Replace UUID file mechanism with per-directory 'map' attribute [v2]

The UUID files would be placed in each font directory to provide the
unique cache name, independent of path, for that directory. The UUID
files are undesireable for a couple of reasons:

 1) They must be placed in the font directories to be useful. This
    requires modifying the font directories themselves, introducing
    potential visible timestamp changes when running multiple
    applications, and makes the cache processing inconsistent between
    applications with permission to write to the font directories and
    applications without such permission.

 2) The UUID contents were generated randomly, which makes the font
    cache not reproducible across multiple runs.

One proposed fix for 2) is to make the UUID dependent on the font
directory path, but once we do that, we can simply use the font
directory path itself as the key as the original MD5-based font cache
naming mechanism did.

The goal of the UUID file mechanism was to fix startup time of
flatpaks; as the font path names inside the flatpak did not match the
font path names in the base system, the font cache would need to be
reconstructed the first time the flatpak was launched.

The new mechanism for doing this is to allow each '<dir>' element in
the configuration include a 'map' attribute. When looking for a cache
file for a particular directory, if the directory name starts with the
contents of the <dir> element, that portion of the name will be
replaced with the value of the 'map' attribute.

Outside of the flatpak, nothing need change -- fontconfig will build
cache files using real directory names.

Inside the flatpak, the custom fonts.conf file will now include
mappings such as this:

	<dir map="/usr/share/fonts">/run/host/fonts</dir>

When scanning the directory /run/host/fonts/ttf, fontconfig will
use the name /usr/share/fonts/ttf as the source for building the cache
file name.

The existing FC_FILE replacement code used for the UUID-based
implementation continues to correctly adapt font path names seen by
applications.

v2:
	Leave FcDirCacheCreateUUID stub around to avoid removing
	public API function.

	Document 'map' attribute of <dir> element in
	fontconfig-user.sgml

	Suggested-by: Akira TAGOH <akira@tagoh.org>

Signed-off-by: Keith Packard <keithp@keithp.com>

configure.ac

@@ -332,39 +332,6 @@ AM_CONDITIONAL(FREETYPE_PCF_LONG_FAMILY_NAMES, test "x$have_pcf_long_family_name
 LIBS="$fontconfig_save_libs"
 CFLAGS="$fontconfig_save_cflags"
 
-#
-# Check for uuid
-#
-if test "$os_win32" != "yes"; then
-	use_pkgconfig_for_uuid=yes
-	if test -n "${UUID_LIBS}"; then
-		save_UUID_LIBS=$UUID_LIBS
-	fi
-	PKG_CHECK_MODULES([UUID], [uuid],
-			  [use_pkgconfig_for_uuid=yes],
-			  [use_pkgconfig_for_uuid=no])
-	if test "x$use_pkgconfig_for_uuid" = "xno"; then
-		AC_MSG_CHECKING([where uuid functions comes from])
-		AC_TRY_LINK([#include <uuid/uuid.h>],
-			[uuid_t a; uuid_generate(a);],
-			[AC_MSG_RESULT([builtin])
-			 UUID_CFLAGS=""
-			 UUID_LIBS=""
-			],[AC_MSG_ERROR([
-*** uuid is required. install util-linux.
-			])])
-	else
-		if test -z "${save_UUID_LIBS+x}" && test "x${UUID_LIBS}" != "x"; then
-			PKGCONFIG_REQUIRES_PRIVATELY="$PKGCONFIG_REQUIRES_PRIVATELY uuid"
-		fi
-	fi
-else
-	UUID_CFLAGS=""
-	UUID_LIBS=""
-fi
-AC_SUBST(UUID_CFLAGS)
-AC_SUBST(UUID_LIBS)
-
 #
 # Check expat configuration
 #

doc/fccache.fncs

@@ -88,20 +88,6 @@ to <parameter>config</parameter>.
 @SINCE@		2.9.91
 @@
 
-@RET@		FcBool
-@FUNC@		FcDirCacheCreateUUID
-@TYPE1@		FcChar8 *			@ARG1@		dir
-@TYPE2@		FcBool				@ARG2@		force
-@TYPE3@		FcConfig *			@ARG3@		config
-@PURPOSE@	Create .uuid file at a directory
-@DESC@
-This is to create .uuid file containing an UUID at a font directory of
-<parameter>dir</parameter>.
-The UUID will be used to identify the font directory and is used to determine
-the cache filename if available.
-@SINCE@		2.12.92
-@@
-
 @RET@		FcBool
 @FUNC@		FcDirCacheDeleteUUID
 @TYPE1@		const FcChar8 *			@ARG1@		dir

