ -431,7 +431,7 @@ static struct {
int do_not_match;
regex_t* value_regex;
int multi_replace;
off_t offset[MAX_MATCHES];
size_t offset[MAX_MATCHES];
enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
int seen;
} store;
@ -579,11 +579,11 @@ static int store_write_pair(int fd, const char* key, const char* value)
return 1;
}
static int find_beginning_of_line(const char* contents, int size,
int offset_, int* found_bracket)
static ssize_t find_beginning_of_line(const char* contents, size_t size,
size_t offset_, int* found_bracket)
{
int equal_offset = size, bracket_offset = size;
int offset;
size_t equal_offset = size, bracket_offset = size;
ssize_t offset;
for (offset = offset_-2; offset > 0
&& contents[offset] != '\n'; offset--)
@ -727,7 +727,8 @@ int git_config_set_multivar(const char* key, const char* value,
} else {
struct stat st;
char* contents;
int i, copy_begin, copy_end, new_line = 0;
size_t contents_sz, copy_begin, copy_end;
int i, new_line = 0;
if (value_regex == NULL)
store.value_regex = NULL;
@ -784,7 +785,8 @@ int git_config_set_multivar(const char* key, const char* value,
}
fstat(in_fd, &st);
contents = xmmap(NULL, st.st_size, PROT_READ,
contents_sz = xsize_t(st.st_size);
contents = xmmap(NULL, contents_sz, PROT_READ,
MAP_PRIVATE, in_fd, 0);
close(in_fd);
@ -793,12 +795,12 @@ int git_config_set_multivar(const char* key, const char* value,
for (i = 0, copy_begin = 0; i < store.seen; i++) {
if (store.offset[i] == 0) {
store.offset[i] = copy_end = st.st_size;
store.offset[i] = copy_end = contents_sz;
} else if (store.state != KEY_SEEN) {
copy_end = store.offset[i];
} else
copy_end = find_beginning_of_line(
contents, st.st_size,
contents, contents_sz,
store.offset[i]-2, &new_line);
/* write the first part of the config */
@ -825,13 +827,13 @@ int git_config_set_multivar(const char* key, const char* value,
}
/* write the rest of the config */
if (copy_begin < st.st_size)
if (copy_begin < contents_sz)
if (write_in_full(fd, contents + copy_begin,
st.st_size - copy_begin) <
st.st_size - copy_begin)
contents_sz - copy_begin) <
contents_sz - copy_begin)
goto write_err_out;
munmap(contents, st.st_size);
munmap(contents, contents_sz);
unlink(config_filename);
}