unix_capture.c: Optionally use dirfd-relative functions (openat(), etc)
authorEric Biggers <ebiggers3@gmail.com>
Wed, 14 May 2014 04:37:41 +0000 (23:37 -0500)
committerEric Biggers <ebiggers3@gmail.com>
Wed, 14 May 2014 05:02:14 +0000 (00:02 -0500)
configure.ac
src/unix_capture.c

index f4b143d..75f4bd6 100644 (file)
@@ -48,7 +48,8 @@ AC_PROG_CC
 AM_PROG_CC_C_O
 AC_CANONICAL_HOST
 
-AC_CHECK_FUNCS([utimensat lutimes utime flock mempcpy])
+AC_CHECK_FUNCS([utimensat lutimes utime flock mempcpy  \
+               openat fstatat readlinkat fdopendir])
 
 # Note: some of the following header checks are only to define the appropriate
 # HAVE_*_H macro so that the NTFS-3g headers don't get confused and try to skip
index 1de0b80..a76fbc3 100644 (file)
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 2012, 2013 Eric Biggers
+ * Copyright (C) 2012, 2013, 2014 Eric Biggers
  *
  * This file is part of wimlib, a library for working with WIM files.
  *
@@ -29,7 +29,8 @@
 
 #include <dirent.h>
 #include <errno.h>
-#include <limits.h>
+#include <fcntl.h>
+#include <limits.h> /* for PATH_MAX */
 #include <sys/stat.h>
 #include <unistd.h>
 
 #include "wimlib/dentry.h"
 #include "wimlib/error.h"
 #include "wimlib/lookup_table.h"
-#include "wimlib/paths.h"
 #include "wimlib/reparse.h"
 #include "wimlib/timestamp.h"
 
+#ifdef HAVE_FDOPENDIR
+#  define my_fdopendir(dirfd_p) fdopendir(*(dirfd_p))
+#else
+static DIR *
+my_fdopendir(int *dirfd_p)
+{
+       DIR *dir = NULL;
+       int old_pwd;
+
+       old_pwd = open(".", O_RDONLY);
+       if (old_pwd >= 0) {
+               if (!fchdir(*dirfd_p)) {
+                       dir = opendir(".");
+                       if (dir) {
+                               close(*dirfd_p);
+                               *dirfd_p = dirfd(dir);
+                       }
+                       fchdir(old_pwd);
+               }
+               close(old_pwd);
+       }
+       return dir;
+}
+#endif
+
+#ifdef HAVE_OPENAT
+#  define my_openat(full_path, dirfd, relpath, flags) \
+               openat((dirfd), (relpath), (flags))
+#else
+#  define my_openat(full_path, dirfd, relpath, flags) \
+               open((full_path), (flags))
+#endif
+
+#ifdef HAVE_READLINKAT
+#  define my_readlinkat(full_path, dirfd, relpath, buf, bufsize) \
+               readlinkat((dirfd), (relpath), (buf), (bufsize))
+#else
+#  define my_readlinkat(full_path, dirfd, relpath, buf, bufsize) \
+               readlink((full_path), (buf), (bufsize))
+#endif
+
+#ifdef HAVE_FSTATAT
+#  define my_fstatat(full_path, dirfd, relpath, stbuf, flags)  \
+       fstatat((dirfd), (relpath), (stbuf), (flags))
+#else
+#  define my_fstatat(full_path, dirfd, relpath, stbuf, flags)  \
+       ((flags) & AT_SYMLINK_NOFOLLOW) ? \
+               lstat((full_path), (stbuf)) : \
+               stat((full_path), (stbuf))
+#endif
+
+#ifndef AT_FDCWD
+#  define AT_FDCWD     -100
+#endif
+
+#ifndef AT_SYMLINK_NOFOLLOW
+#  define AT_SYMLINK_NOFOLLOW  0x100
+#endif
+
 static int
-unix_capture_regular_file(const char *path,
-                         u64 size,
-                         struct wim_inode *inode,
-                         struct list_head *unhashed_streams)
+unix_scan_regular_file(const char *path, u64 size, struct wim_inode *inode,
+                      struct list_head *unhashed_streams)
 {
+       struct wim_lookup_table_entry *lte;
+       char *file_on_disk;
+
        inode->i_attributes = FILE_ATTRIBUTE_NORMAL;
 
