The buffers used to construct a PDB URL overflow when the "age" property
is greater than 0xf, so grow it. This also simplifies the logic of the
URL construction to use one buffer instead of two to avoid the chore to
synchronize the sizes of two buffers.

Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
---
 contrib/elf2dmp/main.c | 32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/contrib/elf2dmp/main.c b/contrib/elf2dmp/main.c
index d046a72ae67f..a62abadcc049 100644
--- a/contrib/elf2dmp/main.c
+++ b/contrib/elf2dmp/main.c
@@ -494,18 +494,6 @@ static bool pe_check_pdb_name(uint64_t base, void *start_addr,
     return !strcmp(pdb_name, PDB_NAME);
 }
 
-static void pe_get_pdb_symstore_hash(OMFSignatureRSDS *rsds, char *hash)
-{
-    sprintf(hash, "%.08x%.04x%.04x%.02x%.02x", rsds->guid.a, rsds->guid.b,
-            rsds->guid.c, rsds->guid.d[0], rsds->guid.d[1]);
-    hash += 20;
-    for (unsigned int i = 0; i < 6; i++, hash += 2) {
-        sprintf(hash, "%.02x", rsds->guid.e[i]);
-    }
-
-    sprintf(hash, "%.01x", rsds->age);
-}
-
 int main(int argc, char *argv[])
 {
     int err = 1;
@@ -517,9 +505,7 @@ int main(int argc, char *argv[])
     uint64_t KernBase;
     void *nt_start_addr = NULL;
     WinDumpHeader64 header;
-    char pdb_hash[34];
-    char pdb_url[] = SYM_URL_BASE PDB_NAME
-        "/0123456789ABCDEF0123456789ABCDEFx/" PDB_NAME;
+    g_autofree char *pdb_url = NULL;
     struct pdb_reader pdb;
     uint64_t KdDebuggerDataBlock;
     KDDEBUGGER_DATA64 *kdbg;
@@ -583,9 +569,21 @@ int main(int argc, char *argv[])
     printf("KernBase = 0x%016"PRIx64", signature is \'%.2s\'\n", KernBase,
             (char *)nt_start_addr);
 
-    pe_get_pdb_symstore_hash(&rsds, pdb_hash);
+    pdb_url = g_strdup_printf("%s"
+                              "%.08x%.04x%.04x"
+                              "%.02x%.02x"
+                              "%.02x%.02x"
+                              "%.02x%.02x"
+                              "%.02x%.02x%.01x"
+                              "%s",
+                              SYM_URL_BASE PDB_NAME "/",
+                              rsds.guid.a, rsds.guid.b, rsds.guid.c,
+                              rsds.guid.d[0], rsds.guid.d[1],
+                              rsds.guid.e[0], rsds.guid.e[1],
+                              rsds.guid.e[2], rsds.guid.e[3],
+                              rsds.guid.e[4], rsds.guid.e[5], rsds.age,
+                              "/" PDB_NAME);
 
-    sprintf(pdb_url, "%s%s/%s/%s", SYM_URL_BASE, PDB_NAME, pdb_hash, PDB_NAME);
     printf("PDB URL is %s\n", pdb_url);
 
     if (!download_url(PDB_NAME, pdb_url)) {

-- 
2.53.0

On Thu, 5 Mar 2026 at 06:18, Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp> wrote:
>
> The buffers used to construct a PDB URL overflow when the "age" property
> is greater than 0xf, so grow it. This also simplifies the logic of the
> URL construction to use one buffer instead of two to avoid the chore to
> synchronize the sizes of two buffers.
>
> Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
> ---
>  contrib/elf2dmp/main.c | 32 +++++++++++++++-----------------
>  1 file changed, 15 insertions(+), 17 deletions(-)
>
> diff --git a/contrib/elf2dmp/main.c b/contrib/elf2dmp/main.c
> index d046a72ae67f..a62abadcc049 100644
> --- a/contrib/elf2dmp/main.c
> +++ b/contrib/elf2dmp/main.c
> @@ -494,18 +494,6 @@ static bool pe_check_pdb_name(uint64_t base, void *start_addr,
>      return !strcmp(pdb_name, PDB_NAME);
>  }
>
> -static void pe_get_pdb_symstore_hash(OMFSignatureRSDS *rsds, char *hash)
> -{
> -    sprintf(hash, "%.08x%.04x%.04x%.02x%.02x", rsds->guid.a, rsds->guid.b,
> -            rsds->guid.c, rsds->guid.d[0], rsds->guid.d[1]);
> -    hash += 20;
> -    for (unsigned int i = 0; i < 6; i++, hash += 2) {
> -        sprintf(hash, "%.02x", rsds->guid.e[i]);
> -    }
> -
> -    sprintf(hash, "%.01x", rsds->age);
> -}
> -
>  int main(int argc, char *argv[])
>  {
>      int err = 1;
> @@ -517,9 +505,7 @@ int main(int argc, char *argv[])
>      uint64_t KernBase;
>      void *nt_start_addr = NULL;
>      WinDumpHeader64 header;
> -    char pdb_hash[34];
> -    char pdb_url[] = SYM_URL_BASE PDB_NAME
> -        "/0123456789ABCDEF0123456789ABCDEFx/" PDB_NAME;
> +    g_autofree char *pdb_url = NULL;
>      struct pdb_reader pdb;
>      uint64_t KdDebuggerDataBlock;
>      KDDEBUGGER_DATA64 *kdbg;
> @@ -583,9 +569,21 @@ int main(int argc, char *argv[])
>      printf("KernBase = 0x%016"PRIx64", signature is \'%.2s\'\n", KernBase,
>              (char *)nt_start_addr);
>
> -    pe_get_pdb_symstore_hash(&rsds, pdb_hash);
> +    pdb_url = g_strdup_printf("%s"
> +                              "%.08x%.04x%.04x"
> +                              "%.02x%.02x"
> +                              "%.02x%.02x"
> +                              "%.02x%.02x"
> +                              "%.02x%.02x%.01x"
> +                              "%s",
> +                              SYM_URL_BASE PDB_NAME "/",
> +                              rsds.guid.a, rsds.guid.b, rsds.guid.c,
> +                              rsds.guid.d[0], rsds.guid.d[1],
> +                              rsds.guid.e[0], rsds.guid.e[1],
> +                              rsds.guid.e[2], rsds.guid.e[3],
> +                              rsds.guid.e[4], rsds.guid.e[5], rsds.age,
> +                              "/" PDB_NAME);

This is definitely better. I think it would be slightly
easier to read if we put the "/" characters in the
format string rather than string-concatenating them into
the arguments, but either way

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM