Re: [RFC v2 6/6] linux-user: Add '-native-bypass' option

["Alex Bennée" <alex.bennee@linaro.org>]

Manos Pitsidianakis <manos.pitsidianakis@linaro.org> writes:

> On Wed, 07 Jun 2023 19:47, Yeqi Fu <fufuyqqqqqq@gmail.com> wrote:
>>--- a/linux-user/main.c
>>+++ b/linux-user/main.c
>>+    /* Set the library for native bypass  */
>>+    if (native_lib != NULL) {
>>+        char *token = malloc(strlen(native_lib) + 12);
>
> malloc() can fail (in rare circumstances). Check for the return value
> here. Or use g_malloc() which terminates on alloc failure.

We avoid malloc in favour of g_malloc(). You can use g_try_malloc for
certain cases (although this is not one of them). However you can make
this glibs problem with something like:

    /* Set the library for native bypass  */
    if (native_lib != NULL) {
        GString *lib = g_string_new(native_lib);
        lib = g_string_prepend(lib, "LD_PRELOAD=");
        if (envlist_appendenv(envlist, g_string_free(lib, false), ":") != 0) {
            usage(EXIT_FAILURE);
        }
    }


>
>>+        strcpy(token, "LD_PRELOAD=");
>>+        strcat(token, native_lib);
>
> (You could alternatively use snprintf() here)

We have a section on strings in the developer manual:

 https://qemu.readthedocs.io/en/latest/devel/style.html#string-manipulation

so we have things like pstrcat and pstrcpy. However this isn't criticl
performance path so GString provides a nice memory safe wrapper for all
this sort of manipulation.

<snip>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro