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filename.c

/*
 * Copyright (C) 1984-2000  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


/*
 * Routines to mess around with filenames (and files).
 * Much of this is very OS dependent.
 */

#include "less.h"
#include "lglob.h"
#if MSDOS_COMPILER
#include <dos.h>
#if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER)
#include <dir.h>
#endif
#if MSDOS_COMPILER==DJGPPC
#include <glob.h>
#include <dir.h>
#include <limits.h>
#define _MAX_PATH PATH_MAX
#endif
#endif
#ifdef _OSK
#include <rbf.h>
#ifndef _OSK_MWC32
#include <modes.h>
#endif
#endif

#if HAVE_STAT
#include <sys/stat.h>
#ifndef S_ISDIR
#define     S_ISDIR(m)  (((m) & S_IFMT) == S_IFDIR)
#endif
#ifndef S_ISREG
#define     S_ISREG(m)  (((m) & S_IFMT) == S_IFREG)
#endif
#endif


extern int force_open;
extern int secure;
extern IFILE curr_ifile;
extern IFILE old_ifile;
#if SPACES_IN_FILENAMES
extern char openquote;
extern char closequote;
#endif

/*
 * Remove quotes around a filename.
 */
      public char *
unquote_file(str)
      char *str;
{
#if SPACES_IN_FILENAMES
      char *name;
      char *p;

      if (*str != openquote)
            return (save(str));
      name = (char *) ecalloc(strlen(str), sizeof(char));
      strcpy(name, str+1);
      p = name + strlen(name) - 1;
      if (*p == closequote)
            *p = '\0';
      return (name);
#else
      return (save(str));
#endif
}

/*
 * Return a pathname that points to a specified file in a specified directory.
 * Return NULL if the file does not exist in the directory.
 */
      static char *
dirfile(dirname, filename)
      char *dirname;
      char *filename;
{
      char *pathname;
      char *qpathname;
      int f;

      if (dirname == NULL || *dirname == '\0')
            return (NULL);
      /*
       * Construct the full pathname.
       */
      pathname = (char *) calloc(strlen(dirname) + strlen(filename) + 2, 
                              sizeof(char));
      if (pathname == NULL)
            return (NULL);
      sprintf(pathname, "%s%s%s", dirname, PATHNAME_SEP, filename);
      /*
       * Make sure the file exists.
       */
      qpathname = unquote_file(pathname);
      f = open(qpathname, OPEN_READ);
      if (f < 0)
      {
            free(pathname);
            pathname = NULL;
      } else
      {
            close(f);
      }
      free(qpathname);
      return (pathname);
}

/*
 * Return the full pathname of the given file in the "home directory".
 */
      public char *
homefile(filename)
      char *filename;
{
      register char *pathname;

      /*
       * Try $HOME/filename.
       */
      pathname = dirfile(lgetenv("HOME"), filename);
      if (pathname != NULL)
            return (pathname);
#if OS2
      /*
       * Try $INIT/filename.
       */
      pathname = dirfile(lgetenv("INIT"), filename);
      if (pathname != NULL)
            return (pathname);
#endif
#if MSDOS_COMPILER || OS2
      /*
       * Look for the file anywhere on search path.
       */
      pathname = (char *) calloc(_MAX_PATH, sizeof(char));
#if MSDOS_COMPILER==DJGPPC
      {
            char *res = searchpath(filename);
            if (res == 0)
                  *pathname = '\0';
            else
                  strcpy(pathname, res);
      }
#else
      _searchenv(filename, "PATH", pathname);
#endif
      if (*pathname != '\0')
            return (pathname);
      free(pathname);
#endif
      return (NULL);
}

/*
 * Expand a string, substituting any "%" with the current filename,
 * and any "#" with the previous filename.
 * But a string of N "%"s is just replaced with N-1 "%"s.
 * Likewise for a string of N "#"s.
 * {{ This is a lot of work just to support % and #. }}
 */
      public char *
fexpand(s)
      char *s;
{
      register char *fr, *to;
      register int n;
      register char *e;
      IFILE ifile;