        /* Empty files do not have to have a lookup table entry. */
-       if (size != 0) {
-               struct wim_lookup_table_entry *lte;
-               char *file_on_disk;
-
-               file_on_disk = STRDUP(path);
-               if (!file_on_disk)
-                       return WIMLIB_ERR_NOMEM;
-               lte = new_lookup_table_entry();
-               if (!lte) {
-                       FREE(file_on_disk);
-                       return WIMLIB_ERR_NOMEM;
-               }
-               lte->file_on_disk = file_on_disk;
-               lte->resource_location = RESOURCE_IN_FILE_ON_DISK;
-               lte->size = size;
-               add_unhashed_stream(lte, inode, 0, unhashed_streams);
-               inode->i_lte = lte;
+       if (!size)
+               return 0;
+
+       file_on_disk = STRDUP(path);
+       if (!file_on_disk)
+               return WIMLIB_ERR_NOMEM;
+       lte = new_lookup_table_entry();
+       if (!lte) {
+               FREE(file_on_disk);
+               return WIMLIB_ERR_NOMEM;
        }
+       lte->file_on_disk = file_on_disk;
+       lte->resource_location = RESOURCE_IN_FILE_ON_DISK;
+       lte->size = size;
+       add_unhashed_stream(lte, inode, 0, unhashed_streams);
+       inode->i_lte = lte;
        return 0;
 }
 
 static int
-unix_build_dentry_tree_recursive(struct wim_dentry **root_ret,
-                                char *path,
-                                size_t path_len,
+unix_build_dentry_tree_recursive(struct wim_dentry **tree_ret,
+                                char *path, size_t path_len,
+                                int dirfd, const char *relpath,
                                 struct add_image_params *params);
 
 static int
-unix_capture_directory(struct wim_dentry *dir_dentry,
-                      char *path,
-                      size_t path_len,
-                      struct add_image_params *params)
+unix_scan_directory(struct wim_dentry *dir_dentry,
+                   char *full_path, size_t full_path_len,
+                   int parent_dirfd, const char *dir_relpath,
+                   struct add_image_params *params)
 {
 
+       int dirfd;
        DIR *dir;
-       struct dirent *entry;
-       struct wim_dentry *child;
        int ret;
 
+       dirfd = my_openat(full_path, parent_dirfd, dir_relpath, O_RDONLY);
+       if (dirfd < 0) {
+               ERROR_WITH_ERRNO("\"%s\": Can't open directory", full_path);
+               return WIMLIB_ERR_OPENDIR;
+       }
+
        dir_dentry->d_inode->i_attributes = FILE_ATTRIBUTE_DIRECTORY;
-       dir = opendir(path);
+       dir = my_fdopendir(&dirfd);
        if (!dir) {
-               ERROR_WITH_ERRNO("Failed to open the directory `%s'",
-                                path);
+               ERROR_WITH_ERRNO("\"%s\": Can't open directory", full_path);
+               close(dirfd);
                return WIMLIB_ERR_OPENDIR;
        }
 
-       /* Recurse on directory contents */
        ret = 0;
        for (;;) {
+               struct dirent *entry;
+               struct wim_dentry *child;
+               size_t name_len;
+
                errno = 0;
                entry = readdir(dir);
                if (!entry) {
                        if (errno) {
                                ret = WIMLIB_ERR_READ;
-                               ERROR_WITH_ERRNO("Error reading the "
-                                                "directory `%s'", path);
+                               ERROR_WITH_ERRNO("\"%s\": Error reading directory",
+                                                full_path);
                        }
                        break;
                }
 
