Re: [PATCH v2 makewhatis] refactor HOMEBREWDIR into READ_ALLOWED_PATH

[Ingo Schwarze <schwarze@usta.de>]

Hi Lukas,

sternenseemann wrote on Sat, Aug 07, 2021 at 02:29:52AM +0200:
> On 8/5/21 2:35 PM, Ingo Schwarze wrote:

>> Does this version work for you?

> I did a normal rebuild of my db with this patch and everything
> seemed to work fine, so that is a yes overall from my side!

Thank you for testing and confirming!
This is very helpful because i have no MacOS X, NixOS, or Guix
systems and i don't like committing half-untested patches.

>> +# Nix package manager and/or NixOS Linux distibution:
> Typo: should be distribution
>> +# GNU Guix package manager and/or GNU Guix Linux distibution:
> Same here.

Thanks for catching that one, fixed in the commit.

Yours,
  Ingo


Log Message:
-----------
Rename the compile-time configuration variable $HOMEBREWDIR to
$READ_ALLOWED_PATH, allow it to contain more than one directory,
and explain how to use it for NixOS and for GNU Guix Linux.

Feature improvement based on observations, input, and earlier patches
from Lukas Epple <sternenseemann at systemli dot org>, and final
patch also tested by Lukas.

Modified Files:
--------------
    mandoc:
        configure
        configure.local.example
        mandocdb.c

Revision Data
-------------
Index: configure
===================================================================
RCS file: /home/cvs/mandoc/mandoc/configure,v
retrieving revision 1.77
retrieving revision 1.78
diff -Lconfigure -Lconfigure -u -p -r1.77 -r1.78
--- configure
+++ configure
@@ -107,7 +107,7 @@ BIN_FROM_SBIN=
 INCLUDEDIR=
 LIBDIR=
 MANDIR=
-HOMEBREWDIR=
+READ_ALLOWED_PATH=
 
 WWWPREFIX="/var/www"
 HTDOCDIR=
@@ -461,7 +461,8 @@ echo "#define MANPATH_DEFAULT \"${MANPAT
 echo "#define OSENUM ${OSENUM}"
 [ -n "${OSNAME}" ] && echo "#define OSNAME \"${OSNAME}\""
 [ -n "${UTF8_LOCALE}" ] && echo "#define UTF8_LOCALE \"${UTF8_LOCALE}\""
-[ -n "${HOMEBREWDIR}" ] && echo "#define HOMEBREWDIR \"${HOMEBREWDIR}\""
+[ -n "${READ_ALLOWED_PATH}" ] \
+	&& echo "#define READ_ALLOWED_PATH \"${READ_ALLOWED_PATH}\""
 [ ${HAVE_ATTRIBUTE} -eq 0 ] && echo "#define __attribute__(x)"
 [ ${HAVE_EFTYPE} -eq 0 ] && echo "#define EFTYPE EINVAL"
 [ ${HAVE_O_DIRECTORY} -eq 0 ] && echo "#define O_DIRECTORY 0"
Index: mandocdb.c
===================================================================
RCS file: /home/cvs/mandoc/mandoc/mandocdb.c,v
retrieving revision 1.267
retrieving revision 1.268
diff -Lmandocdb.c -Lmandocdb.c -u -p -r1.267 -r1.268
--- mandocdb.c
+++ mandocdb.c
@@ -165,6 +165,9 @@ static	void	 putkey(const struct mpage *
 static	void	 putkeys(const struct mpage *, char *, size_t, uint64_t);
 static	void	 putmdockey(const struct mpage *,
 			const struct roff_node *, uint64_t, int);
+#ifdef READ_ALLOWED_PATH
+static	int	 read_allowed(const char *);
+#endif
 static	int	 render_string(char **, size_t *);
 static	void	 say(const char *, const char *, ...)
 			__attribute__((__format__ (__printf__, 2, 3)));
@@ -612,8 +615,8 @@ treescan(void)
 				continue;
 			}
 			if (strncmp(buf, basedir, basedir_len) != 0
-#ifdef HOMEBREWDIR
-			    && strncmp(buf, HOMEBREWDIR, strlen(HOMEBREWDIR))
+#ifdef READ_ALLOWED_PATH
+			    && !read_allowed(buf)
 #endif
 			) {
 				if (warnings) say("",
@@ -823,8 +826,8 @@ filescan(const char *infile)
 		start = usefile;
 	else if (strncmp(usefile, basedir, basedir_len) == 0)
 		start = usefile + basedir_len;
-#ifdef HOMEBREWDIR
-	else if (strncmp(usefile, HOMEBREWDIR, strlen(HOMEBREWDIR)) == 0)
+#ifdef READ_ALLOWED_PATH
+	else if (read_allowed(usefile))
 		start = usefile;
 #endif
 	else {
@@ -2380,6 +2383,25 @@ set_basedir(const char *targetdir, int r
 	}
 	return 1;
 }
+
+#ifdef READ_ALLOWED_PATH
+static int
+read_allowed(const char *candidate)
+{
+	const char	*cp;
+	size_t		 len;
+
+	for (cp = READ_ALLOWED_PATH;; cp += len) {
+		while (*cp == ':')
+			cp++;
+		if (*cp == '\0')
+			return 0;
+		len = strcspn(cp, ":");
+		if (strncmp(candidate, cp, len) == 0)
+			return 1;
+	}
+}
+#endif
 
 static void
 say(const char *file, const char *format, ...)
Index: configure.local.example
===================================================================
RCS file: /home/cvs/mandoc/mandoc/configure.local.example,v
retrieving revision 1.39
retrieving revision 1.40
diff -Lconfigure.local.example -Lconfigure.local.example -u -p -r1.39 -r1.40
--- configure.local.example
+++ configure.local.example
@@ -209,14 +209,28 @@ INSTALL_LIB="${INSTALL} -m 0444"
 INSTALL_MAN="${INSTALL} -m 0444"
 INSTALL_DATA="${INSTALL} -m 0444"
 
-# When using the "homebrew" package manager on Mac OS X, the actual
-# manuals are located in a so-called "cellar" and only symlinked
-# into the manual trees.  To allow mandoc to follow such symlinks,
-# you have to specify the physical location of the cellar as returned
-# by realpath(3), for example:
+# By default, makewhatis(8) can only read from the paths passed on the
+# command line or configured in man.conf(5).
+# But some package managers on some operating systems store manual pages
+# in separate "cellar" or "store" directories and only symlink them
+# into the manual trees.
+# To support one or more such package managers, give makewhatis(8)
+# read access to the cellars and stores on your system, in the form
+# of a colon-separated path:
 
+# Homebrow package manager on Mac OS X:
 PREFIX="/usr/local"
-HOMEBREWDIR="${PREFIX}/Cellar"
+READ_ALLOWED_PATH="${PREFIX}/Cellar"
+
+# Nix package manager and/or NixOS Linux distribution:
+READ_ALLOWED_PATH="/nix/store"
+
+# GNU Guix package manager and/or GNU Guix Linux distribution:
+READ_ALLOWED_PATH="/gnu/store"
+
+# If multiple package managers are used concurrently:
+PREFIX="/usr/local"
+READ_ALLOWED_PATH="/nix/store:${PREFIX}/Cellar"
 
 # --- user settings for the mandoc(3) library --------------------------
 
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