path: root/modules/libmar/src/mar_read.c

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include "mar_private.h"
#include "mar.h"

#ifdef XP_WIN
#include <winsock2.h>
#else
#include <netinet/in.h>
#endif


/* this is the same hash algorithm used by nsZipArchive.cpp */
static uint32_t mar_hash_name(const char *name) {
  uint32_t val = 0;
  unsigned char* c;

  for (c = (unsigned char *) name; *c; ++c)
    val = val*37 + *c;

  return val % TABLESIZE;
}

static int mar_insert_item(MarFile *mar, const char *name, int namelen,
                           uint32_t offset, uint32_t length, uint32_t flags) {
  MarItem *item, *root;
  uint32_t hash;
  
  item = (MarItem *) malloc(sizeof(MarItem) + namelen);
  if (!item)
    return -1;
  item->next = NULL;
  item->offset = offset;
  item->length = length;
  item->flags = flags;
  memcpy(item->name, name, namelen + 1);

  hash = mar_hash_name(name);

  root = mar->item_table[hash];
  if (!root) {
    mar->item_table[hash] = item;
  } else {
    /* append item */
    while (root->next)
      root = root->next;
    root->next = item;
  }
  return 0;
}

static int mar_consume_index(MarFile *mar, char **buf, const char *buf_end) {
  /*
   * Each item has the following structure:
   *   uint32_t offset      (network byte order)
   *   uint32_t length      (network byte order)
   *   uint32_t flags       (network byte order)
   *   char     name[N]     (where N >= 1)
   *   char     null_byte;
   */
  uint32_t offset;
  uint32_t length;
  uint32_t flags;
  const char *name;
  int namelen;

  if ((buf_end - *buf) < (int)(3*sizeof(uint32_t) + 2))
    return -1;

  memcpy(&offset, *buf, sizeof(offset));
  *buf += sizeof(offset);

  memcpy(&length, *buf, sizeof(length));
  *buf += sizeof(length);

  memcpy(&flags, *buf, sizeof(flags));
  *buf += sizeof(flags);

  offset = ntohl(offset);
  length = ntohl(length);
  flags = ntohl(flags);

  name = *buf;
  /* find namelen; must take care not to read beyond buf_end */
  while (**buf) {
    /* buf_end points one byte past the end of buf's allocation */
    if (*buf == (buf_end - 1))
      return -1;
    ++(*buf);
  }
  namelen = (*buf - name);
  /* must ensure that namelen is valid */
  if (namelen < 0) {
    return -1;
  }
  /* consume null byte */
  if (*buf == buf_end)
    return -1;
  ++(*buf);

  return mar_insert_item(mar, name, namelen, offset, length, flags);
}

static int mar_read_index(MarFile *mar) {
  char id[MAR_ID_SIZE], *buf, *bufptr, *bufend;
  uint32_t offset_to_index, size_of_index;

  /* verify MAR ID */
  fseek(mar->fp, 0, SEEK_SET);
  if (fread(id, MAR_ID_SIZE, 1, mar->fp) != 1)
    return -1;
  if (memcmp(id, MAR_ID, MAR_ID_SIZE) != 0)
    return -1;

  if (fread(&offset_to_index, sizeof(uint32_t), 1, mar->fp) != 1)
    return -1;
  offset_to_index = ntohl(offset_to_index);

  if (fseek(mar->fp, offset_to_index, SEEK_SET))
    return -1;
  if (fread(&size_of_index, sizeof(uint32_t), 1, mar->fp) != 1)
    return -1;
  size_of_index = ntohl(size_of_index);

  buf = (char *) malloc(size_of_index);
  if (!buf)
    return -1;
  if (fread(buf, size_of_index, 1, mar->fp) != 1) {
    free(buf);
    return -1;
  }

  bufptr = buf;
  bufend = buf + size_of_index;
  while (bufptr < bufend && mar_consume_index(mar, &bufptr, bufend) == 0);

  free(buf);
  return (bufptr == bufend) ? 0 : -1;
}

/**
 * Internal shared code for mar_open and mar_wopen.
 * On failure, will fclose(fp).
 */
static MarFile *mar_fpopen(FILE *fp)
{
  MarFile *mar;

  mar = (MarFile *) malloc(sizeof(*mar));
  if (!mar) {
    fclose(fp);
    return NULL;
  }

  mar->fp = fp;
  mar->item_table_is_valid = 0;
  memset(mar->item_table, 0, sizeof(mar->item_table));

  return mar;
}

MarFile *mar_open(const char *path) {
  FILE *fp;

  fp = fopen(path, "rb");
  if (!fp) {
    fprintf(stderr, "ERROR: could not open file in mar_open()\n");
    perror(path);
    return NULL;
  }

  return mar_fpopen(fp);
}

#ifdef XP_WIN
MarFile *mar_wopen(const wchar_t *path) {
  FILE *fp;

