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refactor setxid return path to use __syscall_ret

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this avoids some spurious negation and duplicated errno logic, and
brings the code in line with the newly-added multithreaded setgroups.
This commit is contained in:
Rich Felker 2020-10-27 01:12:56 -04:00
parent ccba23459e
commit 613ccabeb0
1 changed files with 9 additions and 14 deletions
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23
src/unistd/setxid.c
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@ -1,20 +1,19 @@
#include <unistd.h> #include <unistd.h>
#include <errno.h> #include <signal.h>
#include "syscall.h" #include "syscall.h"
#include "libc.h" #include "libc.h"
#include "pthread_impl.h"
struct ctx { struct ctx {
int id, eid, sid; int id, eid, sid;
int nr, err; int nr, ret;
}; };
static void do_setxid(void *p) static void do_setxid(void *p)
{ {
struct ctx *c = p; struct ctx *c = p;
if (c->err>0) return; if (c->ret<0) return;
int ret = -__syscall(c->nr, c->id, c->eid, c->sid); int ret = __syscall(c->nr, c->id, c->eid, c->sid);
if (ret && !c->err) { if (ret && !c->ret) {
/* If one thread fails to set ids after another has already /* If one thread fails to set ids after another has already
* succeeded, forcibly killing the process is the only safe * succeeded, forcibly killing the process is the only safe
* thing to do. State is inconsistent and dangerous. Use * thing to do. State is inconsistent and dangerous. Use
@ -22,18 +21,14 @@ static void do_setxid(void *p)
__block_all_sigs(0); __block_all_sigs(0);
__syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL); __syscall(SYS_kill, __syscall(SYS_getpid), SIGKILL);
} }
c->err = ret; c->ret = ret;
} }
int __setxid(int nr, int id, int eid, int sid) int __setxid(int nr, int id, int eid, int sid)
{ {
/* err is initially nonzero so that failure of the first thread does not /* ret is initially nonzero so that failure of the first thread does not
* trigger the safety kill above. */ * trigger the safety kill above. */
struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .err = -1 }; struct ctx c = { .nr = nr, .id = id, .eid = eid, .sid = sid, .ret = 1 };
__synccall(do_setxid, &c); __synccall(do_setxid, &c);
if (c.err) { return __syscall_ret(c.ret);
if (c.err>0) errno = c.err;
return -1;
}
return 0;
} }