doc/fontconfig-user.sgml

@@ -310,9 +310,15 @@ following structure:
 This is the top level element for a font configuration and can contain
 <literal>&lt;dir&gt;</literal>, <literal>&lt;cachedir&gt;</literal>, <literal>&lt;include&gt;</literal>, <literal>&lt;match&gt;</literal> and <literal>&lt;alias&gt;</literal> elements in any order.
   </para></refsect2>
-  <refsect2><title><literal>&lt;dir prefix="default"&gt;</literal></title><para>
+  <refsect2><title><literal>&lt;dir prefix="default" map=""&gt;</literal></title><para>
 This element contains a directory name which will be scanned for font files
 to include in the set of available fonts. If 'prefix' is set to "default" or "cwd", the current working directory will be added as the path prefix prior to the value. If 'prefix' is set to "xdg", the value in the XDG_DATA_HOME environment variable will be added as the path prefix. please see XDG Base Directory Specification for more details. If 'prefix' is set to "relative", the path of current file will be added prior to the value.
+</para><para>
+If a 'map' attribute is specified, its value will replace the
+directory path when matching cached information for fonts contained in
+this directory. This is useful if the directory name is an alias
+(via a bind mount or symlink) to another directory in the system for
+which cached font information is likely to exist.
   </para></refsect2>
   <refsect2><title><literal>&lt;cachedir prefix="default"&gt;</literal></title><para>
 This element contains a directory name that is supposed to be stored or read

fc-cache/fc-cache.c

@@ -203,7 +203,6 @@ scanDirs (FcStrList *list, FcConfig *config, FcBool force, FcBool really_force,
 	if (really_force)
 	{
 	    FcDirCacheUnlink (dir, config);
-	    FcDirCacheCreateUUID ((FcChar8 *) dir, FcTrue, config);
 	}
 
 	cache = NULL;

fonts.dtd

@@ -14,6 +14,7 @@
 -->
 <!ELEMENT dir (#PCDATA)>
 <!ATTLIST dir
+	  map       CDATA                         #IMPLIED
 	  prefix    (default|xdg|relative|cwd)    "default"
 	  xml:space (default|preserve)            'preserve'>
 

src/Makefile.am

@@ -77,7 +77,6 @@ AM_CPPFLAGS = 						\
 	$(ICONV_CFLAGS)					\
 	$(LIBXML2_CFLAGS)				\
 	$(EXPAT_CFLAGS)					\
-	$(UUID_CFLAGS)					\
 	$(WARN_CFLAGS)					\
 	-DFC_CACHEDIR='"$(FC_CACHEDIR)"'                \
 	-DFONTCONFIG_PATH='"$(BASECONFIGDIR)"'		\
@@ -167,7 +166,7 @@ lib_LTLIBRARIES = libfontconfig.la
 libfontconfig_la_LDFLAGS =			\
 	-version-info @LIBT_VERSION_INFO@ -no-undefined $(export_symbols)
 
-libfontconfig_la_LIBADD = $(ICONV_LIBS) $(FREETYPE_LIBS) $(LIBXML2_LIBS) $(EXPAT_LIBS) $(UUID_LIBS) $(LTLIBINTL)
+libfontconfig_la_LIBADD = $(ICONV_LIBS) $(FREETYPE_LIBS) $(LIBXML2_LIBS) $(EXPAT_LIBS) $(LTLIBINTL)
 
 libfontconfig_la_DEPENDENCIES = $(fontconfig_def_dependency)
 

src/fccache.c

@@ -51,103 +51,7 @@ FcDirCacheCreateUUID (FcChar8  *dir,
 		      FcBool    force,
 		      FcConfig *config)
 {
-    FcBool ret = FcTrue;
+    return FcTrue;
-#ifndef _WIN32
-    const FcChar8 *sysroot = FcConfigGetSysRoot (config);
-    FcChar8 *target;
-    FcChar8 *uuidname;
-
-    if (sysroot)
-	target = FcStrBuildFilename (sysroot, dir, NULL);
-    else
-	target = FcStrdup (dir);
-    uuidname = FcStrBuildFilename (target, ".uuid", NULL);
-
-    if (!uuidname)
-    {
-	FcStrFree (target);
-	return FcFalse;
-    }
-
-    if (force || access ((const char *) uuidname, F_OK) < 0)
-    {
-	FcAtomic *atomic;
-	int fd;
-	uuid_t uuid;
-	char out[37];
-	FcBool (* hash_add) (FcHashTable *, void*, void*);
-	struct stat statb;
-	struct timeval times[2];
-
-	if (FcStat (target, &statb) != 0)
-	{
-	    ret = FcFalse;
-	    goto bail1;
-	}
-	atomic = FcAtomicCreate (uuidname);
-	if (!atomic)
-	{
-	    ret = FcFalse;
-	    goto bail1;
-	}
-	if (!FcAtomicLock (atomic))
-	{
-	    ret = FcFalse;
-	    goto bail2;
-	}
-	fd = FcOpen ((char *)FcAtomicNewFile (atomic), O_RDWR | O_CREAT, 0644);
-	if (fd == -1)
-	{
-	    ret = FcFalse;
-	    goto bail3;
-	}
-	uuid_generate_random (uuid);
-	if (force)
-	    hash_add = FcHashTableReplace;
-	else
-	    hash_add = FcHashTableAdd;
-	if (!hash_add (config->uuid_table, target, uuid))
-	{
-	    ret = FcFalse;
-	    FcAtomicDeleteNew (atomic);
-	    close (fd);
-	    goto bail3;
-	}
-	uuid_unparse (uuid, out);
-	if (FcDebug () & FC_DBG_CACHE)
-	    printf ("FcDirCacheCreateUUID %s: %s\n", uuidname, out);
-	write (fd, out, strlen (out));
-	close (fd);
-	FcAtomicReplaceOrig (atomic);
-    bail3:
-	FcAtomicUnlock (atomic);
-    bail2:
-	FcAtomicDestroy (atomic);
-
-	if (ret)
-	{
-	    /* revert mtime of the directory */
-	    times[0].tv_sec = statb.st_atime;
-	    times[1].tv_sec = statb.st_mtime;
-#ifdef HAVE_STRUCT_STAT_ST_MTIM
-	    times[0].tv_usec = statb.st_atim.tv_nsec / 1000;
-	    times[1].tv_usec = statb.st_mtim.tv_nsec / 1000;
-#else
-	    times[0].tv_usec = 0;
-	    times[1].tv_usec = 0;
-#endif
-	    if (utimes ((const  char *) target, times) != 0)
-	    {
-		fprintf (stderr, "Unable to revert mtime: %s\n", target);
-	    }
-	}
-    }
-bail1:
-    FcStrFree (uuidname);
-    FcStrFree (target);
-#endif
-
-    return ret;
 }
 
 FcBool
@@ -187,7 +91,6 @@ FcDirCacheDeleteUUID (const FcChar8  *dir,
 	{
 	    fprintf (stderr, "Unable to revert mtime: %s\n", d);
 	}
-	FcHashTableRemove (config->uuid_table, target);
     }
     FcStrFree (target);
 bail:
@@ -197,59 +100,6 @@ bail:
     return ret;
 }
 
-#ifndef _WIN32
-static void
-FcDirCacheReadUUID (FcChar8  *dir,
-		    FcConfig *config)
-{
-    void *u;
-    uuid_t uuid;
-    const FcChar8 *sysroot = FcConfigGetSysRoot (config);
-    FcChar8 *target;
-
-    if (sysroot)
-	target = FcStrBuildFilename (sysroot, dir, NULL);
-    else
-	target = FcStrdup (dir);
-
-    if (!FcHashTableFind (config->uuid_table, target, &u))
-    {
-	FcChar8 *uuidname = FcStrBuildFilename (target, ".uuid", NULL);
-	int fd;
-
-	if ((fd = FcOpen ((char *) uuidname, O_RDONLY)) >= 0)
-	{
-	    char suuid[37];
-	    ssize_t len;
-
-	    memset (suuid, 0, sizeof (suuid));
-	    len = read (fd, suuid, 36);
-	    if (len != -1)
-	    {
-		suuid[len] = 0;
-		memset (uuid, 0, sizeof (uuid));
-		if (uuid_parse (suuid, uuid) == 0)
-		{
-		    if (FcDebug () & FC_DBG_CACHE)
-			printf ("FcDirCacheReadUUID %s -> %s\n", uuidname, suuid);
-		    FcHashTableAdd (config->uuid_table, target, uuid);
-		}
-	    }
-	    close (fd);
-	}
-	else
-	{
-	    if (FcDebug () & FC_DBG_CACHE)
-		printf ("FcDirCacheReadUUID Unable to read %s\n", uuidname);
-	}
-	FcStrFree (uuidname);
-    }
-    else
-	FcHashUuidFree (u);
-    FcStrFree (target);
-}
-#endif
-
 struct MD5Context {
         FcChar32 buf[4];
         FcChar32 bits[2];
@@ -300,18 +150,26 @@ static const char bin2hex[] = { '0', '1', '2', '3',
 				'c', 'd', 'e', 'f' };
 
 static FcChar8 *
-FcDirCacheBasenameMD5 (const FcChar8 *dir, FcChar8 cache_base[CACHEBASE_LEN])
+FcDirCacheBasenameMD5 (FcConfig *config, const FcChar8 *dir, FcChar8 cache_base[CACHEBASE_LEN])
 {
+    FcChar8		*new_dir;
     unsigned char 	hash[16];
     FcChar8		*hex_hash;
     int			cnt;
     struct MD5Context 	ctx;
 
