Add posix_spawn_file_actions_addchdir() support

Signed-off-by: Laurent Bercot <ska@appnovation.com>

5 files changed, 122 insertions, 14 deletions

diff --git a/configure b/configure
index 1e058c0..ff11ca6 100755
--- a/configure
+++ b/configure
@@ -642,6 +642,8 @@ choose cl getrandom 'getrandom()'
 choose cl grndinsecure 'GRND_INSECURE'
 choose cl chroot 'chroot()'
 choose cl posixspawnsetsid 'POSIX_SPAWN_SETSID' $spawn_lib
+choose cl posixspawnchdir 'posix_spawn_file_actions_addchdir()' $spawn_lib
+choose cl posixspawnchdirnp 'posix_spawn_file_actions_addchdir_np()' $spawn_lib
 
 # Here are the evil irreducible run-time sysdeps.
 choose clr devurandom '/dev/urandom'
diff --git a/src/include/skalibs/cspawn.h b/src/include/skalibs/cspawn.h
index 01f6570..fa5c934 100644
--- a/src/include/skalibs/cspawn.h
+++ b/src/include/skalibs/cspawn.h
@@ -10,10 +10,15 @@
 #define CSPAWN_FLAGS_SIGBLOCKNONE 0x0002U
 #define CSPAWN_FLAGS_SETSID 0x0004U
 
-#define CSPAWN_FA_CLOSE 0x0000U
-#define CSPAWN_FA_COPY 0x0001U
-#define CSPAWN_FA_MOVE 0x0002U
-#define CSPAWN_FA_OPEN 0x0003U
+enum cspawn_fileaction_type_e
+{
+  CSPAWN_FA_CLOSE,
+  CSPAWN_FA_COPY,
+  CSPAWN_FA_MOVE,
+  CSPAWN_FA_OPEN,
+  CSPAWN_FA_CHDIR,
+  CSPAWN_FA_FCHDIR
+} ;
 
 struct cspawn_fa_openinfo_s
 {
@@ -27,20 +32,21 @@ union cspawn_fileaction_u
 {
   int fd ;
   int fd2[2] ;
+  char const *path ;
   struct cspawn_fa_openinfo_s openinfo ;
 } ;
 
 typedef struct cspawn_fileaction_s cspawn_fileaction, *cspawn_fileaction_ref ;
 struct cspawn_fileaction_s
 {
-  uint32_t type ;
+  enum cspawn_fileaction_type_e type ;
   union cspawn_fileaction_u x ;
 } ;
 
 
  /* Generic interface for posix_spawn() with a fork()+execve() fallback */
 
-extern pid_t cspawn (char const *, char const *const *, char const *const *, uint32_t, cspawn_fileaction const *, size_t) ;
+extern pid_t cspawn (char const *, char const *const *, char const *const *, uint16_t, cspawn_fileaction const *, size_t) ;
 
 
  /* Simple spawn functions with 0 or 1 communicating fds. */
diff --git a/src/libstddjb/cspawn.c b/src/libstddjb/cspawn.c
index 461ccd6..2baad0e 100644
--- a/src/libstddjb/cspawn.c
+++ b/src/libstddjb/cspawn.c
@@ -18,7 +18,7 @@
 
 #include <skalibs/cspawn.h>
 
-static inline void cspawn_child_exec (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n)
+static inline void cspawn_child_exec (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
 {
   for (size_t i = 0 ; i < n ; i++)
   {
@@ -38,6 +38,12 @@ static inline void cspawn_child_exec (char const *prog, char const *const *argv,
         if (fd_move(fa[i].x.openinfo.fd, fd) == -1) return ;
         break ;
       }
+      case CSPAWN_FA_CHDIR :
+        if (chdir(fa[i].x.path) == -1) return ;
+        break ;
+      case CSPAWN_FA_FCHDIR :
+        if (fchdir(fa[i].x.fd) == -1) return ;
+        break ;
       default :
         errno = EINVAL ; return ;
     }
@@ -50,7 +56,7 @@ static inline void cspawn_child_exec (char const *prog, char const *const *argv,
   exec_ae(prog, argv, envp) ;
 }
 
-static inline pid_t cspawn_fork (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n)
+static inline pid_t cspawn_fork (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
 {
   pid_t pid ;
   int p[2] ;
@@ -131,7 +137,7 @@ static inline pid_t cspawn_workaround (pid_t pid, int const *p)
 