  _wfopen_s(&fp, path, L"rb");
  if (!fp) {
    fprintf(stderr, "ERROR: could not open file in mar_wopen()\n");
    _wperror(path);
    return NULL;
  }

  return mar_fpopen(fp);
}
#endif

void mar_close(MarFile *mar) {
  MarItem *item;
  int i;

  fclose(mar->fp);

  for (i = 0; i < TABLESIZE; ++i) {
    item = mar->item_table[i];
    while (item) {
      MarItem *temp = item;
      item = item->next;
      free(temp);
    }
  }

  free(mar);
}

/**
 * Determines the MAR file information.
 *
 * @param fp                     An opened MAR file in read mode.
 * @param hasSignatureBlock      Optional out parameter specifying if the MAR
 *                               file has a signature block or not.
 * @param numSignatures          Optional out parameter for storing the number
 *                               of signatures in the MAR file.
 * @param hasAdditionalBlocks    Optional out parameter specifying if the MAR
 *                               file has additional blocks or not.
 * @param offsetAdditionalBlocks Optional out parameter for the offset to the 
 *                               first additional block. Value is only valid if
 *                               hasAdditionalBlocks is not equal to 0.
 * @param numAdditionalBlocks    Optional out parameter for the number of
 *                               additional blocks.  Value is only valid if
 *                               hasAdditionalBlocks is not equal to 0.
 * @return 0 on success and non-zero on failure.
 */
int get_mar_file_info_fp(FILE *fp, 
                         int *hasSignatureBlock,
                         uint32_t *numSignatures,
                         int *hasAdditionalBlocks,
                         uint32_t *offsetAdditionalBlocks,
                         uint32_t *numAdditionalBlocks)
{
  uint32_t offsetToIndex, offsetToContent, signatureCount, signatureLen, i;
  
  /* One of hasSignatureBlock or hasAdditionalBlocks must be non NULL */
  if (!hasSignatureBlock && !hasAdditionalBlocks) {
    return -1;
  }


  /* Skip to the start of the offset index */
  if (fseek(fp, MAR_ID_SIZE, SEEK_SET)) {
    return -1;
  }

  /* Read the offset to the index. */
  if (fread(&offsetToIndex, sizeof(offsetToIndex), 1, fp) != 1) {
    return -1;
  }
  offsetToIndex = ntohl(offsetToIndex);

  if (numSignatures) {
     /* Skip past the MAR file size field */
    if (fseek(fp, sizeof(uint64_t), SEEK_CUR)) {
      return -1;
    }

    /* Read the number of signatures field */
    if (fread(numSignatures, sizeof(*numSignatures), 1, fp) != 1) {
      return -1;
    }
    *numSignatures = ntohl(*numSignatures);
  }

  /* Skip to the first index entry past the index size field 
     We do it in 2 calls because offsetToIndex + sizeof(uint32_t) 
     could oerflow in theory. */
  if (fseek(fp, offsetToIndex, SEEK_SET)) {
    return -1;
  }

  if (fseek(fp, sizeof(uint32_t), SEEK_CUR)) {
    return -1;
  }

  /* Read the first offset to content field. */
  if (fread(&offsetToContent, sizeof(offsetToContent), 1, fp) != 1) {
    return -1;
  }
  offsetToContent = ntohl(offsetToContent);

  /* Check if we have a new or old MAR file */
  if (hasSignatureBlock) {
    if (offsetToContent == MAR_ID_SIZE + sizeof(uint32_t)) {
      *hasSignatureBlock = 0;
    } else {
      *hasSignatureBlock = 1;
    }
  }

  /* If the caller doesn't care about the product info block 
     value, then just return */
  if (!hasAdditionalBlocks) {
    return 0;
  }

   /* Skip to the start of the signature block */
  if (fseeko(fp, SIGNATURE_BLOCK_OFFSET, SEEK_SET)) {
    return -1;
  }

