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-rw-r--r--src/realpath.c278
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diff --git a/src/realpath.c b/src/realpath.c
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+++ b/src/realpath.c
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+/* 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;
+}
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