[Qemu-devel] Re: [PATCH][UPDATED] Add support to linux-user for dropping LD_PRELOAD

["Lauri Leukkunen" <lle@rahina.org>]

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And while I'm at it here's the same with properly deallocated environ strings.

On 5/22/07, Lauri Leukkunen <lle@rahina.org> wrote:
> And here is the actual patch itself.
>
> On 5/22/07, Lauri Leukkunen <lle@rahina.org> wrote:
> > This patch adds an option "-drop-ld-preload" which results in the
> > target process not having LD_PRELOAD set in its environment. This is
> > useful when running inside environments like scratchbox.
> >
> > This version of the patch doesn't unset("LD_PRELOAD") but modifies the
> > envp argument to loader_exec() instead.
> >
> > /lauri
> >
>
>

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Index: linux-user/main.c
===================================================================
RCS file: /sources/qemu/qemu/linux-user/main.c,v
retrieving revision 1.109
diff -u -r1.109 main.c
--- linux-user/main.c	13 May 2007 13:58:00 -0000	1.109
+++ linux-user/main.c	21 May 2007 23:49:05 -0000
@@ -1666,11 +1666,12 @@
            "usage: qemu-" TARGET_ARCH " [-h] [-g] [-d opts] [-L path] [-s size] [-cpu model] program [arguments...]\n"
            "Linux CPU emulator (compiled for %s emulation)\n"
            "\n"
-           "-h           print this help\n"
-           "-g port      wait gdb connection to port\n"
-           "-L path      set the elf interpreter prefix (default=%s)\n"
-           "-s size      set the stack size in bytes (default=%ld)\n"
-           "-cpu model   select CPU (-cpu ? for list)\n"
+           "-h                print this help\n"
+           "-g port           wait gdb connection to port\n"
+           "-L path           set the elf interpreter prefix (default=%s)\n"
+           "-s size           set the stack size in bytes (default=%ld)\n"
+           "-cpu model        select CPU (-cpu ? for list)\n"
+           "-drop-ld-preload  drop LD_PRELOAD for target process\n"
            "\n"
            "debug options:\n"
 #ifdef USE_CODE_COPY
@@ -1702,7 +1703,9 @@
     int optind;
     const char *r;
     int gdbstub_port = 0;
-    
+    int drop_ld_preload = 0, environ_count = 0;
+    char **target_environ, **wrk, **dst;
+
     if (argc <= 1)
         usage();
 
@@ -1774,6 +1777,8 @@
 #endif
                 _exit(1);
             }
+        } else if (!strcmp(r, "drop-ld-preload")) {
+            drop_ld_preload = 1;
         } else 
 #ifdef USE_CODE_COPY
         if (!strcmp(r, "no-code-copy")) {
@@ -1802,11 +1807,29 @@
     env = cpu_init();
     global_env = env;
     
-    if (loader_exec(filename, argv+optind, environ, regs, info) != 0) {
-	printf("Error loading %s\n", filename);
-	_exit(1);
+    wrk = environ;
+    while (*(wrk++))
+        environ_count++;
+
+    target_environ = malloc((environ_count + 1) * sizeof(char *));
+    for (wrk = environ, dst = target_environ; *wrk; wrk++) {
+        if (drop_ld_preload && !strncmp(*wrk, "LD_PRELOAD=", 11))
+            continue;
+        *(dst++) = strdup(*wrk);
+    }
+    dst = NULL; /* NULL terminate target_environ */
+
+    if (loader_exec(filename, argv+optind, target_environ, regs, info) != 0) {
+        printf("Error loading %s\n", filename);
+        _exit(1);
+    }
+
+    for (wrk = target_environ; *wrk; wrk++) {
+        free(*wrk);
     }
     
+    free(target_environ);
+
     if (loglevel) {
         page_dump(logfile);