Add pathchk(1)

New command, including man page.
UTF-8 compatible and should be POSIX-compliant.

Signed-off-by: Mattias Andrée <maandree@kth.se>

LICENSE

@@ -59,3 +59,4 @@ Authors/contributors include:
 © 2015 Quentin Rameau <quinq@quinq.eu.org>
 © 2015 Dionysis Grigoropoulos <info@erethon.com>
 © 2015 Wolfgang Corcoran-Mathe <first.lord.of.teal@gmail.com>
+© 2016 Mattias Andrée <maandree@kth.se>

Makefile

@@ -120,6 +120,7 @@ BIN =\
 	nl\
 	nohup\
 	od\
+	pathchk\
 	paste\
 	printenv\
 	printf\

README

@@ -58,6 +58,7 @@ The following tools are implemented:
 #*|o nl          .
 =*|o nohup       .
 =*|o od          .
+#* o pathchk     .
 #*|o paste       .
 =*|x printenv    .
 #*|o printf      .

TODO

@@ -10,7 +10,6 @@ diff
 ed manpage
 install
 patch
-pathchk
 stty
 
 If you are looking for some work to do on sbase, another option is to

pathchk.1

@@ -0,0 +1,35 @@
+.Dd 2016-02-03
+.Dt PATHCHK 1
+.Os sbase
+.Sh NAME
+.Nm pathchk
+.Nd validate filename validity or portability
+.Sh SYNOPSIS
+.Nm
+.Op Fl p
+.Op Fl P
+.Ar file Ar ...
+.Sh DESCRIPTION
+.Nm
+checks that filenames are valid for the system,
+and optional on other POSIX systems.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl p
+Check for most POSIX systems.
+.It Fl P
+Check for empty pathnames and leading hythens.
+.El
+.Sh EXIT STATUS
+.Bl -tag -width Ds
+.It 0
+A filename was not valid or portable.
+.It > 0
+An error occurred.
+.El
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the
+.St -p1003.1-2013
+specification.

pathchk.c

@@ -0,0 +1,123 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <stdint.h>
+#include <errno.h>
+#include <sys/stat.h>
+
+#include "util.h"
+#include "arg.h"
+
+#define PORTABLE_CHARACTER_SET "0123456789._-qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM"
+/* If your system supports more other characters, but not all non-NUL characters, define SYSTEM_CHARACTER_SET. */
+
+#ifndef PATH_MAX
+# define PATH_MAX SIZE_MAX
+#endif
+#ifndef NAME_MAX
+# define NAME_MAX SIZE_MAX
+#endif
+
+static int most = 0;
+static int extra = 0;
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: %s [-pP] filename...\n", argv0);
+	exit(1);
+}
+
+static int
+pathchk(char *filename)
+{
+	char *invalid, *invalid_end, *p, *q;
+	const char *character_set;
+	size_t len, maxlen;
+	struct stat _attr;
+
+	/* Empty? */
+	if (extra && !*filename) {
+		fprintf(stderr, "%s: empty filename\n", argv0);
+		return 1;
+	}
+
+	/* Leading hyphen? */
+	if (extra && ((*filename == '-') || strstr(filename, "/-"))) {
+		fprintf(stderr, "%s: %s: leading '-' in component of filename\n", argv0, filename);
+		return 1;
+	}
+
+	/* Nonportable character? */
+#ifdef SYSTEM_CHARACTER_SET
+	character_set = "/"SYSTEM_CHARACTER_SET;
+#else
+	character_set = 0;
+#endif
+	if (most)
+		character_set = "/"PORTABLE_CHARACTER_SET;
+	if (character_set && *(invalid = filename + strspn(filename, character_set))) {
+		for (invalid_end = invalid + 1; *invalid_end & 0x80; invalid_end++);
+		fprintf(stderr, "%s: %s: ", argv0, filename);
+		*invalid_end = 0;
+		fprintf(stderr, "nonportable character '%s'\n", invalid);
+		return 1;
+	}
+
+	/* Symlink error? Non-searchable directory? */
+	if (lstat(filename, &_attr) && errno != ENOENT) {
+		/* lstat rather than stat, so that if filename is a bad symlink, but
+		 * all parents are OK, no error will be detected. */
+		fprintf(stderr, "%s: %s: %s\n", argv0, filename, strerror(errno));
+		return 1;
+	}
+
+	/* Too long pathname? */
+	maxlen = most ? _POSIX_PATH_MAX : PATH_MAX;
+	if (strlen(filename) >= maxlen) {
+		fprintf(stderr, "%s: %s: is longer than %zu bytes\n",
+		        argv0, filename, maxlen);
+		return 1;
+	}
+
+	/* Too long component? */
+	maxlen = most ? _POSIX_NAME_MAX : NAME_MAX;
+	for (p = filename; p; p = q) {
+		q = strchr(p, '/');
+		len = q ? (size_t)(q++ - p) : strlen(p);
+		if (len > maxlen) {
+			fprintf(stderr, "%s: %s: includes component longer than %zu bytes\n",
+			        argv0, filename, maxlen);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int ret = 0;
+
+	ARGBEGIN {
+	case 'p':
+		most = 1;
+		break;
+	case 'P':
+		extra = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (!argc)
+		usage();
+
+	for (; argc--; argv++)
+		ret |= pathchk(*argv);
+
+	return ret;
+}