+    new_dir = FcConfigMapFontPath(config, dir);
+    if (new_dir)
+	dir = new_dir;
+
     MD5Init (&ctx);
     MD5Update (&ctx, (const unsigned char *)dir, strlen ((const char *) dir));
 
     MD5Final (hash, &ctx);
 
+    if (new_dir)
+	FcStrFree(new_dir);
+
     cache_base[0] = '/';
     hex_hash = cache_base + 1;
     for (cnt = 0; cnt < 16; ++cnt)
@@ -325,31 +183,6 @@ FcDirCacheBasenameMD5 (const FcChar8 *dir, FcChar8 cache_base[CACHEBASE_LEN])
     return cache_base;
 }
 
-#ifndef _WIN32
-static FcChar8 *
-FcDirCacheBasenameUUID (const FcChar8 *dir, FcChar8 cache_base[CACHEBASE_LEN], FcConfig *config)
-{
-    void *u;
-    FcChar8 *target;
-    const FcChar8 *sysroot = FcConfigGetSysRoot (config);
-
-    if (sysroot)
-	target = FcStrBuildFilename (sysroot, dir, NULL);
-    else
-	target = FcStrdup (dir);
-    if (FcHashTableFind (config->uuid_table, target, &u))
-    {
-	uuid_unparse (u, (char *) cache_base);
-	strcat ((char *) cache_base, "-" FC_ARCHITECTURE FC_CACHE_SUFFIX);
-	FcHashUuidFree (u);
-	FcStrFree (target);
-	return cache_base;
-    }
-    FcStrFree (target);
-    return NULL;
-}
-#endif
-
 FcBool
 FcDirCacheUnlink (const FcChar8 *dir, FcConfig *config)
 {
@@ -359,10 +192,7 @@ FcDirCacheUnlink (const FcChar8 *dir, FcConfig *config)
     FcChar8	*cache_dir;
     const FcChar8 *sysroot = FcConfigGetSysRoot (config);
 
-#ifndef _WIN32
+    FcDirCacheBasenameMD5 (config, dir, cache_base);
-    if (!FcDirCacheBasenameUUID (dir, cache_base, config))
-#endif
-	FcDirCacheBasenameMD5 (dir, cache_base);
 
     list = FcStrListCreate (config->cacheDirs);
     if (!list)
@@ -439,10 +269,7 @@ FcDirCacheProcess (FcConfig *config, const FcChar8 *dir,
     }
     FcStrFree (d);
 
-#ifndef _WIN32
+    FcDirCacheBasenameMD5 (config, dir, cache_base);
-    if (!FcDirCacheBasenameUUID (dir, cache_base, config))
-#endif
-	FcDirCacheBasenameMD5 (dir, cache_base);
 
     list = FcStrListCreate (config->cacheDirs);
     if (!list)
@@ -1070,9 +897,6 @@ FcDirCacheLoad (const FcChar8 *dir, FcConfig *config, FcChar8 **cache_file)
 {
     FcCache *cache = NULL;
 
-#ifndef _WIN32
-    FcDirCacheReadUUID ((FcChar8 *) dir, config);
-#endif
     if (!FcDirCacheProcess (config, dir,
 			    FcDirCacheMapHelper,
 			    &cache, cache_file))
@@ -1377,10 +1201,7 @@ FcDirCacheWrite (FcCache *cache, FcConfig *config)
     if (!cache_dir)
 	return FcFalse;
 
-#ifndef _WIN32
+    FcDirCacheBasenameMD5 (config, dir, cache_base);
-    if (!FcDirCacheBasenameUUID (dir, cache_base, config))
-#endif
-	FcDirCacheBasenameMD5 (dir, cache_base);
     cache_hashed = FcStrBuildFilename (cache_dir, cache_base, NULL);
     FcStrFree (cache_dir);
     if (!cache_hashed)
@@ -1577,10 +1398,7 @@ FcDirCacheLock (const FcChar8 *dir,
     const FcChar8 *sysroot = FcConfigGetSysRoot (config);
     int fd = -1;
 
-#ifndef _WIN32
+    FcDirCacheBasenameMD5 (config, dir, cache_base);
-    if (!FcDirCacheBasenameUUID (dir, cache_base, config))
-#endif
-	FcDirCacheBasenameMD5 (dir, cache_base);
     list = FcStrListCreate (config->cacheDirs);
     if (!list)
 	return -1;

src/fccfg.c

@@ -52,18 +52,6 @@ retry:
     return config;
 }
 
-static FcChar32
-FcHashAsStrIgnoreCase (const void *data)
-{
-    return FcStrHashIgnoreCase (data);
-}
-
-static int
-FcCompareAsStr (const void *v1, const void *v2)
-{
-    return FcStrCmp (v1, v2);
-}
-
 static void
 FcDestroyAsRule (void *data)
 {
@@ -76,12 +64,6 @@ FcDestroyAsRuleSet (void *data)
     FcRuleSetDestroy (data);
 }
 
-static void
-FcDestroyAsStr (void *data)
-{
-    FcStrFree (data);
-}
-
 FcBool
 FcConfigInit (void)
 {
@@ -127,6 +109,10 @@ FcConfigCreate (void)
     if (!config->configDirs)
 	goto bail1;
 
+    config->configMapDirs = FcStrSetCreate();
+    if (!config->configMapDirs)
+	goto bail1_5;
+
     config->configFiles = FcStrSetCreate ();
     if (!config->configFiles)
 	goto bail2;
@@ -182,13 +168,6 @@ FcConfigCreate (void)
     if (!config->availConfigFiles)
 	goto bail10;
 
-    config->uuid_table = FcHashTableCreate (FcHashAsStrIgnoreCase,
-					    FcCompareAsStr,
-					    FcHashStrCopy,
-					    FcHashUuidCopy,
-					    FcDestroyAsStr,
-					    FcHashUuidFree);
-
     FcRefInit (&config->ref, 1);
 
     return config;
@@ -213,6 +192,8 @@ bail4:
 bail3:
     FcStrSetDestroy (config->configFiles);
 bail2:
+    FcStrSetDestroy (config->configMapDirs);
+bail1_5:
     FcStrSetDestroy (config->configDirs);
 bail1:
     free (config);
@@ -324,6 +305,7 @@ FcConfigDestroy (FcConfig *config)
     (void) fc_atomic_ptr_cmpexch (&_fcConfig, config, NULL);
 
     FcStrSetDestroy (config->configDirs);
+    FcStrSetDestroy (config->configMapDirs);
     FcStrSetDestroy (config->fontDirs);
     FcStrSetDestroy (config->cacheDirs);
     FcStrSetDestroy (config->configFiles);
@@ -350,8 +332,6 @@ FcConfigDestroy (FcConfig *config)
     if (config->sysRoot)
 	FcStrFree (config->sysRoot);
 
-    FcHashTableDestroy (config->uuid_table);
-
     free (config);
 }
 
@@ -559,9 +539,10 @@ FcConfigGetConfigDirs (FcConfig   *config)
 
 FcBool
 FcConfigAddFontDir (FcConfig	    *config,
-		    const FcChar8   *d)
+		    const FcChar8   *d,
+		    const FcChar8   *m)
 {
-    return FcStrSetAddFilename (config->fontDirs, d);
+    return FcStrSetAddFilenamePair (config->fontDirs, d, m);
 }
 
 FcStrList *
@@ -576,6 +557,47 @@ FcConfigGetFontDirs (FcConfig	*config)
     return FcStrListCreate (config->fontDirs);
 }
 
+static FcBool
+FcConfigPathStartsWith(const FcChar8	*path,
+		       const FcChar8	*start)
+{
+    int len = strlen((char *) start);
+
+    if (strncmp((char *) path, (char *) start, len) != 0)
+	return FcFalse;
+
+    switch (path[len]) {
+    case '\0':
+    case FC_DIR_SEPARATOR:
+	return FcTrue;
+    default:
+	return FcFalse;
+    }
+}
+
+FcChar8 *
+FcConfigMapFontPath(FcConfig		*config,
+		    const FcChar8	*path)
+{
+    FcStrList	*list;
+    FcChar8	*dir;
+    FcChar8	*map;
+
+    list = FcConfigGetFontDirs(config);
+    if (!list)
+	return 0;
+    while ((dir = FcStrListNext(list)))
+	if (FcConfigPathStartsWith(path, dir))
+	    break;
+    FcStrListDone(list);
+    if (!dir)
+	return 0;
+    map = FcStrPairSecond(dir);
+    if (!map)
+	return 0;
+    return FcStrBuildFilename(map, path + strlen((char *) dir), NULL);
+}
+
 FcBool
 FcConfigAddCacheDir (FcConfig	    *config,
 		     const FcChar8  *d)

src/fcdir.c

@@ -413,7 +413,6 @@ FcDirCacheRead (const FcChar8 *dir, FcBool force, FcConfig *config)
 {
     FcCache		*cache = NULL;
 
