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[libvirt] [PATCH 05/11] util: Add util to parse the stable scsi host address



By traversing sysfs directory like "/sys/bus/pci/devices/0000:00:1f:2/"
to find out the scsi host whose "unique_id" has the specified value.
And returns the host number.

Address like "0000:00:1f:2" will be retrieved from the "parent" of
scsi_host adapter. E.g.

  <adapter type='scsi_host' parent='pci_0000_00_1f_2' unique_id='2'/>
---
 src/libvirt_private.syms                           |   1 +
 src/util/virutil.c                                 | 128 +++++++++++++++++++++
 src/util/virutil.h                                 |   6 +
 .../ata1/host0/scsi_host/host0/unique_id           |   1 +
 .../ata2/host1/scsi_host/host1/unique_id           |   1 +
 tests/utiltest.c                                   |  65 +++++++++--
 6 files changed, 192 insertions(+), 10 deletions(-)
 create mode 100644 tests/sysfs/bus/pci/devices/0000:00:1f.2/ata1/host0/scsi_host/host0/unique_id
 create mode 100644 tests/sysfs/bus/pci/devices/0000:00:1f.2/ata2/host1/scsi_host/host1/unique_id

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index f6ae42d..ce39cc6 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1954,6 +1954,7 @@ virIsCapableVport;
 virIsDevMapperDevice;
 virManageVport;
 virParseNumber;
+virParseStableScsiHostAddress;
 virParseVersionString;
 virPipeReadUntilEOF;
 virReadFCHost;
diff --git a/src/util/virutil.c b/src/util/virutil.c
index 8309568..a80574f 100644
--- a/src/util/virutil.c
+++ b/src/util/virutil.c
@@ -2137,6 +2137,125 @@ cleanup:
     }
     return ret;
 }
+
+struct virParseStableScsiHostAddressData {
+    const char *filename;
+    unsigned int unique_id;
+};
+
+static int
+virParseStableScsiHostAddressCallback(const char *fpath,
+                                      void *opaque)
+{
+    struct virParseStableScsiHostAddressData *data  = opaque;
+    unsigned int unique_id;
+    char *buf = NULL;
+    char *p;
+    int ret = -1;
+
+    p = strrchr(fpath, '/');
+    p++;
+
+    if (STRNEQ(p, data->filename))
+        return -1;
+
+    if (virFileReadAll(fpath, 1024, &buf) < 0)
+        return -1;
+
+    if ((p = strchr(buf, '\n')))
+        *p = 0;
+
+    if (virStrToLong_ui(buf, NULL, 10, &unique_id) < 0)
+        goto cleanup;
+
+    if (unique_id != data->unique_id)
+        goto cleanup;
+
+    ret = 0;
+cleanup:
+    VIR_FREE(buf);
+    return ret;
+}
+
+# define SYSFS_BUS_PCI_DEVICES "/sys/bus/pci/devices"
+
+/**
+ * virParseStableScsiHostAddress:
+ * @sysfs_prefix: The directory path where starts to traverse, defaults
+ *                to SYSFS_BUS_PCI_DEVICES.
+ * @addr: The parent's PCI address
+ * @unique_id: The value of sysfs "unique_id" of the scsi host.
+ *
+ * Returns the host name (e.g. host10) of the scsi host whose parent
+ * has address @addr, and "unique_id" has value @unique_id, on success.
+ * Or NULL on failure.
+ */
+char *
+virParseStableScsiHostAddress(const char *sysfs_prefix,
+                              const char *address,
+                              unsigned int unique_id)
+{
+    const char *prefix = sysfs_prefix ? sysfs_prefix : SYSFS_BUS_PCI_DEVICES;
+    unsigned int flags = 0;
+    char **paths = NULL;
+    int npaths = 0;
+    char *dir = NULL;
+    char *p1 = NULL;
+    char *p2 = NULL;
+    char *ret = NULL;
+    int i;
+
+    struct virParseStableScsiHostAddressData data = {
+        .filename = "unique_id",
+        .unique_id = unique_id,
+    };
+
+    if (virAsprintf(&dir, "%s/%s", prefix, address) < 0) {
+        virReportOOMError();
+        return NULL;
+    }
+
+    flags |= (VIR_TRAVERSE_DIRECTORY_IGNORE_HIDDEN_FILES |
+              VIR_TRAVERSE_DIRECTORY_FALL_THROUGH);
+
+    if ((npaths = virTraverseDirectory(dir, 4, flags,
+                                       virParseStableScsiHostAddressCallback,
+                                       NULL, &data, &paths)) < 0) {
+        goto cleanup;
+    } else if (npaths == 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unable to find scsi host with PCI address "
+                         "'%s' unique_id '%u'"), address, unique_id);
+        goto cleanup;
+    } else if (npaths != 1) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unexpected multiple paths returned for PCI address "
+                         "'%s' unique_id '%u'"), address, unique_id);
+        goto cleanup;
+    }
+
+    if (!(p1 = strstr(paths[0], "scsi_host"))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("unexpected returned path '%s' for PCI address "
+                         "'%s' unique_id '%u'"), paths[0], address, unique_id);
+        goto cleanup;
+    }
+
+    p1 += strlen("scsi_host");
+    p2 = strrchr(p1, '/');
+
+    if (VIR_STRNDUP(ret, p1 + 1, p2 - p1 -1) < 0)
+        goto cleanup;
+
+cleanup:
+    VIR_FREE(dir);
+    if (npaths > 0) {
+        for (i = 0; i < npaths; i++)
+            VIR_FREE(paths[i]);
+        VIR_FREE(paths);
+    }
+    return ret;
+}
 #else
 int
 virReadFCHost(const char *sysfs_prefix ATTRIBUTE_UNUSED,
@@ -2198,6 +2317,15 @@ virFindPCIDeviceByVPD(const char *sysfs_prefix,
     virReportSystemError(ENOSYS, "%s", _("Not supported on this platform"));
     return NULL;
 }
+
+char *
+virParseStableScsiHostAddress(const char *sysfs_prefix,
+                              const char *address,
+                              unsigned int unique_id)
+{
+    virReportSystemError(ENOSYS, "%s", _("Not supported on this platform"));
+    return NULL;
+}
 #endif /* __linux__ */
 
