/src/postgres/src/port/path.c

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/*-------------------------------------------------------------------------
 *
 * path.c
 *    portable path handling routines
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/port/path.c
 *
 *-------------------------------------------------------------------------
 */

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#include <ctype.h>
#include <sys/stat.h>
#ifdef WIN32
#ifdef _WIN32_IE
#undef _WIN32_IE
#endif
#define _WIN32_IE 0x0500
#ifdef near
#undef near
#endif
#define near
#include <shlobj.h>
#else
#include <pwd.h>
#include <unistd.h>
#endif

#include "mb/pg_wchar.h"
#include "pg_config_paths.h"


#ifndef WIN32
#define IS_PATH_VAR_SEP(ch) ((ch) == ':')
#else
#define IS_PATH_VAR_SEP(ch) ((ch) == ';')
#endif

#ifdef WIN32
static void debackslash_path(char *path, int encoding);
static int  pg_sjis_mblen(const unsigned char *s);
#endif
static void make_relative_path(char *ret_path, const char *target_path,
                 const char *bin_path, const char *my_exec_path);
static char *trim_directory(char *path);
static void trim_trailing_separator(char *path);
static char *append_subdir_to_path(char *path, char *subdir);


/*
 * skip_drive
 *
 * On Windows, a path may begin with "C:" or "//network/".  Advance over
 * this and point to the effective start of the path.
 */
#ifdef WIN32

static char *
skip_drive(const char *path)
{
  if (IS_DIR_SEP(path[0]) && IS_DIR_SEP(path[1]))
  {
    path += 2;
    while (*path && !IS_DIR_SEP(*path))
      path++;
  }
  else if (isalpha((unsigned char) path[0]) && path[1] == ':')
  {
    path += 2;
  }
  return (char *) path;
}
#else

#define skip_drive(path)  (path)
#endif

/*
 *  has_drive_prefix
 *
 * Return true if the given pathname has a drive prefix.
 */
bool
has_drive_prefix(const char *path)
{
#ifdef WIN32
  return skip_drive(path) != path;
#else
  return false;
#endif
}

/*
 *  first_dir_separator
 *
 * Find the location of the first directory separator, return
 * NULL if not found.
 */
char *
first_dir_separator(const char *filename)
{
  const char *p;

  for (p = skip_drive(filename); *p; p++)
    if (IS_DIR_SEP(*p))
      return unconstify(char *, p);
  return NULL;
}

/*
 *  first_path_var_separator
 *
 * Find the location of the first path separator (i.e. ':' on
 * Unix, ';' on Windows), return NULL if not found.
 */
char *
first_path_var_separator(const char *pathlist)
{
  const char *p;

  /* skip_drive is not needed */
  for (p = pathlist; *p; p++)
    if (IS_PATH_VAR_SEP(*p))
      return unconstify(char *, p);
  return NULL;
}

/*
 *  last_dir_separator
 *
 * Find the location of the last directory separator, return
 * NULL if not found.
 */
char *
last_dir_separator(const char *filename)
{
  const char *p,
         *ret = NULL;

  for (p = skip_drive(filename); *p; p++)
    if (IS_DIR_SEP(*p))
      ret = p;
  return unconstify(char *, ret);
}


#ifdef WIN32

/*
 * Convert '\' to '/' within the given path, assuming the path
 * is in the specified encoding.
 */
static void
debackslash_path(char *path, int encoding)
{
  char     *p;

  /*
   * Of the supported encodings, only Shift-JIS has multibyte characters
   * that can include a byte equal to '\' (0x5C).  So rather than implement
   * a fully encoding-aware conversion, we special-case SJIS.  (Invoking the
   * general encoding-aware logic in wchar.c is impractical here for
   * assorted reasons.)
   */
  if (encoding == PG_SJIS)
  {
    for (p = path; *p; p += pg_sjis_mblen((const unsigned char *) p))
    {
      if (*p == '\\')
        *p = '/';
    }
  }
  else
  {
    for (p = path; *p; p++)
    {
      if (*p == '\\')
        *p = '/';
    }
  }
}

