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nix-daemon: Don't splice with len=SIZE_MAX

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Currently, 'nix-daemon --stdio' is always failing for me, due to the
splice call always failing with (on a 32-bit host):

splice(0, NULL, 3, NULL, 4294967295, SPLICE_F_MOVE) = -1 EINVAL (Invalid argument)

With a bit of ftracing (and luck) the problem seems to be that splice()
always fails with EINVAL if the len cast as ssize_t is negative:
http://lxr.free-electrons.com/source/fs/read_write.c?v=4.4#L384

So use SSIZE_MAX instead of SIZE_MAX.
This commit is contained in:
Tuomas Tynkkynen 2017-02-13 15:06:46 +02:00
parent 4724903c78
commit 649a81bcd6
1 changed files with 3 additions and 2 deletions
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5
src/nix-daemon/nix-daemon.cc
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@ -23,6 +23,7 @@
#include <pwd.h> #include <pwd.h>
#include <grp.h> #include <grp.h>
#include <fcntl.h> #include <fcntl.h>
#include <limits.h>
#if __APPLE__ || __FreeBSD__ #if __APPLE__ || __FreeBSD__
#include <sys/ucred.h> #include <sys/ucred.h>
@ -967,14 +968,14 @@ int main(int argc, char * * argv)
if (select(nfds, &fds, nullptr, nullptr, nullptr) == -1) if (select(nfds, &fds, nullptr, nullptr, nullptr) == -1)
throw SysError("waiting for data from client or server"); throw SysError("waiting for data from client or server");
if (FD_ISSET(s, &fds)) { if (FD_ISSET(s, &fds)) {
auto res = splice(s, nullptr, STDOUT_FILENO, nullptr, SIZE_MAX, SPLICE_F_MOVE); auto res = splice(s, nullptr, STDOUT_FILENO, nullptr, SSIZE_MAX, SPLICE_F_MOVE);
if (res == -1) if (res == -1)
throw SysError("splicing data from daemon socket to stdout"); throw SysError("splicing data from daemon socket to stdout");
else if (res == 0) else if (res == 0)
throw EndOfFile("unexpected EOF from daemon socket"); throw EndOfFile("unexpected EOF from daemon socket");
} }
if (FD_ISSET(STDIN_FILENO, &fds)) { if (FD_ISSET(STDIN_FILENO, &fds)) {
auto res = splice(STDIN_FILENO, nullptr, s, nullptr, SIZE_MAX, SPLICE_F_MOVE); auto res = splice(STDIN_FILENO, nullptr, s, nullptr, SSIZE_MAX, SPLICE_F_MOVE);
if (res == -1) if (res == -1)
throw SysError("splicing data from stdin to daemon socket"); throw SysError("splicing data from stdin to daemon socket");
else if (res == 0) else if (res == 0)