From 689fce307911b4cebac8114c122bc5149c8d3766 Mon Sep 17 00:00:00 2001
From: Robert Spalek <robert@ucw.cz>
Date: Mon, 14 Jun 2004 17:26:35 +0000
Subject: [PATCH] print a fancy message when SIGSEGV is caught at the
 decompression

---
 lib/lizard.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/lizard.c b/lib/lizard.c
index 3968a710..ad1a7897 100644
--- a/lib/lizard.c
+++ b/lib/lizard.c
@@ -15,6 +15,7 @@
 #include <sys/mman.h>
 #include <sys/user.h>
 #include <fcntl.h>
+#include <signal.h>
 
 typedef u16 hash_ptr_t;
 struct hash_record {
@@ -419,6 +420,12 @@ lizard_free(struct lizard_buffer *buf)
   xfree(buf);
 }
 
+static void
+sigsegv_handler(int UNUSED whatsit)
+{
+  die("SIGSEGV caught when decompressing.");
+}
+
 int
 lizard_decompress_safe(byte *in, struct lizard_buffer *buf, uns expected_length)
   /* Decompresses into buf->ptr and returns the length of the uncompressed
@@ -430,7 +437,10 @@ lizard_decompress_safe(byte *in, struct lizard_buffer *buf, uns expected_length)
     return -1;
   mprotect(buf->ptr, lock_offset, PROT_READ | PROT_WRITE);
   mprotect(buf->ptr + lock_offset, PAGE_SIZE, PROT_READ);
-  return lizard_decompress(in, buf->ptr);
+  sighandler_t old_handler = signal(SIGSEGV, sigsegv_handler);
+  int len = lizard_decompress(in, buf->ptr);
+  signal(SIGSEGV, old_handler);
+  return len;
 }
 
 /*
-- 
2.39.5