Save/restore errno in all safe wrappers

40 files changed, 152 insertions, 66 deletions

diff --git a/src/libenvexec/cspawn.c b/src/libenvexec/cspawn.c
index a6e1cc1..73efa0d 100644
--- a/src/libenvexec/cspawn.c
+++ b/src/libenvexec/cspawn.c
@@ -125,8 +125,10 @@ static inline pid_t cspawn_workaround (pid_t pid, int const *p)
   if (r == -1) return 0 ;
   if (r) return (errno = EILSEQ, 0) ;  /* child wrote, wtf */
 
+  int se = errno ;
   do e = waitid(P_PID, pid, &si, WEXITED | WNOHANG | WNOWAIT) ;
   while (e == -1 && errno == EINTR) ;
+  errno = se ;
   if (e == -1) return pid ;  /* we're in trouble, but don't leak a child */
   if (!si.si_pid) return pid ;  /* child is running */
   if (si.si_code != CLD_EXITED || si.si_status != 127) return pid ; /* child died after execve(), let caller handle it */
diff --git a/src/librandom/random_buf_early.c b/src/librandom/random_buf_early.c
index d14cd24..8af75b3 100644
--- a/src/librandom/random_buf_early.c
+++ b/src/librandom/random_buf_early.c
@@ -24,6 +24,7 @@ void random_buf_early (char *s, size_t n)
 {
   static int broken = 0 ;
   if (broken) goto bleh ;
+  int e = errno ;
   while (n)
   {
     ssize_t r = getrandom(s, n, GRND_INSECURE) ;
@@ -35,9 +36,11 @@ void random_buf_early (char *s, size_t n)
     s += r ;
     n -= r ;
   }
+  errno = e ;
   return ;
  breakit:
   broken = 1 ;
+  errno = e ;
  bleh:
   random_devurandom(s, n) ;
 }
diff --git a/src/libstddjb/dir_close.c b/src/libstddjb/dir_close.c
index 4c5d0cf..946f512 100644
--- a/src/libstddjb/dir_close.c
+++ b/src/libstddjb/dir_close.c
@@ -1,6 +1,7 @@
 /* ISC license. */
 
 #include <errno.h>
+
 #include <skalibs/direntry.h>
 
 void dir_close (DIR *dir)
diff --git a/src/libstddjb/fd_chdir.c b/src/libstddjb/fd_chdir.c
index f506ccc..e295017 100644
--- a/src/libstddjb/fd_chdir.c
+++ b/src/libstddjb/fd_chdir.c
@@ -2,13 +2,15 @@
 
 #include <unistd.h>
 #include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 int fd_chdir (int d)
 {
+  int e = errno ;
   int r ;
-  do
-    r = fchdir(d) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  do r = fchdir(d) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_chmod.c b/src/libstddjb/fd_chmod.c
index be0e0b8..e882711 100644
--- a/src/libstddjb/fd_chmod.c
+++ b/src/libstddjb/fd_chmod.c
@@ -1,16 +1,20 @@
 /* ISC license. */
 
  /* OpenBSD manages to bork the fchmod declaration */
+
 #include <skalibs/nonposix.h>
+
 #include <sys/stat.h>
 #include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 int fd_chmod (int fd, unsigned int mode)
 {
+  int e = errno ;
   int r ;
-  do
-    r = fchmod(fd, (mode_t)mode) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  do r = fchmod(fd, (mode_t)mode) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_chown.c b/src/libstddjb/fd_chown.c
index 80e98c7..7f2fcab 100644
--- a/src/libstddjb/fd_chown.c
+++ b/src/libstddjb/fd_chown.c
@@ -2,13 +2,15 @@
 
 #include <unistd.h>
 #include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 int fd_chown (int fd, uid_t uid, gid_t gid)
 {
+  int e = errno ;
   int r ;
-  do
-    r = fchown(fd, uid, gid) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  do r = fchown(fd, uid, gid) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_copy.c b/src/libstddjb/fd_copy.c
index 80b887e..1afad1f 100644
--- a/src/libstddjb/fd_copy.c
+++ b/src/libstddjb/fd_copy.c
@@ -2,14 +2,16 @@
 
