xheader.c

gnu tar 源码包。 tar 软件是 Unix 系统下的一个打包软件

/* POSIX extended headers for tar.

   Copyright (C) 2003, 2004, 2005, 2006, 2007 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 3, 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.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <system.h>

#include <fnmatch.h>
#include <hash.h>
#include <inttostr.h>
#include <quotearg.h>

#include "common.h"

#include <fnmatch.h>

static bool xheader_protected_pattern_p (char const *pattern);
static bool xheader_protected_keyword_p (char const *keyword);
static void xheader_set_single_keyword (char *) __attribute__ ((noreturn));

/* Used by xheader_finish() */
static void code_string (char const *string, char const *keyword,
			 struct xheader *xhdr);

/* Number of global headers written so far. */
static size_t global_header_count;
/* FIXME: Possibly it should be reset after changing the volume.
   POSIX %n specification says that it is expanded to the sequence
   number of current global header in *the* archive. However, for
   multi-volume archives this will yield duplicate header names
   in different volumes, which I'd like to avoid. The best way
   to solve this would be to use per-archive header count as required
   by POSIX *and* set globexthdr.name to, say,
   $TMPDIR/GlobalHead.%p.$NUMVOLUME.%n.

   However it should wait until buffer.c is finally rewritten */


/* Interface functions to obstacks */

static void
x_obstack_grow (struct xheader *xhdr, const char *ptr, size_t length)
{
  obstack_grow (xhdr->stk, ptr, length);
  xhdr->size += length;
}

static void
x_obstack_1grow (struct xheader *xhdr, char c)
{
  obstack_1grow (xhdr->stk, c);
  xhdr->size++;
}

static void
x_obstack_blank (struct xheader *xhdr, size_t length)
{
  obstack_blank (xhdr->stk, length);
  xhdr->size += length;
}


/* Keyword options */

struct keyword_list
{
  struct keyword_list *next;
  char *pattern;
  char *value;
};


/* List of keyword patterns set by delete= option */
static struct keyword_list *keyword_pattern_list;

/* List of keyword/value pairs set by `keyword=value' option */
static struct keyword_list *keyword_global_override_list;

/* List of keyword/value pairs set by `keyword:=value' option */
static struct keyword_list *keyword_override_list;

/* List of keyword/value pairs decoded from the last 'g' type header */
static struct keyword_list *global_header_override_list;

/* Template for the name field of an 'x' type header */
static char *exthdr_name;

/* Template for the name field of a 'g' type header */
static char *globexthdr_name;

bool
xheader_keyword_deleted_p (const char *kw)
{
  struct keyword_list *kp;

  for (kp = keyword_pattern_list; kp; kp = kp->next)
    if (fnmatch (kp->pattern, kw, 0) == 0)
      return true;
  return false;
}

static bool
xheader_keyword_override_p (const char *keyword)
{
  struct keyword_list *kp;

  for (kp = keyword_override_list; kp; kp = kp->next)
    if (strcmp (kp->pattern, keyword) == 0)
      return true;
  return false;
}

static void
xheader_list_append (struct keyword_list **root, char const *kw,
		     char const *value)
{
  struct keyword_list *kp = xmalloc (sizeof *kp);
  kp->pattern = xstrdup (kw);
  kp->value = value ? xstrdup (value) : NULL;
  kp->next = *root;
  *root = kp;
}

static void
xheader_list_destroy (struct keyword_list **root)
{
  if (root)
    {
      struct keyword_list *kw = *root;
      while (kw)
	{
	  struct keyword_list *next = kw->next;
	  free (kw->pattern);
	  free (kw->value);
	  free (kw);
	  kw = next;
	}
      *root = NULL;
    }
}

static void
xheader_set_single_keyword (char *kw)
{
  USAGE_ERROR ((0, 0, _("Keyword %s is unknown or not yet implemented"), kw));
}

static void
xheader_set_keyword_equal (char *kw, char *eq)
{
  bool global = true;
  char *p = eq;

  if (eq[-1] == ':')
    {
      p--;
      global = false;
    }

  while (p > kw && isspace (*p))
    p--;