#define     fchar_ifile(c) \
      ((c) == '%' ? curr_ifile : \
       (c) == '#' ? old_ifile : NULL_IFILE)

      /*
       * Make one pass to see how big a buffer we 
       * need to allocate for the expanded string.
       */
      n = 0;
      for (fr = s;  *fr != '\0';  fr++)
      {
            switch (*fr)
            {
            case '%':
            case '#':
                  if (fr > s && fr[-1] == *fr)
                  {
                        /*
                         * Second (or later) char in a string
                         * of identical chars.  Treat as normal.
                         */
                        n++;
                  } else if (fr[1] != *fr)
                  {
                        /*
                         * Single char (not repeated).  Treat specially.
                         */
                        ifile = fchar_ifile(*fr);
                        if (ifile == NULL_IFILE)
                              n++;
                        else
                              n += strlen(get_filename(ifile));
                  }
                  /*
                   * Else it is the first char in a string of
                   * identical chars.  Just discard it.
                   */
                  break;
            default:
                  n++;
                  break;
            }
      }

      e = (char *) ecalloc(n+1, sizeof(char));

      /*
       * Now copy the string, expanding any "%" or "#".
       */
      to = e;
      for (fr = s;  *fr != '\0';  fr++)
      {
            switch (*fr)
            {
            case '%':
            case '#':
                  if (fr > s && fr[-1] == *fr)
                  {
                        *to++ = *fr;
                  } else if (fr[1] != *fr)
                  {
                        ifile = fchar_ifile(*fr);
                        if (ifile == NULL_IFILE)
                              *to++ = *fr;
                        else
                        {
                              strcpy(to, get_filename(ifile));
                              to += strlen(to);
                        }
                  }
                  break;
            default:
                  *to++ = *fr;
                  break;
            }
      }
      *to = '\0';
      return (e);
}

#if TAB_COMPLETE_FILENAME

/*
 * Return a blank-separated list of filenames which "complete"
 * the given string.
 */
      public char *
fcomplete(s)
      char *s;
{
      char *fpat;

      if (secure)
            return (NULL);
      /*
       * Complete the filename "s" by globbing "s*".
       */
#if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
      /*
       * But in DOS, we have to glob "s*.*".
       * But if the final component of the filename already has
       * a dot in it, just do "s*".  
       * (Thus, "FILE" is globbed as "FILE*.*", 
       *  but "FILE.A" is globbed as "FILE.A*").
       */
      {
            char *slash;
            for (slash = s+strlen(s)-1;  slash > s;  slash--)
                  if (*slash == *PATHNAME_SEP || *slash == '/')
                        break;
            fpat = (char *) ecalloc(strlen(s)+4, sizeof(char));
            if (strchr(slash, '.') == NULL)
                  sprintf(fpat, "%s*.*", s);
            else
                  sprintf(fpat, "%s*", s);
      }
#else
      fpat = (char *) ecalloc(strlen(s)+2, sizeof(char));
      sprintf(fpat, "%s*", s);
#endif
      s = lglob(fpat);
      if (strcmp(s,fpat) == 0)
      {
            /*
             * The filename didn't expand.
             */
            free(s);
            s = NULL;
      }
      free(fpat);
      return (s);
}
#endif

/*
 * Try to determine if a file is "binary".
 * This is just a guess, and we need not try too hard to make it accurate.
 */
      public int
bin_file(f)
      int f;
{
      int i;
      int n;
      unsigned char data[64];

      if (!seekable(f))
            return (0);
      if (lseek(f, (off_t)0, 0) == BAD_LSEEK)
            return (0);
      n = read(f, data, sizeof(data));
      for (i = 0;  i < n;  i++)
            if (binary_char(data[i]))
                  return (1);
      return (0);
}

/*
 * Try to determine the size of a file by seeking to the end.
 */
      static POSITION
seek_filesize(f)
      int f;
{
      off_t spos;

      spos = lseek(f, (off_t)0, 2);
      if (spos == BAD_LSEEK)
            return (NULL_POSITION);
      return ((POSITION) spos);
}

/*
 * Read a string from a file.
 * Return a pointer to the string in memory.
 */
      static char *
readfd(fd)
      FILE *fd;
{
      int len;
      int ch;
      char *buf;
      char *p;
      
      /* 
       * Make a guess about how many chars in the string
       * and allocate a buffer to hold it.
       */
      len = 100;
      buf = (char *) ecalloc(len, sizeof(char));
      for (p = buf;  ;  p++)
      {
            if ((ch = getc(fd)) == '\n' || ch == EOF)
                  break;
            if (p - buf >= len-1)
            {
                  /*
                   * The string is too big to fit in the buffer we have.
                   * Allocate a new buffer, twice as big.
                   */
                  len *= 2;
                  *p = '\0';
                  p = (char *) ecalloc(len, sizeof(char));
                  strcpy(p, buf);
                  free(buf);
                  buf = p;
                  p = buf + strlen(buf);
            }
            *p = ch;
      }
      *p = '\0';
      return (buf);
}

#if HAVE_SHELL

/*
 * Get the shell's escape character.
 */
      static char *
get_meta_escape()
{
      char *s;

      s = lgetenv("LESSMETAESCAPE");
      if (s == NULL)
            s = DEF_METAESCAPE;
      return (s);
}

/*
 * Is this a shell metacharacter?
 */
      static int
metachar(c)
      char c;
{
      static char *metachars = NULL;

      if (metachars == NULL)
      {
            metachars = lgetenv("LESSMETACHARS");
            if (metachars == NULL)
                  metachars = DEF_METACHARS;
      }
      return (strchr(metachars, c) != NULL);
}

/*
 * Insert a backslash before each metacharacter in a string.
 */
      public char *
esc_metachars(s)
      char *s;
{
      char *p;
      char *newstr;
      int len;
      char *esc;
      int esclen;

      /*
       * Determine how big a string we need to allocate.
       */
      esc = get_meta_escape();
      esclen = strlen(esc);
      len = 1; /* Trailing null byte */
      for (p = s;  *p != '\0';  p++)
      {
            len++;
            if (metachar(*p))
            {
                  if (*esc == '\0')
                  {
                        /*
                         * We've got a metachar, but this shell 
                         * doesn't support escape chars.  Give up.
                         */
                        return (NULL);
                  }
                  /*
                   * Allow space for the escape char.
                   */
                  len += esclen;
            }
      }
      /*
       * Allocate and construct the new string.
       */
      newstr = p = (char *) ecalloc(len, sizeof(char));
      while (*s != '\0')
      {
            if (metachar(*s))
            {
                  /*
                   * Add the escape char.
                   */
                  strcpy(p, esc);
                  p += esclen;
            }
            *p++ = *s++;
      }
      *p = '\0';
      return (newstr);
}

#else /* HAVE_SHELL */

      public char *
esc_metachars(s)
      char *s;
{
      return (save(s));
}

#endif /* HAVE_SHELL */


#if HAVE_POPEN

FILE *popen();

/*
 * Execute a shell command.
 * Return a pointer to a pipe connected to the shell command's standard output.
 */
      static FILE *
shellcmd(cmd)
      char *cmd;
{
      FILE *fd;

#if HAVE_SHELL
      char *shell;

      shell = lgetenv("SHELL");
      if (shell != NULL && *shell != '\0')
      {
            char *scmd;
            char *esccmd;