-               if (entry->d_name[0] == '.' && (entry->d_name[1] == '\0'
-                     || (entry->d_name[1] == '.' && entry->d_name[2] == '\0')))
-                               continue;
+               if (entry->d_name[0] == '.' &&
+                   (entry->d_name[1] == '\0' ||
+                    (entry->d_name[1] == '.' && entry->d_name[2] == '\0')))
+                       continue;
 
-               size_t name_len = strlen(entry->d_name);
-
-               path[path_len] = '/';
-               memcpy(&path[path_len + 1], entry->d_name, name_len + 1);
+               full_path[full_path_len] = '/';
+               name_len = strlen(entry->d_name);
+               memcpy(&full_path[full_path_len + 1], entry->d_name, name_len + 1);
                ret = unix_build_dentry_tree_recursive(&child,
-                                                      path,
-                                                      path_len + 1 + name_len,
+                                                      full_path,
+                                                      full_path_len + 1 + name_len,
+                                                      dirfd,
+                                                      &full_path[full_path_len + 1],
                                                       params);
+               full_path[full_path_len] = '\0';
                if (ret)
                        break;
                if (child)
                        dentry_add_child(dir_dentry, child);
        }
-       path[path_len] = '\0';
        closedir(dir);
        return ret;
 }
 
 static int
-unix_capture_symlink(struct wim_dentry **root_p,
-                    const char *path,
-                    struct wim_inode *inode,
-                    struct add_image_params *params)
+unix_scan_symlink(struct wim_dentry **root_p, const char *full_path,
+                 int dirfd, const char *relpath,
+                 struct wim_inode *inode, struct add_image_params *params)
 {
        char deref_name_buf[4096];
        ssize_t deref_name_len;
@@ -150,18 +217,17 @@ unix_capture_symlink(struct wim_dentry **root_p,
        /* The idea here is to call readlink() to get the UNIX target of the
         * symbolic link, then turn the target into a reparse point data buffer
         * that contains a relative or absolute symbolic link. */
-       deref_name_len = readlink(path, deref_name_buf,
-                                 sizeof(deref_name_buf) - 1);
+       deref_name_len = my_readlinkat(full_path, dirfd, relpath,
+                                      deref_name_buf, sizeof(deref_name_buf) - 1);
        if (deref_name_len < 0) {
-               ERROR_WITH_ERRNO("Failed to read target of "
-                                "symbolic link `%s'", path);
+               ERROR_WITH_ERRNO("\"%s\": Can't read target of symbolic link",
+                                full_path);
                return WIMLIB_ERR_READLINK;
        }
 
        dest = deref_name_buf;
 
        dest[deref_name_len] = '\0';
-       DEBUG("Read symlink `%s'", dest);
 
        if ((params->add_flags & WIMLIB_ADD_FLAG_RPFIX) &&
             dest[0] == '/')
@@ -169,13 +235,13 @@ unix_capture_symlink(struct wim_dentry **root_p,
                dest = capture_fixup_absolute_symlink(dest,
                                                      params->capture_root_ino,
                                                      params->capture_root_dev);
-               if (dest == NULL) {
+               if (!dest) {
                        /* RPFIX (reparse point fixup) mode:  Ignore
                         * absolute symbolic link that points out of the
                         * tree to be captured.  */
                        free_dentry(*root_p);
                        *root_p = NULL;
-                       params->progress.scan.cur_path = path;
+                       params->progress.scan.cur_path = full_path;
                        params->progress.scan.symlink_target = deref_name_buf;
                        do_capture_progress(params,
                                            WIMLIB_SCAN_DENTRY_EXCLUDED_SYMLINK,
@@ -193,69 +259,72 @@ unix_capture_symlink(struct wim_dentry **root_p,
         * FILE_ATTRIBUTE_DIRECTORY needs to be set on the symbolic link if the
         * *target* of the symbolic link is a directory.  */
        struct stat stbuf;
-       if (stat(path, &stbuf) == 0 && S_ISDIR(stbuf.st_mode))
+       if (my_fstatat(full_path, dirfd, relpath, &stbuf, 0) == 0 &&
+           S_ISDIR(stbuf.st_mode))
                inode->i_attributes |= FILE_ATTRIBUTE_DIRECTORY;
        return 0;
 }
 
