mf_format.cc

/* Copyright (c) 2000, 2022, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
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/**
  @file mysys/mf_format.cc
*/

#include <string.h>
#include <sys/types.h>
#include <algorithm>
#include <cstring>

#include "m_string.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "my_macros.h"
#include "my_sys.h"

/**
  Formats a filename with possible replace of directory of extension
  Function can handle the case where 'to' == 'name'
  For a description of the flag values, consult my_sys.h
  The arguments should be in unix format.

  Pre-condition: At least FN_REFLEN bytes can be stored in buffer
  pointed to by 'to'. 'name', 'dir' and 'extension' are
  '\0'-terminated byte buffers (or nullptr where permitted).

  Post-condition: At most FN_REFLEN bytes will have been written to
  'to'. If the combined length of 'from' and any expanded elements
  exceeds FN_REFLEN-1, the result is truncated and likely not what the
  caller expects.

  @param to destination buffer.
  @param name file name component.
  @param dir directory component.
  @param extension filename extension
  @param flag bitset of 'Bits in last argument of fn_format' from
  @<my_sys.h@> like MY_REPLACE_DIR

  @return to (destination buffer), or nullptr if overflow and
  MY_SAFE_PATH is used.
*/

char *fn_format(char *to, const char *name, const char *dir,
                const char *extension, uint flag) {
  char dev[FN_REFLEN], buff[FN_REFLEN], *pos;
  const char *ext;
  size_t dev_length;
  DBUG_TRACE;
  assert(name != nullptr);
  assert(extension != nullptr);
  DBUG_PRINT("enter", ("name: %s  dir: %s  extension: %s  flag: %d", name, dir,
                       extension, flag));

  /* Copy and skip directory */
  const char *startpos = name;
  size_t length = dirname_part(dev, name, &dev_length);
  name += length;
  if (length == 0 || (flag & MY_REPLACE_DIR)) {
    assert(dir != nullptr);
    /* Use given directory */
    convert_dirname(dev, dir, NullS); /* Fix to this OS */
  } else if ((flag & MY_RELATIVE_PATH) && !test_if_hard_path(dev)) {
    assert(dir != nullptr);
    /* Put 'dir' before the given path */
    strmake(buff, dev, sizeof(buff) - 1);
    pos = convert_dirname(dev, dir, NullS);
    strmake(pos, buff, sizeof(buff) - 1 - (int)(pos - dev));
  }

  if (flag & MY_UNPACK_FILENAME)
    (void)unpack_dirname(dev, dev); /* Replace ~/.. with dir */

  if (!(flag & MY_APPEND_EXT) &&
      (pos = const_cast<char *>(std::strchr(name, FN_EXTCHAR))) != nullptr) {
    if ((flag & MY_REPLACE_EXT) == 0) /* If we should keep old ext */
    {
      length = strlength(name); /* Use old extension */
      ext = "";
    } else {
      length = pos - name; /* Change extension */
      ext = extension;
    }
  } else {
    length = strlength(name); /* No ext, use the now one */
    ext = extension;
  }

  if (strlen(dev) + length + strlen(ext) >= FN_REFLEN || length >= FN_LEN) {
    /* To long path, return original or NULL */
    size_t tmp_length;
    if (flag & MY_SAFE_PATH) return NullS;
    tmp_length = strlength(startpos);
    DBUG_PRINT("error",
               ("dev: '%s'  ext: '%s'  length: %u", dev, ext, (uint)length));
    (void)strmake(to, startpos, std::min(tmp_length, size_t{FN_REFLEN - 1}));
  } else {
    if (to == startpos) {
      memmove(buff, name, length); /* Save name for last copy */
      name = buff;
    }
    pos = strmake(my_stpcpy(to, dev), name, length);
    (void)my_stpcpy(pos, ext); /* Don't convert extension */
  }
  /*
    If MY_RETURN_REAL_PATH and MY_RESOLVE_SYMLINK is given, only do
    realpath if the file is a symbolic link
  */
  if (flag & MY_RETURN_REAL_PATH)
    (void)my_realpath(to, to,
                      MYF(flag & MY_RESOLVE_SYMLINKS ? MY_RESOLVE_LINK : 0));
  else if (flag & MY_RESOLVE_SYMLINKS) {
    my_stpcpy(buff, to);
    (void)my_readlink(to, buff, MYF(0));
  }
  return to;
} /* fn_format */

/**
  Calculate the length of str not including any trailing ' '-bytes.

  Pre-condition: 'str' is a '\0'-terminated byte buffer.
  @param str input to calculate the length of.
  @return length of string with end-space:s not counted.
*/

size_t strlength(const char *str) {
  const char *pos;
  const char *found;
  DBUG_TRACE;

  pos = found = str;

  while (*pos) {
    if (*pos != ' ') {
      while (*++pos && *pos != ' ') {
      };
      if (!*pos) {
        found = pos; /* String ends here */
        break;
      }
    }
    found = pos;
    while (*++pos == ' ') {
    };
  }
  return (size_t)(found - str);
} /* strlength */