            /*
             * Try to escape any metacharacters in the command.
             * If we can't do that, just put the command in quotes.
             * (But that doesn't work well if the command itself 
             * contains quotes.)
             */
            if ((esccmd = esc_metachars(cmd)) == NULL)
            {
                  /*
                   * Cannot escape the metacharacters, so use quotes.
                   * Read the output of <$SHELL -c "cmd">.
                   */
                  scmd = (char *) ecalloc(strlen(shell) + strlen(cmd) + 7,
                                    sizeof(char));
                  sprintf(scmd, "%s -c \"%s\"", shell, cmd);
            } else
            {
                  /*
                   * Read the output of <$SHELL -c cmd>.  
                   * No quotes; use the escaped cmd.
                   */
                  scmd = (char *) ecalloc(strlen(shell) + strlen(esccmd) + 5,
                                    sizeof(char));
                  sprintf(scmd, "%s -c %s", shell, esccmd);
                  free(esccmd);
            }
            fd = popen(scmd, "r");
            free(scmd);
      } else
#endif
      {
            fd = popen(cmd, "r");
            /*
             * Redirection in `popen' might have messed with the
             * standard devices.  Restore binary input mode.
             */
            SET_BINARY(0);
      }
      return (fd);
}

#endif /* HAVE_POPEN */


/*
 * Expand a filename, doing any system-specific metacharacter substitutions.
 */
      public char *
lglob(filename)
      char *filename;
{
      char *gfilename;
      char *ofilename;

      ofilename = fexpand(filename);
      if (secure)
            return (ofilename);
      filename = unquote_file(ofilename);

#ifdef DECL_GLOB_LIST
{
      /*
       * The globbing function returns a list of names.
       */
      int length;
      char *p;
      DECL_GLOB_LIST(list)

      GLOB_LIST(filename, list);
      if (GLOB_LIST_FAILED(list))
      {
            free(filename);
            return (ofilename);
      }
      length = 1; /* Room for trailing null byte */
      for (SCAN_GLOB_LIST(list, p))
      {
            INIT_GLOB_LIST(list, p);
            length += strlen(p) + 1;
#if SPACES_IN_FILENAMES
            if (strchr(p, ' ') != NULL)
                  length += 2; /* Allow for quotes */
#endif
      }
      gfilename = (char *) ecalloc(length, sizeof(char));
      for (SCAN_GLOB_LIST(list, p))
      {
            INIT_GLOB_LIST(list, p);
#if SPACES_IN_FILENAMES
            if (strchr(p, ' ') != NULL)
                  sprintf(gfilename + strlen(gfilename), "%c%s%c ",
                        openquote, p, closequote);
            else
#endif
                  sprintf(gfilename + strlen(gfilename), "%s ", p);
      }
      /*
       * Overwrite the final trailing space with a null terminator.
       */
      *--p = '\0';
      GLOB_LIST_DONE(list);
}
#else
#ifdef DECL_GLOB_NAME
{
      /*
       * The globbing function returns a single name, and
       * is called multiple times to walk thru all names.
       */
      register char *p;
      register int len;
      register int n;
#if SPACES_IN_FILENAMES
      register int spaces_in_file;
#endif
      DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
      
      GLOB_FIRST_NAME(filename, &fnd, handle);
      if (GLOB_FIRST_FAILED(handle))
      {
            free(filename);
            return (ofilename);
      }

      _splitpath(filename, drive, dir, fname, ext);
      len = 100;
      gfilename = (char *) ecalloc(len, sizeof(char));
      p = gfilename;
      do {
            n = strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1;
#if SPACES_IN_FILENAMES
            spaces_in_file = 0;
            if (strchr(fnd.GLOB_NAME, ' ') != NULL ||
                strchr(filename, ' ') != NULL)
            {
                  spaces_in_file = 1;
                  n += 2;
            }
#endif
            while (p - gfilename + n+2 >= len)
            {
                  /*
                   * No room in current buffer.  Allocate a bigger one.
                   */
                  len *= 2;
                  *p = '\0';
                  p = (char *) ecalloc(len, sizeof(char));
                  strcpy(p, gfilename);
                  free(gfilename);
                  gfilename = p;
                  p = gfilename + strlen(gfilename);
            }
#if SPACES_IN_FILENAMES
            if (spaces_in_file)
                  sprintf(p, "%c%s%s%s%c ", openquote, 
                        drive, dir, fnd.GLOB_NAME, closequote);
            else
#endif
                  sprintf(p, "%s%s%s ", drive, dir, fnd.GLOB_NAME);
            p += n;
      } while (GLOB_NEXT_NAME(handle, &fnd) == 0);

