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