From 07a1251a207ea0c77c417e3b8ede79b76d3254f1 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <njn@valgrind.org>
Date: Mon, 29 Jun 2009 06:57:30 +0000
Subject: [PATCH] Make the Linux launcher more like the Darwin one in how it
 reads the executable headers.  This means it no longer crashes on an empty
 executable. Fixes bug 156065.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@10384
---
 coregrind/launcher-linux.c      | 11 ++++++-----
 none/tests/empty-exe.stderr.exp |  2 ++
 none/tests/empty-exe.vgtest     |  9 +++++++++
 3 files changed, 17 insertions(+), 5 deletions(-)
 create mode 100644 none/tests/empty-exe.stderr.exp
 create mode 100644 none/tests/empty-exe.vgtest

diff --git a/coregrind/launcher-linux.c b/coregrind/launcher-linux.c
index 1713434e5..34754d02a 100644
--- a/coregrind/launcher-linux.c
+++ b/coregrind/launcher-linux.c
@@ -112,7 +112,8 @@ static const char *find_client(const char *clientname)
 static const char *select_platform(const char *clientname)
 {
    int fd;
-   unsigned char *header;
+   uint8_t header[4096];
+   ssize_t bytes;
    const char *platform = NULL;
    long pagesize = sysconf(_SC_PAGESIZE);
 
@@ -123,11 +124,11 @@ static const char *select_platform(const char *clientname)
       return NULL;
    //   barf("open(%s): %s", clientname, strerror(errno));
 
-   if ((header = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0)) == MAP_FAILED)
-      return NULL;
-   //   barf("mmap(%s): %s", clientname, strerror(errno));
-
+   bytes = read(fd, header, sizeof(header));
    close(fd);
+   if (bytes != sizeof(header)) {
+      return NULL;
+   }
 
    if (header[0] == '#' && header[1] == '!') {
       char *interp = (char *)header + 2;
diff --git a/none/tests/empty-exe.stderr.exp b/none/tests/empty-exe.stderr.exp
new file mode 100644
index 000000000..139597f9c
--- /dev/null
+++ b/none/tests/empty-exe.stderr.exp
@@ -0,0 +1,2 @@
+
+
diff --git a/none/tests/empty-exe.vgtest b/none/tests/empty-exe.vgtest
new file mode 100644
index 000000000..71fef2eda
--- /dev/null
+++ b/none/tests/empty-exe.vgtest
@@ -0,0 +1,9 @@
+# Bug 162020: running an empty executable used to crash Valgrind.  Note that
+# the (old) crash message gets filtered out, so it's the presence of the
+# blank two lines in the .stderr.exp file that are important -- they
+# indicate it ran to completion.  If the crash occurs, the .stderr.out file
+# is empty.
+prereq: touch empty-exe && chmod u+x empty-exe
+prog: empty-exe
+vgopts:
+cleanup: rm -f empty-exe