 #include <unistd.h>
 #include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 int fd_copy (int to, int from)
 {
+  int e = errno ;
   int r ;
   if (to == from) return (errno = EINVAL, -1) ;
-  do
-    r = dup2(from, to) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  do r = dup2(from, to) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_move.c b/src/libstddjb/fd_move.c
index c35e4d6..09662aa 100644
--- a/src/libstddjb/fd_move.c
+++ b/src/libstddjb/fd_move.c
@@ -7,12 +7,13 @@
 
 int fd_move (int to, int from)
 {
+  int e = errno ;
   int r ;
   if (to == from) return uncoe(to) ;
-  do
-    r = dup2(from, to) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  do r = dup2(from, to) ;
+  while (r == -1 && errno == EINTR) ;
   if (r < 0) return r ;
+  errno = e ;
   fd_close(from) ;
   return 0 ;
 }
diff --git a/src/libstddjb/fd_read.c b/src/libstddjb/fd_read.c
index 43453b8..dc6f985 100644
--- a/src/libstddjb/fd_read.c
+++ b/src/libstddjb/fd_read.c
@@ -2,12 +2,15 @@
 
 #include <unistd.h>
 #include <errno.h>
+
 #include <skalibs/allreadwrite.h>
 
 ssize_t fd_read (int fd, char *buf, size_t len)
 {
+  int e = errno ;
   ssize_t r ;
   do r = read(fd, buf, len) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_readv.c b/src/libstddjb/fd_readv.c
index 0d384a4..10f2374 100644
--- a/src/libstddjb/fd_readv.c
+++ b/src/libstddjb/fd_readv.c
@@ -2,12 +2,15 @@
 
 #include <sys/uio.h>
 #include <errno.h>
+
 #include <skalibs/allreadwrite.h>
 
 ssize_t fd_readv (int fd, struct iovec const *v, unsigned int vlen)
 {
+  int e = errno ;
   ssize_t r ;
   do r = readv(fd, v, vlen) ;
   while ((r == -1) && (errno == EINTR)) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_recv.c b/src/libstddjb/fd_recv.c
index 7cca4de..dd56c73 100644
--- a/src/libstddjb/fd_recv.c
+++ b/src/libstddjb/fd_recv.c
@@ -2,12 +2,15 @@
 
 #include <sys/socket.h>
 #include <errno.h>
+
 #include <skalibs/allreadwrite.h>
 
 ssize_t fd_recv (int fd, char *buf, size_t len, unsigned int flags)
 {
+  int e = errno ;
   ssize_t r ;
   do r = recv(fd, buf, len, flags) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_send.c b/src/libstddjb/fd_send.c
index 6b6cd02..8727afa 100644
--- a/src/libstddjb/fd_send.c
+++ b/src/libstddjb/fd_send.c
@@ -2,12 +2,15 @@
 
 #include <sys/socket.h>
 #include <errno.h>
+
 #include <skalibs/allreadwrite.h>
 
 ssize_t fd_send (int fd, char const *buf, size_t len, unsigned int flags)
 {
+  int e = errno ;
   ssize_t r ;
   do r = send(fd, buf, len, flags) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_sync.c b/src/libstddjb/fd_sync.c
index 4506523..45247fe 100644
--- a/src/libstddjb/fd_sync.c
+++ b/src/libstddjb/fd_sync.c
@@ -7,8 +7,10 @@
 
 int fd_sync (int fd)
 {
+  int e = errno ;
   int r ;
   do r = fsync(fd) ;
   while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_write.c b/src/libstddjb/fd_write.c
index a93c2d9..96bdaf6 100644
--- a/src/libstddjb/fd_write.c
+++ b/src/libstddjb/fd_write.c
@@ -2,12 +2,15 @@
 
 #include <unistd.h>
 #include <errno.h>
+
 #include <skalibs/allreadwrite.h>
 
 ssize_t fd_write (int fd, char const *buf, size_t len)
 {
+  int e = errno ;
   ssize_t r ;
   do r = write(fd, buf, len) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/fd_writev.c b/src/libstddjb/fd_writev.c
index 61f7132..ce9dd17 100644
--- a/src/libstddjb/fd_writev.c
+++ b/src/libstddjb/fd_writev.c
@@ -2,12 +2,15 @@
 
 #include <sys/uio.h>
 #include <errno.h>
+
 #include <skalibs/allreadwrite.h>
 
 ssize_t fd_writev (int fd, struct iovec const *v, unsigned int vlen)
 {
+  int e = errno ;
   ssize_t r ;
   do r = writev(fd, v, vlen) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/iopause_stamp.c b/src/libstddjb/iopause_stamp.c
index a2ac8fa..890909b 100644
--- a/src/libstddjb/iopause_stamp.c
+++ b/src/libstddjb/iopause_stamp.c
@@ -1,22 +1,17 @@
 /* ISC license. */
 
