[libvirt] [PATCH v2 09/15] qemu_firmware: Introduce qemuFirmwareFetchConfigs

[Michal Privoznik]

Implementation for yet another part of firmware description
specification. This one covers selecting which files to parse.

There are three locations from which description files can be
loaded. In order of preference, from most generic to most
specific these are:

  /usr/share/qemu/firmware
  /etc/qemu/firmware
  $XDG_CONFIG_HOME/qemu/firmware

If a file is found in two or more locations then the most specific
one is used. Moreover, if file is empty then it means it is
overriding some generic description and disabling it.

Again, this is described in more details and with nice examples
in firmware.json specification (qemu commit 3a0adfc9bf).

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_firmware.c | 134 +++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_firmware.h |   3 +
 2 files changed, 137 insertions(+)

diff --git a/src/qemu/qemu_firmware.c b/src/qemu/qemu_firmware.c
index 8f718ee2a6..a818f60c91 100644
--- a/src/qemu/qemu_firmware.c
+++ b/src/qemu/qemu_firmware.c
@@ -21,9 +21,11 @@
 #include <config.h>
 
 #include "qemu_firmware.h"
+#include "configmake.h"
 #include "qemu_capabilities.h"
 #include "virarch.h"
 #include "virfile.h"
+#include "virhash.h"
 #include "virjson.h"
 #include "virlog.h"
 #include "virstring.h"
@@ -899,3 +901,135 @@ qemuFirmwareFormat(qemuFirmwarePtr fw)
 
     return virJSONValueToString(doc, true);
 }
+
+
+static int
+qemuFirmwareBuildFileList(virHashTablePtr files, const char *dir)
+{
+    DIR *dirp;
+    struct dirent *ent = NULL;
+    int rc;
+    int ret = -1;
+
+    if ((rc = virDirOpenIfExists(&dirp, dir)) < 0)
+        return -1;
+
+    if (rc == 0)
+        return 0;
+
+    while ((rc = virDirRead(dirp, &ent, dir)) > 0) {
+        VIR_AUTOFREE(char *) filename = NULL;
+        VIR_AUTOFREE(char *) path = NULL;
+
+        if (ent->d_type != DT_REG && ent->d_type != DT_LNK)
+            continue;
+
+        if (STRPREFIX(ent->d_name, "."))
+            continue;
+
+        if (VIR_STRDUP(filename, ent->d_name) < 0)
+            goto cleanup;
+
+        if (virAsprintf(&path, "%s/%s", dir, filename) < 0)
+            goto cleanup;
+
+        if (virHashUpdateEntry(files, filename, path) < 0)
+            goto cleanup;
+
+        path = NULL;
+    }
+
+    if (rc < 0)
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    virDirClose(&dirp);
+    return ret;
+}
+
+static int
+qemuFirmwareFilesSorter(const virHashKeyValuePair *a,
+                        const virHashKeyValuePair *b)
+{
+    return strcmp(a->key, b->key);
+}
+
+#define QEMU_FIRMWARE_SYSTEM_LOCATION PREFIX "/share/qemu/firmware"
+#define QEMU_FIRMWARE_ETC_LOCATION SYSCONFDIR "/qemu/firmware"
+
+int
+qemuFirmwareFetchConfigs(char ***firmwares)
+{
+    VIR_AUTOPTR(virHashTable) files = NULL;
+    VIR_AUTOFREE(char *) homeConfig = NULL;
+    VIR_AUTOFREE(char *) xdgConfig = NULL;
+    VIR_AUTOFREE(virHashKeyValuePairPtr) pairs = NULL;
+    virHashKeyValuePairPtr tmp = NULL;
+
+    *firmwares = NULL;
+
+    if (VIR_STRDUP(xdgConfig, virGetEnvBlockSUID("XDG_CONFIG_HOME")) < 0)
+        return -1;
+
+    if (!xdgConfig) {
+        VIR_AUTOFREE(char *) home = virGetUserDirectory();
+
+        if (!home)
+            return -1;
+
+        if (virAsprintf(&xdgConfig, "%s/.config", home) < 0)
+            return -1;
+    }
+
+    if (virAsprintf(&homeConfig, "%s/qemu/firmware", xdgConfig) < 0)
+        return -1;
+
+    if (!(files = virHashCreate(10, virHashValueFree)))
+        return -1;
+
+    if (qemuFirmwareBuildFileList(files, QEMU_FIRMWARE_SYSTEM_LOCATION) < 0)
+        return -1;
+
+    if (qemuFirmwareBuildFileList(files, QEMU_FIRMWARE_ETC_LOCATION) < 0)
+        return -1;
+
+    if (qemuFirmwareBuildFileList(files, homeConfig) < 0)
+        return -1;
+
+    /* At this point, the @files hash table contains unique set of filenames
+     * where each filename (as key) has the highest priority full pathname
+     * associated with it. */
+
+    if (virHashSize(files) == 0)
+        return 0;
+
+    if (!(pairs = virHashGetItems(files, qemuFirmwareFilesSorter)))
+        return -1;
+
+    for (tmp = pairs; tmp->key; tmp++) {
+        const char *path = tmp->value;
+        off_t len;
+
+        if ((len = virFileLength(path, -1)) < 0) {
+            virReportSystemError(errno,
+                                 _("unable to get size of '%s'"),
+                                 path);
+            return -1;
+        }
+
+        VIR_DEBUG("firmware description path '%s' len=%jd",
+                  path, (intmax_t) len);
+
+        if (len == 0) {
+            /* Empty files are used to mask less specific instances
+             * of the same file. */
+            continue;
+        }
+
+        if (virStringListAdd(firmwares, path) < 0)
+            return -1;
+    }
+
+    return 0;
+}
diff --git a/src/qemu/qemu_firmware.h b/src/qemu/qemu_firmware.h
index 952615d42b..321169f56c 100644
--- a/src/qemu/qemu_firmware.h
+++ b/src/qemu/qemu_firmware.h
@@ -37,4 +37,7 @@ qemuFirmwareParse(const char *path);
 char *
 qemuFirmwareFormat(qemuFirmwarePtr fw);
 
+int
+qemuFirmwareFetchConfigs(char ***firmwares);
+
 #endif /* LIBVIRT_QEMU_FIRMWARE_H */
-- 
2.19.2