  *p = 0;

  for (p = eq + 1; *p && isspace (*p); p++)
    ;

  if (strcmp (kw, "delete") == 0)
    {
      if (xheader_protected_pattern_p (p))
	USAGE_ERROR ((0, 0, _("Pattern %s cannot be used"), quote (p)));
      xheader_list_append (&keyword_pattern_list, p, NULL);
    }
  else if (strcmp (kw, "exthdr.name") == 0)
    assign_string (&exthdr_name, p);
  else if (strcmp (kw, "globexthdr.name") == 0)
    assign_string (&globexthdr_name, p);
  else
    {
      if (xheader_protected_keyword_p (kw))
	USAGE_ERROR ((0, 0, _("Keyword %s cannot be overridden"), kw));
      if (global)
	xheader_list_append (&keyword_global_override_list, kw, p);
      else
	xheader_list_append (&keyword_override_list, kw, p);
    }
}

void
xheader_set_option (char *string)
{
  char *token;
  for (token = strtok (string, ","); token; token = strtok (NULL, ","))
    {
      char *p = strchr (token, '=');
      if (!p)
	xheader_set_single_keyword (token);
      else
	xheader_set_keyword_equal (token, p);
    }
}

/*
    string Includes:          Replaced By:
     %d                       The directory name of the file,
                              equivalent to the result of the
                              dirname utility on the translated
                              file name.
     %f                       The filename of the file, equivalent
                              to the result of the basename
                              utility on the translated file name.
     %p                       The process ID of the pax process.
     %n                       The value of the 3rd argument.
     %%                       A '%' character. */

char *
xheader_format_name (struct tar_stat_info *st, const char *fmt, size_t n)
{
  char *buf;
  size_t len = strlen (fmt);
  char *q;
  const char *p;
  char *dirp = NULL;
  char *dir = NULL;
  char *base = NULL;
  char pidbuf[UINTMAX_STRSIZE_BOUND];
  char const *pptr;
  char nbuf[UINTMAX_STRSIZE_BOUND];
  char const *nptr = NULL;

  for (p = fmt; *p && (p = strchr (p, '%')); )
    {
      switch (p[1])
	{
	case '%':
	  len--;
	  break;

	case 'd':
	  if (st)
	    {
	      if (!dirp)
		dirp = dir_name (st->orig_file_name);
	      dir = safer_name_suffix (dirp, false, absolute_names_option);
	      len += strlen (dir) - 2;
	    }
	  break;

	case 'f':
	  if (st)
	    {
	      base = last_component (st->orig_file_name);
	      len += strlen (base) - 2;
	    }
	  break;

	case 'p':
	  pptr = umaxtostr (getpid (), pidbuf);
	  len += pidbuf + sizeof pidbuf - 1 - pptr - 2;
	  break;

	case 'n':
	  nptr = umaxtostr (n, nbuf);
	  len += nbuf + sizeof nbuf - 1 - nptr - 2;
	  break;
	}
      p++;
    }

  buf = xmalloc (len + 1);
  for (q = buf, p = fmt; *p; )
    {
      if (*p == '%')
	{
	  switch (p[1])
	    {
	    case '%':
	      *q++ = *p++;
	      p++;
	      break;

	    case 'd':
	      if (dir)
		q = stpcpy (q, dir);
	      p += 2;
	      break;

	    case 'f':
	      if (base)
		q = stpcpy (q, base);
	      p += 2;
	      break;

	    case 'p':
	      q = stpcpy (q, pptr);
	      p += 2;
	      break;

	    case 'n':
	      if (nptr)
		{
		  q = stpcpy (q, nptr);
		  p += 2;
		  break;
		}
	      /* else fall through */

	    default:
	      *q++ = *p++;
	      if (*p)
		*q++ = *p++;
	    }
	}
      else
	*q++ = *p++;
    }

  free (dirp);

  /* Do not allow it to end in a slash */
  while (q > buf && ISSLASH (q[-1]))
    q--;
  *q = 0;
  return buf;
}

char *
xheader_xhdr_name (struct tar_stat_info *st)
{
  if (!exthdr_name)
    assign_string (&exthdr_name, "%d/PaxHeaders.%p/%f");
  return xheader_format_name (st, exthdr_name, 0);
}

