src/libpspp/zip-writer.c

   1 /* PSPP - a program for statistical analysis.
   2    Copyright (C) 2010, 2012, 2014 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>. */
  16
  17 #include <config.h>
  18
  19 #include "libpspp/zip-writer.h"
  20 #include "libpspp/zip-private.h"
  21
  22 #include <byteswap.h>
  23 #include <errno.h>
  24 #include <stdlib.h>
  25 #include <time.h>
  26
  27 #include "gl/crc.h"
  28 #include "gl/fwriteerror.h"
  29 #include "gl/xalloc.h"
  30
  31 #include "libpspp/message.h"
  32
  33 #include "gettext.h"
  34 #define _(msgid) gettext (msgid)
  35
  36 struct zip_writer
  37   {
  38     char *file_name;            /* File name, for use in error mesages. */
  39     FILE *file;                 /* Output stream. */
  40
  41     uint16_t date, time;        /* Date and time in MS-DOS format. */
  42
  43     bool ok;
  44
  45     /* Members already added to the file, so that we can summarize them to the
  46        central directory at the end of the ZIP file. */
  47     struct zip_member *members;
  48     size_t n_members, allocated_members;
  49   };
  50
  51 struct zip_member
  52   {
  53     uint32_t offset;            /* Starting offset in file. */
  54     uint32_t size;              /* Length of member file data, in bytes. */
  55     uint32_t crc;               /* CRC-32 of member file data.. */
  56     char *name;                 /* Name of member file. */
  57   };
  58
  59 static void
  60 put_bytes (struct zip_writer *zw, const void *p, size_t n)
  61 {
  62   fwrite (p, 1, n, zw->file);
  63 }
  64
  65 static void
  66 put_u16 (struct zip_writer *zw, uint16_t x)
  67 {
  68 #ifdef WORDS_BIGENDIAN
  69   x = bswap_16 (x);
  70 #endif
  71   put_bytes (zw, &x, sizeof x);
  72 }
  73
  74 static void
  75 put_u32 (struct zip_writer *zw, uint32_t x)
  76 {
  77 #ifdef WORDS_BIGENDIAN
  78   x = bswap_32 (x);
  79 #endif
  80   put_bytes (zw, &x, sizeof x);
  81 }
  82
  83 /* Starts writing a new ZIP file named FILE_NAME.  Returns a new zip_writer if
  84    successful, otherwise a null pointer. */
  85 struct zip_writer *
  86 zip_writer_create (const char *file_name)
  87 {
  88   struct zip_writer *zw;
  89   struct tm *tm;
  90   time_t now;
  91   FILE *file;
  92
  93   file = fopen (file_name, "wb");
  94   if (file == NULL)
  95     {
  96       msg_error (errno, _("%s: error opening output file"), file_name);
  97       return NULL;
  98     }
  99
 100   zw = xmalloc (sizeof *zw);
 101   zw->file_name = xstrdup (file_name);
 102   zw->file = file;
 103
 104   zw->ok = true;
 105
 106   now = time (NULL);
 107   tm = localtime (&now);
 108   zw->date = tm->tm_mday + ((tm->tm_mon + 1) << 5) + ((tm->tm_year - 80) << 9);
 109   zw->time = tm->tm_sec / 2 + (tm->tm_min << 5) + (tm->tm_hour << 11);
 110
 111   zw->members = NULL;
 112   zw->n_members = 0;
 113   zw->allocated_members = 0;
 114
 115   return zw;
 116 }
 117
 118 static void
 119 put_local_header (struct zip_writer *zw, const char *member_name, uint32_t crc,
 120                   uint32_t size, int flag)
 121 {
 122   put_u32 (zw, MAGIC_LHDR);     /* local file header signature */
 123   put_u16 (zw, 10);             /* version needed to extract */
 124   put_u16 (zw, flag);           /* general purpose bit flag */
 125   put_u16 (zw, 0);              /* compression method */
 126   put_u16 (zw, zw->time);       /* last mod file time */
 127   put_u16 (zw, zw->date);       /* last mod file date */
 128   put_u32 (zw, crc);            /* crc-32 */
 129   put_u32 (zw, size);           /* compressed size */
 130   put_u32 (zw, size);           /* uncompressed size */
 131   put_u16 (zw, strlen (member_name)); /* file name length */
 132   put_u16 (zw, 0);                    /* extra field length */
 133   put_bytes (zw, member_name, strlen (member_name));
 134 }
 135
 136 /* Adds the contents of FILE, with name MEMBER_NAME, to ZW. */
 137 void
 138 zip_writer_add (struct zip_writer *zw, FILE *file, const char *member_name)
 139 {
 140   struct zip_member *member;
 141   uint32_t offset, size;
 142   size_t bytes_read;
 143   uint32_t crc;
 144   char buf[4096];
 145
 146   /* Local file header. */
 147   offset = ftello (zw->file);
 148   put_local_header (zw, member_name, 0, 0, 1 << 3);
 149
 150   /* File data. */
 151   size = crc = 0;
 152   fseeko (file, 0, SEEK_SET);