-    FcDirCacheCreateUUID ((FcChar8 *) dir, FcFalse, config);
     /* Try to use existing cache file */
     if (!force)
 	cache = FcDirCacheLoad (dir, config, NULL);

src/fchash.c

@@ -52,23 +52,6 @@ FcHashStrCopy (const void  *src,
     return *dest != NULL;
 }
 
-FcBool
-FcHashUuidCopy (const void  *src,
-		void       **dest)
-{
-#ifndef _WIN32
-    *dest = malloc (sizeof (uuid_t));
-    uuid_copy (*dest, src);
-#endif
-    return FcTrue;
-}
-
-void
-FcHashUuidFree (void *data)
-{
-    free (data);
-}
-
 FcHashTable *
 FcHashTableCreate (FcHashFunc    hash_func,
 		   FcCompareFunc compare_func,

src/fcint.h

@@ -509,6 +509,7 @@ struct _FcConfig {
      * and those directives may occur in any order
      */
     FcStrSet	*configDirs;	    /* directories to scan for fonts */
+    FcStrSet	*configMapDirs;	    /* mapped names to generate cache entries */
     /*
      * List of directories containing fonts,
      * built by recursively scanning the set
@@ -565,7 +566,6 @@ struct _FcConfig {
     FcChar8     *sysRoot;	    /* override the system root directory */
     FcStrSet	*availConfigFiles;  /* config files available */
     FcPtrList	*rulesetList;	    /* List of rulesets being installed */
-    FcHashTable *uuid_table;	    /* UUID table for cachedirs */
 };
 
 typedef struct _FcFileTime {
@@ -659,7 +659,12 @@ FcConfigAddConfigDir (FcConfig	    *config,
 
 FcPrivate FcBool
 FcConfigAddFontDir (FcConfig	    *config,
-		    const FcChar8   *d);
+		    const FcChar8   *d,
+		    const FcChar8   *m);
+
+FcPrivate FcChar8 *
+FcConfigMapFontPath(FcConfig		*config,
+		    const FcChar8	*path);
 
 FcPrivate FcBool
 FcConfigAddCacheDir (FcConfig	    *config,
@@ -1236,6 +1241,15 @@ FcStrSetAddLangs (FcStrSet *strs, const char *languages);
 FcPrivate void
 FcStrSetSort (FcStrSet * set);
 
+FcPrivate FcBool
+FcStrSetAddPair (FcStrSet *set, const FcChar8 *a, const FcChar8 *b);
+
+FcPrivate FcChar8 *
+FcStrPairSecond (FcChar8 *s);
+
+FcPrivate FcBool
+FcStrSetAddFilenamePair (FcStrSet *strs, const FcChar8 *d, const FcChar8 *m);
+
 FcPrivate void
 FcStrBufInit (FcStrBuf *buf, FcChar8 *init, int size);
 

src/fcstr.c

@@ -36,6 +36,27 @@ FcStrCopy (const FcChar8 *s)
     return FcStrdup (s);
 }
 
+static FcChar8 *
+FcStrMakePair (const FcChar8 *s1, const FcChar8 *s2)
+{
+    int	    s1l = s1 ? strlen ((char *) s1) : 0;
+    int	    s2l = s2 ? strlen ((char *) s2) : 0;
+    int	    l = s1l + 1 + s2l + 1;
+    FcChar8 *s = malloc (l);
+
+    if (!s)
+	return 0;
+    if (s1)
+	memcpy (s, s1, s1l + 1);
+    else
+	s[0] = '\0';
+    if (s2)
+	memcpy (s + s1l + 1, s2, s2l + 1);
+    else
+	s[s1l + 1] = '\0';
+    return s;
+}
+
 FcChar8 *
 FcStrPlus (const FcChar8 *s1, const FcChar8 *s2)
 {
@@ -1233,6 +1254,30 @@ FcStrSetAdd (FcStrSet *set, const FcChar8 *s)
     return FcTrue;
 }
 
