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gpgtar: Create extended header for long file names
* tools/gpgtar-create.c (global_header_count): new. (myreadlink): New. (build_header): New arg r_exthdr. Detect and store long file and link names. Factor checkum computation out to ... (compute_checksum): new. (add_extended_header_record): New. (write_extended_header): New. (write_file): Write extended header. -- GnuPG-bug-id: 5754
This commit is contained in:
Werner Koch
parent
f9c9938b28
commit
3a1c556b2c
@ -1,4 +1,6 @@
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/* gpgtar-create.c - Create a TAR archive
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* Copyright (C) 2016-2017, 2019-2022 g10 Code GmbH
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* Copyright (C) 2010, 2012, 2013 Werner Koch
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* Copyright (C) 2010 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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@ -39,6 +41,7 @@
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#include "../common/exectool.h"
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#include "../common/sysutils.h"
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#include "../common/ccparray.h"
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#include "../common/membuf.h"
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#include "gpgtar.h"
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#ifndef HAVE_LSTAT
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@ -46,6 +49,11 @@
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#endif
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/* Count the number of written headers. Extended headers are not
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* counted. */
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static unsigned long global_header_count;
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/* Object to control the file scanning. */
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struct scanctrl_s;
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typedef struct scanctrl_s *scanctrl_t;
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@ -488,7 +496,7 @@ store_xoctal (char *buffer, size_t length, unsigned long long value)
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size_t n;
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unsigned long long v;
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assert (length > 1);
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log_assert (length > 1);
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v = value;
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n = length;
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@ -593,16 +601,75 @@ store_gname (char *buffer, size_t length, unsigned long gid)
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}
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static void
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compute_checksum (void *record)
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{
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struct ustar_raw_header *raw = record;
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unsigned long chksum = 0;
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unsigned char *p;
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size_t n;
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memset (raw->checksum, ' ', sizeof raw->checksum);
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p = record;
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for (n=0; n < RECORDSIZE; n++)
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chksum += *p++;
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store_xoctal (raw->checksum, sizeof raw->checksum - 1, chksum);
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raw->checksum[7] = ' ';
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}
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/* Read a symlink without truncating it. Caller must release the
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* returned buffer. Returns NULL on error. */
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#ifndef HAVE_W32_SYSTEM
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static char *
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myreadlink (const char *name)
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{
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char *buffer;
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size_t size;
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int nread;
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for (size = 1024; size <= 65536; size *= 2)
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{
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buffer = xtrymalloc (size);
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if (!buffer)
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return NULL;
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nread = readlink (name, buffer, size - 1);
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if (nread < 0)
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{
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xfree (buffer);
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return NULL;
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}
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if (nread < size - 1)
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{
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buffer[nread] = 0;
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return buffer; /* Got it. */
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}
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xfree (buffer);
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}
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gpg_err_set_errno (ERANGE);
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return NULL;
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}
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#endif /*Unix*/
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/* Build a header. If the filename or the link name ist too long
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* allocate an exthdr and use a replacement file name in RECORD.
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* Caller should always release R_EXTHDR; this function initializes it
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* to point to NULL. */
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static gpg_error_t
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build_header (void *record, tar_header_t hdr)
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build_header (void *record, tar_header_t hdr, strlist_t *r_exthdr)
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{
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gpg_error_t err;
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struct ustar_raw_header *raw = record;
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size_t namelen, n;
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unsigned long chksum;
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unsigned char *p;
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strlist_t sl;
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memset (record, 0, RECORDSIZE);
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*r_exthdr = NULL;
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/* Store name and prefix. */
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namelen = strlen (hdr->name);
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@ -623,11 +690,24 @@ build_header (void *record, tar_header_t hdr)
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}
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else
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{
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err = gpg_error (GPG_ERR_TOO_LARGE);
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/* Too long - prepare extended header. */
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sl = add_to_strlist_try (r_exthdr, hdr->name);
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if (!sl)
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{
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err = gpg_error_from_syserror ();
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log_error ("error storing file '%s': %s\n",
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hdr->name, gpg_strerror (err));
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return err;
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}
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sl->flags = 1; /* Mark as path */
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/* The name we use is not POSIX compliant but because we
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* expect that (for security issues) a tarball will anyway
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* be extracted to a unique new directory, a simple counter
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* will do. To ease testing we also put in the PID. The
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* count is bumped after the header has been written. */
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snprintf (raw->name, sizeof raw->name-1, "_@paxheader.%u.%lu",
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(unsigned int)getpid(), global_header_count + 1);
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}
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}
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store_xoctal (raw->mode, sizeof raw->mode, hdr->mode);
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@ -659,6 +739,7 @@ build_header (void *record, tar_header_t hdr)
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if (hdr->typeflag == TF_SYMLINK)
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{
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int nread;
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char *p;
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nread = readlink (hdr->name, raw->linkname, sizeof raw->linkname -1);
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if (nread < 0)
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@ -669,22 +750,133 @@ build_header (void *record, tar_header_t hdr)
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return err;
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}
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raw->linkname[nread] = 0;
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if (nread == sizeof raw->linkname -1)
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{
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/* Truncated - read again and store as extended header. */
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p = myreadlink (hdr->name);
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if (!p)
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{
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err = gpg_error_from_syserror ();
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log_error ("error reading symlink '%s': %s\n",
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hdr->name, gpg_strerror (err));
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return err;
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}
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#endif /*HAVE_W32_SYSTEM*/