/*
 * SJIS character length
 *
 * This must match the behavior of
 *    pg_encoding_mblen_bounded(PG_SJIS, s)
 * In particular, unlike the version of pg_sjis_mblen in src/common/wchar.c,
 * do not allow caller to accidentally step past end-of-string.
 */
static int
pg_sjis_mblen(const unsigned char *s)
{
  int     len;

  if (*s >= 0xa1 && *s <= 0xdf)
    len = 1;        /* 1 byte kana? */
  else if (IS_HIGHBIT_SET(*s) && s[1] != '\0')
    len = 2;        /* kanji? */
  else
    len = 1;        /* should be ASCII */
  return len;
}

#endif              /* WIN32 */


/*
 *  make_native_path - on WIN32, change '/' to '\' in the path
 *
 *  This reverses the '\'-to-'/' transformation of debackslash_path.
 *  We need not worry about encodings here, since '/' does not appear
 *  as a byte of a multibyte character in any supported encoding.
 *
 *  This is required because WIN32 COPY is an internal CMD.EXE
 *  command and doesn't process forward slashes in the same way
 *  as external commands.  Quoting the first argument to COPY
 *  does not convert forward to backward slashes, but COPY does
 *  properly process quoted forward slashes in the second argument.
 *
 *  COPY works with quoted forward slashes in the first argument
 *  only if the current directory is the same as the directory
 *  of the first argument.
 */
void
make_native_path(char *filename)
{
#ifdef WIN32
  char     *p;

  for (p = filename; *p; p++)
    if (*p == '/')
      *p = '\\';
#endif
}


/*
 * This function cleans up the paths for use with either cmd.exe or Msys
 * on Windows. We need them to use filenames without spaces, for which a
 * short filename is the safest equivalent, eg:
 *    C:/Progra~1/
 *
 * Presently, this is only used on paths that we can assume are in a
 * server-safe encoding, so there's no need for an encoding-aware variant.
 */
void
cleanup_path(char *path)
{
#ifdef WIN32
  /*
   * GetShortPathName() will fail if the path does not exist, or short names
   * are disabled on this file system.  In both cases, we just return the
   * original path.  This is particularly useful for --sysconfdir, which
   * might not exist.
   */
  GetShortPathName(path, path, MAXPGPATH - 1);

  /* Replace '\' with '/' */
  /* All server-safe encodings are alike here, so just use PG_SQL_ASCII */
  debackslash_path(path, PG_SQL_ASCII);
#endif
}


/*
 * join_path_components - join two path components, inserting a slash
 *
 * We omit the slash if either given component is empty.
 *
 * ret_path is the output area (must be of size MAXPGPATH)
 *
 * ret_path can be the same as head, but not the same as tail.
 */
void
join_path_components(char *ret_path,
           const char *head, const char *tail)
{
  if (ret_path != head)
    strlcpy(ret_path, head, MAXPGPATH);

  /*
   * We used to try to simplify some cases involving "." and "..", but now
   * we just leave that to be done by canonicalize_path() later.
   */

  if (*tail)
  {
    /* only separate with slash if head wasn't empty */
    snprintf(ret_path + strlen(ret_path), MAXPGPATH - strlen(ret_path),
         "%s%s",
         (*(skip_drive(head)) != '\0') ? "/" : "",
         tail);
  }
}


/* State-machine states for canonicalize_path */
typedef enum
{
  ABSOLUTE_PATH_INIT,     /* Just past the leading '/' (and Windows
                 * drive name if any) of an absolute path */
  ABSOLUTE_WITH_N_DEPTH,    /* We collected 'pathdepth' directories in an
                 * absolute path */
  RELATIVE_PATH_INIT,     /* At start of a relative path */
  RELATIVE_WITH_N_DEPTH,    /* We collected 'pathdepth' directories in a
                 * relative path */
  RELATIVE_WITH_PARENT_REF, /* Relative path containing only double-dots */
} canonicalize_state;

