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sortix--sortix/libc/getcwd.cpp
Jonas 'Sortie' Termansen 1444683ea8 Refactor kernel VFS.
Note: This is an incompatible ABI change.
2013-12-17 14:30:24 +01:00

137 lines
3.3 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
getcwd.cpp
Returns the current working directory.
*******************************************************************************/
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static int dup_handles_cwd(int fd)
{
if ( fd == AT_FDCWD )
return open(".", O_RDONLY | O_DIRECTORY);
return dup(fd);
}
static char* FindDirectoryEntryAt(int dirfd, ino_t inode, dev_t dev)
{
int dupdirfd = dup_handles_cwd(dirfd);
if ( dupdirfd < 0 )
return NULL;
DIR* dir = fdopendir(dupdirfd);
if ( !dir ) { close(dupdirfd); return NULL; }
struct dirent* entry;
while ( (entry = readdir(dir)) )
{
if ( !strcmp(entry->d_name, "..") )
continue;
struct stat st;
if ( fstatat(dupdirfd, entry->d_name, &st, 0) )
continue; // Not ideal, but missing permissions, broken symlinks..
if ( st.st_ino == inode && st.st_dev == dev )
{
char* result = strdup(entry->d_name);
closedir(dir);
return result;
}
}
closedir(dir);
errno = ENOENT;
return NULL;
}
extern "C" char* get_current_dir_name(void)
{
int fd;
int parent;
struct stat fdst;
struct stat parentst;
size_t retlen = 0;
size_t newretlen;
char* ret = NULL;
char* newret;
char* elem;
fd = open(".", O_RDONLY | O_DIRECTORY);
if ( fd < 0 )
goto cleanup_done;
if ( fstat(fd, &fdst) )
goto cleanup_fd;
next_parent:
parent = openat(fd, "..", O_RDONLY | O_DIRECTORY);
if ( parent < 0 )
goto cleanup_fd;
if ( fstat(parent, &parentst) )
goto cleanup_parent;
if ( fdst.st_ino == parentst.st_ino &&
fdst.st_dev == parentst.st_dev )
{
close(fd);
close(parent);
return ret ? ret : strdup("/");
}
elem = FindDirectoryEntryAt(parent, fdst.st_ino, fdst.st_dev);
if ( !elem )
goto cleanup_parent;
newretlen = 1 + strlen(elem) + retlen;
newret = (char*) malloc(sizeof(char) * (newretlen + 1));
if ( !newret )
goto cleanup_elem;
stpcpy(stpcpy(stpcpy(newret, "/"), elem), ret ? ret : "");
free(elem);
free(ret);
ret = newret;
retlen = newretlen;
close(fd);
fd = parent;
fdst = parentst;
goto next_parent;
cleanup_elem:
free(elem);
cleanup_parent:
close(parent);
cleanup_fd:
close(fd);
cleanup_done:
free(ret);
return NULL;
}
extern "C" char* getcwd(char* buf, size_t size)
{
char* cwd = get_current_dir_name();
if ( !buf )
return cwd;
if ( !cwd )
return NULL;
if ( size < strlen(cwd)+1 ) { free(cwd); errno = ERANGE; return NULL; }
strcpy(buf, cwd);
free(cwd);
return buf;
}