database: extract common method to handle machine id and architecture

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/425>

src/pulsecore/database-gdbm.c

@@ -59,17 +59,24 @@ void pa_datum_free(pa_datum *d) {
     pa_zero(d);
 }
 
-pa_database* pa_database_open(const char *fn, bool for_write) {
-    GDBM_FILE f;
-    int gdbm_cache_size;
-    char *path;
-
-    pa_assert(fn);
-
+const char* pa_database_get_arch_suffix(void) {
     /* We include the host identifier in the file name because gdbm
      * files are CPU dependent, and we don't want things to go wrong
      * if we are on a multiarch system. */
-    path = pa_sprintf_malloc("%s."CANONICAL_HOST".gdbm", fn);
+
+    return CANONICAL_HOST;
+}
+
+const char* pa_database_get_filename_suffix(void) {
+    return ".gdbm";
+}
+
+pa_database* pa_database_open_internal(const char *path, bool for_write) {
+    GDBM_FILE f;
+    int gdbm_cache_size;
+
+    pa_assert(path);
+
     errno = 0;
 
     /* We need to set the block size explicitly here, since otherwise
@@ -80,8 +87,6 @@ pa_database* pa_database_open(const char *fn, bool for_write) {
     if (f)
         pa_log_debug("Opened GDBM database '%s'", path);
 
-    pa_xfree(path);
-
     if (!f) {
         if (errno == 0)
             errno = EIO;

src/pulsecore/database-simple.c

@@ -222,14 +222,21 @@ static int fill_data(simple_data *db, FILE *f) {
     return pa_hashmap_size(db->map);
 }
 
-pa_database* pa_database_open(const char *fn, bool for_write) {
+const char* pa_database_get_arch_suffix(void) {
+    /* Simple database binary file format is CPU dependent. */
+    return CANONICAL_HOST;
+}
+
+const char* pa_database_get_filename_suffix(void) {
+    return ".simple";
+}
+
+pa_database* pa_database_open_internal(const char *path, bool for_write) {
     FILE *f;
-    char *path;
     simple_data *db;
 
-    pa_assert(fn);
+    pa_assert(path);
 
-    path = pa_sprintf_malloc("%s."CANONICAL_HOST".simple", fn);
     errno = 0;
 
     f = pa_fopen_cloexec(path, "r");
@@ -251,8 +258,6 @@ pa_database* pa_database_open(const char *fn, bool for_write) {
         db = NULL;
     }
 
-    pa_xfree(path);
-
     return (pa_database*) db;
 }
 

src/pulsecore/database-tdb.c

@@ -97,18 +97,23 @@ finish:
     return c;
 }
 
-pa_database* pa_database_open(const char *fn, bool for_write) {
+const char* pa_database_get_arch_suffix(void) {
+    /* TDB binary file format is not dependent on system architecture */
+    return NULL;
+}
+
+const char* pa_database_get_filename_suffix(void) {
+    return ".tdb";
+}
+
+pa_database* pa_database_open_internal(const char *path, bool for_write) {
     struct tdb_context *c;
-    char *path;
 
-    pa_assert(fn);
+    pa_assert(path);
 
-    path = pa_sprintf_malloc("%s.tdb", fn);
     if ((c = tdb_open_cloexec(path, 0, TDB_NOSYNC|TDB_NOLOCK, (for_write ? O_RDWR|O_CREAT : O_RDONLY), 0644)))
         pa_log_debug("Opened TDB database '%s'", path);
 
-    pa_xfree(path);
-
     if (!c) {
         if (errno == 0)
             errno = EIO;

src/pulsecore/database.c

@@ -0,0 +1,72 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2020 Igor V. Kovalenko <igor.v.kovalenko@gmail.com>
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <errno.h>
+
+#include <pulse/xmalloc.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/log.h>
+
+#include "database.h"
+#include "core-error.h"
+
+pa_database* pa_database_open(const char *path, const char *fn, bool prependmid, bool for_write) {
+
+    const char *arch_suffix = pa_database_get_arch_suffix();
+    const char *filename_suffix = pa_database_get_filename_suffix();
+
+    char *machine_id = NULL, *filename_prefix, *full_path;
+
+    pa_database *f;
+
+    pa_assert(!arch_suffix || arch_suffix[0]);
+    pa_assert(filename_suffix && filename_suffix[0]);
+
+    if (prependmid && !(machine_id = pa_machine_id())) {
+        return NULL;
+    }
+
+    /* We include the host identifier in the file name because some database files are
+     * CPU dependent, and we don't want things to go wrong if we are on a multiarch system. */
+    filename_prefix = pa_sprintf_malloc("%s%s%s%s%s",
+            machine_id?:"", machine_id?"-":"",
+            fn,
+            arch_suffix?".":"", arch_suffix?:"");
+
+    full_path = pa_sprintf_malloc("%s" PA_PATH_SEP "%s%s", path, filename_prefix, filename_suffix);
+
+    f = pa_database_open_internal(full_path, for_write);
+
+    if (f)
+        pa_log_info("Successfully opened '%s' database file '%s'.", fn, full_path);
+    else
+        pa_log("Failed to open '%s' database file '%s': %s", fn, full_path, pa_cstrerror(errno));
+
+    pa_xfree(full_path);
+    pa_xfree(filename_prefix);
+
+    /* deallocate machine_id if it was used to construct file name */
+    pa_xfree(machine_id);
+
+    return f;
+}

src/pulsecore/database.h

@@ -38,8 +38,17 @@ typedef struct pa_datum {
 
 void pa_datum_free(pa_datum *d);
 
-/* This will append a suffix to the filename */
-pa_database* pa_database_open(const char *fn, bool for_write);
+/* Database implementation; returns non-empty system architecture name string if database file format depends on system architecture, or NULL otherwise. */
+const char* pa_database_get_arch_suffix(void);
+/* Database implementation; returns non-empty database filename extension string */
+const char* pa_database_get_filename_suffix(void);
+
+/* This will attempt opening database file matching compiled CANONICAL_HOST identifier.
+ * If prependmid is true, file name is augmented with machine id prefix. */
+pa_database* pa_database_open(const char *path, const char *fn, bool prependmid, bool for_write);
+
+/* Database implementation; opens specified database file using provided path. */
+pa_database* pa_database_open_internal(const char *path, bool for_write);
 void pa_database_close(pa_database *db);
 
 pa_datum* pa_database_get(pa_database *db, const pa_datum *key, pa_datum* data);

src/pulsecore/meson.build

@@ -14,6 +14,7 @@ libpulsecore_sources = [
   'cpu-orc.c',
   'cpu-x86.c',
   'device-port.c',
+  'database.c',
   'ffmpeg/resample2.c',
   'filter/biquad.c',
   'filter/crossover.c',