/*
 * canonicalize_path()
 *
 *  Clean up path by:
 *    o  make Win32 path use Unix slashes
 *    o  remove trailing quote on Win32
 *    o  remove trailing slash
 *    o  remove duplicate (adjacent) separators
 *    o  remove '.' (unless path reduces to only '.')
 *    o  process '..' ourselves, removing it if possible
 *  Modifies path in-place.
 *
 * This comes in two variants: encoding-aware and not.  The non-aware version
 * is only safe to use on strings that are in a server-safe encoding.
 */
void
canonicalize_path(char *path)
{
  /* All server-safe encodings are alike here, so just use PG_SQL_ASCII */
  canonicalize_path_enc(path, PG_SQL_ASCII);
}

void
canonicalize_path_enc(char *path, int encoding)
{
  char     *p,
         *to_p;
  char     *spath;
  char     *parsed;
  char     *unparse;
  bool    was_sep = false;
  canonicalize_state state;
  int     pathdepth = 0;  /* counts collected regular directory names */

#ifdef WIN32

  /*
   * The Windows command processor will accept suitably quoted paths with
   * forward slashes, but barfs badly with mixed forward and back slashes.
   * Hence, start by converting all back slashes to forward slashes.
   */
  debackslash_path(path, encoding);

  /*
   * In Win32, if you do: prog.exe "a b" "\c\d\" the system will pass \c\d"
   * as argv[2], so trim off trailing quote.
   */
  p = path + strlen(path);
  if (p > path && *(p - 1) == '"')
    *(p - 1) = '/';
#endif

  /*
   * Removing the trailing slash on a path means we never get ugly double
   * trailing slashes. Also, Win32 can't stat() a directory with a trailing
   * slash. Don't remove a leading slash, though.
   */
  trim_trailing_separator(path);

  /*
   * Remove duplicate adjacent separators
   */
  p = path;
#ifdef WIN32
  /* Don't remove leading double-slash on Win32 */
  if (*p)
    p++;
#endif
  to_p = p;
  for (; *p; p++, to_p++)
  {
    /* Handle many adjacent slashes, like "/a///b" */
    while (*p == '/' && was_sep)
      p++;
    if (to_p != p)
      *to_p = *p;
    was_sep = (*p == '/');
  }
  *to_p = '\0';

  /*
   * Remove any uses of "." and process ".." ourselves
   *
   * Note that "/../.." should reduce to just "/", while "../.." has to be
   * kept as-is.  Also note that we want a Windows drive spec to be visible
   * to trim_directory(), but it's not part of the logic that's looking at
   * the name components; hence distinction between path and spath.
   *
   * This loop overwrites the path in-place.  This is safe since we'll never
   * make the path longer.  "unparse" points to where we are reading the
   * path, "parse" to where we are writing.
   */
  spath = skip_drive(path);
  if (*spath == '\0')
    return;         /* empty path is returned as-is */

  if (*spath == '/')
  {
    state = ABSOLUTE_PATH_INIT;
    /* Skip the leading slash for absolute path */
    parsed = unparse = (spath + 1);
  }
  else
  {
    state = RELATIVE_PATH_INIT;
    parsed = unparse = spath;
  }

  while (*unparse != '\0')
  {
    char     *unparse_next;
    bool    is_double_dot;

    /* Split off this dir name, and set unparse_next to the next one */
    unparse_next = unparse;
    while (*unparse_next && *unparse_next != '/')
      unparse_next++;
    if (*unparse_next != '\0')
      *unparse_next++ = '\0';

    /* Identify type of this dir name */
    if (strcmp(unparse, ".") == 0)
    {
      /* We can ignore "." components in all cases */
      unparse = unparse_next;
      continue;
    }

    if (strcmp(unparse, "..") == 0)
      is_double_dot = true;
    else
    {
      /* adjacent separators were eliminated above */
      Assert(*unparse != '\0');
      is_double_dot = false;
    }

    switch (state)
    {
      case ABSOLUTE_PATH_INIT:
        /* We can ignore ".." immediately after / */
        if (!is_double_dot)
        {
          /* Append first dir name (we already have leading slash) */
          parsed = append_subdir_to_path(parsed, unparse);
          state = ABSOLUTE_WITH_N_DEPTH;
          pathdepth++;
        }
        break;
      case ABSOLUTE_WITH_N_DEPTH:
        if (is_double_dot)
        {
          /* Remove last parsed dir */
          /* (trim_directory won't remove the leading slash) */
          *parsed = '\0';
          parsed = trim_directory(path);
          if (--pathdepth == 0)
            state = ABSOLUTE_PATH_INIT;
        }
        else
        {
          /* Append normal dir */
          *parsed++ = '/';
          parsed = append_subdir_to_path(parsed, unparse);
          pathdepth++;
        }
        break;
      case RELATIVE_PATH_INIT:
        if (is_double_dot)
        {
          /* Append irreducible double-dot (..) */
          parsed = append_subdir_to_path(parsed, unparse);
          state = RELATIVE_WITH_PARENT_REF;
        }
        else
        {
          /* Append normal dir */
          parsed = append_subdir_to_path(parsed, unparse);
          state = RELATIVE_WITH_N_DEPTH;
          pathdepth++;
        }
        break;
      case RELATIVE_WITH_N_DEPTH:
        if (is_double_dot)
        {
          /* Remove last parsed dir */
          *parsed = '\0';
          parsed = trim_directory(path);
          if (--pathdepth == 0)
          {
            /*
             * If the output path is now empty, we're back to the
             * INIT state.  However, we could have processed a
             * path like "../dir/.." and now be down to "..", in
             * which case enter the correct state for that.
             */
            if (parsed == spath)
              state = RELATIVE_PATH_INIT;
            else
              state = RELATIVE_WITH_PARENT_REF;
          }
        }
        else
        {
          /* Append normal dir */
          *parsed++ = '/';
          parsed = append_subdir_to_path(parsed, unparse);
          pathdepth++;
        }
        break;
      case RELATIVE_WITH_PARENT_REF:
        if (is_double_dot)
        {
          /* Append next irreducible double-dot (..) */
          *parsed++ = '/';
          parsed = append_subdir_to_path(parsed, unparse);
        }
        else
        {
          /* Append normal dir */
          *parsed++ = '/';
          parsed = append_subdir_to_path(parsed, unparse);

          /*
           * We can now start counting normal dirs.  But if later
           * double-dots make us remove this dir again, we'd better
           * revert to RELATIVE_WITH_PARENT_REF not INIT state.
           */
          state = RELATIVE_WITH_N_DEPTH;
          pathdepth = 1;
        }
        break;
    }

    unparse = unparse_next;
  }

  /*
   * If our output path is empty at this point, insert ".".  We don't want
   * to do this any earlier because it'd result in an extra dot in corner
   * cases such as "../dir/..".  Since we rejected the wholly-empty-path
   * case above, there is certainly room.
   */
  if (parsed == spath)
    *parsed++ = '.';

  /* And finally, ensure the output path is nul-terminated. */
  *parsed = '\0';
}

/*
 * Detect whether a path contains any parent-directory references ("..")
 *
 * The input *must* have been put through canonicalize_path previously.
 */
bool
path_contains_parent_reference(const char *path)
{
  /*
   * Once canonicalized, an absolute path cannot contain any ".." at all,
   * while a relative path could contain ".."(s) only at the start.  So it
   * is sufficient to check the start of the path, after skipping any
   * Windows drive/network specifier.
   */
  path = skip_drive(path); /* C: shouldn't affect our conclusion */

  if (path[0] == '.' &&
    path[1] == '.' &&
    (path[2] == '\0' || path[2] == '/'))
    return true;

  return false;
}

/*
 * Detect whether a path is only in or below the current working directory.
 *
 * The input *must* have been put through canonicalize_path previously.
 *
 * An absolute path that matches the current working directory should
 * return false (we only want relative to the cwd).
 */
bool
path_is_relative_and_below_cwd(const char *path)
{
  if (is_absolute_path(path))
    return false;
  /* don't allow anything above the cwd */
  else if (path_contains_parent_reference(path))
    return false;
#ifdef WIN32

  /*
   * On Win32, a drive letter _not_ followed by a slash, e.g. 'E:abc', is
   * relative to the cwd on that drive, or the drive's root directory if
   * that drive has no cwd.  Because the path itself cannot tell us which is
   * the case, we have to assume the worst, i.e. that it is not below the
   * cwd.  We could use GetFullPathName() to find the full path but that
   * could change if the current directory for the drive changes underneath
   * us, so we just disallow it.
   */
  else if (isalpha((unsigned char) path[0]) && path[1] == ':' &&
       !IS_DIR_SEP(path[2]))
    return false;
#endif
  else
    return true;
}

