Re: [PATCH 1/5] hw/smbios: support loading OEM strings values from a file

[Philippe Mathieu-Daudé]

Hi Daniel,

On 9/8/20 6:54 PM, Daniel P. Berrangé wrote:
> Some applications want to pass quite large values for the OEM strings
> entries. Rather than having huge strings on the command line, it would
> be better to load them from a file, as supported with -fw_cfg.
> 
> This introduces the "valuefile" parameter allowing for:
> 
>   $ echo -n "thisthing" > mydata.txt
>   $ qemu-system-x86_64 \
>     -smbios type=11,value=something \
>     -smbios type=11,valuefile=mydata.txt \
>     -smbios type=11,value=somemore \
>     ...other args...
> 
> Now in the guest
> 
> $ dmidecide -t 11
> Getting SMBIOS data from sysfs.
> SMBIOS 2.8 present.
> 
> Handle 0x0E00, DMI type 11, 5 bytes
> OEM Strings
>       String 1: something
>       String 2: thisthing
>       String 3: somemore
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  hw/smbios/smbios.c | 72 +++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 59 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
> index 7cc950b41c..8450fad285 100644
> --- a/hw/smbios/smbios.c
> +++ b/hw/smbios/smbios.c
> @@ -110,7 +110,7 @@ static struct {
>  
>  static struct {
>      size_t nvalues;
> -    const char **values;
> +    char **values;
>  } type11;
>  
>  static struct {
> @@ -314,6 +314,11 @@ static const QemuOptDesc qemu_smbios_type11_opts[] = {
>          .type = QEMU_OPT_STRING,
>          .help = "OEM string data",
>      },
> +    {
> +        .name = "path",
> +        .type = QEMU_OPT_STRING,
> +        .help = "OEM string data from file",
> +    },
>  };
>  
>  static const QemuOptDesc qemu_smbios_type17_opts[] = {
> @@ -641,6 +646,8 @@ static void smbios_build_type_11_table(void)
>  
>      for (i = 0; i < type11.nvalues; i++) {
>          SMBIOS_TABLE_SET_STR_LIST(11, type11.values[i]);
> +        g_free(type11.values[i]);
> +        type11.values[i] = NULL;
>      }
>  
>      SMBIOS_BUILD_TABLE_POST;
> @@ -940,9 +947,8 @@ static void save_opt(const char **dest, QemuOpts *opts, 
> const char *name)
>  
>  
>  struct opt_list {
> -    const char *name;
>      size_t *ndest;
> -    const char ***dest;
> +    char ***dest;
>  };
>  
>  static int save_opt_one(void *opaque,
> @@ -951,23 +957,61 @@ static int save_opt_one(void *opaque,
>  {
>      struct opt_list *opt = opaque;
>  
> -    if (!g_str_equal(name, opt->name)) {
> -        return 0;
> +    if (g_str_equal(name, "path")) {
> +        g_autoptr(GByteArray) data = g_byte_array_new();
> +        g_autofree char *buf = g_new(char, 4096);
> +        ssize_t ret;
> +        int fd = qemu_open(value, O_RDONLY);

While not use g_file_get_contents()?

> +        if (fd < 0) {
> +            error_setg(errp, "Unable to open %s: %s", value, 
> strerror(errno));
> +            return -1;
> +        }
> +
> +        while (1) {
> +            ret = read(fd, buf, 4096);
> +            if (ret == 0) {
> +                break;
> +            }
> +            if (ret < 0) {
> +                error_setg(errp, "Unable to read from %s: %s",
> +                           value, strerror(errno));
> +                return -1;
> +            }
> +            if (memchr(buf, '\0', ret)) {
> +                error_setg(errp, "NUL in OEM strings value in %s", value);
> +                return -1;
> +            }
> +            g_byte_array_append(data, (guint8 *)buf, ret);
> +        }
> +
> +        close(fd);
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