 #include <errno.h>
+
 #include <skalibs/tai.h>
 #include <skalibs/iopause.h>
 
 int iopause_stamp (iopause_fd *x, unsigned int n, tain const *deadline, tain *stamp)
 {
+  int e = errno ;
   int r ;
-  do
-  {
-    r = iopause(x, n, deadline, stamp) ;
-    if (stamp)
-    {
-      int e = errno ;
-      tain_now(stamp) ;
-      errno = e ;
-    }
-  }
-  while ((r < 0) && (errno == EINTR)) ;
+  do r = iopause(x, n, deadline, stamp) ;
+  while (r == -1 && errno == EINTR) ;
+  if (stamp) tain_now(stamp) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/ipc_accept.c b/src/libstddjb/ipc_accept.c
index 83886ff..1a6f48d 100644
--- a/src/libstddjb/ipc_accept.c
+++ b/src/libstddjb/ipc_accept.c
@@ -2,6 +2,7 @@
 
 #include <skalibs/sysdeps.h>
 #include <skalibs/nonposix.h>
+
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <string.h>
@@ -14,33 +15,35 @@
 
 int ipc_accept_internal (int s, char *p, size_t l, int *trunc, unsigned int options)
 {
+  int e = errno ;
   struct sockaddr_un sa ;
   socklen_t dummy = sizeof sa ;
   int fd ;
   memset(&sa, 0, dummy) ;
   do
 #ifdef SKALIBS_HASACCEPT4
-    fd = accept4(s, (struct sockaddr *)&sa, &dummy, ((options & O_NONBLOCK) ? SOCK_NONBLOCK : 0) | ((options & O_CLOEXEC) ? SOCK_CLOEXEC : 0)) ;
+    fd = accept4(s, (struct sockaddr *)&sa, &dummy, (options & O_NONBLOCK ? SOCK_NONBLOCK : 0) | (options & O_CLOEXEC ? SOCK_CLOEXEC : 0)) ;
 #else
     fd = accept(s, (struct sockaddr *)&sa, &dummy) ;
 #endif
-  while ((fd == -1) && (errno == EINTR)) ;
+  while (fd == -1 && errno == EINTR) ;
   if (fd == -1) return -1 ;
 #ifndef SKALIBS_HASACCEPT4
-  if ((((options & O_NONBLOCK) ? ndelay_on(fd) : ndelay_off(fd)) < 0)
-   || (((options & O_CLOEXEC) ? coe(fd) : uncoe(fd)) < 0))
+  if (((options & O_NONBLOCK ? ndelay_on(fd) : ndelay_off(fd)) == -1)
+   || ((options & O_CLOEXEC ? coe(fd) : uncoe(fd)) == -1))
   {
     fd_close(fd) ;
     return -1 ;
   }
 #endif
+  errno = e ;
 
   if (p)
   {
     dummy = byte_chr(sa.sun_path, dummy, 0) ;
     *trunc = 1 ;
     if (!l) return fd ;
-    if (l < (dummy + 1)) dummy = l - 1 ;
+    if (l < dummy + 1) dummy = l - 1 ;
     else *trunc = 0 ;
     memcpy(p, sa.sun_path, dummy) ;
     p[dummy] = 0 ;
diff --git a/src/libstddjb/ipc_connect.c b/src/libstddjb/ipc_connect.c
index 7ccba09..339a0f0 100644
--- a/src/libstddjb/ipc_connect.c
+++ b/src/libstddjb/ipc_connect.c
@@ -1,6 +1,7 @@
 /* ISC license. */
 
 #include <skalibs/nonposix.h>
+
 #include <errno.h>
 #include <sys/socket.h>
 #include <sys/un.h>
diff --git a/src/libstddjb/ipc_recv.c b/src/libstddjb/ipc_recv.c
index 407b3cc..695a524 100644
--- a/src/libstddjb/ipc_recv.c
+++ b/src/libstddjb/ipc_recv.c
@@ -1,6 +1,7 @@
 /* ISC license. */
 