/*
 * Detect whether path1 is a prefix of path2 (including equality).
 *
 * This is pretty trivial, but it seems better to export a function than
 * to export IS_DIR_SEP.
 */
bool
path_is_prefix_of_path(const char *path1, const char *path2)
{
  int     path1_len = strlen(path1);

  if (strncmp(path1, path2, path1_len) == 0 &&
    (IS_DIR_SEP(path2[path1_len]) || path2[path1_len] == '\0'))
    return true;
  return false;
}

/*
 * Extracts the actual name of the program as called -
 * stripped of .exe suffix if any
 */
const char *
get_progname(const char *argv0)
{
  const char *nodir_name;
  char     *progname;

  nodir_name = last_dir_separator(argv0);
  if (nodir_name)
    nodir_name++;
  else
    nodir_name = skip_drive(argv0);

  /*
   * Make a copy in case argv[0] is modified by ps_status. Leaks memory, but
   * called only once.
   */
  progname = strdup(nodir_name);
  if (progname == NULL)
  {
    fprintf(stderr, "%s: out of memory\n", nodir_name);
    abort();        /* This could exit the postmaster */
  }

#if defined(__CYGWIN__) || defined(WIN32)
  /* strip ".exe" suffix, regardless of case */
  if (strlen(progname) > sizeof(EXE) - 1 &&
    pg_strcasecmp(progname + strlen(progname) - (sizeof(EXE) - 1), EXE) == 0)
    progname[strlen(progname) - (sizeof(EXE) - 1)] = '\0';
#endif

  return progname;
}


/*
 * dir_strcmp: strcmp except any two DIR_SEP characters are considered equal,
 * and we honor filesystem case insensitivity if known
 */
static int
dir_strcmp(const char *s1, const char *s2)
{
  while (*s1 && *s2)
  {
    if (
#ifndef WIN32
      *s1 != *s2
#else
    /* On windows, paths are case-insensitive */
      pg_tolower((unsigned char) *s1) != pg_tolower((unsigned char) *s2)
#endif
      && !(IS_DIR_SEP(*s1) && IS_DIR_SEP(*s2)))
      return (int) *s1 - (int) *s2;
    s1++, s2++;
  }
  if (*s1)
    return 1;       /* s1 longer */
  if (*s2)
    return -1;       /* s2 longer */
  return 0;
}


/*
 * make_relative_path - make a path relative to the actual binary location
 *
 * This function exists to support relocation of installation trees.
 *
 *  ret_path is the output area (must be of size MAXPGPATH)
 *  target_path is the compiled-in path to the directory we want to find
 *  bin_path is the compiled-in path to the directory of executables
 *  my_exec_path is the actual location of my executable
 *
 * We determine the common prefix of target_path and bin_path, then compare
 * the remainder of bin_path to the last directory component(s) of
 * my_exec_path.  If they match, build the result as the part of my_exec_path
 * preceding the match, joined to the remainder of target_path.  If no match,
 * return target_path as-is.
 *
 * For example:
 *    target_path  = '/usr/local/share/postgresql'
 *    bin_path   = '/usr/local/bin'
 *    my_exec_path = '/opt/pgsql/bin/postgres'
 * Given these inputs, the common prefix is '/usr/local/', the tail of
 * bin_path is 'bin' which does match the last directory component of
 * my_exec_path, so we would return '/opt/pgsql/share/postgresql'
 */
static void
make_relative_path(char *ret_path, const char *target_path,
           const char *bin_path, const char *my_exec_path)
{
  int     prefix_len;
  int     tail_start;
  int     tail_len;
  int     i;

  /*
   * Determine the common prefix --- note we require it to end on a
   * directory separator, consider eg '/usr/lib' and '/usr/libexec'.
   */
  prefix_len = 0;
  for (i = 0; target_path[i] && bin_path[i]; i++)
  {
    if (IS_DIR_SEP(target_path[i]) && IS_DIR_SEP(bin_path[i]))
      prefix_len = i + 1;
    else if (target_path[i] != bin_path[i])
      break;
  }
  if (prefix_len == 0)
    goto no_match;     /* no common prefix? */
  tail_len = strlen(bin_path) - prefix_len;