+FcBool
+FcStrSetAddPair (FcStrSet *set, const FcChar8 *a, const FcChar8 *b)
+{
+    FcChar8 *new = FcStrMakePair (a, b);
+    if (!new)
+	return FcFalse;
+    if (!_FcStrSetAppend (set, new))
+    {
+	FcStrFree (new);
+	return FcFalse;
+    }
+    return FcTrue;
+}
+
+FcChar8 *
+FcStrPairSecond (FcChar8 *str)
+{
+    FcChar8 *second = str + strlen((char *) str) + 1;
+
+    if (*second == '\0')
+	return 0;
+    return second;
+}
+
 FcBool
 FcStrSetAddFilename (FcStrSet *set, const FcChar8 *s)
 {
@@ -1247,6 +1292,37 @@ FcStrSetAddFilename (FcStrSet *set, const FcChar8 *s)
     return FcTrue;
 }
 
+FcBool
+FcStrSetAddFilenamePair (FcStrSet *set, const FcChar8 *a, const FcChar8 *b)
+{
+    FcChar8 *new_a = NULL;
+    FcChar8 *new_b = NULL;
+    FcBool  ret;
+
+    if (a)
+    {
+	new_a = FcStrCopyFilename (a);
+	if (!new_a)
+	    return FcFalse;
+    }
+    if (b)
+    {
+	new_b = FcStrCopyFilename(b);
+	if (!new_b)
+	{
+	    if (new_a)
+		FcStrFree(new_a);
+	    return FcFalse;
+	}
+    }
+    ret = FcStrSetAddPair (set, new_a, new_b);
+    if (new_a)
+	FcStrFree (new_a);
+    if (new_b)
+	FcStrFree (new_b);
+    return ret;
+}
+
 FcBool
 FcStrSetAddLangs (FcStrSet *strs, const char *languages)
 {

src/fcxml.c

@@ -2071,13 +2071,14 @@ FcParseUnary (FcConfigParse *parse, FcOp op)
 static void
 FcParseDir (FcConfigParse *parse)
 {
-    const FcChar8 *attr, *data;
+    const FcChar8 *attr, *data, *map;
     FcChar8 *prefix = NULL, *p;
 #ifdef _WIN32
     FcChar8         buffer[1000];
 #endif
 
     attr = FcConfigGetAttribute (parse, "prefix");
+    map = FcConfigGetAttribute (parse, "map");
     data = FcStrBufDoneStatic (&parse->pstack->str);
     if (attr)
     {
@@ -2188,7 +2189,7 @@ FcParseDir (FcConfigParse *parse)
 	FcConfigMessage (parse, FcSevereWarning, "empty font directory name ignored");
     else if (!parse->scanOnly && (!FcStrUsesHome (data) || FcConfigHome ()))
     {
-	if (!FcConfigAddFontDir (parse->config, data))
+	if (!FcConfigAddFontDir (parse->config, data, map))
 	    FcConfigMessage (parse, FcSevereError, "out of memory; cannot add directory %s", data);
     }
     FcStrBufDestroy (&parse->pstack->str);

test/Makefile.am

@@ -1,4 +1,4 @@
-check_SCRIPTS=run-test.sh
+check_SCRIPTS=run-test.sh run-test-map.sh
 TEST_EXTENSIONS = \
 	.sh \
 	$(NULL)

test/fonts.conf.in

@@ -1,4 +1,4 @@
 <fontconfig>
-<dir>@FONTDIR@</dir>
+<dir @MAP@>@FONTDIR@</dir>
 <cachedir>@CACHEDIR@</cachedir>
 </fontconfig>