 #include <skalibs/nonposix.h>
+
 #include <string.h>
 #include <errno.h>
 #include <sys/socket.h>
@@ -11,14 +12,16 @@
 
 ssize_t ipc_recv (int fd, char *s, size_t len, char *path)
 {
+  int e = errno ;
   struct sockaddr_un sa = { .sun_family = AF_UNIX } ;
   socklen_t total = sizeof sa ;
   char tmp[len] ;
   ssize_t r ;
   do r = recvfrom(fd, tmp, len, 0, (struct sockaddr *)&sa, &total) ;
-  while ((r == -1) && (errno == EINTR)) ;
-  if (r < 0) return r ;
+  while (r == -1 && errno == EINTR) ;
+  if (r == -1) return r ;
   if (sa.sun_family != AF_UNIX) return (errno = EPROTO, -1) ;
+  errno = e ;
   if (path)
   {
     if (total == sizeof(sa_family_t)) path[0] = 0 ;
diff --git a/src/libstddjb/open2.c b/src/libstddjb/open2.c
index 0f23183..cf3e740 100644
--- a/src/libstddjb/open2.c
+++ b/src/libstddjb/open2.c
@@ -13,9 +13,11 @@
 
 int open2 (char const *s, unsigned int flags)
 {
+  int e = errno ;
   int r ;
   do r = open(s, flags) ;
   while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
 
@@ -23,6 +25,7 @@ int open2 (char const *s, unsigned int flags)
 
 int open2 (char const *s, unsigned int flags)
 {
+  int e = errno ;
   int fd ;
   do fd = open(s, flags & ~O_CLOEXEC) ;
   while (fd == -1 && errno == EINTR) ;
@@ -32,6 +35,7 @@ int open2 (char const *s, unsigned int flags)
     fd_close(fd) ;
     return -1 ;
   }
+  errno = e ;
   return fd ;
 }
 
diff --git a/src/libstddjb/open3.c b/src/libstddjb/open3.c
index a9ff9e6..b7e5a4e 100644
--- a/src/libstddjb/open3.c
+++ b/src/libstddjb/open3.c
@@ -13,9 +13,11 @@
 
 int open3 (char const *s, unsigned int flags, unsigned int mode)
 {
+  int e = errno ;
   int r ;
   do r = open(s, flags, mode) ;
   while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
 
@@ -23,6 +25,7 @@ int open3 (char const *s, unsigned int flags, unsigned int mode)
 
 int open3 (char const *s, unsigned int flags, unsigned int mode)
 {
+  int e = errno ;
   int fd ;
   do fd = open(s, flags & ~O_CLOEXEC, mode) ;
   while (fd == -1 && errno == EINTR) ;
@@ -32,6 +35,7 @@ int open3 (char const *s, unsigned int flags, unsigned int mode)
     fd_close(fd) ;
     return -1 ;
   }
+  errno = e ;
   return fd ;
 }
 
diff --git a/src/libstddjb/socket_accept4.c b/src/libstddjb/socket_accept4.c
index 0c11023..8045092 100644
--- a/src/libstddjb/socket_accept4.c
+++ b/src/libstddjb/socket_accept4.c
@@ -15,25 +15,27 @@
 
 int socket_accept4_internal (int s, char *ip, uint16_t *port, unsigned int options)
 {
+  int e = errno ;
   int fd ;
   struct sockaddr_in sa ;
   socklen_t dummy = sizeof sa ;
   do
 #ifdef SKALIBS_HASACCEPT4
-    fd = accept4(s, (struct sockaddr *)&sa, &dummy, ((options & O_NONBLOCK) ? SOCK_NONBLOCK : 0) | ((options & O_CLOEXEC) ? SOCK_CLOEXEC : 0)) ;
+    fd = accept4(s, (struct sockaddr *)&sa, &dummy, (options & O_NONBLOCK ? SOCK_NONBLOCK : 0) | (options & O_CLOEXEC ? SOCK_CLOEXEC : 0)) ;
 #else
     fd = accept(s, (struct sockaddr *)&sa, &dummy) ;
 #endif
-  while ((fd < 0) && (errno == EINTR)) ;
+  while (fd == -1 && errno == EINTR) ;
   if (fd < 0) return -1 ;
 #ifndef SKALIBS_HASACCEPT4
-  if ((((options & O_NONBLOCK) ? ndelay_on(fd) : ndelay_off(fd)) < 0)
-   || (((options & O_CLOEXEC) ? coe(fd) : uncoe(fd)) < 0))
+  if (((options & O_NONBLOCK ? ndelay_on(fd) : ndelay_off(fd)) == -1)
+   || ((options & O_CLOEXEC ? coe(fd) : uncoe(fd)) == -1))
   {
     fd_close(fd) ;
     return -1 ;
   }
 #endif
+  errno = e ;
   memcpy(ip, &sa.sin_addr.s_addr, 4) ;
   *port = uint16_big(sa.sin_port) ;
   return fd ;
diff --git a/src/libstddjb/socket_accept6.c b/src/libstddjb/socket_accept6.c
index 229178d..c20b8b1 100644
--- a/src/libstddjb/socket_accept6.c
+++ b/src/libstddjb/socket_accept6.c
@@ -18,25 +18,27 @@
 