 /**
diff --git a/src/util/virutil.h b/src/util/virutil.h
index 99d3ea2..2747cf1 100644
--- a/src/util/virutil.h
+++ b/src/util/virutil.h
@@ -223,4 +223,10 @@ char *virFindPCIDeviceByVPD(const char *sysfs_prefix,
                             const char *product)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
+char *virParseStableScsiHostAddress(const char *sysfs_prefix,
+                                    const char *address,
+                                    unsigned int unique_id)
+
+    ATTRIBUTE_NONNULL(2);
+
 #endif /* __VIR_UTIL_H__ */
diff --git a/tests/sysfs/bus/pci/devices/0000:00:1f.2/ata1/host0/scsi_host/host0/unique_id b/tests/sysfs/bus/pci/devices/0000:00:1f.2/ata1/host0/scsi_host/host0/unique_id
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/sysfs/bus/pci/devices/0000:00:1f.2/ata1/host0/scsi_host/host0/unique_id
@@ -0,0 +1 @@
+1
diff --git a/tests/sysfs/bus/pci/devices/0000:00:1f.2/ata2/host1/scsi_host/host1/unique_id b/tests/sysfs/bus/pci/devices/0000:00:1f.2/ata2/host1/scsi_host/host1/unique_id
new file mode 100644
index 0000000..0cfbf08
--- /dev/null
+++ b/tests/sysfs/bus/pci/devices/0000:00:1f.2/ata2/host1/scsi_host/host1/unique_id
@@ -0,0 +1 @@
+2
diff --git a/tests/utiltest.c b/tests/utiltest.c
index 8d3dbfa..41fdd7e 100644
--- a/tests/utiltest.c
+++ b/tests/utiltest.c
@@ -11,10 +11,12 @@
 #include "virutil.h"
 #include "virstring.h"
 #include "virfile.h"
+#include "virerror.h"
 