      /*
       * Overwrite the final trailing space with a null terminator.
       */
      *--p = '\0';
      GLOB_NAME_DONE(handle);
}
#else
#if HAVE_POPEN
{
      /*
       * We get the shell to glob the filename for us by passing
       * an "echo" command to the shell and reading its output.
       */
      FILE *fd;
      char *s;
      char *lessecho;
      char *cmd;

      lessecho = lgetenv("LESSECHO");
      if (lessecho == NULL || *lessecho == '\0')
            lessecho = "lessecho";
      s = esc_metachars(filename);
      if (s == NULL)
      {
            /*
             * There may be dangerous metachars in this name.
             * We can't risk passing it to the shell.
             * {{ For example, do "!;TAB" when the first file 
             *    in the dir is named "rm". }}
             */
            free(filename);
            return (ofilename);
      }
      /*
       * Invoke lessecho, and read its output (a globbed list of filenames).
       */
      cmd = (char *) ecalloc(strlen(lessecho) + strlen(s) + 24, sizeof(char));
      sprintf(cmd, "%s -p0x%x -d0x%x -- %s", 
            lessecho, openquote, closequote, s);
      fd = shellcmd(cmd);
      free(s);
      free(cmd);
      if (fd == NULL)
      {
            /*
             * Cannot create the pipe.
             * Just return the original (fexpanded) filename.
             */
            free(filename);
            return (ofilename);
      }
      gfilename = readfd(fd);
      pclose(fd);
      if (*gfilename == '\0')
      {
            free(gfilename);
            free(filename);
            return (ofilename);
      }
}
#else
      /*
       * No globbing functions at all.  Just use the fexpanded filename.
       */
      gfilename = save(filename);
#endif
#endif
#endif
      free(filename);
      free(ofilename);
      return (gfilename);
}

/*
 * See if we should open a "replacement file" 
 * instead of the file we're about to open.
 */
      public char *
open_altfile(filename, pf, pfd)
      char *filename;
      int *pf;
      void **pfd;
{
#if !HAVE_POPEN
      return (NULL);
#else
      char *lessopen;
      char *gfilename;
      char *cmd;
      FILE *fd;
#if HAVE_FILENO
      int returnfd = 0;
#endif
      
      if (secure)
            return (NULL);
      ch_ungetchar(-1);
      if ((lessopen = lgetenv("LESSOPEN")) == NULL)
            return (NULL);
      if (strcmp(filename, "-") == 0)
            return (NULL);
      if (*lessopen == '|')
      {
            /*
             * If LESSOPEN starts with a |, it indicates 
             * a "pipe preprocessor".
             */
#if HAVE_FILENO
            lessopen++;
            returnfd = 1;
#else
            error("LESSOPEN pipe is not supported", NULL_PARG);
            return (NULL);
#endif
      }

      gfilename = esc_metachars(filename);
      if (gfilename == NULL)
      {
            /*
             * Cannot escape metacharacters.
             */
            return (NULL);
      }
      cmd = (char *) ecalloc(strlen(lessopen) + strlen(gfilename) + 2, 
                  sizeof(char));
      sprintf(cmd, lessopen, gfilename);
      fd = shellcmd(cmd);
      free(gfilename);
      free(cmd);
      if (fd == NULL)
      {
            /*
             * Cannot create the pipe.
             */
            return (NULL);
      }
#if HAVE_FILENO
      if (returnfd)
      {
            int f;
            char c;

