mgetgroups: new module, taken from coreutils

[pspp] / lib / at-func.c

diff --git a/lib/at-func.c b/lib/at-func.c
index 3188770c65fe2da485136ca967e3120b33779084..73be401a3e3f2b1c8ee8329287499023fc9aa07a 100644 (file)
--- a/lib/at-func.c
+++ b/lib/at-func.c
@@ -16,6 +16,11 @@
 
 /* written by Jim Meyering */
 
+#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+#include "openat.h"
+#include "openat-priv.h"
+#include "save-cwd.h"
+
 #ifdef AT_FUNC_USE_F1_COND
 # define CALL_FUNC(F)                          \
   (flag == AT_FUNC_USE_F1_COND                 \
@@ -25,7 +30,7 @@
   if (flag & ~AT_FUNC_USE_F1_COND)             \
     {                                          \
       errno = EINVAL;                          \
-      return -1;                               \
+      return FUNC_FAIL;                                \
     }
 #else
 # define CALL_FUNC(F) (AT_FUNC_F1 (F AT_FUNC_POST_FILE_ARGS))
@@ -38,11 +43,18 @@
 # define FUNC_RESULT int
 #endif
 
+#ifdef AT_FUNC_FAIL
+# define FUNC_FAIL AT_FUNC_FAIL
+#else
+# define FUNC_FAIL -1
+#endif
+
 /* Call AT_FUNC_F1 to operate on FILE, which is in the directory
    open on descriptor FD.  If AT_FUNC_USE_F1_COND is defined to a value,
    AT_FUNC_POST_FILE_PARAM_DECLS must inlude a parameter named flag;
    call AT_FUNC_F2 if FLAG is 0 or fail if FLAG contains more bits than
-   AT_FUNC_USE_F1_COND.  If possible, do it without changing the
+   AT_FUNC_USE_F1_COND.  Return int and fail with -1 unless AT_FUNC_RESULT
+   or AT_FUNC_FAIL are defined.  If possible, do it without changing the
    working directory.  Otherwise, resort to using save_cwd/fchdir,
    then AT_FUNC_F?/restore_cwd.  If either the save_cwd or the restore_cwd
    fails, then give a diagnostic and exit nonzero.  */
@@ -65,36 +77,45 @@ AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
     char *proc_file = openat_proc_name (proc_buf, fd, file);
     if (proc_file)
       {
-       FUNC_RESULT proc_result = CALL_FUNC (proc_file);
-       int proc_errno = errno;
-       if (proc_file != proc_buf)
-         free (proc_file);
-       /* If the syscall succeeds, or if it fails with an unexpected
-          errno value, then return right away.  Otherwise, fall through
-          and resort to using save_cwd/restore_cwd.  */
-       if (0 <= proc_result)
-         return proc_result;
-       if (! EXPECTED_ERRNO (proc_errno))
-         {
-           errno = proc_errno;
-           return proc_result;
-         }
+        FUNC_RESULT proc_result = CALL_FUNC (proc_file);
+        int proc_errno = errno;
+        if (proc_file != proc_buf)
+          free (proc_file);
+        /* If the syscall succeeds, or if it fails with an unexpected
+           errno value, then return right away.  Otherwise, fall through
+           and resort to using save_cwd/restore_cwd.  */
+        if (FUNC_FAIL != proc_result)
+          return proc_result;
+        if (! EXPECTED_ERRNO (proc_errno))
+          {
+            errno = proc_errno;
+            return proc_result;
+          }
       }
   }
 
   if (save_cwd (&saved_cwd) != 0)
     openat_save_fail (errno);
+  if (0 <= fd && fd == saved_cwd.desc)
+    {
+      /* If saving the working directory collides with the user's
+         requested fd, then the user's fd must have been closed to
+         begin with.  */
+      free_cwd (&saved_cwd);
+      errno = EBADF;
+      return FUNC_FAIL;
+    }
 
   if (fchdir (fd) != 0)
     {
       saved_errno = errno;
       free_cwd (&saved_cwd);
       errno = saved_errno;
-      return -1;
+      return FUNC_FAIL;
     }
 
   err = CALL_FUNC (file);
-  saved_errno = (err < 0 ? errno : 0);
+  saved_errno = (err == FUNC_FAIL ? errno : 0);
 
   if (restore_cwd (&saved_cwd) != 0)
     openat_restore_fail (errno);
@@ -107,3 +128,4 @@ AT_FUNC_NAME (int fd, char const *file AT_FUNC_POST_FILE_PARAM_DECLS)
 }
 #undef CALL_FUNC
 #undef FUNC_RESULT
+#undef FUNC_FAIL