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cp: prefer signed types in copy-file-data.c

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* src/copy-file-data.c (sparse_copy, lseek_copy)
(copy_file_data): Prefer idx_t to size_t.
(copy_file_data): Defend against st_size < 0, which can happen on
ancient buggy platforms.  Check for overflow; the old code was
wrong on theoretical-but-valid hosts where SIZE_MAX <= INT_MAX.
This commit is contained in:
Paul Eggert
2025-08-06 12:11:34 -07:00
parent 12d03a0444
commit c80f6eebdf
1 changed files with 13 additions and 11 deletions
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24
src/copy-file-data.c
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@@ -110,7 +110,7 @@ is_CLONENOTSUP (int err)
If successful, return the number of bytes copied,
otherwise diagnose the failure and return -1. */
static intmax_t
sparse_copy (int src_fd, int dest_fd, char **abuf, size_t buf_size,
sparse_copy (int src_fd, int dest_fd, char **abuf, idx_t buf_size,
bool allow_reflink,
char const *src_name, char const *dst_name,
count_t max_n_read, off_t *hole_size,
@@ -206,7 +206,7 @@ sparse_copy (int src_fd, int dest_fd, char **abuf, size_t buf_size,
whole buffer. struct stat does not report the minimum hole
size for a file, so use ST_NBLOCKSIZE which should be the
minimum for all file systems on this platform. */
size_t csize = hole_size ? ST_NBLOCKSIZE : buf_size;
idx_t csize = hole_size ? ST_NBLOCKSIZE : buf_size;
char *cbuf = buf;
char *pbuf = buf;
@@ -315,7 +315,7 @@ write_zeros (int fd, off_t n_bytes, char **abuf, idx_t buf_size)
otherwise diagnose the failure and return -1. */
static off_t
lseek_copy (int src_fd, int dest_fd, char **abuf, size_t buf_size,
lseek_copy (int src_fd, int dest_fd, char **abuf, idx_t buf_size,
off_t src_pos, count_t ibytes,
struct scan_inference const *scan_inference, off_t src_total_size,
enum Sparse_type sparse_mode,
@@ -501,6 +501,8 @@ infer_scantype (int fd, struct stat const *sb, off_t pos,
/* Copy data from input file (descriptor IFD, status IST, initial file
offset IPOS, and name INAME) to output file (OFD, OST, OPOS, ONAME).
If IPOS and OPOS are negative, their values are not known, perhaps
because the files are not seekable so their positions are irrelevant.
Copy until IBYTES have been copied or until end of file;
if IBYTES is COUNT_MAX that suffices to copy to end of file.
Respect copy options X's sparse_mode and reflink_mode settings.
@@ -514,7 +516,7 @@ copy_file_data (int ifd, struct stat const *ist, off_t ipos, char const *iname,
count_t ibytes, struct cp_options const *x, struct copy_debug *debug)
{
/* Choose a suitable buffer size; it may be adjusted later. */
size_t buf_size = io_blksize (ost);
idx_t buf_size = io_blksize (ost);
/* Deal with sparse files. */
struct scan_inference scan_inference;
@@ -542,24 +544,24 @@ copy_file_data (int ifd, struct stat const *ist, off_t ipos, char const *iname,
{
/* Compute the least common multiple of the input and output
buffer sizes, adjusting for outlandish values.
blcm is at most IDX_MAX - 1 so that buf_size cannot become 0 below.
Note we read in multiples of the reported block size
to support (unusual) devices that have this constraint. */
size_t blcm_max = MIN (SIZE_MAX, SSIZE_MAX);
size_t blcm = buffer_lcm (io_blksize (ist), buf_size,
blcm_max);
idx_t blcm_max = MIN (MIN (IDX_MAX - 1, SSIZE_MAX), SIZE_MAX);
idx_t blcm = buffer_lcm (io_blksize (ist), buf_size,
blcm_max);
/* Do not bother with a buffer larger than the input file, plus one
byte to make sure the file has not grown while reading it. */
if (S_ISREG (ist->st_mode) && ist->st_size < buf_size)
if (S_ISREG (ist->st_mode) && 0 <= ist->st_size
&& ist->st_size < buf_size)
buf_size = ist->st_size + 1;
/* However, stick with a block size that is a positive multiple of
blcm, overriding the above adjustments. Watch out for
overflow. */
buf_size += blcm - 1;
buf_size = ckd_add (&buf_size, buf_size, blcm - 1) ? IDX_MAX : buf_size;
buf_size -= buf_size % blcm;
if (buf_size == 0 || blcm_max < buf_size)
buf_size = blcm;
}
char *buf = nullptr;