 static int
-unix_build_dentry_tree_recursive(struct wim_dentry **root_ret,
-                                char *path,
-                                size_t path_len,
+unix_build_dentry_tree_recursive(struct wim_dentry **tree_ret,
+                                char *full_path, size_t full_path_len,
+                                int dirfd, const char *relpath,
                                 struct add_image_params *params)
 {
-       struct wim_dentry *root = NULL;
-       int ret;
+       struct wim_dentry *tree = NULL;
        struct wim_inode *inode = NULL;
+       int ret;
        struct stat stbuf;
+       int stat_flags;
 
-       if (should_exclude_path(path + params->capture_root_nchars,
-                               path_len - params->capture_root_nchars,
+       if (should_exclude_path(full_path + params->capture_root_nchars,
+                               full_path_len - params->capture_root_nchars,
                                params->config))
        {
                ret = 0;
                goto out_progress;
        }
 
-       if ((params->add_flags & WIMLIB_ADD_FLAG_DEREFERENCE) ||
-           (params->add_flags & WIMLIB_ADD_FLAG_ROOT))
-               ret = stat(path, &stbuf);
+       if (params->add_flags & (WIMLIB_ADD_FLAG_DEREFERENCE |
+                                WIMLIB_ADD_FLAG_ROOT))
+               stat_flags = 0;
        else
-               ret = lstat(path, &stbuf);
+               stat_flags = AT_SYMLINK_NOFOLLOW;
+
+       ret = my_fstatat(full_path, dirfd, relpath, &stbuf, stat_flags);
 
        if (ret) {
-               ERROR_WITH_ERRNO("Failed to stat \"%s\"", path);
+               ERROR_WITH_ERRNO("\"%s\": Can't read metadata", full_path);
                ret = WIMLIB_ERR_STAT;
                goto out;
        }
 
-       if (!S_ISREG(stbuf.st_mode) &&
-           !S_ISDIR(stbuf.st_mode) &&
-           !S_ISLNK(stbuf.st_mode))
+       if (unlikely(!S_ISREG(stbuf.st_mode) &&
+                    !S_ISDIR(stbuf.st_mode) &&
+                    !S_ISLNK(stbuf.st_mode)))
        {
                if (params->add_flags & WIMLIB_ADD_FLAG_NO_UNSUPPORTED_EXCLUDE)
                {
-                       ERROR("Can't archive unsupported file \"%s\"", path);
+                       ERROR("\"%s\": File type is unsupported", full_path);
                        ret = WIMLIB_ERR_UNSUPPORTED_FILE;
                        goto out;
                }
-               params->progress.scan.cur_path = path;
+               params->progress.scan.cur_path = full_path;
                do_capture_progress(params, WIMLIB_SCAN_DENTRY_UNSUPPORTED, NULL);
                ret = 0;
                goto out;
        }
 
-       ret = inode_table_new_dentry(params->inode_table,
-                                    path_basename_with_len(path, path_len),
+       ret = inode_table_new_dentry(params->inode_table, relpath,
                                     stbuf.st_ino, stbuf.st_dev,
-                                    S_ISDIR(stbuf.st_mode), &root);
+                                    S_ISDIR(stbuf.st_mode), &tree);
        if (ret)
                goto out;
 