 int socket_accept6_internal (int s, char *ip6, uint16_t *port, unsigned int options)
 {
+  int e = errno ;
   int fd ;
   struct sockaddr_in6 sa ;
   socklen_t dummy = sizeof sa ;
   do
 #ifdef SKALIBS_HASACCEPT4
-    fd = accept4(s, (struct sockaddr *)&sa, &dummy, ((options & O_NONBLOCK) ? SOCK_NONBLOCK : 0) | ((options & O_CLOEXEC) ? SOCK_CLOEXEC : 0)) ;
+    fd = accept4(s, (struct sockaddr *)&sa, &dummy, (options & O_NONBLOCK ? SOCK_NONBLOCK : 0) | (options & O_CLOEXEC ? SOCK_CLOEXEC : 0)) ;
 #else
     fd = accept(s, (struct sockaddr *)&sa, &dummy) ;
 #endif
-  while ((fd < 0) && (errno == EINTR)) ;
+  while (fd == -1 && errno == EINTR) ;
   if (fd < 0) return -1 ;
 #ifndef SKALIBS_HASACCEPT4
-  if ((((options & O_NONBLOCK) ? ndelay_on(fd) : ndelay_off(fd)) < 0)
-   || (((options & O_CLOEXEC) ? coe(fd) : uncoe(fd)) < 0))
+  if (((options & O_NONBLOCK ? ndelay_on(fd) : ndelay_off(fd)) == -1)
+   || ((options & O_CLOEXEC ? coe(fd) : uncoe(fd)) == -1))
   {
     fd_close(fd) ;
     return -1 ;
   }
 #endif
+  errno = e ;
   memcpy(ip6, sa.sin6_addr.s6_addr, 16) ;
   *port = uint16_big(sa.sin6_port) ;
   return fd ;
diff --git a/src/libstddjb/socket_connect4.c b/src/libstddjb/socket_connect4.c
index a6dcadf..634044e 100644
--- a/src/libstddjb/socket_connect4.c
+++ b/src/libstddjb/socket_connect4.c
@@ -12,6 +12,7 @@
 
 int socket_connect4 (int s, char const *ip, uint16_t port)
 {
+  int e = errno ;
   int r ;
   struct sockaddr_in sa ;
   memset(&sa, 0, sizeof sa) ;
@@ -19,7 +20,8 @@ int socket_connect4 (int s, char const *ip, uint16_t port)
   sa.sin_port = uint16_big(port) ;
   memcpy(&sa.sin_addr.s_addr, ip, 4) ;
   do r = connect(s, (struct sockaddr *)&sa, sizeof sa) ;
-  while ((r == -1) && (errno == EINTR)) ;
-  if ((r == -1) && (errno == EALREADY)) errno = EINPROGRESS ;
+  while (r == -1 && errno == EINTR) ;
+  if (r == -1 && errno == EALREADY) errno = EINPROGRESS ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/socket_connect6.c b/src/libstddjb/socket_connect6.c
index f5186e0..93bb164 100644
--- a/src/libstddjb/socket_connect6.c
+++ b/src/libstddjb/socket_connect6.c
@@ -15,6 +15,7 @@
 
 int socket_connect6 (int s, char const *ip6, uint16_t port)
 {
+  int e = errno ;
   struct sockaddr_in6 sa ;
   int r ;
   memset(&sa, 0, sizeof sa) ;
@@ -22,8 +23,9 @@ int socket_connect6 (int s, char const *ip6, uint16_t port)
   sa.sin6_port = uint16_big(port) ;
   memcpy(sa.sin6_addr.s6_addr, ip6, 16) ;
   do r = connect(s, (struct sockaddr *)&sa, sizeof sa) ;
-  while ((r == -1) && (errno == EINTR)) ;
-  if ((r == -1) && (errno == EALREADY)) errno = EINPROGRESS ;
+  while (r == -1 && errno == EINTR) ;
+  if (r == -1 && errno == EALREADY) errno = EINPROGRESS ;
+  if (r >= 0) errno = e ;
   return r ;
 }
 