 #endif
 
-static inline pid_t cspawn_pspawn (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n)
+static inline pid_t cspawn_pspawn (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
 {
   pid_t pid ;
   posix_spawnattr_t attr ;
@@ -192,6 +198,27 @@ static inline pid_t cspawn_pspawn (char const *prog, char const *const *argv, ch
           e = posix_spawn_file_actions_addopen(&actions, fa[i].x.openinfo.fd, fa[i].x.openinfo.file, fa[i].x.openinfo.oflag, fa[i].x.openinfo.mode) ;
           if (e) goto erractions ;
           break ;
+#ifdef SKALIBS_HASPOSIXSPAWNCHDIR
+        case CSPAWN_FA_CHDIR :
+          e = posix_spawn_file_actions_addchdir(&actions, fa[i].x.path) ;
+          if (e) goto erractions ;
+          break ;
+        case CSPAWN_FA_FCHDIR :
+          e = posix_spawn_file_actions_addfchdir(&actions, fa[i].x.fd) ;
+          if (e) goto erractions ;
+          break ;
+#else
+#ifdef SKALIBS_HASPOSIXSPAWNCHDIRNP
+        case CSPAWN_FA_CHDIR :
+          e = posix_spawn_file_actions_addchdir_np(&actions, fa[i].x.path) ;
+          if (e) goto erractions ;
+          break ;
+        case CSPAWN_FA_FCHDIR :
+          e = posix_spawn_file_actions_addfchdir_np(&actions, fa[i].x.fd) ;
+          if (e) goto erractions ;
+          break ;
+#endif
+#endif
         default :
           e = EINVAL ;
           goto erractions ;
@@ -225,25 +252,36 @@ static inline pid_t cspawn_pspawn (char const *prog, char const *const *argv, ch
   return 0 ;
 }
 
-#ifdef SKALIBS_HASPOSIXSPAWNSETSID
+#if defined(SKALIBS_HASPOSIXSPAWNSETSID) && (defined(SKALIBS_HASPOSIXSPAWNCHDIR) || defined(SKALIBS_HASPOSIXSPAWNCHDIRNP))
 
-pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n)
+pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
 {
   return cspawn_pspawn(prog, argv, envp, flags, fa, n) ;
 }
 
 #else
 
-pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n)
+pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
 {
-  return flags & CSPAWN_FLAGS_SETSID ? cspawn_fork(prog, argv, envp, flags, fa, n) : cspawn_pspawn(prog, argv, envp, flags, fa, n) ;
+#if !defined(SKALIBS_HASPOSIXSPAWNSETSID)
+  if (flags & CSPAWN_FLAGS_SETSID) goto dofork ;
+#endif
+#if !defined(SKALIBS_HASPOSIXSPAWNCHDIR) && !defined(SKALIBS_HASPOSIXSPAWNCHDIRNP)
+  for (size_t i = 0 ; i < n ; i++)
+    if (fa[i].type == CSPAWN_FA_CHDIR || fa[i].type == CSPAWN_FA_FCHDIR)
+      goto dofork ;
+#endif
+  return cspawn_pspawn(prog, argv, envp, flags, fa, n) ;
+
+ dofork:
+  return cspawn_fork(prog, argv, envp, flags, fa, n) ;
 }
 
 #endif
 
 #else
 
-pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n)
+pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint16_t flags, cspawn_fileaction const *fa, size_t n)
 {
   return cspawn_fork(prog, argv, envp, flags, fa, n) ;
 }
diff --git a/src/sysdeps/tryposixspawnchdir.c b/src/sysdeps/tryposixspawnchdir.c
new file mode 100644
index 0000000..7c08346
--- /dev/null
+++ b/src/sysdeps/tryposixspawnchdir.c
@@ -0,0 +1,31 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#ifndef _XPG4_2
+#define _XPG4_2
+#endif
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
+
+#include <spawn.h>
+
+int main (void)
+{
+  pid_t pid ;
+  posix_spawn_file_actions_t actions ;
+  posix_spawnattr_t attr ;
+  char *const argv[2] = { "/bin/true", 0 } ;
+  char *const envp[1] = { 0 } ;
+  posix_spawn_file_actions_init(&actions) ;
+  posix_spawn_file_actions_addchdir(&actions, "/") ;
+  posix_spawn_file_actions_addfchdir(&actions, -1) ;
+  return posix_spawn(&pid, argv[0], 0, 0, argv, envp) ;
+}
diff --git a/src/sysdeps/tryposixspawnchdirnp.c b/src/sysdeps/tryposixspawnchdirnp.c
new file mode 100644
index 0000000..19481f3
--- /dev/null
+++ b/src/sysdeps/tryposixspawnchdirnp.c
@@ -0,0 +1,31 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#ifndef _XPG4_2
+#define _XPG4_2
+#endif
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
+
+#include <spawn.h>
+
+int main (void)
+{
+  pid_t pid ;
+  posix_spawn_file_actions_t actions ;
+  posix_spawnattr_t attr ;
+  char *const argv[2] = { "/bin/true", 0 } ;
+  char *const envp[1] = { 0 } ;
+  posix_spawn_file_actions_init(&actions) ;
+  posix_spawn_file_actions_addchdir_np(&actions, "/") ;
+  posix_spawn_file_actions_addfchdir_np(&actions, -1) ;
+  return posix_spawn(&pid, argv[0], 0, 0, argv, envp) ;
+}