Implement execvpe.

There is some existing practice in other OSes and it's trivial to
implement giving the existing code.  Fixes BZ #10221.

1 files changed, 221 insertions, 0 deletions

diff --git a/posix/execvpe.c b/posix/execvpe.c
new file mode 100644
index 0000000..b4f40d3
--- /dev/null
+++ b/posix/execvpe.c
@@ -0,0 +1,221 @@
+/* Copyright (C) 1991,92, 1995-99, 2002, 2004, 2005, 2007, 2009
+   Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <alloca.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <paths.h>
+
+
+/* The file is accessible but it is not an executable file.  Invoke
+   the shell to interpret it as a script.  */
+static void
+internal_function
+scripts_argv (const char *file, char *const argv[], int argc, char **new_argv)
+{
+  /* Construct an argument list for the shell.  */
+  new_argv[0] = (char *) _PATH_BSHELL;
+  new_argv[1] = (char *) file;
+  while (argc > 1)
+    {
+      new_argv[argc] = argv[argc - 1];
+      --argc;
+    }
+}
+
+
+/* Execute FILE, searching in the `PATH' environment variable if it contains
+   no slashes, with arguments ARGV and environment from ENVP.  */
+int
+__execvpe (file, argv, envp)
+     const char *file;
+     char *const argv[];
+     char *const envp[];
+{
+  if (*file == '\0')
+    {
+      /* We check the simple case first. */
+      __set_errno (ENOENT);
+      return -1;
+    }
+
+  if (strchr (file, '/') != NULL)
+    {
+      /* Don't search when it contains a slash.  */
+      __execve (file, argv, envp);
+
+      if (errno == ENOEXEC)
+	{
+	  /* Count the arguments.  */
+	  int argc = 0;
+	  while (argv[argc++])
+	    ;
+	  size_t len = (argc + 1) * sizeof (char *);
+	  char **script_argv;
+	  void *ptr = NULL;
+	  if (__libc_use_alloca (len))
+	    script_argv = alloca (len);
+	  else
+	    script_argv = ptr = malloc (len);
+
+	  if (script_argv != NULL)
+	    {
+	      scripts_argv (file, argv, argc, script_argv);
+	      __execve (script_argv[0], script_argv, envp);
+
+	      free (ptr);
+	    }
+	}
+    }
+  else
+    {
+      size_t pathlen;
+      size_t alloclen = 0;
+      char *path = getenv ("PATH");
+      if (path == NULL)
+	{
+	  pathlen = confstr (_CS_PATH, (char *) NULL, 0);
+	  alloclen = pathlen + 1;
+	}
+      else
+	pathlen = strlen (path);
+
+      size_t len = strlen (file) + 1;
+      alloclen += pathlen + len + 1;
+
+      char *name;
+      char *path_malloc = NULL;
+      if (__libc_use_alloca (alloclen))
+	name = alloca (alloclen);
+      else
+	{
+	  path_malloc = name = malloc (alloclen);
+	  if (name == NULL)
+	    return -1;
+	}
+
+      if (path == NULL)
+	{
+	  /* There is no `PATH' in the environment.
+	     The default search path is the current directory
+	     followed by the path `confstr' returns for `_CS_PATH'.  */
+	  path = name + pathlen + len + 1;
+	  path[0] = ':';
+	  (void) confstr (_CS_PATH, path + 1, pathlen);
+	}
+
+      /* Copy the file name at the top.  */
+      name = (char *) memcpy (name + pathlen + 1, file, len);
+      /* And add the slash.  */
+      *--name = '/';
+
+      char **script_argv = NULL;
+      void *script_argv_malloc = NULL;
+      bool got_eacces = false;
+      char *p = path;
+      do
+	{
+	  char *startp;
+
+	  path = p;
+	  p = __strchrnul (path, ':');
+
+	  if (p == path)
+	    /* Two adjacent colons, or a colon at the beginning or the end
+	       of `PATH' means to search the current directory.  */
+	    startp = name + 1;
+	  else
+	    startp = (char *) memcpy (name - (p - path), path, p - path);
+
+	  /* Try to execute this name.  If it works, execve will not return. */
+	  __execve (startp, argv, envp);
+
+	  if (errno == ENOEXEC)
+	    {
+	      if (script_argv == NULL)
+		{
+		  /* Count the arguments.  */
+		  int argc = 0;
+		  while (argv[argc++])
+		    ;
+		  size_t arglen = (argc + 1) * sizeof (char *);
+		  if (__libc_use_alloca (alloclen + arglen))
+		    script_argv = alloca (arglen);
+		  else
+		    script_argv = script_argv_malloc = malloc (arglen);
+		  if (script_argv == NULL)
+		    {
+		      /* A possible EACCES error is not as important as
+			 the ENOMEM.  */
+		      got_eacces = false;
+		      break;
+		    }
+		  scripts_argv (startp, argv, argc, script_argv);
+		}
+
+	      __execve (script_argv[0], script_argv, envp);
+	    }
+
+	  switch (errno)
+	    {
+	    case EACCES:
+	      /* Record the we got a `Permission denied' error.  If we end
+		 up finding no executable we can use, we want to diagnose
+		 that we did find one but were denied access.  */
+	      got_eacces = true;
+	    case ENOENT:
+	    case ESTALE:
+	    case ENOTDIR:
+	      /* Those errors indicate the file is missing or not executable
+		 by us, in which case we want to just try the next path
+		 directory.  */
+	    case ENODEV:
+	    case ETIMEDOUT:
+	      /* Some strange filesystems like AFS return even
+		 stranger error numbers.  They cannot reasonably mean
+		 anything else so ignore those, too.  */
+	      break;
+
+	    default:
+	      /* Some other error means we found an executable file, but
+		 something went wrong executing it; return the error to our
+		 caller.  */
+	      return -1;
+	    }
+	}
+      while (*p++ != '\0');
+
+      /* We tried every element and none of them worked.  */
+      if (got_eacces)
+	/* At least one failure was due to permissions, so report that
+	   error.  */
+	__set_errno (EACCES);
+
+      free (script_argv_malloc);
+      free (path_malloc);
+    }
+
+  /* Return the error from the last attempt (probably ENOENT).  */
+  return -1;
+}
+weak_alias (__execvpe, execvpe)