pcache.c

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    pc->tail = node;
  } else {
    pc->head = pc->tail = node;
  };
  return 0;
}

/*.......................................................................
 * Scan a given directory for files of interest, record their names
 * in mem->sg and append pointers to them to the mem->files[] array.
 *
 * Input:
 *  pc        PathCache *  The filename cache.
 *  dirname  const char *  The pathname of the directory to be scanned.
 *  mem        CacheMem *  The memory in which to store filenames of
 *                         interest.
 * Output:
 *  return          int    The number of files recorded, or -1 if a
 *                         memory error occurs. Note that the
 *                         inability to read the contents of the
 *                         directory is not counted as an error.
 */
static int pca_scan_dir(PathCache *pc, const char *dirname, CacheMem *mem)
{
  int nfile = 0;        /* The number of filenames recorded */
  const char *filename; /* The name of the file being looked at */
/*
 * Attempt to open the directory. If the directory can't be read then
 * there are no accessible files of interest in the directory.
 */
  if(_dr_open_dir(pc->dr, dirname, NULL))
    return 0;
/*
 * Record the names of all files in the directory in the cache.
 */
  while((filename = _dr_next_file(pc->dr))) {
    char *copy;        /* A copy of the filename */
/*
 * Make a temporary copy of the filename with an extra byte prepended.
 */
    _pn_clear_path(pc->path);
    if(_pn_append_to_path(pc->path, " ", 1, 0) == NULL ||
       _pn_append_to_path(pc->path, filename, -1, 1) == NULL) {
      strcpy(pc->errmsg, "Insufficient memory to record filename");
      return -1;
    };
/*
 * Store the filename.
 */
    copy = _sg_store_string(mem->sg, pc->path->name, 0);
    if(!copy) {
      strcpy(pc->errmsg, "Insufficient memory to cache file name.");
      return -1;
    };
/*
 * Mark the filename as unchecked.
 */
    copy[0] = PCA_F_ENIGMA;
/*
 * Make room to store a pointer to the copy in mem->files[].
 */
    if(mem->nfiles + 1 > mem->files_dim) {
      int needed = mem->files_dim + FILES_BLK_FACT;
      char **files = (char **) realloc(mem->files, sizeof(*mem->files)*needed);
      if(!files) {
	strcpy(pc->errmsg, "Insufficient memory to extend filename cache.");
	return 1;
      };
      mem->files = files;
      mem->files_dim = needed;
    };
/*
 * Record a pointer to the copy of the filename at the end of the files[]
 * array.
 */
    mem->files[mem->nfiles++] = copy;
/*
 * Keep a record of the number of files matched so far.
 */
    nfile++;
  };
/*
 * Sort the list of files into lexical order.
 */
  qsort(mem->files + mem->nfiles - nfile, nfile, sizeof(*mem->files),
	pca_cmp_matches);
/*
 * Return the number of files recorded in mem->files[].
 */
  return nfile;
}

/*.......................................................................
 * A qsort() comparison function for comparing the cached filename
 * strings pointed to by two (char **) array elements. Note that
 * this ignores the initial cache-status byte of each filename.
 *
 * Input:
 *  v1, v2   void *  Pointers to the pointers of two strings to be compared.
 * Output:
 *  return    int    -1 -> v1 < v2.
 *                    0 -> v1 == v2
 *                    1 -> v1 > v2
 */
static int pca_cmp_matches(const void *v1, const void *v2)
{
  const char **s1 = (const char **) v1;
  const char **s2 = (const char **) v2;
  return strcmp(*s1+1, *s2+1);
}

/*.......................................................................
 * Given the simple name of a file, search the cached list of files
 * in the order in which they where found in the list of directories
 * previously presented to pca_scan_path(), and return the pathname
 * of the first file which has this name. If a pathname to a file is
 * given instead of a simple filename, this is returned without being
 * looked up in the cache, but with any initial ~username expression
 * expanded, and optionally, unescaped backslashes removed.
 *
 * Input:
 *  pc     PathCache *  The cached list of files.
 *  name  const char *  The name of the file to lookup.
 *  name_len     int    The length of the filename string at the
 *                      beginning of name[], or -1 to indicate that
 *                      the filename occupies the whole of the
 *                      string.
 *  literal      int    If this argument is zero, lone backslashes
 *                      in name[] are ignored during comparison
 *                      with filenames in the cache, under the
 *                      assumption that they were in the input line
 *                      soley to escape the special significance of
 *                      characters like spaces. To have them treated
 *                      as normal characters, give this argument a
 *                      non-zero value, such as 1.
 * Output:
 *  return      char *  The pathname of the first matching file,
 *                      or NULL if not found. Note that the returned
 *                      pointer points to memory owned by *pc, and
 *                      will become invalid on the next call to any
 *                      function in the PathCache module.
 */
char *pca_lookup_file(PathCache *pc, const char *name, int name_len,
		      int literal)
{
  PathNode *node;   /* A node in the list of directories in the path */
  char **match;     /* A pointer to a matching filename string in the cache */
/*
 * Check the arguments.
 */
  if(!pc || !name || name_len==0)
    return NULL;
/*
 * If no length was specified, determine the length of the string to
 * be looked up.
 */
  if(name_len < 0)
    name_len = strlen(name);
/*
 * If the word starts with a ~username expression, the root directory,
 * of it contains any directory separators, then treat it isn't a simple
 * filename that can be looked up in the cache, but rather appears to
 * be the pathname of a file. If so, return a copy of this pathname with
 * escapes removed, if requested, and any initial ~username expression
 * expanded.
 */
  if(cpa_cmd_contains_path(name, name_len)) {
    const char *nptr;
    if(pca_expand_tilde(pc, name, name_len, literal, &nptr) || 
       _pn_append_to_path(pc->path, nptr, name_len - (nptr-name),
			  !literal) == NULL)
      return NULL;
    return pc->path->name;
  };
/*
 * Look up the specified filename in each of the directories of the path,
 * in the same order that they were listed in the path, and stop as soon
 * as an instance of the file is found.
 */
  for(node=pc->head; node; node=node->next) {
/*
 * If the directory of the latest node is a relative pathname,
 * scan it for files of interest.
 */
    if(node->relative) {
      rst_CacheMem(node->mem);
      if(pca_scan_dir(pc, node->dir, node->mem) < 1)
	continue;
      node->files = node->mem->files;
      node->nfile = node->mem->nfiles;
    };
/*
 * Copy the filename into a temporary buffer, while interpretting
 * escape characters if needed.
 */
    _pn_clear_path(pc->path);
    if(_pn_append_to_path(pc->path, name, name_len, !literal) == NULL)
      return NULL;
/*
 * Perform a binary search for the requested filename.
 */
    match = (char **)bsearch(pc->path->name, node->files, node->nfile,
		             sizeof(*node->files), pca_cmp_file);
    if(match) {
/*
 * Prepend the pathname in which the directory was found, which we have
 * guaranteed to end in a directory separator, to the located filename.
 */
      if(_pn_prepend_to_path(pc->path, node->dir, -1, 0) == NULL)
	return NULL;
/*
 * Return the matching pathname unless it is rejected by the application.
 */
      if(!pc->check_fn || (*match)[0] == PCA_F_WANTED ||
	 ((*match)[0]==PCA_F_ENIGMA && pc->check_fn(pc->data, pc->path->name))){
	(*match)[0] = PCA_F_WANTED;
	return pc->path->name;
      } else {
	*(match)[0] = PCA_F_IGNORE;
      };
    };
  };
/*
 * File not found.
 */
  return NULL;
}

/*.......................................................................
 * A qsort() comparison function for comparing a filename string to
 * a cached filename string pointed to by a (char **) array element.
 * This ignores the initial code byte at the start of the cached filename
 * string.
 *
 * Input:
 *  v1, v2   void *  Pointers to the pointers of two strings to be compared.
 * Output:
 *  return    int    -1 -> v1 < v2.
 *                    0 -> v1 == v2
 *                    1 -> v1 > v2
 */
static int pca_cmp_file(const void *v1, const void *v2)
{
  const char *file_name = (const char *) v1;
  const char **cache_name = (const char **) v2;
  return strcmp(file_name, *cache_name + 1);
}

/*.......................................................................
 * The PcaPathConf structure may have options added to it in the future.
 * To allow your application to be linked against a shared version of the
 * tecla library, without these additions causing your application to
 * crash, you should use new_PcaPathConf() to allocate such structures.
 * This will set all of the configuration options to their default values,
 * which you can then change before passing the structure to
 * pca_path_completions().
 *
 * Input:
 *  pc         PathCache *  The filename cache in which to look for
 *                          file name completions.
 * Output:
 *  return   PcaPathConf *  The new configuration structure, or NULL
 *                          on error. A descripition of the error
 *                          can be found by calling pca_last_error(pc).
 */
PcaPathConf *new_PcaPathConf(PathCache *pc)
{
  PcaPathConf *ppc;  /* The object to be returned */
/*
 * Check the arguments.
 */
  if(!pc)
    return NULL;
/*
 * Allocate the container.
 */
  ppc = (PcaPathConf *)malloc(sizeof(PcaPathConf));
  if(!ppc) {
    strcpy(pc->errmsg, "Insufficient memory.");
    return NULL;
  };
/*
 * Before attempting any operation that might fail, initialize the
 * container at least up to the point at which it can safely be passed
 * to del_PcaPathConf().
 */
  if(pca_init_PcaPathConf(ppc, pc))
    return del_PcaPathConf(ppc);
  return ppc;
}

