scsi, pci, qdev, isa-bus, sysbus: don't let *_get_fw_dev_path return NULL

Use g_strdup rather than strdup, because the sole caller
(qdev_get_fw_dev_path_helper) assumes it gets non-NULL, and dereferences
it.  Besides, in that caller, the allocated buffer is already freed with
g_free, so it's better to allocate with a matching g_strdup.

In one case, (scsi-bus.c) it was trivial, so I replaced an snprintf+
g_strdup combination with an equivalent g_strdup_printf use.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
index 5ea9b8f..f2e4ea4 100644
--- a/hw/ide/qdev.c
+++ b/hw/ide/qdev.c
@@ -60,7 +60,7 @@
     snprintf(path, sizeof(path), "%s@%d", qdev_fw_name(dev),
              ((IDEBus*)dev->parent_bus)->bus_id);
 
-    return strdup(path);
+    return g_strdup(path);
 }
 
 static int ide_qdev_init(DeviceState *qdev)
diff --git a/hw/isa-bus.c b/hw/isa-bus.c
index f9b2373..47c93d3 100644
--- a/hw/isa-bus.c
+++ b/hw/isa-bus.c
@@ -236,7 +236,7 @@
         snprintf(path + off, sizeof(path) - off, "@%04x", d->ioport_id);
     }
 
-    return strdup(path);
+    return g_strdup(path);
 }
 
 MemoryRegion *isa_address_space(ISADevice *dev)
diff --git a/hw/pci.c b/hw/pci.c
index f855cf3..de4b448 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -1962,7 +1962,7 @@
                    PCI_SLOT(d->devfn));
     if (PCI_FUNC(d->devfn))
         snprintf(path + off, sizeof(path) + off, ",%x", PCI_FUNC(d->devfn));
-    return strdup(path);
+    return g_strdup(path);
 }
 
 static char *pcibus_get_dev_path(DeviceState *dev)
diff --git a/hw/qdev.c b/hw/qdev.c
index b5a52ac..3b5ce33 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -520,7 +520,7 @@
 
     path[l-1] = '\0';
 
-    return strdup(path);
+    return g_strdup(path);
 }
 
 char *qdev_get_dev_path(DeviceState *dev)
diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c
index 058d3b2..dfb2631 100644
--- a/hw/scsi-bus.c
+++ b/hw/scsi-bus.c
@@ -1723,12 +1723,8 @@
 static char *scsibus_get_fw_dev_path(DeviceState *dev)
 {
     SCSIDevice *d = SCSI_DEVICE(dev);
-    char path[100];
-
-    snprintf(path, sizeof(path), "channel@%x/%s@%x,%x", d->channel,
-             qdev_fw_name(dev), d->id, d->lun);
-
-    return strdup(path);
+    return g_strdup_printf("channel@%x/%s@%x,%x", d->channel,
+                           qdev_fw_name(dev), d->id, d->lun);
 }
 
 SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
diff --git a/hw/sysbus.c b/hw/sysbus.c
index 9d8b1ea..c173840 100644
--- a/hw/sysbus.c
+++ b/hw/sysbus.c
@@ -211,7 +211,7 @@
         snprintf(path + off, sizeof(path) - off, "@i%04x", s->pio[0]);
     }
 
-    return strdup(path);
+    return g_strdup(path);
 }
 
 void sysbus_add_memory(SysBusDevice *dev, target_phys_addr_t addr,