  /*
   * Set up my_exec_path without the actual executable name, and
   * canonicalize to simplify comparison to bin_path.
   */
  strlcpy(ret_path, my_exec_path, MAXPGPATH);
  trim_directory(ret_path); /* remove my executable name */
  canonicalize_path(ret_path);

  /*
   * Tail match?
   */
  tail_start = (int) strlen(ret_path) - tail_len;
  if (tail_start > 0 &&
    IS_DIR_SEP(ret_path[tail_start - 1]) &&
    dir_strcmp(ret_path + tail_start, bin_path + prefix_len) == 0)
  {
    ret_path[tail_start] = '\0';
    trim_trailing_separator(ret_path);
    join_path_components(ret_path, ret_path, target_path + prefix_len);
    canonicalize_path(ret_path);
    return;
  }

no_match:
  strlcpy(ret_path, target_path, MAXPGPATH);
  canonicalize_path(ret_path);
}


/*
 * make_absolute_path
 *
 * If the given pathname isn't already absolute, make it so, interpreting
 * it relative to the current working directory.
 *
 * Also canonicalizes the path.  The result is always a malloc'd copy.
 *
 * In backend, failure cases result in ereport(ERROR); in frontend,
 * we write a complaint on stderr and return NULL.
 *
 * Note: interpretation of relative-path arguments during postmaster startup
 * should happen before doing ChangeToDataDir(), else the user will probably
 * not like the results.
 */
char *
make_absolute_path(const char *path)
{
  char     *new;

  /* Returning null for null input is convenient for some callers */
  if (path == NULL)
    return NULL;

  if (!is_absolute_path(path))
  {
    char     *buf;
    size_t    buflen;

    buflen = MAXPGPATH;
    for (;;)
    {
      buf = malloc(buflen);
      if (!buf)
      {
#ifndef FRONTEND
        ereport(ERROR,
            (errcode(ERRCODE_OUT_OF_MEMORY),
             errmsg("out of memory")));
#else
        fprintf(stderr, _("out of memory\n"));
        return NULL;
#endif
      }

      if (getcwd(buf, buflen))
        break;
      else if (errno == ERANGE)
      {
        free(buf);
        buflen *= 2;
        continue;
      }
      else
      {
        int     save_errno = errno;

        free(buf);
        errno = save_errno;
#ifndef FRONTEND
        elog(ERROR, "could not get current working directory: %m");
#else
        fprintf(stderr, _("could not get current working directory: %m\n"));
        return NULL;
#endif
      }
    }

    new = malloc(strlen(buf) + strlen(path) + 2);
    if (!new)
    {
      free(buf);
#ifndef FRONTEND
      ereport(ERROR,
          (errcode(ERRCODE_OUT_OF_MEMORY),
           errmsg("out of memory")));
#else
      fprintf(stderr, _("out of memory\n"));
      return NULL;
#endif
    }
    sprintf(new, "%s/%s", buf, path);
    free(buf);
  }
  else
  {
    new = strdup(path);
    if (!new)
    {
#ifndef FRONTEND
      ereport(ERROR,
          (errcode(ERRCODE_OUT_OF_MEMORY),
           errmsg("out of memory")));
#else
      fprintf(stderr, _("out of memory\n"));
      return NULL;
#endif
    }
  }

  /* Make sure punctuation is canonical, too */
  canonicalize_path(new);

  return new;
}


/*
 *  get_share_path
 */
void
get_share_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, PGSHAREDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_etc_path
 */
void
get_etc_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, SYSCONFDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_include_path
 */
void
get_include_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, INCLUDEDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_pkginclude_path
 */
void
get_pkginclude_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, PKGINCLUDEDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_includeserver_path
 */
void
get_includeserver_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, INCLUDEDIRSERVER, PGBINDIR, my_exec_path);
}

/*
 *  get_lib_path
 */
void
get_lib_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, LIBDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_pkglib_path
 */
void
get_pkglib_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, PKGLIBDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_locale_path
 */
void
get_locale_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, LOCALEDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_doc_path
 */
void
get_doc_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, DOCDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_html_path
 */
void
get_html_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, HTMLDIR, PGBINDIR, my_exec_path);
}

