[Crash-utility] [PATCH] crash: add python wrapper script

[Alexey Dobriyan]

Add simple script with caching (just one startup can take quite some time and
it saved hours during debugging).

Script expects 2 symlinks ("crash vmlinux core") and is designed
for post-mortem analysis.

Script contains one example: fetching all inodes.

Basically it is an example on how to run "crash" from Python.
---

diff --git a/contrib/crash.py b/contrib/crash.py
new file mode 100755
index 0000000..8dae0e1
--- /dev/null
+++ b/contrib/crash.py
@@ -0,0 +1,88 @@
+#!/usr/bin/python2
+import hashlib
+import os
+import subprocess
+import tempfile
+
+# create "vmlinux" and "core" symlinks before running
+#CRASH='/usr/bin/crash'
+CRASH=os.path.join(os.path.expanduser('~'), 'bin', 'crash')
+
+# split() without empty strings
+def xsplit(s, c):
+    i = 0
+    while True:
+        j = s.find(c, i)
+        if j == -1:
+            if i == len(s):
+                return
+            yield s[i:]
+            return
+        elif i == j:
+            i = i + 1
+            continue
+        else:
+            yield s[i:j]
+            i = j + 1
+
+_CRASH_CACHE_DIR='.crash'
+def crash(cmd):
+    idx = cmd.find('\n')
+    if idx >= 0:
+        print 'CRASH "%s" ...' % cmd[:idx]
+    else:
+        print 'CRASH "%s"' % cmd
+
+    try:
+        os.mkdir(_CRASH_CACHE_DIR)
+    except OSError:
+        pass
+
+    cache_filename = os.path.join(_CRASH_CACHE_DIR, hashlib.sha1(cmd).hexdigest())
+    if os.path.isfile(cache_filename):
+        with open(cache_filename, 'r') as f:
+            return f.read()
+
+    fd, filename = tempfile.mkstemp()
+    f = os.fdopen(fd, 'w')
+    f.write(cmd)
+    if cmd[-1] != '\n':
+        f.write('\n')
+    f.write('q\n')
+    f.close()
+
+    with open(filename, 'r') as f:
+        x = subprocess.check_output([CRASH, '-s', 'vmlinux', 'core'], stdin=f)
+    os.unlink(filename)
+
+    with open(cache_filename, 'w+') as f:
+        f.write(x)
+    return x
+
+def make_cmd(fmt, it):
+    return '\n'.join(map(lambda x: fmt % x, it))
+
+#def struct_inode():
+#    cmd = 'list -H super_blocks super_block.s_list'
+#    x = crash(cmd)
+#    list_sb = map(lambda x: int(x, 16), xsplit(x, '\n'))
+#
+#    cmd = 'struct super_block.s_inodes'
+#    x = crash(cmd)
+#    s = [line for line in xsplit(x, '\n')]
+#    OFFSETOF_STRUCT_INODE_S_INODES = int(s[1].split()[0][1:-1])
+#
+##    set_inode = set()
+##    for sb in list_sb:
+##        cmd = 'list -H %x inode.i_sb_list' % (sb + OFFSETOF_STRUCT_INODE_S_INODES)
+##        x = crash(cmd)
+##        set_inode.update(map(lambda x: int(x, 16), xsplit(x, '\n')))
+##    print len(set_inode)
+#
+#    set_inode = set()
+#    cmd = make_cmd('list -H %x inode.i_sb_list', map(lambda x: x + OFFSETOF_STRUCT_INODE_S_INODES, list_sb))
+#    x = crash(cmd)
+#    set_inode = set(map(lambda x: int(x, 16), xsplit(x, '\n')))
+#    print len(set_inode)
+#
+#struct_inode()