GNU fileutils 4.0.35

lib/modechange.c

@@ -0,0 +1,445 @@
+/* modechange.c -- file mode manipulation
+   Copyright (C) 1989, 1990, 1997, 1998, 1999 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+/* Written by David MacKenzie <[email protected]> */
+
+/* The ASCII mode string is compiled into a linked list of `struct
+   modechange', which can then be applied to each file to be changed.
+   We do this instead of re-parsing the ASCII string for each file
+   because the compiled form requires less computation to use; when
+   changing the mode of many files, this probably results in a
+   performance gain. */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "modechange.h"
+#include <sys/stat.h>
+#include "xstrtol.h"
+
+#if STDC_HEADERS
+# include <stdlib.h>
+#else
+char *malloc ();
+#endif
+
+#ifndef NULL
+# define NULL 0
+#endif
+
+#if STAT_MACROS_BROKEN
+# undef S_ISDIR
+#endif
+
+#if !defined(S_ISDIR) && defined(S_IFDIR)
+# define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
+#endif
+
+#ifndef S_ISUID
+# define S_ISUID 04000
+#endif
+#ifndef S_ISGID
+# define S_ISGID 04000
+#endif
+#ifndef S_ISVTX
+# define S_ISVTX 01000
+#endif
+#ifndef S_IRUSR
+# define S_IRUSR 0400
+#endif
+#ifndef S_IWUSR
+# define S_IWUSR 0200
+#endif
+#ifndef S_IXUSR
+# define S_IXUSR 0100
+#endif
+#ifndef S_IRGRP
+# define S_IRGRP 0040
+#endif
+#ifndef S_IWGRP
+# define S_IWGRP 0020
+#endif
+#ifndef S_IXGRP
+# define S_IXGRP 0010
+#endif
+#ifndef S_IROTH
+# define S_IROTH 0004
+#endif
+#ifndef S_IWOTH
+# define S_IWOTH 0002
+#endif
+#ifndef S_IXOTH
+# define S_IXOTH 0001
+#endif
+#ifndef S_IRWXU
+# define S_IRWXU 0700
+#endif
+#ifndef S_IRWXG
+# define S_IRWXG 0070
+#endif
+#ifndef S_IRWXO
+# define S_IRWXO 0007
+#endif
+
+/* All the mode bits that can be affected by chmod.  */
+#define CHMOD_MODE_BITS \
+  (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
+
+/* Return newly allocated memory to hold one element of type TYPE. */
+#define talloc(type) ((type *) malloc (sizeof (type)))
+
+/* Create a mode_change entry with the specified `=ddd'-style
+   mode change operation, where NEW_MODE is `ddd'.  Return the
+   new entry, or NULL upon failure.  */
+
+static struct mode_change *
+make_node_op_equals (mode_t new_mode)
+{
+  struct mode_change *p;
+  p = talloc (struct mode_change);
+  if (p == NULL)
+    return p;
+  p->next = NULL;
+  p->op = '=';
+  p->flags = 0;
+  p->value = new_mode;
+  p->affected = CHMOD_MODE_BITS;	/* Affect all permissions. */
+  return p;
+}
+
+/* Append entry E to the end of the link list with the specified
+   HEAD and TAIL.  */
+
+static void
+mode_append_entry (struct mode_change **head,
+		   struct mode_change **tail,
+		   struct mode_change *e)
+{
+  if (*head == NULL)
+    *head = *tail = e;
+  else
+    {
+      (*tail)->next = e;
+      *tail = e;
+    }
+}
+
+/* Return a linked list of file mode change operations created from
+   MODE_STRING, an ASCII string that contains either an octal number
+   specifying an absolute mode, or symbolic mode change operations with
+   the form:
+   [ugoa...][[+-=][rwxXstugo...]...][,...]
+   MASKED_OPS is a bitmask indicating which symbolic mode operators (=+-)
+   should not affect bits set in the umask when no users are given.
+   Operators not selected in MASKED_OPS ignore the umask.
+
+   Return MODE_INVALID if `mode_string' does not contain a valid
+   representation of file mode change operations;
+   return MODE_MEMORY_EXHAUSTED if there is insufficient memory. */
+
+struct mode_change *
+mode_compile (const char *mode_string, unsigned int masked_ops)
+{
+  struct mode_change *head;	/* First element of the linked list. */
+  struct mode_change *tail;	/* An element of the linked list. */
+  uintmax_t mode_value;		/* The mode value, if octal.  */
+  char *string_end;		/* Pointer to end of parsed value.  */
+  mode_t umask_value;		/* The umask value (surprise). */
+
+  head = NULL;
+#ifdef lint
+  tail = NULL;
+#endif
+
+  if (xstrtoumax (mode_string, &string_end, 8, &mode_value, "") == LONGINT_OK)
+    {
+      struct mode_change *p;
+      if (mode_value != (mode_value & CHMOD_MODE_BITS))
+	return MODE_INVALID;
+      p = make_node_op_equals ((mode_t) mode_value);
+      if (p == NULL)
+	return MODE_MEMORY_EXHAUSTED;
+      mode_append_entry (&head, &tail, p);
+      return head;
+    }
+
+  umask_value = umask (0);
+  umask (umask_value);		/* Restore the old value. */
+  --mode_string;
+
+  /* One loop iteration for each "ugoa...=+-rwxXstugo...[=+-rwxXstugo...]". */
+  do
+    {
+      /* Which bits in the mode are operated on. */
+      mode_t affected_bits = 0;
+      /* `affected_bits' modified by umask. */
+      mode_t affected_masked;
+      /* Operators to actually use umask on. */
+      unsigned ops_to_mask = 0;
+
+      int who_specified_p;
+
+      affected_bits = 0;
+      ops_to_mask = 0;
+      /* Turn on all the bits in `affected_bits' for each group given. */
+      for (++mode_string;; ++mode_string)
+	switch (*mode_string)
+	  {
+	  case 'u':
+	    affected_bits |= S_ISUID | S_IRWXU;
+	    break;
+	  case 'g':
+	    affected_bits |= S_ISGID | S_IRWXG;
+	    break;
+	  case 'o':
+	    affected_bits |= S_ISVTX | S_IRWXO;
+	    break;
+	  case 'a':
+	    affected_bits |= CHMOD_MODE_BITS;
+	    break;
+	  default:
+	    goto no_more_affected;
+	  }
+
+    no_more_affected:
+      /* If none specified, affect all bits, except perhaps those
+	 set in the umask. */
+      if (affected_bits)
+	who_specified_p = 1;
+      else
+	{
+	  who_specified_p = 0;
+	  affected_bits = CHMOD_MODE_BITS;
+	  ops_to_mask = masked_ops;
+	}
+
+      while (*mode_string == '=' || *mode_string == '+' || *mode_string == '-')
+	{
+	  struct mode_change *change = talloc (struct mode_change);
+	  if (change == NULL)
+	    {
+	      mode_free (head);
+	      return MODE_MEMORY_EXHAUSTED;
+	    }
+
+	  change->next = NULL;
+	  change->op = *mode_string;	/* One of "=+-". */
+	  affected_masked = affected_bits;
+
+	  /* Per the Single Unix Spec, if `who' is not specified and the
+	     `=' operator is used, then clear all the bits first.  */
+	  if (!who_specified_p &&
+	      ops_to_mask & (*mode_string == '=' ? MODE_MASK_EQUALS : 0))
+	    {
+	      struct mode_change *p = make_node_op_equals (0);
+	      if (p == NULL)
+		return MODE_MEMORY_EXHAUSTED;
+	      mode_append_entry (&head, &tail, p);
+	    }
+
+	  if (ops_to_mask & (*mode_string == '=' ? MODE_MASK_EQUALS
+			     : *mode_string == '+' ? MODE_MASK_PLUS
+			     : MODE_MASK_MINUS))
+	    affected_masked &= ~umask_value;
+	  change->affected = affected_masked;
+	  change->value = 0;
+	  change->flags = 0;
+
+	  /* Add the element to the tail of the list, so the operations
+	     are performed in the correct order. */
+	  mode_append_entry (&head, &tail, change);
+
+	  /* Set `value' according to the bits set in `affected_masked'. */
+	  for (++mode_string;; ++mode_string)
+	    switch (*mode_string)
+	      {
+	      case 'r':
+		change->value |= ((S_IRUSR | S_IRGRP | S_IROTH)
+				  & affected_masked);
+		break;
+	      case 'w':
+		change->value |= ((S_IWUSR | S_IWGRP | S_IWOTH)
+				  & affected_masked);
+		break;
+	      case 'X':
+		change->flags |= MODE_X_IF_ANY_X;
+		/* Fall through. */
+	      case 'x':
+		change->value |= ((S_IXUSR | S_IXGRP | S_IXOTH)
+				  & affected_masked);
+		break;
+	      case 's':
+		/* Set the setuid/gid bits if `u' or `g' is selected. */
+		change->value |= (S_ISUID | S_ISGID) & affected_masked;
+		break;
+	      case 't':
+		/* Set the "save text image" bit if `o' is selected. */
+		change->value |= S_ISVTX & affected_masked;
+		break;
+	      case 'u':