/*
 *  get_man_path
 */
void
get_man_path(const char *my_exec_path, char *ret_path)
{
  make_relative_path(ret_path, MANDIR, PGBINDIR, my_exec_path);
}


/*
 *  get_home_path
 *
 * On Unix, this actually returns the user's home directory.  On Windows
 * it returns the PostgreSQL-specific application data folder.
 */
bool
get_home_path(char *ret_path)
{
#ifndef WIN32
  /*
   * We first consult $HOME.  If that's unset, try to get the info from
   * <pwd.h>.
   */
  const char *home;

  home = getenv("HOME");
  if (home && home[0])
  {
    strlcpy(ret_path, home, MAXPGPATH);
    return true;
  }
  else
  {
    struct passwd pwbuf;
    struct passwd *pw;
    char    buf[1024];
    int     rc;

    rc = getpwuid_r(geteuid(), &pwbuf, buf, sizeof buf, &pw);
    if (rc != 0 || !pw)
      return false;
    strlcpy(ret_path, pw->pw_dir, MAXPGPATH);
    return true;
  }
#else
  char     *tmppath;

  /*
   * Note: We use getenv() here because the more modern SHGetFolderPath()
   * would force the backend to link with shell32.lib, which eats valuable
   * desktop heap.  XXX This function is used only in psql, which already
   * brings in shell32 via libpq.  Moving this function to its own file
   * would keep it out of the backend, freeing it from this concern.
   */
  tmppath = getenv("APPDATA");
  if (!tmppath)
    return false;
  snprintf(ret_path, MAXPGPATH, "%s/postgresql", tmppath);
  return true;
#endif
}


/*
 * get_parent_directory
 *
 * Modify the given string in-place to name the parent directory of the
 * named file.
 *
 * If the input is just a file name with no directory part, the result is
 * an empty string, not ".".  This is appropriate when the next step is
 * join_path_components(), but might need special handling otherwise.
 *
 * Caution: this will not produce desirable results if the string ends
 * with "..".  For most callers this is not a problem since the string
 * is already known to name a regular file.  If in doubt, apply
 * canonicalize_path() first.
 */
void
get_parent_directory(char *path)
{
  trim_directory(path);
}


/*
 *  trim_directory
 *
 *  Trim trailing directory from path, that is, remove any trailing slashes,
 *  the last pathname component, and the slash just ahead of it --- but never
 *  remove a leading slash.
 *
 * For the convenience of canonicalize_path, the path's new end location
 * is returned.
 */
static char *
trim_directory(char *path)
{
  char     *p;

  path = skip_drive(path);

  if (path[0] == '\0')
    return path;

  /* back up over trailing slash(es) */
  for (p = path + strlen(path) - 1; IS_DIR_SEP(*p) && p > path; p--)
    ;
  /* back up over directory name */
  for (; !IS_DIR_SEP(*p) && p > path; p--)
    ;
  /* if multiple slashes before directory name, remove 'em all */
  for (; p > path && IS_DIR_SEP(*(p - 1)); p--)
    ;
  /* don't erase a leading slash */
  if (p == path && IS_DIR_SEP(*p))
    p++;
  *p = '\0';
  return p;
}


/*
 *  trim_trailing_separator
 *
 * trim off trailing slashes, but not a leading slash
 */
static void
trim_trailing_separator(char *path)
{
  char     *p;

  path = skip_drive(path);
  p = path + strlen(path);
  if (p > path)
    for (p--; p > path && IS_DIR_SEP(*p); p--)
      *p = '\0';
}

/*
 *  append_subdir_to_path
 *
 * Append the currently-considered subdirectory name to the output
 * path in canonicalize_path.  Return the new end location of the
 * output path.
 *
 * Since canonicalize_path updates the path in-place, we must use
 * memmove not memcpy, and we don't yet terminate the path with '\0'.
 */
static char *
append_subdir_to_path(char *path, char *subdir)
{
  size_t    len = strlen(subdir);

  /* No need to copy data if path and subdir are the same. */
  if (path != subdir)
    memmove(path, subdir, len);

  return path + len;
}

Coverage Report

Created: 2025-06-13 06:06