 153   while ((bytes_read = fread (buf, 1, sizeof buf, file)) > 0)
 154     {
 155       put_bytes (zw, buf, bytes_read);
 156       size += bytes_read;
 157       crc = crc32_update (crc, buf, bytes_read);
 158     }
 159
 160   /* Try to seek back to the local file header.  If successful, overwrite it
 161      with the correct file size and CRC.  Otherwise, write data descriptor. */
 162   if (fseeko (zw->file, offset, SEEK_SET) == 0)
 163     {
 164       put_local_header (zw, member_name, crc, size, 0);
 165       if (fseeko (zw->file, size, SEEK_CUR)
 166           && zw->ok)
 167         {
 168           msg_error (errno, _("%s: error seeking in output file"), zw->file_name);
 169           zw->ok = false;
 170         }
 171     }
 172   else
 173     {
 174       put_u32 (zw, MAGIC_DDHD);
 175       put_u32 (zw, crc);
 176       put_u32 (zw, size);
 177       put_u32 (zw, size);
 178     }
 179
 180   /* Add to set of members. */
 181   if (zw->n_members >= zw->allocated_members)
 182     zw->members = x2nrealloc (zw->members, &zw->allocated_members,
 183                               sizeof *zw->members);
 184   member = &zw->members[zw->n_members++];
 185   member->offset = offset;
 186   member->size = size;
 187   member->crc = crc;
 188   member->name = xstrdup (member_name);
 189 }
 190
 191 /* Finalizes the contents of ZW and closes it.  Returns true if successful,
 192    false if a write error occurred while finalizing the file or at any earlier
 193    time. */
 194 bool
 195 zip_writer_close (struct zip_writer *zw)
 196 {
 197   uint32_t dir_start, dir_end;
 198   size_t i;
 199   bool ok;
 200
 201   if (zw == NULL)
 202     return true;
 203
 204   dir_start = ftello (zw->file);
 205   for (i = 0; i < zw->n_members; i++)
 206     {
 207       struct zip_member *m = &zw->members[i];
 208
 209       /* Central directory file header. */
 210       put_u32 (zw, MAGIC_SOCD);       /* central file header signature */
 211       put_u16 (zw, 63);               /* version made by */
 212       put_u16 (zw, 10);               /* version needed to extract */
 213       put_u16 (zw, 1 << 3);           /* general purpose bit flag */
 214       put_u16 (zw, 0);                /* compression method */
 215       put_u16 (zw, zw->time);         /* last mod file time */
 216       put_u16 (zw, zw->date);         /* last mod file date */
 217       put_u32 (zw, m->crc);           /* crc-32 */
 218       put_u32 (zw, m->size);          /* compressed size */
 219       put_u32 (zw, m->size);          /* uncompressed size */
 220       put_u16 (zw, strlen (m->name)); /* file name length */
 221       put_u16 (zw, 0);                /* extra field length */
 222       put_u16 (zw, 0);                /* file comment length */
 223       put_u16 (zw, 0);                /* disk number start */
 224       put_u16 (zw, 0);                /* internal file attributes */
 225       put_u32 (zw, 0);                /* external file attributes */
 226       put_u32 (zw, m->offset);        /* relative offset of local header */
 227       put_bytes (zw, m->name, strlen (m->name));
 228       free (m->name);
 229     }
 230   free (zw->members);
 231   dir_end = ftello (zw->file);
 232
 233   /* End of central directory record. */
 234   put_u32 (zw, MAGIC_EOCD);     /* end of central dir signature */
 235   put_u16 (zw, 0);              /* number of this disk */
 236   put_u16 (zw, 0);              /* number of the disk with the
 237                                    start of the central directory */
 238   put_u16 (zw, zw->n_members);  /* total number of entries in the
 239                                    central directory on this disk */
 240   put_u16 (zw, zw->n_members);  /* total number of entries in
 241                                    the central directory */
 242   put_u32 (zw, dir_end - dir_start); /* size of the central directory */
 243   put_u32 (zw, dir_start);      /* offset of start of central
 244                                    directory with respect to
 245                                    the starting disk number */
 246   put_u16 (zw, 0);              /* .ZIP file comment length */
 247
 248   ok = zw->ok;
 249   if (ok && fwriteerror (zw->file))
 250     {
 251       msg_error (errno, _("%s: write failed"), zw->file_name);
 252       ok = false;
 253     }
 254
 255   free (zw->file_name);
 256   free (zw);
 257
 258   return ok;
 259 }