            /*
             * Read one char to see if the pipe will produce any data.
             * If it does, push the char back on the pipe.
             */
            f = fileno(fd);
            SET_BINARY(f);
            if (read(f, &c, 1) != 1)
            {
                  /*
                   * Pipe is empty.  This means there is no alt file.
                   */
                  pclose(fd);
                  return (NULL);
            }
            ch_ungetchar(c);
            *pfd = (void *) fd;
            *pf = f;
            return (save("-"));
      }
#endif
      gfilename = readfd(fd);
      pclose(fd);
      if (*gfilename == '\0')
            /*
             * Pipe is empty.  This means there is no alt file.
             */
            return (NULL);
      return (gfilename);
#endif /* HAVE_POPEN */
}

/*
 * Close a replacement file.
 */
      public void
close_altfile(altfilename, filename, pipefd)
      char *altfilename;
      char *filename;
      void *pipefd;
{
#if HAVE_POPEN
      char *lessclose;
      char *gfilename;
      char *galtfilename;
      FILE *fd;
      char *cmd;
      
      if (secure)
            return;
      if (pipefd != NULL)
            pclose((FILE*) pipefd);
      if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
            return;
      gfilename = esc_metachars(filename);
      if (gfilename == NULL)
      {
            return;
      }
      galtfilename = esc_metachars(altfilename);
      if (galtfilename == NULL)
      {
            free(gfilename);
            return;
      }
      cmd = (char *) ecalloc(strlen(lessclose) + strlen(gfilename) + 
                  strlen(galtfilename) + 2, sizeof(char));
      sprintf(cmd, lessclose, gfilename, galtfilename);
      fd = shellcmd(cmd);
      free(galtfilename);
      free(gfilename);
      free(cmd);
      if (fd != NULL)
            pclose(fd);
#endif
}
            
/*
 * Is the specified file a directory?
 */
      public int
is_dir(filename)
      char *filename;
{
      int isdir = 0;

      filename = unquote_file(filename);
#if HAVE_STAT
{
      int r;
      struct stat statbuf;

      r = stat(filename, &statbuf);
      isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
}
#else
#ifdef _OSK
{
      register int f;

      f = open(filename, S_IREAD | S_IFDIR);
      if (f >= 0)
            close(f);
      isdir = (f >= 0);
}
#endif
#endif
      free(filename);
      return (isdir);
}

/*
 * Returns NULL if the file can be opened and
 * is an ordinary file, otherwise an error message
 * (if it cannot be opened or is a directory, etc.)
 */
      public char *
bad_file(filename)
      char *filename;
{
      register char *m = NULL;

      filename = unquote_file(filename);
      if (is_dir(filename))
      {
            static char is_dir[] = " is a directory";

            m = (char *) ecalloc(strlen(filename) + sizeof(is_dir), 
                  sizeof(char));
            strcpy(m, filename);
            strcat(m, is_dir);
      } else
      {
#if HAVE_STAT
            int r;
            struct stat statbuf;

            r = stat(filename, &statbuf);
            if (r < 0)
            {
                  m = errno_message(filename);
            } else if (force_open)
            {
                  m = NULL;
            } else if (!S_ISREG(statbuf.st_mode))
            {
                  static char not_reg[] = " is not a regular file (use -f to see it)";
                  m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
                        sizeof(char));
                  strcpy(m, filename);
                  strcat(m, not_reg);
            }
#endif
      }
      free(filename);
      return (m);
}

/*
 * Return the size of a file, as cheaply as possible.
 * In Unix, we can stat the file.
 */
      public POSITION
filesize(f)
      int f;
{
#if HAVE_STAT
      struct stat statbuf;

      if (fstat(f, &statbuf) >= 0)
            return ((POSITION) statbuf.st_size);
#else
#ifdef _OSK
      long size;

      if ((size = (long) _gs_size(f)) >= 0)
            return ((POSITION) size);
#endif
#endif
      return (seek_filesize(f));
}


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