pcache.c

xorp源码hg

/*
 * Copyright (c) 2000, 2001 by Martin C. Shepherd.
 * 
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, and/or sell copies of the Software, and to permit persons
 * to whom the Software is furnished to do so, provided that the above
 * copyright notice(s) and this permission notice appear in all copies of
 * the Software and that both the above copyright notice(s) and this
 * permission notice appear in supporting documentation.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
 * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
 * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 * 
 * Except as contained in this notice, the name of a copyright holder
 * shall not be used in advertising or otherwise to promote the sale, use
 * or other dealings in this Software without prior written authorization
 * of the copyright holder.
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include "libtecla.h"
#include "pathutil.h"
#include "homedir.h"
#include "freelist.h"
#include "direader.h"
#include "stringrp.h"

/*
 * The new_PcaPathConf() constructor sets the integer first member of
 * the returned object to the following magic number. This is then
 * checked for by pca_path_completions() as a sanity check.
 */
#define PPC_ID_CODE 4567

/*
 * A pointer to a structure of the following type can be passed to
 * the builtin path-completion callback function to modify its behavior.
 */
struct PcaPathConf {
  int id;          /* This is set to PPC_ID_CODE by new_PcaPathConf() */
  PathCache *pc;   /* The path-list cache in which to look up the executables */
  int escaped;     /* If non-zero, backslashes in the input line are */
                   /*  interpreted as escaping special characters and */
                   /*  spaces, and any special characters and spaces in */
                   /*  the listed completions will also be escaped with */
                   /*  added backslashes. This is the default behaviour. */
                   /* If zero, backslashes are interpreted as being */
                   /*  literal parts of the file name, and none are added */
                   /*  to the completion suffixes. */
  int file_start;  /* The index in the input line of the first character */
                   /*  of the file name. If you specify -1 here, */
                   /*  pca_path_completions() identifies the */
                   /*  the start of the file by looking backwards for */
                   /*  an unescaped space, or the beginning of the line. */
};

/*
 * Prepended to each chached filename is a character which contains
 * one of the following status codes. When a given filename (minus
 * this byte) is passed to the application's check_fn(), the result
 * is recorded in this byte, such that the next time it is looked
 * up, we don't have to call check_fn() again. These codes are cleared
 * whenever the path is scanned and whenever the check_fn() callback
 * is changed.
 */
typedef enum {
  PCA_F_ENIGMA='?', /* The file remains to be checked */
  PCA_F_WANTED='+', /* The file has been selected by the caller's callback */
  PCA_F_IGNORE='-'  /* The file has been rejected by the caller's callback */
} PcaFileStatus;

/*
 * Encapsulate the memory management objects which supply memoy for
 * the arrays of filenames.
 */
typedef struct {
  StringGroup *sg;       /* The memory used to record the names of files */
  size_t files_dim;      /* The allocated size of files[] */
  char **files;          /* Memory for 'files_dim' pointers to files */
  size_t nfiles;         /* The number of filenames currently in files[] */
} CacheMem;

static CacheMem *new_CacheMem(void);
static CacheMem *del_CacheMem(CacheMem *cm);
static void rst_CacheMem(CacheMem *cm);

/*
 * Lists of nodes of the following type are used to record the
 * names and contents of individual directories.
 */
typedef struct PathNode PathNode;
struct PathNode {
  PathNode *next;   /* The next directory in the path */
  int relative;     /* True if the directory is a relative pathname */
  CacheMem *mem;    /* The memory used to store dir[] and files[] */
  char *dir;        /* The directory pathname (stored in pc->sg) */
  int nfile;        /* The number of filenames stored in 'files' */
  char **files;     /* Files of interest in the current directory, */
                    /*  or NULL if dir[] is a relative pathname */
                    /*  who's contents can't be cached. This array */
                    /*  and its contents are taken from pc->abs_mem */
                    /*  or pc->rel_mem */
};

/*
 * Append a new node to the list of directories in the path.
 */
static int add_PathNode(PathCache *pc, const char *dirname);

/*
 * Set the max length of the error-reporting string. There is no point
 * in this being longer than the width of a typical terminal window.
 * In composing error messages, I have assumed that this number is
 * at least 80, so you don't decrease it below this number.
 */
#define ERRLEN 200

/*
 * Set the maximum length allowed for usernames.
 * names.
 */
#define USR_LEN 100