diff --git a/src/libstddjb/socket_recv4.c b/src/libstddjb/socket_recv4.c
index afaaa9a..d9484bf 100644
--- a/src/libstddjb/socket_recv4.c
+++ b/src/libstddjb/socket_recv4.c
@@ -12,12 +12,14 @@
 
 ssize_t socket_recv4 (int s, char *buf, size_t len, char *ip, uint16_t *port)
 {
+  int e = errno ;
   ssize_t r ;
   struct sockaddr_in sa ;
   socklen_t dummy = sizeof sa ;
   do r = recvfrom(s, buf, len, 0, (struct sockaddr *)&sa, &dummy) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
   if (r == -1) return -1 ;
+  errno = e ;
   memcpy(ip, &sa.sin_addr, 4) ;
   *port = uint16_big(sa.sin_port) ;
   return r ;
diff --git a/src/libstddjb/socket_recv6.c b/src/libstddjb/socket_recv6.c
index fccb4f5..0c2112f 100644
--- a/src/libstddjb/socket_recv6.c
+++ b/src/libstddjb/socket_recv6.c
@@ -15,12 +15,14 @@
 
 ssize_t socket_recv6 (int s, char *buf, size_t len, char *ip6, uint16_t *port)
 {
+  int e = errno ;
   struct sockaddr_in6 sa ;
   socklen_t dummy = sizeof sa ;
   ssize_t r ;
   do r = recvfrom(s, buf, len, 0, (struct sockaddr *)&sa, &dummy) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
   if (r == -1) return -1 ;
+  errno = e ;
   memcpy(ip6, sa.sin6_addr.s6_addr, 16) ;
   *port = uint16_big(sa.sin6_port) ;
   return r ;
diff --git a/src/libstddjb/socket_send4.c b/src/libstddjb/socket_send4.c
index 81e991f..9252b11 100644
--- a/src/libstddjb/socket_send4.c
+++ b/src/libstddjb/socket_send4.c
@@ -12,6 +12,7 @@
 
 ssize_t socket_send4 (int s, char const *buf, size_t len, char const *ip, uint16_t port)
 {
+  int e = errno ;
   ssize_t r ;
   struct sockaddr_in sa ;
   memset(&sa, 0, sizeof sa) ;
@@ -19,6 +20,7 @@ ssize_t socket_send4 (int s, char const *buf, size_t len, char const *ip, uint16
   sa.sin_port = uint16_big(port) ;
   memcpy(&sa.sin_addr, ip, 4) ;
   do r = sendto(s, buf, len, 0, (struct sockaddr *)&sa, sizeof sa) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/socket_send6.c b/src/libstddjb/socket_send6.c
index 6eb276b..aa3b159 100644
--- a/src/libstddjb/socket_send6.c
+++ b/src/libstddjb/socket_send6.c
@@ -15,6 +15,7 @@
 
 ssize_t socket_send6 (int s, char const *buf, size_t len, char const *ip6, uint16_t port)
 {
+  int e = errno ;
   ssize_t r ;
   struct sockaddr_in6 sa ;
   memset(&sa, 0, sizeof sa) ;
@@ -22,7 +23,8 @@ ssize_t socket_send6 (int s, char const *buf, size_t len, char const *ip6, uint1
   sa.sin6_port = uint16_big(port) ;
   memcpy(sa.sin6_addr.s6_addr, ip6, 16) ;
   do r = sendto(s, buf, len, 0, (struct sockaddr *)&sa, sizeof sa) ;
-  while ((r == -1) && (errno == EINTR)) ;
+  while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
 
diff --git a/src/libstddjb/wait_nointr.c b/src/libstddjb/wait_nointr.c
index 4e7a17a..6b7d606 100644
--- a/src/libstddjb/wait_nointr.c
+++ b/src/libstddjb/wait_nointr.c
@@ -2,13 +2,15 @@
 
 #include <sys/wait.h>
 #include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 pid_t wait_nointr (int *wstat)
 {
+  int e = errno ;
   pid_t r ;
-  do
-    r = wait(wstat) ;
-  while ((r == (pid_t)-1) && (errno == EINTR)) ;
+  do r = wait(wstat) ;
+  while (r == (pid_t)-1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libstddjb/wait_reap.c b/src/libstddjb/wait_reap.c
index 051b11e..e0de653 100644
--- a/src/libstddjb/wait_reap.c
+++ b/src/libstddjb/wait_reap.c
@@ -1,11 +1,15 @@
 /* ISC license. */
 
