include errno string in more messages

Introduce a die_error() helper that includes strerror in a fatal error
message and use it where possible.  In particular, when running
radeontool as non-root, instead of the cryptic

	fatal error: mapping ctrl region

the operator will get a more helpful diagnosis:

	fatal error: cannot map ctrl region: Permission denied

Inspired by a patch by Tormod Volden.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 17 insertions, 6 deletions

diff --git a/radeontool.c b/radeontool.c
index dbab763..bf1dc3c 100644
--- a/radeontool.c
+++ b/radeontool.c
@@ -42,6 +42,13 @@ static void die(const char *why)
     exit(-1);
 }
 
+static void die_error(int err, const char *why)
+{
+    fprintf(stderr, "fatal error: %s: %s\n", why, strerror(err));
+    pci_system_cleanup();
+    exit(-1);
+}
+
 static unsigned int radeon_get(unsigned long offset, const char *name)
 {
     unsigned int value;
@@ -916,10 +923,11 @@ static void map_radeon_cntl_mem(void)
     struct pci_device_iterator *iter;
     struct pci_device *device;
     pciaddr_t fb_base, fb_size, ctrl_base, ctrl_size;
-    int i = 0;
+    int i = 0, ret;
 
-    if (pci_system_init() != 0)
-        die("failed to initialise libpciaccess");
+    ret = pci_system_init();
+    if (ret)
+        die_error(ret, "failed to initialise libpciaccess");
 
     match.domain = PCI_MATCH_ANY;
     match.bus = PCI_MATCH_ANY;
@@ -949,9 +957,12 @@ static void map_radeon_cntl_mem(void)
 
     ctrl_base = device->regions[2].base_addr;
     ctrl_size = device->regions[2].size;
-    if (!ctrl_size || pci_device_map_range(device, ctrl_base, ctrl_size,
-			     PCI_DEV_MAP_FLAG_WRITABLE, (void **) &ctrl_mem))
-        die("mapping ctrl region");
+    if (!ctrl_size)
+        die("missing ctrl region");
+    ret = pci_device_map_range(device, ctrl_base, ctrl_size,
+			     PCI_DEV_MAP_FLAG_WRITABLE, (void **) &ctrl_mem);
+    if (ret)
+        die_error(ret, "cannot map ctrl region");
 
     fb_base = device->regions[0].base_addr;
     fb_size = device->regions[0].size;