Re: [Qemu-ppc] [PATCH] tests/boot-sector: Use mkstemp() to create a unique file name

[Peter Maydell]

On 11 October 2016 at 14:32, Thomas Huth <address@hidden> wrote:
> The pxe-test is run for three different targets now (x86_64, i386
> and ppc64), and the bios-tables-test is run for two targets (x86_64
> and i386). But each of the tests is using an invariant name for the
> disk image with the boot sector code - so if the tests are running
> in parallel, there is a race condition that they destroy the disk
> image of a parallel test program. Let's use mkstemp() to create
> unique temporary files here instead.
>
> Reported-by: Sascha Silbe <address@hidden>
> Signed-off-by: Thomas Huth <address@hidden>
> ---
>  tests/bios-tables-test.c | 2 +-
>  tests/boot-sector.c      | 9 +++++++--
>  tests/boot-sector.h      | 4 ++--
>  tests/pxe-test.c         | 2 +-
>  4 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/tests/bios-tables-test.c b/tests/bios-tables-test.c
> index 6ea2b6d..812f830 100644
> --- a/tests/bios-tables-test.c
> +++ b/tests/bios-tables-test.c
> @@ -112,7 +112,7 @@ typedef struct {
>      g_assert_cmpstr(ACPI_ASSERT_CMP_str, ==, expected); \
>  } while (0)
>
> -static const char *disk = "tests/acpi-test-disk.raw";
> +static char disk[] = "tests/acpi-test-disk-XXXXXX";
>  static const char *data_dir = "tests/acpi-test-data";
>  #ifdef CONFIG_IASL
>  static const char *iasl = stringify(CONFIG_IASL);
> diff --git a/tests/boot-sector.c b/tests/boot-sector.c
> index e3193c0..e75572f 100644
> --- a/tests/boot-sector.c
> +++ b/tests/boot-sector.c
> @@ -69,10 +69,15 @@ static uint8_t boot_sector[0x7e000] = {
>  };
>
>  /* Create boot disk file.  */
> -int boot_sector_init(const char *fname)
> +int boot_sector_init(char *fname)
>  {
> -    FILE *f = fopen(fname, "w");
> +    FILE *f = NULL;
> +    int fd;
>
> +    fd = mkstemp(fname);
> +    if (fd != -1) {
> +        f = fdopen(fd, "w");
> +    }

Given that we're only writing a pile of bytes, we could
just use write() and close() in this function rather
than doing an fdopen() to use fwrite() and fclose().
But I can see the attraction of not doing that in this
patch for review purposes.

>      if (!f) {
>          fprintf(stderr, "Couldn't open \"%s\": %s", fname, strerror(errno));
>          return 1;
> diff --git a/tests/boot-sector.h b/tests/boot-sector.h
> index f64b477..35d61c7 100644
> --- a/tests/boot-sector.h
> +++ b/tests/boot-sector.h
> @@ -14,8 +14,8 @@
>  #ifndef TEST_BOOT_SECTOR_H
>  #define TEST_BOOT_SECTOR_H
>
> -/* Create boot disk file.  */
> -int boot_sector_init(const char *fname);
> +/* Create boot disk file. fname must be a suitable string for mkstemp() */
> +int boot_sector_init(char *fname);
>
>  /* Loop until signature in memory is OK.  */
>  void boot_sector_test(void);
> diff --git a/tests/pxe-test.c b/tests/pxe-test.c
> index 5d3ddbe..34282d3 100644
> --- a/tests/pxe-test.c
> +++ b/tests/pxe-test.c
> @@ -19,7 +19,7 @@
>
>  #define NETNAME "net0"
>
> -static const char *disk = "tests/pxe-test-disk.raw";
> +static char disk[] = "tests/pxe-test-disk-XXXXXX";
>
>  static void test_pxe_one(const char *params, bool ipv6)
>  {

Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM