path: root/src/realpath.c

/* realpath - print the resolved path Copyright (C) 2011-2025 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>. *//* Written by Pádraig Brady. */#include <config.h>#include <getopt.h>#include <stdio.h>#include <sys/types.h>#include"system.h"#include"canonicalize.h"#include"relpath.h"/* The official name of this program (e.g., no 'g' prefix). */#define PROGRAM_NAME"realpath"#define AUTHORS proper_name_lite ("Padraig Brady","P\303\241draig Brady")enum{ RELATIVE_TO_OPTION = CHAR_MAX +1, RELATIVE_BASE_OPTION };static bool verbose =true;static bool logical;static bool use_nuls;static char const*can_relative_to;static char const*can_relative_base;static struct option const longopts[] ={{"canonicalize-existing", no_argument,nullptr,'e'},{"canonicalize-missing", no_argument,nullptr,'m'},{"relative-to", required_argument,nullptr, RELATIVE_TO_OPTION},{"relative-base", required_argument,nullptr, RELATIVE_BASE_OPTION},{"quiet", no_argument,nullptr,'q'},{"strip", no_argument,nullptr,'s'},{"no-symlinks", no_argument,nullptr,'s'},{"zero", no_argument,nullptr,'z'},{"logical", no_argument,nullptr,'L'},{"physical", no_argument,nullptr,'P'},{GETOPT_HELP_OPTION_DECL},{GETOPT_VERSION_OPTION_DECL},{nullptr,0,nullptr,0}};voidusage(int status){if(status != EXIT_SUCCESS)emit_try_help();else{printf(_("Usage: %s [OPTION]... FILE...\n"), program_name);fputs(_("\Print the resolved absolute file name;\n\all but the last component must exist\n\\n\"), stdout);fputs(_("\ -e, --canonicalize-existing all components of the path must exist\n\ -m, --canonicalize-missing no path components need exist or be a directory\\n\ -L, --logical resolve '..' components before symlinks\n\ -P, --physical resolve symlinks as encountered (default)\n\ -q, --quiet suppress most error messages\n\ --relative-to=DIR print the resolved path relative to DIR\n\ --relative-base=DIR print absolute paths unless paths below DIR\n\ -s, --strip, --no-symlinks don't expand symlinks\n\ -z, --zero end each output line with NUL, not newline\n\"), stdout);fputs(HELP_OPTION_DESCRIPTION, stdout);fputs(VERSION_OPTION_DESCRIPTION, stdout);emit_ancillary_info(PROGRAM_NAME);}exit(status);}/* A wrapper around canonicalize_filename_mode(), to call it twice when in LOGICAL mode. */static char*realpath_canon(char const*fname,int can_mode){char*can_fname =canonicalize_filename_mode(fname, can_mode);if(logical && can_fname)/* canonicalize again to resolve symlinks. */{ can_mode &= ~CAN_NOLINKS;char*can_fname2 =canonicalize_filename_mode(can_fname, can_mode);free(can_fname);return can_fname2;}return can_fname;}/* Test whether canonical prefix is parent or match of path. */ ATTRIBUTE_PURE static boolpath_prefix(char const*prefix,char const*path){/* We already know prefix[0] and path[0] are '/'. */ prefix++; path++;/* '/' is the prefix of everything except '//' (since we know '//' is only present after canonicalization if it is distinct). */if(!*prefix)return*path !='/';/* Likewise, '//' is a prefix of any double-slash path. */if(*prefix =='/'&& !prefix[1])return*path =='/';/* Any other prefix has a non-slash portion. */while(*prefix && *path){if(*prefix != *path)break; prefix++; path++;}return(!*prefix && (*path =='/'|| !*path));}static boolisdir(char const*path){struct stat sb;if(stat(path, &sb) !=0)error(EXIT_FAILURE, errno,_("cannot stat %s"),quoteaf(path));returnS_ISDIR(sb.st_mode);}static boolprocess_path(char const*fname,int can_mode){char*can_fname =realpath_canon(fname, can_mode);if(!can_fname){if(verbose)error(0, errno,"%s",quotef(fname));return false;}if(!can_relative_to || (can_relative_base && !path_prefix(can_relative_base, can_fname))|| (can_relative_to && !relpath(can_fname, can_relative_to,nullptr,0)))fputs(can_fname, stdout);putchar(use_nuls ?'\0':'\n');free(can_fname);return true;}intmain(int argc,char**argv){bool ok =true;int can_mode = CAN_ALL_BUT_LAST;char const*relative_to =nullptr;char const*relative_base =nullptr;initialize_main(&argc, &argv);set_program_name(argv[0]);setlocale(LC_ALL,"");bindtextdomain(PACKAGE, LOCALEDIR);textdomain(PACKAGE);atexit(close_stdout);while(true){int c =getopt_long(argc, argv,"eLmPqsz", longopts,nullptr);if(c == -1)break;switch(c){case'e': can_mode &= ~CAN_MODE_MASK; can_mode |= CAN_EXISTING;break;case'm': can_mode &= ~CAN_MODE_MASK; can_mode |= CAN_MISSING;break;case'L': can_mode |= CAN_NOLINKS; logical =true;break;case's': can_mode |= CAN_NOLINKS; logical =false;break;case'P': can_mode &= ~CAN_NOLINKS; logical =false;break;case'q': verbose =false;break;case'z': use_nuls =true;break;case RELATIVE_TO_OPTION: relative_to = optarg;break;case RELATIVE_BASE_OPTION: relative_base = optarg;break; case_GETOPT_HELP_CHAR;case_GETOPT_VERSION_CHAR(PROGRAM_NAME, AUTHORS);default:usage(EXIT_FAILURE);}}if(optind >= argc){error(0,0,_("missing operand"));usage(EXIT_FAILURE);}if(relative_base && !relative_to) relative_to = relative_base;bool need_dir = (can_mode & CAN_MODE_MASK) == CAN_EXISTING;if(relative_to){ can_relative_to =realpath_canon(relative_to, can_mode);if(!can_relative_to)error(EXIT_FAILURE, errno,"%s",quotef(relative_to));if(need_dir && !isdir(can_relative_to))error(EXIT_FAILURE, ENOTDIR,"%s",quotef(relative_to));}if(relative_base == relative_to) can_relative_base = can_relative_to;else if(relative_base){char*base =realpath_canon(relative_base, can_mode);if(!base)error(EXIT_FAILURE, errno,"%s",quotef(relative_base));if(need_dir && !isdir(base))error(EXIT_FAILURE, ENOTDIR,"%s",quotef(relative_base));/* --relative-to is a no-op if it does not have --relative-base as a prefix */if(path_prefix(base, can_relative_to)) can_relative_base = base;else{free(base); can_relative_base = can_relative_to; can_relative_to =nullptr;}}for(; optind < argc; ++optind) ok &=process_path(argv[optind], can_mode);return ok ? EXIT_SUCCESS : EXIT_FAILURE;}