/*
 * PathCache objects encapsulate the resources needed to record
 * files of interest from comma-separated lists of directories.
 */
struct PathCache {
  FreeList *node_mem;    /* A free-list of PathNode objects */
  CacheMem *abs_mem;     /* Memory for the filenames of absolute paths */
  CacheMem *rel_mem;     /* Memory for the filenames of relative paths */
  PathNode *head;        /* The head of the list of directories in the */
                         /*  path, or NULL if no path has been scanned yet. */
  PathNode *tail;        /* The tail of the list of directories in the */
                         /*  path, or NULL if no path has been scanned yet. */
  PathName *path;        /* The fully qualified name of a file */
  HomeDir *home;         /* Home-directory lookup object */
  DirReader *dr;         /* A portable directory reader */
  CplFileConf *cfc;      /* Configuration parameters to pass to */
                         /*  cpl_file_completions() */
  CplCheckFn *check_fn;  /* The callback used to determine if a given */
                         /*  filename should be recorded in the cache. */
  void *data;            /* Annonymous data to be passed to pc->check_fn() */
  char usrnam[USR_LEN+1];/* The buffer used when reading the names of */
                         /*  users. */
  char errmsg[ERRLEN+1]; /* Error-report buffer */
};

/*
 * Empty the cache.
 */
static void pca_clear_cache(PathCache *pc);

/*
 * Read a username from string[] and record it in pc->usrnam[].
 */
static int pca_read_username(PathCache *pc, const char *string, int slen,
			     int literal, const char **nextp);

/*
 * Extract the next component of a colon separated list of directory
 * paths.
 */
static int pca_extract_dir(PathCache *pc, const char *path,
			   const char **nextp);

/*
 * Scan absolute directories for files of interest, recording their names
 * in mem->sg and recording pointers to these names in mem->files[].
 */
static int pca_scan_dir(PathCache *pc, const char *dirname, CacheMem *mem);

/*
 * 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.
 */
static int pca_cmp_matches(const void *v1, const void *v2);

/*
 * A qsort() comparison function for comparing a filename
 * against an element of an array of pointers to filename cache
 * entries.
 */
static int pca_cmp_file(const void *v1, const void *v2);

/*
 * Initialize a PcaPathConf configuration objects with the default
 * options.
 */
static int pca_init_PcaPathConf(PcaPathConf *ppc, PathCache *pc);

/*
 * Make a copy of a completion suffix, suitable for passing to
 * cpl_add_completion().
 */
static int pca_prepare_suffix(PathCache *pc, const char *suffix,
			      int add_escapes);

/*
 * Return non-zero if the specified string appears to start with a pathname.
 */
static int cpa_cmd_contains_path(const char *prefix, int prefix_len);

/*
 * Return a given prefix with escapes optionally removed.
 */
static const char *pca_prepare_prefix(PathCache *pc, const char *prefix,
				      size_t prefix_len, int escaped);

/*
 * If there is a tilde expression at the beginning of the specified path,
 * place the corresponding home directory into pc->path. Otherwise
 * just clear pc->path.
 */
static int pca_expand_tilde(PathCache *pc, const char *path, int pathlen,
			    int literal, const char **endp);

/*
 * Clear the filename status codes that are recorded before each filename
 * in the cache.
 */
static void pca_remove_marks(PathCache *pc);

/*
 * Specify how many PathNode's to allocate at a time.
 */
#define PATH_NODE_BLK 30

/*
 * Specify the amount by which the files[] arrays are to be extended
 * whenever they are found to be too small.
 */
#define FILES_BLK_FACT 256