+		/* Set the affected bits to the value of the `u' bits
+		   on the same file.  */
+		if (change->value)
+		  goto invalid;
+		change->value = S_IRWXU;
+		change->flags |= MODE_COPY_EXISTING;
+		break;
+	      case 'g':
+		/* Set the affected bits to the value of the `g' bits
+		   on the same file.  */
+		if (change->value)
+		  goto invalid;
+		change->value = S_IRWXG;
+		change->flags |= MODE_COPY_EXISTING;
+		break;
+	      case 'o':
+		/* Set the affected bits to the value of the `o' bits
+		   on the same file.  */
+		if (change->value)
+		  goto invalid;
+		change->value = S_IRWXO;
+		change->flags |= MODE_COPY_EXISTING;
+		break;
+	      default:
+		goto no_more_values;
+	      }
+	no_more_values:;
+	}
+  } while (*mode_string == ',');
+  if (*mode_string == 0)
+    return head;
+invalid:
+  mode_free (head);
+  return MODE_INVALID;
+}
+
+/* Return a file mode change operation that sets permissions to match those
+   of REF_FILE.  Return MODE_BAD_REFERENCE if REF_FILE can't be accessed.  */
+
+struct mode_change *
+mode_create_from_ref (const char *ref_file)
+{
+  struct mode_change *change;	/* the only change element */
+  struct stat ref_stats;
+
+  if (stat (ref_file, &ref_stats))
+    return MODE_BAD_REFERENCE;
+
+  change = talloc (struct mode_change);
+
+  if (change == NULL)
+    return MODE_MEMORY_EXHAUSTED;
+
+  change->op = '=';
+  change->flags = 0;
+  change->affected = CHMOD_MODE_BITS;
+  change->value = ref_stats.st_mode;
+  change->next = NULL;
+
+  return change;
+}
+
+/* Return file mode OLDMODE, adjusted as indicated by the list of change
+   operations CHANGES.  If OLDMODE is a directory, the type `X'
+   change affects it even if no execute bits were set in OLDMODE.
+   The returned value has the S_IFMT bits cleared. */
+
+mode_t
+mode_adjust (mode_t oldmode, const struct mode_change *changes)
+{
+  mode_t newmode;	/* The adjusted mode and one operand. */
+  mode_t value;		/* The other operand. */
+
+  newmode = oldmode & CHMOD_MODE_BITS;
+
+  for (; changes; changes = changes->next)
+    {
+      if (changes->flags & MODE_COPY_EXISTING)
+	{
+	  /* Isolate in `value' the bits in `newmode' to copy, given in
+	     the mask `changes->value'. */
+	  value = newmode & changes->value;
+
+	  if (changes->value & S_IRWXU)
+	    /* Copy `u' permissions onto `g' and `o'. */
+	    value |= ((value & S_IRUSR ? S_IRGRP | S_IROTH : 0)
+		      | (value & S_IWUSR ? S_IWGRP | S_IROTH : 0)
+		      | (value & S_IXUSR ? S_IXGRP | S_IXOTH : 0));
+	  else if (changes->value & S_IRWXG)
+	    /* Copy `g' permissions onto `u' and `o'. */
+	    value |= ((value & S_IRGRP ? S_IRUSR | S_IROTH : 0)
+		      | (value & S_IWGRP ? S_IWUSR | S_IROTH : 0)
+		      | (value & S_IXGRP ? S_IXUSR | S_IXOTH : 0));
+	  else
+	    /* Copy `o' permissions onto `u' and `g'. */
+	    value |= ((value & S_IROTH ? S_IRUSR | S_IRGRP : 0)
+		      | (value & S_IWOTH ? S_IWUSR | S_IRGRP : 0)
+		      | (value & S_IXOTH ? S_IXUSR | S_IXGRP : 0));
+
+	  /* In order to change only `u', `g', or `o' permissions,
+	     or some combination thereof, clear unselected bits.
+	     This can not be done in mode_compile because the value
+	     to which the `changes->affected' mask is applied depends
+	     on the old mode of each file. */
+	  value &= changes->affected;
+	}
+      else
+	{
+	  value = changes->value;
+	  /* If `X', do not affect the execute bits if the file is not a
+	     directory and no execute bits are already set. */
+	  if ((changes->flags & MODE_X_IF_ANY_X)
+	      && !S_ISDIR (oldmode)
+	      && (newmode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
+	    /* Clear the execute bits. */
+	    value &= ~ (S_IXUSR | S_IXGRP | S_IXOTH);
+	}
+
+      switch (changes->op)
+	{
+	case '=':
+	  /* Preserve the previous values in `newmode' of bits that are
+	     not affected by this change operation. */
+	  newmode = (newmode & ~changes->affected) | value;
+	  break;
+	case '+':
+	  newmode |= value;
+	  break;
+	case '-':
+	  newmode &= ~value;
+	  break;
+	}
+    }
+  return newmode;
+}
+
+/* Free the memory used by the list of file mode change operations
+   CHANGES. */
+
+void
+mode_free (register struct mode_change *changes)
+{
+  register struct mode_change *next;
+
+  while (changes)
+    {
+      next = changes->next;
+      free (changes);
+      changes = next;
+    }
+}