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#include "../git-compat-util.h"
#include "../wrapper.h"
ssize_t git_writev(int fd, const struct iovec *iov, int iovcnt)
{
size_t sum = 0;
if (iovcnt <= 0) {
errno = EINVAL;
return -1;
}
/*
* According to writev(3p), the syscall shall error with EINVAL in case
* the sum of `iov_len` overflows `ssize_t`.
*/
for (int i = 0; i < iovcnt; i++) {
if (iov[i].iov_len > maximum_signed_value_of_type(ssize_t) ||
unsigned_add_overflows(iov[i].iov_len, sum) ||
iov[i].iov_len + sum > maximum_signed_value_of_type(ssize_t)) {
errno = EINVAL;
return -1;
}
sum += iov[i].iov_len;
}
/*
* We only ever write the first non-empty vector so that we can
* guarantee the call to be non-interleaving as guaranteed by POSIX.
* This works just fine as callers have to loop around writev anyway.
*/
for (int i = 0; i < iovcnt; i++) {
if (!iov[i].iov_len)
continue;
return xwrite(fd, iov[i].iov_base, iov[i].iov_len);
}
/* When all iovec members were zero we ought to return 0 according to POSIX. */
return 0;
}
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