test/run-test-map.sh

@@ -0,0 +1,107 @@
+#!/bin/bash
+# fontconfig/test/run-test-cache-map.sh
+#
+# Copyright © 2018 Keith Packard
+#
+# Permission to use, copy, modify, distribute, and sell this software and its
+# documentation for any purpose is hereby granted without fee, provided that
+# the above copyright notice appear in all copies and that both that copyright
+# notice and this permission notice appear in supporting documentation, and
+# that the name of the copyright holders not be used in advertising or
+# publicity pertaining to distribution of the software without specific,
+# written prior permission.  The copyright holders make no representations
+# about the suitability of this software for any purpose.  It is provided "as
+# is" without express or implied warranty.
+#
+# THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+# EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+# DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+# TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+case "$OSTYPE" in
+    msys ) MyPWD=`pwd -W` ;;  # On Msys/MinGW, returns a MS Windows style path.
+    *    ) MyPWD=`pwd`    ;;  # On any other platforms, returns a Unix style path.
+esac
+
+TESTDIR=${srcdir-"$MyPWD"}
+BUILDTESTDIR=${builddir-"$MyPWD"}
+
+FONTDIRA="$MyPWD"/fontsa
+FONTDIRB="$MyPWD"/fontsb
+CACHEDIR="$MyPWD"/cache.dir
+EXPECTEDIN=${EXPECTEDIN-"out-map.expected.in"}
+EXPECTEDA="out-map-a.expected"
+EXPECTEDB="out-map-b.expected"
+EXPECTED="out-map.expected"
+
+FCLIST=../fc-list/fc-list$EXEEXT
+FCCACHE=../fc-cache/fc-cache$EXEEXT
+
+which bwrap > /dev/null 2>&1
+if [ $? -eq 0 ]; then
+    BWRAP=`which bwrap`
+fi
+
+FONT1=$TESTDIR/4x6.pcf
+FONT2=$TESTDIR/8x16.pcf
+
+check () {
+  $FCLIST - file family pixelsize | sort > out
+  echo "=" >> out
+  $FCLIST - file family pixelsize | sort >> out
+  echo "=" >> out
+  $FCLIST - file family pixelsize | sort >> out
+  tr -d '\015' <out >out.tmp; mv out.tmp out
+  if cmp out $BUILDTESTDIR/$EXPECTED > /dev/null ; then : ; else
+    echo "*** Test failed: $TEST"
+    echo "*** output is in 'out', expected output in '$EXPECTED'"
+    exit 1
+  fi
+  rm -f out
+}
+
+prep() {
+  rm -rf $CACHEDIR
+  rm -rf $FONTDIRA $FONTDIRB
+  mkdir $FONTDIRA
+  mkdir $CACHEDIR
+}
+
+dotest () {
+  TEST=$1
+  test x$VERBOSE = x || echo Running: $TEST
+}
+
+sed "s!@FONTDIR@!$FONTDIRA!
+s!@MAP@!!
+s!@CACHEDIR@!$CACHEDIR!" < $TESTDIR/fonts.conf.in > fonts-a.conf
+
+sed "s!@FONTDIR@!$FONTDIRB!
+s!@MAP@!map="'"'"$FONTDIRA"'"'"!
+s!@CACHEDIR@!$CACHEDIR!" < $TESTDIR/fonts.conf.in > fonts-b.conf
+
+sed "s!@FONTDIR@!$FONTDIRA!" < $EXPECTEDIN > $EXPECTEDA
+sed "s!@FONTDIR@!$FONTDIRB!" < $EXPECTEDIN > $EXPECTEDB
+
+FONTCONFIG_FILE="$MyPWD"/fonts-a.conf
+export FONTCONFIG_FILE
+
+dotest "Basic check"
+prep
+cp $FONT1 $FONT2 $FONTDIRA
+cp $EXPECTEDA $EXPECTED
+$FCCACHE $FONTDIRA
+check
+
+dotest "mapped check"
+prep
+cp $FONT1 $FONT2 $FONTDIRA
+cp $EXPECTEDB $EXPECTED
+$FCCACHE $FONTDIRA
+mv $FONTDIRA $FONTDIRB
+export FONTCONFIG_FILE="$MyPWD"/fonts-b.conf
+check

test/run-test.sh

@@ -73,6 +73,7 @@ dotest () {
 }
 
 sed "s!@FONTDIR@!$FONTDIR!
+s!@MAP@!!
 s!@CACHEDIR@!$CACHEDIR!" < $TESTDIR/fonts.conf.in > fonts.conf
 
 FONTCONFIG_FILE="$MyPWD"/fonts.conf
@@ -145,6 +146,7 @@ sleep 1
 ls -l $CACHEDIR > out1
 TESTTMPDIR=`mktemp -d /tmp/fontconfig.XXXXXXXX`
 sed "s!@FONTDIR@!$TESTTMPDIR/fonts!
+s!@MAP@!map="'"'"$FONTDIR"'"'"!
 s!@CACHEDIR@!$TESTTMPDIR/cache.dir!" < $TESTDIR/fonts.conf.in > bind-fonts.conf
 $BWRAP --bind / / --bind $CACHEDIR $TESTTMPDIR/cache.dir --bind $FONTDIR $TESTTMPDIR/fonts --bind .. $TESTTMPDIR/build --dev-bind /dev /dev --setenv FONTCONFIG_FILE $TESTTMPDIR/build/test/bind-fonts.conf $TESTTMPDIR/build/fc-match/fc-match$EXEEXT -f "%{file}\n" ":foundry=Misc" > xxx
 $BWRAP --bind / / --bind $CACHEDIR $TESTTMPDIR/cache.dir --bind $FONTDIR $TESTTMPDIR/fonts --bind .. $TESTTMPDIR/build --dev-bind /dev /dev --setenv FONTCONFIG_FILE $TESTTMPDIR/build/test/bind-fonts.conf $TESTTMPDIR/build/test/test-bz106618$EXEEXT | sort > flist1