#define GLOBAL_HEADER_TEMPLATE "/GlobalHead.%p.%n"

char *
xheader_ghdr_name (void)
{
  if (!globexthdr_name)
    {
      size_t len;
      const char *tmp = getenv ("TMPDIR");
      if (!tmp)
	tmp = "/tmp";
      len = strlen (tmp) + sizeof (GLOBAL_HEADER_TEMPLATE); /* Includes nul */
      globexthdr_name = xmalloc (len);
      strcpy(globexthdr_name, tmp);
      strcat(globexthdr_name, GLOBAL_HEADER_TEMPLATE);
    }

  return xheader_format_name (NULL, globexthdr_name, global_header_count + 1);
}

void
xheader_write (char type, char *name, struct xheader *xhdr)
{
  union block *header;
  size_t size;
  char *p;

  size = xhdr->size;
  header = start_private_header (name, size);
  header->header.typeflag = type;

  simple_finish_header (header);

  p = xhdr->buffer;

  do
    {
      size_t len;

      header = find_next_block ();
      len = BLOCKSIZE;
      if (len > size)
	len = size;
      memcpy (header->buffer, p, len);
      if (len < BLOCKSIZE)
	memset (header->buffer + len, 0, BLOCKSIZE - len);
      p += len;
      size -= len;
      set_next_block_after (header);
    }
  while (size > 0);
  xheader_destroy (xhdr);

  if (type == XGLTYPE)
    global_header_count++;
}

void
xheader_write_global (struct xheader *xhdr)
{
  char *name;
  struct keyword_list *kp;

  if (!keyword_global_override_list)
    return;

  xheader_init (xhdr);
  for (kp = keyword_global_override_list; kp; kp = kp->next)
    code_string (kp->value, kp->pattern, xhdr);
  xheader_finish (xhdr);
  xheader_write (XGLTYPE, name = xheader_ghdr_name (), xhdr);
  free (name);
}


/* General Interface */

struct xhdr_tab
{
  char const *keyword;
  void (*coder) (struct tar_stat_info const *, char const *,
		 struct xheader *, void const *data);
  void (*decoder) (struct tar_stat_info *, char const *, char const *, size_t);
  bool protect;
};

/* This declaration must be extern, because ISO C99 section 6.9.2
   prohibits a tentative definition that has both internal linkage and
   incomplete type.  If we made it static, we'd have to declare its
   size which would be a maintenance pain; if we put its initializer
   here, we'd need a boatload of forward declarations, which would be
   even more of a pain.  */
extern struct xhdr_tab const xhdr_tab[];

static struct xhdr_tab const *
locate_handler (char const *keyword)
{
  struct xhdr_tab const *p;

  for (p = xhdr_tab; p->keyword; p++)
    if (strcmp (p->keyword, keyword) == 0)
      return p;
  return NULL;
}

static bool
xheader_protected_pattern_p (const char *pattern)
{
  struct xhdr_tab const *p;

  for (p = xhdr_tab; p->keyword; p++)
    if (p->protect && fnmatch (pattern, p->keyword, 0) == 0)
      return true;
  return false;
}

static bool
xheader_protected_keyword_p (const char *keyword)
{
  struct xhdr_tab const *p;

  for (p = xhdr_tab; p->keyword; p++)
    if (p->protect && strcmp (p->keyword, keyword) == 0)
      return true;
  return false;
}

/* Decode a single extended header record, advancing *PTR to the next record.
   Return true on success, false otherwise.  */
static bool
decode_record (struct xheader *xhdr,
	       char **ptr,
	       void (*handler) (void *, char const *, char const *, size_t),
	       void *data)
{
  char *start = *ptr;
  char *p = start;
  uintmax_t u;
  size_t len;
  char *len_lim;
  char const *keyword;
  char *nextp;
  size_t len_max = xhdr->buffer + xhdr->size - start;

  while (*p == ' ' || *p == '\t')
    p++;

  if (! ISDIGIT (*p))
    {
      if (*p)
	ERROR ((0, 0, _("Malformed extended header: missing length")));
      return false;
    }

  errno = 0;
  len = u = strtoumax (p, &len_lim, 10);
  if (len != u || errno == ERANGE)
    {
      ERROR ((0, 0, _("Extended header length is out of allowed range")));