-static char *sysfs_devices_prefix;
+static char *test_sysfs;
 
-#define TEST_SYSFS_DEVICES_PREFIX sysfs_devices_prefix
+#define VIR_FROM_THIS VIR_FROM_NONE
+#define TEST_SYSFS test_sysfs
 
 static void
 testQuietError(void *userData ATTRIBUTE_UNUSED,
@@ -158,36 +160,78 @@ testParseVersionString(const void *data ATTRIBUTE_UNUSED)
 static int
 testFindPCIDeviceByVPD(const void *data ATTRIBUTE_UNUSED)
 {
-    char *addr = NULL;
     const char *expected_addr = "0000:00:1f.2";
     const char *vendor = "0x8086";
     const char *device = "0x1e03";
+    char *dir = NULL;
+    char *addr = NULL;
     int ret = -1;
 
-    if (!(addr = virFindPCIDeviceByVPD(TEST_SYSFS_DEVICES_PREFIX,
-                                       vendor, device)))
+    if (virAsprintf(&dir, "%s/%s", TEST_SYSFS, "devices") < 0) {
+        virReportOOMError();
         return -1;
+    }
+
+    if (!(addr = virFindPCIDeviceByVPD(dir, vendor, device)))
+        goto cleanup;
 
     if (STRNEQ(addr, expected_addr))
         goto cleanup;
 
-    if ((addr = virFindPCIDeviceByVPD(TEST_SYSFS_DEVICES_PREFIX,
-                                      "0x7076", "0x2434")))
+    if ((addr = virFindPCIDeviceByVPD(dir, "0x7076", "0x2434")))
         goto cleanup;
 
     ret = 0;
 cleanup:
+    VIR_FREE(dir);
     VIR_FREE(addr);
     return ret;
 }
 
 static int
+testParseStableScsiHostAddress(const void *data ATTRIBUTE_UNUSED)
+{
+    const char *addr = "0000:00:1f.2";
+    unsigned int host0_unique_id = 1;
+    unsigned int host1_unique_id = 2;
+    char *rc0 = NULL;
+    char *rc1 = NULL;
+    char *dir = NULL;
+    int ret = -1;
+
+    if (virAsprintf(&dir, "%s/%s", TEST_SYSFS, "bus/pci/devices") < 0) {
+        virReportOOMError();
+        return -1;
+    }
+
+    if (!(rc0 = virParseStableScsiHostAddress(dir, addr,
+                                              host0_unique_id)))
+        goto cleanup;
+
+    if (STRNEQ(rc0, "host0"))
+        goto cleanup;
+
+    if (!(rc1 = virParseStableScsiHostAddress(dir, addr,
+                                              host1_unique_id)))
+        goto cleanup;
+
+    if (STRNEQ(rc1, "host1"))
+         goto cleanup;
+    ret = 0;
+cleanup:
+    VIR_FREE(dir);
+    VIR_FREE(rc0);
+    VIR_FREE(rc1);
+    return ret;
+}
+
+static int
 mymain(void)
 {
     int result = 0;
 
-    if (virAsprintf(&sysfs_devices_prefix, "%s/%s", abs_srcdir,
-                    "sysfs/devices/") < 0) {
+    if (virAsprintf(&test_sysfs, "%s/%s", abs_srcdir, "sysfs/") < 0) {
+        virReportOOMError();
         result = -1;
         goto cleanup;
     }
@@ -206,9 +250,10 @@ mymain(void)
     DO_TEST(DiskNameToIndex);
     DO_TEST(ParseVersionString);
     DO_TEST(FindPCIDeviceByVPD);
+    DO_TEST(ParseStableScsiHostAddress);
 
 cleanup:
-    VIR_FREE(sysfs_devices_prefix);
+    VIR_FREE(test_sysfs);
     return result == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 }
 
-- 
1.8.1.4


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