+#include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 unsigned int wait_reap ()
 {
+  int e = errno ;
   unsigned int n = 0 ;
   int wstat ;
   while (wait_nohang(&wstat) > 0) n++ ;
+  errno = e ;
   return n ;
 }
diff --git a/src/libstddjb/waitpid_nointr.c b/src/libstddjb/waitpid_nointr.c
index 838359f..aa30342 100644
--- a/src/libstddjb/waitpid_nointr.c
+++ b/src/libstddjb/waitpid_nointr.c
@@ -2,12 +2,15 @@
 
 #include <sys/wait.h>
 #include <errno.h>
+
 #include <skalibs/djbunix.h>
 
 pid_t waitpid_nointr (pid_t pid, int *wstat, int flags)
 {
+  int e = errno ;
   pid_t r ;
   do r = waitpid(pid, wstat, flags) ;
-  while ((r == (pid_t)-1) && (errno == EINTR)) ;
+  while (r == (pid_t)-1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
diff --git a/src/libunixonacid/ancil_recv_fd.c b/src/libunixonacid/ancil_recv_fd.c
index 5ecbb31..0148a43 100644
--- a/src/libunixonacid/ancil_recv_fd.c
+++ b/src/libunixonacid/ancil_recv_fd.c
@@ -50,10 +50,12 @@ int ancil_recv_fd (int sock, char expected_ch)
     .msg_control = ancilbuf,
     .msg_controllen = CMSG_SPACE(sizeof(int))
   } ;
+  int e = errno ;
   do r = recvmsg(sock, &msghdr, awesomeflags) ;
   while (r < 0 && errno == EINTR) ;
   if (r < 0) return r ;
   if (!r) return (errno = EPIPE, -1) ;
+  errno = e ;
   c = CMSG_FIRSTHDR(&msghdr) ;
   if (ch != expected_ch
    || !c
@@ -62,7 +64,7 @@ int ancil_recv_fd (int sock, char expected_ch)
    || (size_t)(c->cmsg_len - (CMSG_DATA(c) - (unsigned char *)c)) != sizeof(int)) return (errno = EPROTO, -1) ;
   memcpy(&fd, CMSG_DATA(c), sizeof(int)) ;
 #ifndef SKALIBS_HASCMSGCLOEXEC
-  if (coe(fd) < 0)
+  if (coe(fd) == -1)
   {
     fd_close(fd) ;
     return -1 ;
diff --git a/src/libunixonacid/ancil_send_fd.c b/src/libunixonacid/ancil_send_fd.c
index 5573d5c..7258eb1 100644
--- a/src/libunixonacid/ancil_send_fd.c
+++ b/src/libunixonacid/ancil_send_fd.c
@@ -31,13 +31,15 @@ int ancil_send_fd (int sock, int fd, char ch)
     .msg_controllen = CMSG_SPACE(sizeof(int))
   } ;
   struct cmsghdr *c = CMSG_FIRSTHDR(&hdr) ;
+  int e = errno ;
   memset(hdr.msg_control, 0, hdr.msg_controllen) ;
   c->cmsg_level = SOL_SOCKET ;
   c->cmsg_type = SCM_RIGHTS ;
   c->cmsg_len = CMSG_LEN(sizeof(int)) ;
   memcpy(CMSG_DATA(c), &fd, sizeof(int)) ;
   do r = sendmsg(sock, &hdr, MSG_NOSIGNAL) ;
-  while (r < 0 && errno == EINTR) ;
+  while (r == -1 && errno == EINTR) ;
   if (r <= 0) return 0 ;
+  errno = e ;
   return 1 ;
 }
diff --git a/src/libunixonacid/open2_at.c b/src/libunixonacid/open2_at.c
index 3afc4fb..0b07f0e 100644
--- a/src/libunixonacid/open2_at.c
+++ b/src/libunixonacid/open2_at.c
@@ -18,9 +18,11 @@
 
 int open2_at (int dirfd, char const *file, int flags)
 {
+  int e = errno ;
   int fd ;
   do fd = openat(dirfd, file, flags) ;  /* all systems supporting openat() have O_CLOEXEC */
   while (fd == -1 && errno == EINTR) ;
+  if (fd >= 0) errno = e ;
   return fd ;
 }
 
diff --git a/src/libunixonacid/open3_at.c b/src/libunixonacid/open3_at.c
index a960339..d1d3f68 100644
--- a/src/libunixonacid/open3_at.c
+++ b/src/libunixonacid/open3_at.c
@@ -17,9 +17,11 @@
 