/*.......................................................................
 * Create a new object who's function is to maintain a cache of
 * filenames found within a list of directories, and provide quick
 * lookup and completion of selected files in this cache.
 *
 * Output:
 *  return     PathCache *  The new, initially empty cache, or NULL
 *                          on error.
 */
PathCache *new_PathCache(void)
{
  PathCache *pc;  /* The object to be returned */
/*
 * Allocate the container.
 */
  pc = (PathCache *)malloc(sizeof(PathCache));
  if(!pc) {
    fprintf(stderr, "new_PathCache: Insufficient memory.\n");
    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_PathCache().
 */
  pc->node_mem = NULL;
  pc->abs_mem = NULL;
  pc->rel_mem = NULL;
  pc->head = NULL;
  pc->tail = NULL;
  pc->path = NULL;
  pc->home = NULL;
  pc->dr = NULL;
  pc->cfc = NULL;
  pc->check_fn = 0;
  pc->data = NULL;
  pc->usrnam[0] = '\0';
  pc->errmsg[0] = '\0';
/*
 * Allocate the freelist of directory list nodes.
 */
  pc->node_mem = _new_FreeList("new_PathCache", sizeof(PathNode),
			       PATH_NODE_BLK);
  if(!pc->node_mem)
    return del_PathCache(pc);
/*
 * Allocate memory for recording names of files in absolute paths.
 */
  pc->abs_mem = new_CacheMem();
  if(!pc->abs_mem)
    return del_PathCache(pc);
/*
 * Allocate memory for recording names of files in relative paths.
 */
  pc->rel_mem = new_CacheMem();
  if(!pc->rel_mem)
    return del_PathCache(pc);
/*
 * Allocate a pathname buffer.
 */
  pc->path = _new_PathName();
  if(!pc->path)
    return del_PathCache(pc);
/*
 * Allocate an object for looking up home-directories.
 */
  pc->home = _new_HomeDir();
  if(!pc->home)
    return del_PathCache(pc);
/*
 * Allocate an object for reading directories.
 */
  pc->dr = _new_DirReader();
  if(!pc->dr)
    return del_PathCache(pc);
/*
 * Allocate a cpl_file_completions() configuration object.
 */
  pc->cfc = new_CplFileConf();
  if(!pc->cfc)
    return del_PathCache(pc);
/*
 * Configure cpl_file_completions() to use check_fn() to select
 * files of interest.
 */
  cfc_set_check_fn(pc->cfc, pc->check_fn, pc->data);
/*
 * Return the cache, ready for use.
 */
  return pc;
}

/*.......................................................................
 * Delete a given cache of files, returning the resources that it
 * was using to the system.
 *
 * Input:
 *  pc      PathCache *  The cache to be deleted (can be NULL).
 * Output:
 *  return  PathCache *  The deleted object (ie. allways NULL).
 */
PathCache *del_PathCache(PathCache *pc)
{
  if(pc) {
/*
 * Delete the memory of the list of path nodes.
 */
    pc->node_mem = _del_FreeList(NULL, pc->node_mem, 1);
/*
 * Delete the memory used to record filenames.
 */
    pc->abs_mem = del_CacheMem(pc->abs_mem);
    pc->rel_mem = del_CacheMem(pc->rel_mem);
/*
 * The list of PathNode's was already deleted when node_mem was
 * deleted.
 */
    pc->head = NULL;
    pc->tail = NULL;
/*
 * Delete the pathname buffer.
 */
    pc->path = _del_PathName(pc->path);
/*
 * Delete the home-directory lookup object.
 */
    pc->home = _del_HomeDir(pc->home);
/*
 * Delete the directory reader.
 */
    pc->dr = _del_DirReader(pc->dr);
/*
 * Delete the cpl_file_completions() config object.
 */
    pc->cfc = del_CplFileConf(pc->cfc);
/*
 * Delete the container.
 */
    free(pc);
  };
  return NULL;
}

/*.......................................................................
 * If you want subsequent calls to pca_lookup_file() and
 * pca_path_completions() to only return the filenames of certain
 * types of files, for example executables, or filenames ending in
 * ".ps", call this function to register a file-selection callback
 * function. This callback function takes the full pathname of a file,
 * plus application-specific data, and returns 1 if the file is of
 * interest, and zero otherwise.
 *
 * Input:
 *  pc         PathCache *  The filename cache.
 *  check_fn  CplCheckFn *  The function to call to see if the name of
 *                          a given file should be included in the
 *                          cache. This determines what type of files
 *                          will reside in the cache. To revert to
 *                          selecting all files, regardless of type,
 *                          pass 0 here.
 *  data            void *  You can pass a pointer to anything you
 *                          like here, including NULL. It will be
 *                          passed to your check_fn() callback
 *                          function, for its private use.
 */
void pca_set_check_fn(PathCache *pc, CplCheckFn *check_fn, void *data)
{
  if(pc) {
/*
 * If the callback or its data pointer have changed, clear the cached
 * statuses of files that were accepted or rejected by the previous
 * calback.
 */