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| -rw-r--r-- | realpath.c | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/realpath.c b/realpath.c new file mode 100644 index 0000000..6ed5f05 --- /dev/null +++ b/realpath.c @@ -0,0 +1,278 @@ +/* realpath - print the resolved path + Copyright (C) 2011-2020 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 "die.h" +#include "error.h" +#include "relpath.h" + +/* The official name of this program (e.g., no 'g' prefix). */ +#define PROGRAM_NAME "realpath" + +#define AUTHORS proper_name ("Padraig Brady") + +enum +{ + RELATIVE_TO_OPTION = CHAR_MAX + 1, + RELATIVE_BASE_OPTION +}; + +static bool verbose = true; +static bool logical; +static bool use_nuls; +static const char *can_relative_to; +static const char *can_relative_base; + +static struct option const longopts[] = +{ + {"canonicalize-existing", no_argument, NULL, 'e'}, + {"canonicalize-missing", no_argument, NULL, 'm'}, + {"relative-to", required_argument, NULL, RELATIVE_TO_OPTION}, + {"relative-base", required_argument, NULL, RELATIVE_BASE_OPTION}, + {"quiet", no_argument, NULL, 'q'}, + {"strip", no_argument, NULL, 's'}, + {"no-symlinks", no_argument, NULL, 's'}, + {"zero", no_argument, NULL, 'z'}, + {"logical", no_argument, NULL, 'L'}, + {"physical", no_argument, NULL, 'P'}, + {GETOPT_HELP_OPTION_DECL}, + {GETOPT_VERSION_OPTION_DECL}, + {NULL, 0, NULL, 0} +}; + +void +usage (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\ +\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 (const char *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. */ +static bool _GL_ATTRIBUTE_PURE +path_prefix (const char *prefix, const char *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 bool +isdir (const char *path) +{ + struct stat sb; + if (stat (path, &sb) != 0) + die (EXIT_FAILURE, errno, _("cannot stat %s"), quoteaf (path)); + return S_ISDIR (sb.st_mode); +} + +static bool +process_path (const char *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, NULL, 0))) + fputs (can_fname, stdout); + + putchar (use_nuls ? '\0' : '\n'); + + free (can_fname); + + return true; +} + +int +main (int argc, char **argv) +{ + bool ok = true; + int can_mode = CAN_ALL_BUT_LAST; + const char *relative_to = NULL; + const char *relative_base = NULL; + + initialize_main (&argc, &argv); + set_program_name (argv[0]); + setlocale (LC_ALL, ""); + bindtextdomain (PACKAGE, LOCALEDIR); + textdomain (PACKAGE); + + atexit (close_stdout); + + while (1) + { + int c = getopt_long (argc, argv, "eLmPqsz", longopts, NULL); + 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) + die (EXIT_FAILURE, errno, "%s", quotef (relative_to)); + if (need_dir && !isdir (can_relative_to)) + die (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) + die (EXIT_FAILURE, errno, "%s", quotef (relative_base)); + if (need_dir && !isdir (base)) + die (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 = NULL; + } + } + + for (; optind < argc; ++optind) + ok &= process_path (argv[optind], can_mode); + + return ok ? EXIT_SUCCESS : EXIT_FAILURE; +} |