 int open3_at (int dirfd, char const *file, int flags, unsigned int mode)
 {
+  int e = errno ;
   int fd ;
   do fd = openat(dirfd, file, flags, mode) ; /* all systems that support openat() have O_CLOEXEC */
   while (fd == -1 && errno == EINTR) ;
+  if (fd >= 0) errno = e ;
   return fd ;
 }
 
diff --git a/src/libunixonacid/symlink_at.c b/src/libunixonacid/symlink_at.c
index 3919a80..3bf98f4 100644
--- a/src/libunixonacid/symlink_at.c
+++ b/src/libunixonacid/symlink_at.c
@@ -18,9 +18,11 @@
 
 int symlink_at (char const *src, int dirfd, char const *dst)
 {
+  int e = errno ;
   int r ;
   do r = symlinkat(src, dirfd, dst) ;
   while (r == -1 && errno == EINTR) ;
+  if (r >= 0) errno = e ;
   return r ;
 }
 
diff --git a/src/libunixonacid/unixmessage_receive.c b/src/libunixonacid/unixmessage_receive.c
index c3e1107..812f5b9 100644
--- a/src/libunixonacid/unixmessage_receive.c
+++ b/src/libunixonacid/unixmessage_receive.c
@@ -50,15 +50,17 @@ static int unixmessage_receiver_fill (unixmessage_receiver *b)
     .msg_control = b->fds_ok & 1 ? ancilbuf : 0,
     .msg_controllen = b->fds_ok & 1 ? CMSG_SPACE(b->auxb.a - 1) : 0
   } ;
+  int e = errno ;
   ssize_t r = -1 ;
   if (cbuffer_isfull(&b->mainb) || ((b->fds_ok & 1) && cbuffer_isfull(&b->auxb)))
     return (errno = ENOBUFS, -1) ;
   cbuffer_wpeek(&b->mainb, iov) ;
-  while (r < 0)
+  while (r == -1)
   {
     r = recvmsg(b->fd, &msghdr, awesomeflags) ;
-    if (!r || (r < 0 && errno != EINTR)) return r ;
+    if (!r || (r == -1 && errno != EINTR)) return r ;
   }
+  if (r > 0) errno = e ;
   if (b->fds_ok & 1)
   {
     struct cmsghdr *c = CMSG_FIRSTHDR(&msghdr) ;
@@ -78,7 +80,7 @@ static int unixmessage_receiver_fill (unixmessage_receiver *b)
       {
         size_t i = 0 ;
         for (; i < auxlen / sizeof(int) ; i++)
-          if (coe(((int *)CMSG_DATA(c))[i]) < 0)
+          if (coe(((int *)CMSG_DATA(c))[i]) == -1)
           {
             i++ ;
             while (i--) fd_close(((int *)CMSG_DATA(c))[i]) ;
diff --git a/src/libunixonacid/unixmessage_sender_flush.c b/src/libunixonacid/unixmessage_sender_flush.c
index 93bbbd7..35178b9 100644
--- a/src/libunixonacid/unixmessage_sender_flush.c
+++ b/src/libunixonacid/unixmessage_sender_flush.c
@@ -98,9 +98,11 @@ int unixmessage_sender_flush (unixmessage_sender *b)
         ((int *)CMSG_DATA(cp))[i] = fd < 0 ? -(fd+1) : fd ;
       }
     }
+    int e = errno ;
     do r = sendmsg(b->fd, &hdr, MSG_NOSIGNAL) ;
-    while (r < 0 && errno == EINTR) ;
+    while (r == -1 && errno == EINTR) ;
     if (r <= 0) return 0 ;
+    errno = e ;
     if (nfds)
     {
       size_t i = 0 ;
diff --git a/src/sysdeps/tryipv6.c b/src/sysdeps/tryipv6.c
index a1db92e..d7e073e 100644
--- a/src/sysdeps/tryipv6.c
+++ b/src/sysdeps/tryipv6.c
@@ -22,7 +22,7 @@ int main (void)
   s = socket(AF_INET6, SOCK_STREAM, 0) ;
   if (s < 0) return 111 ;
   do r = connect(s, (struct sockaddr *)&bar, sizeof bar) ;
-  while ((r == -1) && (errno == EINTR)) ;
-  if ((r == -1) && (errno == EALREADY)) errno = EINPROGRESS ;
+  while (r == -1 && errno == EINTR) ;
+  if (r == -1 && errno == EALREADY) errno = EINPROGRESS ;
   return 0 ;
 }