database: pick old database file from any arch

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

src/pulsecore/database-gdbm.c

@@ -59,14 +59,6 @@ void pa_datum_free(pa_datum *d) {
     pa_zero(d);
 }
 
-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. */
-
-    return CANONICAL_HOST;
-}
-
 const char* pa_database_get_filename_suffix(void) {
     return ".gdbm";
 }

src/pulsecore/database-simple.c

@@ -222,11 +222,6 @@ static int fill_data(simple_data *db, FILE *f) {
     return pa_hashmap_size(db->map);
 }
 
-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";
 }

src/pulsecore/database-tdb.c

@@ -97,11 +97,6 @@ finish:
     return c;
 }
 
-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";
 }

src/pulsecore/database.c

@@ -33,7 +33,6 @@
 
 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;
@@ -43,7 +42,6 @@ pa_database* pa_database_open(const char *path, const char *fn, bool prependmid,
 
     pa_database *f;
 
-    pa_assert(!arch_suffix || arch_suffix[0]);
     pa_assert(filename_suffix && filename_suffix[0]);
 
     if (prependmid && !(machine_id = pa_machine_id())) {
@@ -56,7 +54,6 @@ pa_database* pa_database_open(const char *path, const char *fn, bool prependmid,
     else
         filename_prefix = pa_xstrdup(fn);
 
-    if (arch_suffix) {
     /* Search for existing database directory entry name matching architecture suffix and filename suffix. */
     database_dir = opendir(path);
 
@@ -66,7 +63,7 @@ pa_database* pa_database_open(const char *path, const char *fn, bool prependmid,
             de = readdir(database_dir);
             if (!de) {
                 if (errno) {
-                        pa_log_warn("Unable to search for compatible database file, readdir() failed: %s", pa_cstrerror(errno));
+                    pa_log_warn("Unable to search for existing database file, readdir() failed: %s", pa_cstrerror(errno));
                     /* can continue as if there is no matching database file candidate */
                 }
 
@@ -75,12 +72,11 @@ pa_database* pa_database_open(const char *path, const char *fn, bool prependmid,
 
             if (pa_startswith(de->d_name, filename_prefix)
                 && de->d_name[strlen(filename_prefix)] == '.'
-                    && pa_startswith(de->d_name + strlen(filename_prefix) + 1, arch_suffix)
-                    && pa_endswith(de->d_name + strlen(filename_prefix) + 1 + strlen(arch_suffix), filename_suffix)) {
+                && pa_endswith(de->d_name + strlen(filename_prefix) + 1, filename_suffix)) {
 
                 /* candidate filename found, replace filename_prefix with this one */
 
-                    pa_log_debug("Found compatible database file '%s/%s', using it", path, de->d_name);
+                pa_log_debug("Found existing database file '%s/%s', using it", path, de->d_name);
                 pa_xfree(filename_prefix);
                 filename_prefix = pa_xstrndup(de->d_name, strlen(de->d_name) - strlen(filename_suffix));
                 break;
@@ -89,8 +85,7 @@ pa_database* pa_database_open(const char *path, const char *fn, bool prependmid,
 
         closedir(database_dir);
     } else {
-            pa_log_warn("Unable to search for compatible database file, failed to open directory %s: %s", path, pa_cstrerror(errno));
-        }
+        pa_log_warn("Unable to search for existing database file, failed to open directory %s: %s", path, pa_cstrerror(errno));
     }
 
     full_path = pa_sprintf_malloc("%s" PA_PATH_SEP "%s%s", path, filename_prefix, filename_suffix);

src/pulsecore/database.h

@@ -38,14 +38,25 @@ typedef struct pa_datum {
 
 void pa_datum_free(pa_datum *d);
 
-/* 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 implementation architecture name prefix,
- * or new database file will be created and opened with implementation architecture name suffix if required.
- * If prependmid is true, file name is augmented with machine id prefix. */
+/* Opens a database file. The file is loaded from the directory indicated by
+ * path. The file name is constructed by using fn as the base and then adding
+ * several parts:
+ *   1) If prependmid is true, the machine id is prepended to the file name.
+ *   2) The database implementation specific suffix is added.
+ *   3) Older versions of PulseAudio in some cases added the CPU architecture
+ *      to the file name, which was later deemed unnecessary, but for
+ *      compatibility reasons we still need to look for those files, so we scan
+ *      the directory for files that match the prefix (possible machine id plus
+ *      fn) and the suffix, and if any matches are found, we use the first one.
+ *
+ * When no existing file is found, we create a new file for the database
+ * (without the CPU architecture part in the name).
+ *
+ * For a read-only database, set for_write to false. */
+
 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. */