-       inode = root->d_inode;
+       inode = tree->d_inode;
 
        if (inode->i_nlink > 1) {
-               /* Already captured this inode? */
+               /* Already seen this inode?  */
                ret = 0;
                goto out_progress;
        }
@@ -279,15 +348,23 @@ unix_build_dentry_tree_recursive(struct wim_dentry **root_ret,
                if (ret)
                        goto out;
        }
-       params->add_flags &= ~WIMLIB_ADD_FLAG_ROOT;
-       if (S_ISREG(stbuf.st_mode))
-               ret = unix_capture_regular_file(path, stbuf.st_size,
-                                               inode, params->unhashed_streams);
-       else if (S_ISDIR(stbuf.st_mode))
-               ret = unix_capture_directory(root, path, path_len, params);
-       else {
-               ret = unix_capture_symlink(&root, path, inode, params);
-               if (root == NULL)
+
+       if (params->add_flags & WIMLIB_ADD_FLAG_ROOT) {
+               params->capture_root_ino = stbuf.st_ino;
+               params->capture_root_dev = stbuf.st_dev;
+               params->add_flags &= ~WIMLIB_ADD_FLAG_ROOT;
+       }
+
+       if (S_ISREG(stbuf.st_mode)) {
+               ret = unix_scan_regular_file(full_path, stbuf.st_size,
+                                            inode, params->unhashed_streams);
+       } else if (S_ISDIR(stbuf.st_mode)) {
+               ret = unix_scan_directory(tree, full_path, full_path_len,
+                                         dirfd, relpath, params);
+       } else {
+               ret = unix_scan_symlink(&tree, full_path, dirfd, relpath,
+                                       inode, params);
+               if (!tree)
                        goto out;
        }
 
@@ -295,16 +372,16 @@ unix_build_dentry_tree_recursive(struct wim_dentry **root_ret,
                goto out;
 
 out_progress:
-       params->progress.scan.cur_path = path;
-       if (root == NULL)
-               do_capture_progress(params, WIMLIB_SCAN_DENTRY_EXCLUDED, NULL);
-       else
+       params->progress.scan.cur_path = full_path;
+       if (likely(tree))
                do_capture_progress(params, WIMLIB_SCAN_DENTRY_OK, inode);
+       else
+               do_capture_progress(params, WIMLIB_SCAN_DENTRY_EXCLUDED, NULL);
 out:
-       if (ret)
-               free_dentry_tree(root, params->lookup_table);
+       if (likely(ret == 0))
+               *tree_ret = tree;
        else
-               *root_ret = root;
+               free_dentry_tree(tree, params->lookup_table);
        return ret;
 }
 
@@ -333,24 +410,13 @@ unix_build_dentry_tree(struct wim_dentry **root_ret,
                       const char *root_disk_path,
                       struct add_image_params *params)
 {
-       char *path_buf;
-       int ret;
        size_t path_len;
        size_t path_bufsz;
+       char *path_buf;
+       int ret;
 
-       {
-               struct stat root_stbuf;
-               if (stat(root_disk_path, &root_stbuf)) {
-                       ERROR_WITH_ERRNO("Failed to stat \"%s\"", root_disk_path);
-                       return WIMLIB_ERR_STAT;
-               }
-
-               params->capture_root_ino = root_stbuf.st_ino;
-               params->capture_root_dev = root_stbuf.st_dev;
-       }
-
-       path_bufsz = min(32790, PATH_MAX + 1);
        path_len = strlen(root_disk_path);
+       path_bufsz = min(32790, PATH_MAX + 1);
 
        if (path_len >= path_bufsz)
                return WIMLIB_ERR_INVALID_PARAM;
@@ -362,8 +428,8 @@ unix_build_dentry_tree(struct wim_dentry **root_ret,
 
        params->capture_root_nchars = path_len;
 
-       ret = unix_build_dentry_tree_recursive(root_ret, path_buf,
-                                              path_len, params);
+       ret = unix_build_dentry_tree_recursive(root_ret, path_buf, path_len,
+                                              AT_FDCWD, path_buf, params);
        FREE(path_buf);
        return ret;
 }