libbootimg_architecture: Use uname instead of /proc/cpuinfo

 * A new situation on the Sony X Performance has shown
    that the "Processor" field from cpuinfo can be missing,
    therefore breaking the 32 / 64bits detection

 * Instead, use the native uname handling to get the name of
    the host machine, allowing to detect aarch64/armv8 properly

Change-Id: Ib7f1aa6303390b4cc64e402e7ee242a272ddf722
Signed-off-by: Adrian DC <[email protected]>

src/libbootimg.c

@@ -1258,25 +1258,11 @@ int libbootimg_write_img_and_destroy(struct bootimg *b, const char *dest)
 
 uint8_t libbootimg_architecture(void)
 {
-    FILE* cpuinfo;
-    char buffer[100];
+    struct utsname sysinfo;
+    uname(&sysinfo);
 
-    memset(buffer, 0, sizeof(buffer));
-    cpuinfo = fopen("/proc/cpuinfo", "rb");
-
-    if (cpuinfo == NULL)
-    {
-        return ARCH_32_BITS;
-    }
-
-    if (fread(buffer, 1, sizeof(buffer), cpuinfo) == 0)
-    {
-        fclose(cpuinfo);
-        return ARCH_32_BITS;
-    }
-    fclose(cpuinfo);
-
-    if (strstr(buffer, "aarch64")) {
+    if (strstr(sysinfo.machine, "aarch64")
+            || strstr(sysinfo.machine, "armv8")) {
         return ARCH_64_BITS;
     }