#include "git-compat-util.h"

#include "abspath.h"

#include "strbuf.h"

/*

 * Do not use this for inspecting *tracked* content.  When path is a

 * symlink to a directory, we do not want to say it is a directory when

 * dealing with tracked content in the working tree.

 */

int is_directory(const char *path)

{

  struct stat st;

  return (!stat(path, &st) && S_ISDIR(st.st_mode));

}

/* removes the last path component from 'path' except if 'path' is root */

static void strip_last_component(struct strbuf *path)

{

  size_t offset = offset_1st_component(path->buf);

  size_t len = path->len;

  /* Find start of the last component */

  while (offset < len && !is_dir_sep(path->buf[len - 1]))

    len--;

  /* Skip sequences of multiple path-separators */

  while (offset < len && is_dir_sep(path->buf[len - 1]))

    len--;

  strbuf_setlen(path, len);

}

/* get (and remove) the next component in 'remaining' and place it in 'next' */

static void get_next_component(struct strbuf *next, struct strbuf *remaining)

{

  char *start = NULL;

  char *end = NULL;

  strbuf_reset(next);

  /* look for the next component */

  /* Skip sequences of multiple path-separators */

  for (start = remaining->buf; is_dir_sep(*start); start++)

    ; /* nothing */

  /* Find end of the path component */

  for (end = start; *end && !is_dir_sep(*end); end++)

    ; /* nothing */

  strbuf_add(next, start, end - start);

  /* remove the component from 'remaining' */

  strbuf_remove(remaining, 0, end - remaining->buf);

}

/* copies root part from remaining to resolved, canonicalizing it on the way */

static void get_root_part(struct strbuf *resolved, struct strbuf *remaining)

{

  int offset = offset_1st_component(remaining->buf);

  strbuf_reset(resolved);

  strbuf_add(resolved, remaining->buf, offset);

#ifdef GIT_WINDOWS_NATIVE

  convert_slashes(resolved->buf);

#endif

  strbuf_remove(remaining, 0, offset);

}

/* We allow "recursive" symbolic links. Only within reason, though. */

#ifndef MAXSYMLINKS

#define MAXSYMLINKS 32

#endif

/*

 * If set, any number of trailing components may be missing; otherwise, only one

 * may be.

 */

#define REALPATH_MANY_MISSING (1 << 0)

/* Should we die if there's an error? */

#define REALPATH_DIE_ON_ERROR (1 << 1)

static char *strbuf_realpath_1(struct strbuf *resolved, const char *path,

             int flags)

{

  struct strbuf remaining = STRBUF_INIT;

  struct strbuf next = STRBUF_INIT;

  struct strbuf symlink = STRBUF_INIT;

  char *retval = NULL;

  int num_symlinks = 0;

  struct stat st;

  if (!*path) {

    if (flags & REALPATH_DIE_ON_ERROR)

      die("The empty string is not a valid path");

    else

      goto error_out;

  }

  strbuf_addstr(&remaining, path);

  get_root_part(resolved, &remaining);

  if (!resolved->len) {

    /* relative path; can use CWD as the initial resolved path */

    if (strbuf_getcwd(resolved)) {

      if (flags & REALPATH_DIE_ON_ERROR)

        die_errno("unable to get current working directory");

      else

        goto error_out;

    }

  }

  /* Iterate over the remaining path components */

  while (remaining.len > 0) {

    get_next_component(&next, &remaining);

    if (next.len == 0) {

      continue; /* empty component */

    } else if (next.len == 1 && !strcmp(next.buf, ".")) {

      continue; /* '.' component */

    } else if (next.len == 2 && !strcmp(next.buf, "..")) {

      /* '..' component; strip the last path component */

      strip_last_component(resolved);

      continue;

    }

    /* append the next component and resolve resultant path */

    if (!is_dir_sep(resolved->buf[resolved->len - 1]))

      strbuf_addch(resolved, '/');

    strbuf_addbuf(resolved, &next);

    if (lstat(resolved->buf, &st)) {

      /* error out unless this was the last component */

      if (errno != ENOENT ||

         (!(flags & REALPATH_MANY_MISSING) && remaining.len)) {

        if (flags & REALPATH_DIE_ON_ERROR)

          die_errno("Invalid path '%s'",

              resolved->buf);

        else

          goto error_out;

      }

    } else if (S_ISLNK(st.st_mode)) {

      ssize_t len;

      strbuf_reset(&symlink);

      if (num_symlinks++ > MAXSYMLINKS) {

        errno = ELOOP;

        if (flags & REALPATH_DIE_ON_ERROR)

          die("More than %d nested symlinks "

              "on path '%s'", MAXSYMLINKS, path);

        else

          goto error_out;

      }

      len = strbuf_readlink(&symlink, resolved->buf,

                st.st_size);

      if (len < 0) {

        if (flags & REALPATH_DIE_ON_ERROR)

          die_errno("Invalid symlink '%s'",

              resolved->buf);

        else

          goto error_out;