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/* Compute the checksum. */
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memset (raw->checksum, ' ', sizeof raw->checksum);
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chksum = 0;
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p = record;
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for (n=0; n < RECORDSIZE; n++)
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chksum += *p++;
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store_xoctal (raw->checksum, sizeof raw->checksum - 1, chksum);
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raw->checksum[7] = ' ';
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sl = add_to_strlist_try (r_exthdr, p);
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xfree (p);
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if (!sl)
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{
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err = gpg_error_from_syserror ();
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log_error ("error storing syslink '%s': %s\n",
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hdr->name, gpg_strerror (err));
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return err;
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}
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sl->flags = 2; /* Mark as linkname */
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}
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}
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#endif /*!HAVE_W32_SYSTEM*/
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compute_checksum (record);
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return 0;
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}
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/* Add an extended header record (NAME,VALUE) to the buffer MB. */
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static void
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add_extended_header_record (membuf_t *mb, const char *name, const char *value)
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{
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size_t n, n0, n1;
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char numbuf[35];
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size_t valuelen;
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/* To avoid looping in most cases, we guess the initial value. */
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valuelen = strlen (value);
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n1 = valuelen > 95? 3 : 2;
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do
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{
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n0 = n1;
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/* (3 for the space before name, the '=', and the LF.) */
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n = n0 + strlen (name) + valuelen + 3;
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snprintf (numbuf, sizeof numbuf, "%zu", n);
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n1 = strlen (numbuf);
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}
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while (n0 != n1);
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put_membuf_str (mb, numbuf);
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put_membuf (mb, " ", 1);
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put_membuf_str (mb, name);
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put_membuf (mb, "=", 1);
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put_membuf (mb, value, valuelen);
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put_membuf (mb, "\n", 1);
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}
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/* Write the extended header specified by EXTHDR to STREAM. */
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static gpg_error_t
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write_extended_header (estream_t stream, const void *record, strlist_t exthdr)
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{
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gpg_error_t err = 0;
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struct ustar_raw_header raw;
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strlist_t sl;
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membuf_t mb;
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char *buffer, *p;
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size_t buflen;
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init_membuf (&mb, 2*RECORDSIZE);
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for (sl=exthdr; sl; sl = sl->next)
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{
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if (sl->flags == 1)
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add_extended_header_record (&mb, "path", sl->d);
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else if (sl->flags == 2)
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add_extended_header_record (&mb, "linkpath", sl->d);
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}
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buffer = get_membuf (&mb, &buflen);
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if (!buffer)
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{
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err = gpg_error_from_syserror ();
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log_error ("error building extended header: %s\n", gpg_strerror (err));
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goto leave;
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}
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/* We copy the header from the standard header record, so that an
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* extracted extended header (using a non-pax aware software) is
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* written with the same properties as the original file. The real
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* entry will overwrite it anyway. Of course we adjust the size and
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* the type. */
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memcpy (&raw, record, RECORDSIZE);
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store_xoctal (raw.size, sizeof raw.size, buflen);
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raw.typeflag[0] = 'x'; /* Mark as extended header. */
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compute_checksum (&raw);
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err = write_record (stream, &raw);
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if (err)
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goto leave;
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for (p = buffer; buflen >= RECORDSIZE; p += RECORDSIZE, buflen -= RECORDSIZE)
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{
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err = write_record (stream, p);
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if (err)
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goto leave;
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}
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if (buflen)
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{
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/* Reuse RAW for builidng the last record. */
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memcpy (&raw, p, buflen);
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memset ((char*)&raw+buflen, 0, RECORDSIZE - buflen);
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err = write_record (stream, &raw);
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if (err)
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goto leave;
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}
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leave:
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xfree (buffer);
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return err;
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}
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static gpg_error_t
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write_file (estream_t stream, tar_header_t hdr)
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{
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@ -692,9 +884,10 @@ write_file (estream_t stream, tar_header_t hdr)
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char record[RECORDSIZE];
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estream_t infp;
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size_t nread, nbytes;
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strlist_t exthdr = NULL;
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int any;
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err = build_header (record, hdr);
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err = build_header (record, hdr, &exthdr);
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if (err)
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{
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if (gpg_err_code (err) == GPG_ERR_NOT_SUPPORTED)
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@ -719,9 +912,12 @@ write_file (estream_t stream, tar_header_t hdr)
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else
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infp = NULL;
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if (exthdr && (err = write_extended_header (stream, record, exthdr)))
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goto leave;
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err = write_record (stream, record);
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if (err)
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goto leave;
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global_header_count++;
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if (hdr->typeflag == TF_REGULAR)
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{
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@ -741,6 +937,8 @@ write_file (estream_t stream, tar_header_t hdr)
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any? " (file shrunk?)":"");
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goto leave;
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}
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else if (nbytes < RECORDSIZE)
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memset (record + nbytes, 0, RECORDSIZE - nbytes);
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any = 1;
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err = write_record (stream, record);
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if (err)
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@ -757,6 +955,7 @@ write_file (estream_t stream, tar_header_t hdr)
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else if ((err = es_fclose (infp)))
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log_error ("error closing file '%s': %s\n", hdr->name, gpg_strerror (err));
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free_strlist (exthdr);
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return err;
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}
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