  /* Get the number of signatures */
  if (fread(&signatureCount, sizeof(signatureCount), 1, fp) != 1) {
    return -1;
  }
  signatureCount = ntohl(signatureCount);

  /* Check that we have less than the max amount of signatures so we don't
     waste too much of either updater's or signmar's time. */
  if (signatureCount > MAX_SIGNATURES) {
    return -1;
  }

  /* Skip past the whole signature block */
  for (i = 0; i < signatureCount; i++) {
    /* Skip past the signature algorithm ID */
    if (fseek(fp, sizeof(uint32_t), SEEK_CUR)) {
      return -1;
    }

    /* Read the signature length and skip past the signature */
    if (fread(&signatureLen, sizeof(uint32_t), 1, fp) != 1) {
      return -1;
    }
    signatureLen = ntohl(signatureLen);
    if (fseek(fp, signatureLen, SEEK_CUR)) {
      return -1;
    }
  }

  if ((int64_t)ftell(fp) == (int64_t)offsetToContent) {
    *hasAdditionalBlocks = 0;
  } else {
    if (numAdditionalBlocks) {
      /* We have an additional block, so read in the number of additional blocks
         and set the offset. */
      *hasAdditionalBlocks = 1;
      if (fread(numAdditionalBlocks, sizeof(uint32_t), 1, fp) != 1) {
        return -1;
      }
      *numAdditionalBlocks = ntohl(*numAdditionalBlocks);
      if (offsetAdditionalBlocks) {
        *offsetAdditionalBlocks = ftell(fp);
      }
    } else if (offsetAdditionalBlocks) {
      /* numAdditionalBlocks is not specified but offsetAdditionalBlocks 
         is, so fill it! */
      *offsetAdditionalBlocks = ftell(fp) + sizeof(uint32_t);
    }
  }

  return 0;
}

/** 
 * Reads the product info block from the MAR file's additional block section.
 * The caller is responsible for freeing the fields in infoBlock
 * if the return is successful.
 *
 * @param infoBlock Out parameter for where to store the result to
 * @return 0 on success, -1 on failure
*/
int
read_product_info_block(char *path, 
                        struct ProductInformationBlock *infoBlock)
{
  int rv;
  MarFile mar;
  mar.fp = fopen(path, "rb");
  if (!mar.fp) {
    fprintf(stderr, "ERROR: could not open file in read_product_info_block()\n");
    perror(path);
    return -1;
  }
  rv = mar_read_product_info_block(&mar, infoBlock);
  fclose(mar.fp);
  return rv;
}

/** 
 * Reads the product info block from the MAR file's additional block section.
 * The caller is responsible for freeing the fields in infoBlock
 * if the return is successful.
 *
 * @param infoBlock Out parameter for where to store the result to
 * @return 0 on success, -1 on failure
*/
int
mar_read_product_info_block(MarFile *mar, 
                            struct ProductInformationBlock *infoBlock)
{
  uint32_t i, offsetAdditionalBlocks, numAdditionalBlocks,
    additionalBlockSize, additionalBlockID;
  int hasAdditionalBlocks;

  /* The buffer size is 97 bytes because the MAR channel name < 64 bytes, and 
     product version < 32 bytes + 3 NULL terminator bytes. */
  char buf[97] = { '\0' };
  if (get_mar_file_info_fp(mar->fp, NULL, NULL,
                           &hasAdditionalBlocks,
                           &offsetAdditionalBlocks,
                           &numAdditionalBlocks) != 0) {
    return -1;
  }
  for (i = 0; i < numAdditionalBlocks; ++i) {
    /* Read the additional block size */
    if (fread(&additionalBlockSize, 
              sizeof(additionalBlockSize), 
              1, mar->fp) != 1) {
      return -1;
    }
    additionalBlockSize = ntohl(additionalBlockSize) - 
                          sizeof(additionalBlockSize) - 
                          sizeof(additionalBlockID);

    /* Read the additional block ID */
    if (fread(&additionalBlockID, 
              sizeof(additionalBlockID), 
              1, mar->fp) != 1) {
      return -1;
    }
    additionalBlockID = ntohl(additionalBlockID);

    if (PRODUCT_INFO_BLOCK_ID == additionalBlockID) {
      const char *location;
      int len;