      }

      if (is_absolute_path(symlink.buf)) {

        /* absolute symlink; set resolved to root */

        get_root_part(resolved, &symlink);

      } else {

        /*

         * relative symlink

         * strip off the last component since it will

         * be replaced with the contents of the symlink

         */

        strip_last_component(resolved);

      }

      /*

       * if there are still remaining components to resolve

       * then append them to symlink

       */

      if (remaining.len) {

        strbuf_addch(&symlink, '/');

        strbuf_addbuf(&symlink, &remaining);

      }

      /*

       * use the symlink as the remaining components that

       * need to be resolved

       */

      strbuf_swap(&symlink, &remaining);

    }

  }

  retval = resolved->buf;

error_out:

  strbuf_release(&remaining);

  strbuf_release(&next);

  strbuf_release(&symlink);

  if (!retval)

    strbuf_reset(resolved);

  return retval;

}

/*

 * Return the real path (i.e., absolute path, with symlinks resolved

 * and extra slashes removed) equivalent to the specified path.  (If

 * you want an absolute path but don't mind links, use

 * absolute_path().)  Places the resolved realpath in the provided strbuf.

 *

 * The directory part of path (i.e., everything up to the last

 * dir_sep) must denote a valid, existing directory, but the last

 * component need not exist.  If die_on_error is set, then die with an

 * informative error message if there is a problem.  Otherwise, return

 * NULL on errors (without generating any output).

 */

char *strbuf_realpath(struct strbuf *resolved, const char *path,

          int die_on_error)

{

  return strbuf_realpath_1(resolved, path,

         die_on_error ? REALPATH_DIE_ON_ERROR : 0);

}

/*

 * Just like strbuf_realpath, but allows an arbitrary number of path

 * components to be missing.

 */

char *strbuf_realpath_forgiving(struct strbuf *resolved, const char *path,

        int die_on_error)

{

  return strbuf_realpath_1(resolved, path,

         ((die_on_error ? REALPATH_DIE_ON_ERROR : 0) |

          REALPATH_MANY_MISSING));

}

char *real_pathdup(const char *path, int die_on_error)

{

  struct strbuf realpath = STRBUF_INIT;

  char *retval = NULL;

  if (strbuf_realpath(&realpath, path, die_on_error))

    retval = strbuf_detach(&realpath, NULL);

  strbuf_release(&realpath);

  return retval;

}

/*

 * Use this to get an absolute path from a relative one. If you want

 * to resolve links, you should use strbuf_realpath.

 */

const char *absolute_path(const char *path)

{

  static struct strbuf sb = STRBUF_INIT;

  strbuf_reset(&sb);

  strbuf_add_absolute_path(&sb, path);

  return sb.buf;

}

char *absolute_pathdup(const char *path)

{

  struct strbuf sb = STRBUF_INIT;

  strbuf_add_absolute_path(&sb, path);

  return strbuf_detach(&sb, NULL);

}

char *prefix_filename(const char *pfx, const char *arg)

{

  struct strbuf path = STRBUF_INIT;

  size_t pfx_len = pfx ? strlen(pfx) : 0;

  if (!pfx_len)

    ; /* nothing to prefix */

  else if (is_absolute_path(arg))

    pfx_len = 0;

  else

    strbuf_add(&path, pfx, pfx_len);

  strbuf_addstr(&path, arg);

#ifdef GIT_WINDOWS_NATIVE

  convert_slashes(path.buf + pfx_len);

#endif

  return strbuf_detach(&path, NULL);

}

char *prefix_filename_except_for_dash(const char *pfx, const char *arg)

{

  if (!strcmp(arg, "-"))

    return xstrdup(arg);

  return prefix_filename(pfx, arg);

}

void strbuf_add_absolute_path(struct strbuf *sb, const char *path)

{

  if (!*path)

    die("The empty string is not a valid path");

  if (!is_absolute_path(path)) {

    struct stat cwd_stat, pwd_stat;

    size_t orig_len = sb->len;

    char *cwd = xgetcwd();

    char *pwd = getenv("PWD");

    if (pwd && strcmp(pwd, cwd) &&

        !stat(cwd, &cwd_stat) &&

        (cwd_stat.st_dev || cwd_stat.st_ino) &&

        !stat(pwd, &pwd_stat) &&

        pwd_stat.st_dev == cwd_stat.st_dev &&

        pwd_stat.st_ino == cwd_stat.st_ino)

      strbuf_addstr(sb, pwd);

    else

      strbuf_addstr(sb, cwd);

    if (sb->len > orig_len && !is_dir_sep(sb->buf[sb->len - 1]))

      strbuf_addch(sb, '/');

    free(cwd);

  }

  strbuf_addstr(sb, path);

}

void strbuf_add_real_path(struct strbuf *sb, const char *path)

{

  if (sb->len) {

    struct strbuf resolved = STRBUF_INIT;

    strbuf_realpath(&resolved, path, 1);

    strbuf_addbuf(sb, &resolved);

    strbuf_release(&resolved);

  } else

    strbuf_realpath(sb, path, 1);

}