/*.......................................................................
 * Initialize a PcaPathConf configuration structure with defaults.
 *
 * Input:
 *  ppc   PcaPathConf *  The structre to be initialized.
 *  pc      PathCache *  The cache in which completions will be looked up.
 * Output:
 *  return        int    0 - OK.
 *                       1 - Error. A description of the error can be
 *                           obtained by calling pca_last_error(pc).
 */
static int pca_init_PcaPathConf(PcaPathConf *ppc, PathCache *pc)
{
/*
 * Check the arguments.
 */
  if(!pc)
    return 1;
/*
 * Set the default options.
 */
  ppc->id = PPC_ID_CODE;
  ppc->pc = pc;
  ppc->escaped = 1;
  ppc->file_start = -1;
  return 0;
}

/*.......................................................................
 * Delete a PcaPathConf object.
 *
 * Input:
 *  ppc    PcaPathConf *  The object to be deleted.
 * Output:
 *  return PcaPathConf *  The deleted object (always NULL).
 */
PcaPathConf *del_PcaPathConf(PcaPathConf *ppc)
{
  if(ppc) {
    ppc->pc = NULL;  /* It is up to the caller to delete the cache */
/*
 * Delete the container.
 */
    free(ppc);
  };
  return NULL;
}

/*.......................................................................
 * pca_path_completions() is a completion callback function for use
 * directly with cpl_complete_word() or gl_customize_completions(), or
 * indirectly from your own completion callback function. It requires
 * that a CpaPathArgs object be passed via its 'void *data' argument.
 */
CPL_MATCH_FN(pca_path_completions)
{
  PcaPathConf *ppc;       /* The configuration arguments */
  PathCache *pc;          /* The cache in which to look for completions */
  PathNode *node;         /* A node in the list of directories in the path */
  const char *filename;   /* The name of the file being looked at */
  const char *start_path; /* The pointer to the start of the pathname */
                          /*  in line[]. */
  int word_start;         /* The index in line[] corresponding to start_path */
  const char *prefix;     /* The file-name prefix being searched for */
  size_t prefix_len;      /* The length of the prefix being completed */
  int bot;                /* The lowest index of the array not searched yet */
  int top;                /* The highest index of the array not searched yet */
/*
 * Check the arguments.
 */
  if(!cpl)
    return 1;
  if(!line || word_end < 0 || !data) {
    cpl_record_error(cpl, "pca_path_completions: Invalid arguments.");
    return 1;
  };
/*
 * Get the configuration arguments.
 */
  ppc = (PcaPathConf *) data;
/*
 * Check that the callback data is a PcaPathConf structure returned
 * by new_PcaPathConf().
 */
  if(ppc->id != PPC_ID_CODE) {
    cpl_record_error(cpl,
		     "Invalid callback data passed to pca_path_completions()");
    return 1;
  };
/*
 * Get the filename cache.
 */
  pc = ppc->pc;
/*
 * Get the start of the file name. If not specified by the caller,
 * identify it by searching backwards in the input line for an
 * unescaped space or the start of the line.
 */
  if(ppc->file_start < 0) {
    start_path = _pu_start_of_path(line, word_end);
    if(!start_path) {
      cpl_record_error(cpl, "Unable to find the start of the file name.");
      return 1;
    };
  } else {
    start_path = line + ppc->file_start;
  };
/*
 * Get the index of the start of the word being completed.
 */
  word_start = start_path - line;
/*
 * Work out the length of the prefix that is bein completed.
 */
  prefix_len = word_end - word_start;
/*
 * If the word starts with a ~username expression or the root directory,
 * of it contains any directory separators, then completion must be
 * delegated to cpl_file_completions().
 */
  if(cpa_cmd_contains_path(start_path, prefix_len)) {
    cfc_file_start(pc->cfc, word_start);
    return cpl_file_completions(cpl, pc->cfc, line, word_end);
  };
/*
 * Look up the specified file name in each of the directories of the path,
 * in the same order that they were listed in the path, and stop as soon
 * as an instance of the file is found.
 */
  for(node=pc->head; node; node=node->next) {
/*
 * If the directory of the latest node is a relative pathname,