      /* This block must be at most 104 bytes.
         MAR channel name < 64 bytes, and product version < 32 bytes + 3 NULL 
         terminator bytes. We only check for 96 though because we remove 8 
         bytes above from the additionalBlockSize: We subtract 
         sizeof(additionalBlockSize) and sizeof(additionalBlockID) */
      if (additionalBlockSize > 96) {
        return -1;
      }

    if (fread(buf, additionalBlockSize, 1, mar->fp) != 1) {
        return -1;
      }

      /* Extract the MAR channel name from the buffer.  For now we
         point to the stack allocated buffer but we strdup this
         if we are within bounds of each field's max length. */
      location = buf;
      len = strlen(location);
      infoBlock->MARChannelID = location;
      location += len + 1;
      if (len >= 64) {
        infoBlock->MARChannelID = NULL;
        return -1;
      }

      /* Extract the version from the buffer */
      len = strlen(location);
      infoBlock->productVersion = location;
      location += len + 1;
      if (len >= 32) {
        infoBlock->MARChannelID = NULL;
        infoBlock->productVersion = NULL;
        return -1;
      }
      infoBlock->MARChannelID = 
        strdup(infoBlock->MARChannelID);
      infoBlock->productVersion = 
        strdup(infoBlock->productVersion);
      return 0;
    } else {
      /* This is not the additional block you're looking for. Move along. */
      if (fseek(mar->fp, additionalBlockSize, SEEK_CUR)) {
        return -1;
      }
    }
  }

  /* If we had a product info block we would have already returned */
  return -1;
}

const MarItem *mar_find_item(MarFile *mar, const char *name) {
  uint32_t hash;
  const MarItem *item;

  if (!mar->item_table_is_valid) {
    if (mar_read_index(mar)) {
      return NULL;
    } else {
      mar->item_table_is_valid = 1;
    }
  }

  hash = mar_hash_name(name);

  item = mar->item_table[hash];
  while (item && strcmp(item->name, name) != 0)
    item = item->next;

  return item;
}

int mar_enum_items(MarFile *mar, MarItemCallback callback, void *closure) {
  MarItem *item;
  int i;

  if (!mar->item_table_is_valid) {
    if (mar_read_index(mar)) {
      return -1;
    } else {
      mar->item_table_is_valid = 1;
    }
  }

  for (i = 0; i < TABLESIZE; ++i) {
    item = mar->item_table[i];
    while (item) {
      int rv = callback(mar, item, closure);
      if (rv)
        return rv;
      item = item->next;
    }
  }

  return 0;
}

int mar_read(MarFile *mar, const MarItem *item, int offset, char *buf,
             int bufsize) {
  int nr;

  if (offset == (int) item->length)
    return 0;
  if (offset > (int) item->length)
    return -1;

  nr = item->length - offset;
  if (nr > bufsize)
    nr = bufsize;

  if (fseek(mar->fp, item->offset + offset, SEEK_SET))
    return -1;

  return fread(buf, 1, nr, mar->fp);
}

/**
 * Determines the MAR file information.
 *
 * @param path                   The path of the MAR file to check.
 * @param hasSignatureBlock      Optional out parameter specifying if the MAR
 *                               file has a signature block or not.
 * @param numSignatures          Optional out parameter for storing the number
 *                               of signatures in the MAR file.
 * @param hasAdditionalBlocks    Optional out parameter specifying if the MAR
 *                               file has additional blocks or not.
 * @param offsetAdditionalBlocks Optional out parameter for the offset to the 
 *                               first additional block. Value is only valid if
 *                               hasAdditionalBlocks is not equal to 0.
 * @param numAdditionalBlocks    Optional out parameter for the number of
 *                               additional blocks.  Value is only valid if
 *                               has_additional_blocks is not equal to 0.
 * @return 0 on success and non-zero on failure.
 */
int get_mar_file_info(const char *path, 
                      int *hasSignatureBlock,
                      uint32_t *numSignatures,
                      int *hasAdditionalBlocks,
                      uint32_t *offsetAdditionalBlocks,
                      uint32_t *numAdditionalBlocks)
{
  int rv;
  FILE *fp = fopen(path, "rb");
  if (!fp) {
    fprintf(stderr, "ERROR: could not open file in get_mar_file_info()\n");
    perror(path);
    return -1;
  }

  rv = get_mar_file_info_fp(fp, hasSignatureBlock, 
                            numSignatures, hasAdditionalBlocks,
                            offsetAdditionalBlocks, numAdditionalBlocks);

  fclose(fp);
  return rv;
}