Pull the file writing code for the wallet client into a separate file

so that the srvtab and keytab management can share it.  Write atomically
to a new file and then link and rename to do an atomic update.  Leave a
backup copy of any file that's replaced.

7 files changed, 80 insertions, 55 deletions

diff --git a/Makefile.am b/Makefile.am
index b433f6d..e49ba62 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -27,8 +27,8 @@ util_libutil_a_SOURCES = util/concat.c util/messages.c util/util.h \
 bin_PROGRAMS = client/wallet
 sbin_PROGRAMS = kasetkey/kasetkey
 sbin_SCRIPTS = server/keytab-backend server/wallet-backend
-client_wallet_SOURCES = client/internal.h client/srvtab.c client/wallet.c \
-	system.h
+client_wallet_SOURCES = client/file.c client/internal.h client/srvtab.c \
+	client/wallet.c system.h
 client_wallet_CPPFLAGS = @REMCTL_CPPFLAGS@
 client_wallet_LDFLAGS = @REMCTL_LDFLAGS@
 client_wallet_LDADD = util/libutil.a portable/libportable.a -lremctl -lkrb5
diff --git a/TODO b/TODO
index c99615e..c8f1807 100644
--- a/TODO
+++ b/TODO
@@ -9,10 +9,6 @@ Required to replace leland_srvtab:
   enctype attribute on the object and include the enctypes in the object
   show display.
 
-* Write new files atomically in the wallet client and save backups unless
-  told not to (write to file.new, link the old file to file.old, and do
-  an atomic rename).
-
 * Add support to the test suite for specifying a different database than
   SQLite for testing.  For MySQL and other database types that we can't
   just delete, also requires adding a method to Wallet::Schema to drop all
@@ -50,6 +46,9 @@ Future work:
 
 * Add a help function to wallet-backend listing the commands.
 
+* The client may not compile against Heimdal due to changes in how the
+  krb5_keyblock structure is laid out.  Check and fix.
+
 * Rewrite the client test suite to use Perl and to make better use of
   shared code so that it can be broken into function components.
 
@@ -152,12 +151,12 @@ Future work:
 * Add support for enforcing a naming policy through another policy
   function.
 
-* Add readline support to the wallet client to make it easier to issue
-  multiple commands.
-
 * The keytab backend currently only supports MIT Kerberos.  Add support
   for Heimdal.
 
+* Add readline support to the wallet client to make it easier to issue
+  multiple commands.
+
 * The wallet-backend and wallet documentation share the COMMANDS section.
   Work out some means to assemble the documentation without duplicating
   content.
diff --git a/client/file.c b/client/file.c
new file mode 100644
index 0000000..621b49d
--- /dev/null
+++ b/client/file.c
@@ -0,0 +1,50 @@
+/*  $Id$
+**
+**  File handling for the wallet client.
+**
+**  Written by Russ Allbery <rra@stanford.edu>
+**  Copyright 2007 Board of Trustees, Leland Stanford Jr. University
+**
+**  See README for licensing terms.
+*/
+
+#include <config.h>
+#include <system.h>
+
+#include <fcntl.h>
+
+#include <client/internal.h>
+#include <util/util.h>
+
+/*
+**  Given a filename, some data, and a length, write that data to the given
+**  file safely and atomically by creating file.new, writing the data, linking
+**  file to file.bak, and then renaming file.new to file.
+*/
+void
+write_file(const char *name, const void *data, size_t length)
+{
+    int fd;
+    ssize_t status;
+    char *temp, *backup;
+
+    temp = concat(name, ".new", (char *) 0);
+    backup = concat(name, ".bak", (char *) 0);
+    fd = open(temp, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+    if (fd < 0)
+        sysdie("open of %s failed", temp);
+    status = write(fd, data, length);
+    if (status < 0)
+        sysdie("write to %s failed", temp);
+    else if (status != (ssize_t) length)
+        die("write to %s truncated", temp);
+    if (close(fd) < 0)
+        sysdie("close of %s failed (file probably truncated)", temp);
+    if (access(name, F_OK) == 0)
+        if (link(name, backup) < 0)
+            sysdie("link of %s to %s failed", name, backup);
+    if (rename(temp, name) < 0)
+        sysdie("rename of %s to %s failed", temp, name);
+    free(temp);
+    free(backup);
+}
diff --git a/client/internal.h b/client/internal.h
index 834ec57..186d83f 100644
--- a/client/internal.h
+++ b/client/internal.h
@@ -11,29 +11,8 @@
 #ifndef CLIENT_INTERNAL_H
 #define CLIENT_INTERNAL_H 1
 
-/* __attribute__ is available in gcc 2.5 and later, but only with gcc 2.7
-   could you use the __format__ form of the attributes, which is what we use
-   (to avoid confusion with other macros). */
-#ifndef __attribute__
-# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
-#  define __attribute__(spec)   /* empty */
-# endif
-#endif
-
-/* Used for unused parameters to silence gcc warnings. */
-#define UNUSED  __attribute__((__unused__))
-
-/* BEGIN_DECLS is used at the beginning of declarations so that C++
-   compilers don't mangle their names.  END_DECLS is used at the end. */
-#undef BEGIN_DECLS
-#undef END_DECLS
-#ifdef __cplusplus
-# define BEGIN_DECLS    extern "C" {
-# define END_DECLS      }
-#else
-# define BEGIN_DECLS    /* empty */
-# define END_DECLS      /* empty */
-#endif
+#include <sys/types.h>
+#include <util/util.h>
 
 /* Temporary until we have some real configuration. */
 #ifndef SERVER
@@ -45,6 +24,11 @@
 
 BEGIN_DECLS
 
+/* Given a filename, some data, and a length, write that data to the given
+   file safely and atomically by creating file.new, writing the data, linking
+   file to file.bak, and then renaming file.new to file. */
+void write_file(const char *name, const void *data, size_t length);
+
 /* Given a srvtab file, the Kerberos v5 principal, and the keytab file, write
    a srvtab file for the corresponding Kerberos v4 principal. */
 void write_srvtab(const char *srvtab, const char *principal,
diff --git a/client/srvtab.c b/client/srvtab.c
index b50193e..68a2618 100644
--- a/client/srvtab.c
+++ b/client/srvtab.c
@@ -148,14 +148,5 @@ write_srvtab(const char *srvtab, const char *principal, const char *keytab)
     krb5_free_keytab_entry_contents(ctx, &entry);
 
     /* Write out the srvtab file. */
-    fd = open(srvtab, O_WRONLY | O_CREAT | O_TRUNC, 0600);
-    if (fd < 0)
-        sysdie("open of %s failed", srvtab);
-    status = write(fd, data, length);
-    if (status < 0)
-        sysdie("write to %s failed", srvtab);
-    else if (status != (ssize_t) length)
-        die("write to %s truncated", srvtab);
-    if (close(fd) < 0)
-        sysdie("close of %s failed (file probably truncated)", srvtab);
+    write_file(srvtab, data, length);
 }
diff --git a/client/wallet.c b/client/wallet.c
index e3ca4dd..998ec30 100644
--- a/client/wallet.c
+++ b/client/wallet.c
@@ -140,16 +140,7 @@ main(int argc, char *argv[])
         fprintf(stderr, "wallet: ");
         fwrite(result->stderr_buf, 1, result->stderr_len, stderr);
     } else if (file != NULL && strcmp(command[1], "get") == 0) {
-        fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, 0600);
-        if (fd < 0)
-            sysdie("open of %s failed", file);
-        status = write(fd, result->stdout_buf, result->stdout_len);
-        if (status < 0)
-            sysdie("write to %s failed", file);
-        else if (status != (ssize_t) result->stdout_len)
-            die("write to %s truncated", file);
-        if (close(fd) < 0)
-            sysdie("close of %s failed (file probably truncated)", file);
+        write_file(file, result->stdout_buf, result->stdout_len);
         if (srvtab != NULL)
             write_srvtab(srvtab, command[3], file);
     } else {
diff --git a/tests/client/basic-t.in b/tests/client/basic-t.in
index 50a4ab5..6b05a3a 100644
--- a/tests/client/basic-t.in
+++ b/tests/client/basic-t.in
@@ -54,7 +54,7 @@ runfailure () {
 }
 
 # Print the number of tests.
-echo 10
+echo 12
 
 # Find the client program.
 if [ -f ../data/test.keytab ] ; then
@@ -65,7 +65,7 @@ else
     fi
 fi
 if [ ! -f data/test.keytab ] || [ -z "@REMCTLD@" ] ; then
-    for n in 1 2 3 4 5 6 7 8 9 10 ; do
+    for n in 1 2 3 4 5 6 7 8 9 10 11 12 ; do
         echo ok $n \# skip -- no Kerberos configuration
     done
     exit 0
@@ -125,10 +125,14 @@ done
 runsuccess "" -c fake-wallet get keytab -f keytab service/fake-test
 if cmp keytab data/fake-data >/dev/null 2>&1 ; then
     printcount "ok"
-    rm keytab
 else
     printcount "not ok"
 fi
+if [ -f keytab.bak ] || [ -f keytab.new ] ; then
+    printcount "not ok"
+else
+    printcount "ok"
+fi
 runsuccess "" -c fake-wallet get keytab -f keytab -S srvtab service/fake-srvtab
 if cmp keytab data/fake-keytab >/dev/null 2>&1 ; then
     printcount "ok"
@@ -136,6 +140,12 @@ if cmp keytab data/fake-keytab >/dev/null 2>&1 ; then
 else
     printcount "not ok"
 fi
+if cmp keytab.bak data/fake-data >/dev/null 2>&1 ; then
+    printcount "ok"
+    rm keytab.bak
+else
+    printcount "not ok"
+fi
 if [ -n "$krb5conf" ] ; then
     if cmp srvtab data/fake-srvtab >/dev/null 2>&1 ; then
         printcount "ok"