[PATCH 10/10] fdtdump: add a debug mode

[Mike Frysinger]

When hacking raw fdt files, it's useful to know the actual offsets into
the file each node appears.  Add a --debug mode that includes this.

Signed-off-by: Mike Frysinger <vap...@gentoo.org>
---
 fdtdump.c | 41 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/fdtdump.c b/fdtdump.c
index c2f16ea..723770d 100644
--- a/fdtdump.c
+++ b/fdtdump.c
@@ -19,8 +19,29 @@
 #define PALIGN(p, a)   ((void *)(ALIGN((unsigned long)(p), (a))))
 #define GET_CELL(p)    (p += 4, *((const uint32_t *)(p-4)))
 
-static void dump_blob(void *blob)
+static const char *tagname(uint32_t tag)
 {
+       static const char * const names[] = {
+#define TN(t) [t] #t
+               TN(FDT_BEGIN_NODE),
+               TN(FDT_END_NODE),
+               TN(FDT_PROP),
+               TN(FDT_NOP),
+               TN(FDT_END),
+#undef TN
+       };
+       if (tag < ARRAY_SIZE(names))
+               if (names[tag])
+                       return names[tag];
+       return "FDT_???";
+}
+
+#define dumpf(fmt, args...) \
+       do { if (debug) printf("// " fmt, ## args); } while (0)
+
+static void dump_blob(void *blob, bool debug)
+{
+       uintptr_t blob_off = (uintptr_t)blob;
        struct fdt_header *bph = blob;
        uint32_t off_mem_rsvmap = fdt32_to_cpu(bph->off_mem_rsvmap);
        uint32_t off_dt = fdt32_to_cpu(bph->off_dt_struct);
@@ -74,7 +95,8 @@ static void dump_blob(void *blob)
        p = p_struct;
        while ((tag = fdt32_to_cpu(GET_CELL(p))) != FDT_END) {
 
-               /* printf("tag: 0x%08x (%d)\n", tag, p - p_struct); */
+               dumpf("%04zx: tag: 0x%08x (%s)\n",
+                       (uintptr_t)p - blob_off - 4, tag, tagname(tag));
 
                if (tag == FDT_BEGIN_NODE) {
                        s = p;
@@ -113,6 +135,8 @@ static void dump_blob(void *blob)
 
                p = PALIGN(p + sz, 4);
 
+               dumpf("%04zx: string: %s\n", (uintptr_t)s - blob_off, s);
+               dumpf("%04zx: value\n", (uintptr_t)t - blob_off);
                printf("%*s%s", depth * shift, "", s);
                utilfdt_print_data(t, sz);
                printf(";\n");
@@ -121,12 +145,14 @@ static void dump_blob(void *blob)
 
 /* Usage related data. */
 static const char usage_synopsis[] = "fdtdump [options] <file>";
-static const char usage_short_opts[] = "s" USAGE_COMMON_SHORT_OPTS;
+static const char usage_short_opts[] = "ds" USAGE_COMMON_SHORT_OPTS;
 static struct option const usage_long_opts[] = {
+       {"debug",            no_argument, NULL, 'd'},
        {"scan",             no_argument, NULL, 's'},
        USAGE_COMMON_LONG_OPTS
 };
 static const char * const usage_opts_help[] = {
+       "Dump debug information while decoding the file",
        "Scan for an embedded fdt in file",
        USAGE_COMMON_OPTS_HELP
 };
@@ -136,6 +162,7 @@ int main(int argc, char *argv[])
        int opt;
        const char *file;
        char *buf;
+       bool debug = false;
        bool scan = false;
        off_t len;
 
@@ -143,6 +170,9 @@ int main(int argc, char *argv[])
                switch (opt) {
                case_USAGE_COMMON_FLAGS
 
+               case 'd':
+                       debug = true;
+                       break;
                case 's':
                        scan = true;
                        break;
@@ -179,6 +209,9 @@ int main(int argc, char *argv[])
                                    fdt_off_dt_struct(p) < this_len &&
                                        fdt_off_dt_strings(p) < this_len)
                                        break;
+                               if (debug)
+                                       printf("%s: skipping fdt magic at 
offset %#zx\n",
+                                               file, p - buf);
                        }
                        ++p;
                }
@@ -188,7 +221,7 @@ int main(int argc, char *argv[])
                buf = p;
        }
 
-       dump_blob(buf);
+       dump_blob(buf, debug);
 
        return 0;
 }
-- 
1.8.1.2

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