Skip to main content

Browse the archive

Revision b0e3e2d06ba3b71079d7b9b6402a0f410180c09b authored by Jeff King on 17 January 2023, 03:04:44 UTC, committed by Johannes Schindelin on 12 March 2023, 19:31:54 UTC 
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
 
The IOCTLFUNCTION option has been deprecated, and generates a compiler
warning in recent versions of curl. We can switch to using SEEKFUNCTION
instead. It was added in 2008 via curl 7.18.0; our INSTALL file already
indicates we require at least curl 7.19.4.

But there's one catch: curl says we should use CURL_SEEKFUNC_{OK,FAIL},
and those didn't arrive until 7.19.5. One workaround would be to use a
bare 0/1 here (or define our own macros).  But let's just bump the
minimum required version to 7.19.5. That version is only a minor version
bump from our existing requirement, and is only a 2 month time bump for
versions that are almost 13 years old. So it's not likely that anybody
cares about the distinction.

Switching means we have to rewrite the ioctl functions into seek
functions. In some ways they are simpler (seeking is the only
operation), but in some ways more complex (the ioctl allowed only a full
rewind, but now we can seek to arbitrary offsets).

Curl will only ever use SEEK_SET (per their documentation), so I didn't
bother implementing anything else, since it would naturally be
completely untested. This seems unlikely to change, but I added an
assertion just in case.

Likewise, I doubt curl will ever try to seek outside of the buffer sizes
we've told it, but I erred on the defensive side here, rather than do an
out-of-bounds read.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
1 parent fda237c
Raw File
copy.c 
#include "cache.h"

int copy_fd(int ifd, int ofd)
{
	while (1) {
		char buffer[8192];
		ssize_t len = xread(ifd, buffer, sizeof(buffer));
		if (!len)
			break;
		if (len < 0)
			return COPY_READ_ERROR;
		if (write_in_full(ofd, buffer, len) < 0)
			return COPY_WRITE_ERROR;
	}
	return 0;
}

static int copy_times(const char *dst, const char *src)
{
	struct stat st;
	struct utimbuf times;
	if (stat(src, &st) < 0)
		return -1;
	times.actime = st.st_atime;
	times.modtime = st.st_mtime;
	if (utime(dst, &times) < 0)
		return -1;
	return 0;
}

int copy_file(const char *dst, const char *src, int mode)
{
	int fdi, fdo, status;

	mode = (mode & 0111) ? 0777 : 0666;
	if ((fdi = open(src, O_RDONLY)) < 0)
		return fdi;
	if ((fdo = open(dst, O_WRONLY | O_CREAT | O_EXCL, mode)) < 0) {
		close(fdi);
		return fdo;
	}
	status = copy_fd(fdi, fdo);
	switch (status) {
	case COPY_READ_ERROR:
		error_errno("copy-fd: read returned");
		break;
	case COPY_WRITE_ERROR:
		error_errno("copy-fd: write returned");
		break;
	}
	close(fdi);
	if (close(fdo) != 0)
		return error_errno("%s: close error", dst);

	if (!status && adjust_shared_perm(dst))
		return -1;

	return status;
}

int copy_file_with_time(const char *dst, const char *src, int mode)
{
	int status = copy_file(dst, src, mode);
	if (!status)
		return copy_times(dst, src);
	return status;
}
back to top