On Tue, 18 Dec 2018 12:03:31 +0100
Philippe Mathieu-Daudé <email address hidden> wrote:
> From: Marc-André Lureau <email address hidden>
>
> GCC 8 added a -Wstringop-truncation warning:
>
> The -Wstringop-truncation warning added in GCC 8.0 via r254630 for
> bug 81117 is specifically intended to highlight likely unintended
> uses of the strncpy function that truncate the terminating NUL
> character from the source string.
>
> This new warning leads to compilation failures:
>
> CC hw/acpi/core.o
> In function 'acpi_table_install', inlined from 'acpi_table_add' at qemu/hw/acpi/core.c:296:5:
> qemu/hw/acpi/core.c:184:9: error: 'strncpy' specified bound 4 equals destination size [-Werror=stringop-truncation]
> strncpy(ext_hdr->sig, hdrs->sig, sizeof ext_hdr->sig);
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> make: *** [qemu/rules.mak:69: hw/acpi/core.o] Error 1
>
> The ACPI tables don't require the strings to be NUL-terminated,
> therefore strncpy is the right function to use here.
>
> We could add a #pragma GCC diagnostic ignored "-Wstringop-truncation"
> around, disable the warning globally using -Wno-stringop-truncation,
> but since QEMU provides the strpadcpy() which does the same purpose,
> simply use it to avoid the annoying warning.
>
> Signed-off-by: Marc-André Lureau <email address hidden>
> Reviewed-by: Eric Blake <email address hidden>
> Reviewed-by: Philippe Mathieu-Daudé <email address hidden>
> [PMD: reword commit subject and description]
> Signed-off-by: Philippe Mathieu-Daudé <email address hidden>
On Tue, 18 Dec 2018 12:03:31 +0100
Philippe Mathieu-Daudé <email address hidden> wrote:
> From: Marc-André Lureau <email address hidden> truncation warning: truncation warning added in GCC 8.0 via r254630 for install' , inlined from 'acpi_table_add' at qemu/hw/ acpi/core. c:296:5: acpi/core. c:184:9: error: 'strncpy' specified bound 4 equals destination size [-Werror= stringop- truncation] ext_hdr- >sig, hdrs->sig, sizeof ext_hdr->sig); ~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~ truncation" truncation,
>
> GCC 8 added a -Wstringop-
>
> The -Wstringop-
> bug 81117 is specifically intended to highlight likely unintended
> uses of the strncpy function that truncate the terminating NUL
> character from the source string.
>
> This new warning leads to compilation failures:
>
> CC hw/acpi/core.o
> In function 'acpi_table_
> qemu/hw/
> strncpy(
> ^~~~~~~
> make: *** [qemu/rules.mak:69: hw/acpi/core.o] Error 1
>
> The ACPI tables don't require the strings to be NUL-terminated,
> therefore strncpy is the right function to use here.
>
> We could add a #pragma GCC diagnostic ignored "-Wstringop-
> around, disable the warning globally using -Wno-stringop-
> but since QEMU provides the strpadcpy() which does the same purpose,
> simply use it to avoid the annoying warning.
>
> Signed-off-by: Marc-André Lureau <email address hidden>
> Reviewed-by: Eric Blake <email address hidden>
> Reviewed-by: Philippe Mathieu-Daudé <email address hidden>
> [PMD: reword commit subject and description]
> Signed-off-by: Philippe Mathieu-Daudé <email address hidden>
Reviewed-by: Igor Mammedov <email address hidden>
> --- aml-build. c b/hw/acpi/ aml-build. c .397833462a 100644 aml-build. c aml-build. c aml-build. h" alloc_array( void) BIOSLinker *linker, GArray *table_data, APPNAME6, 6); h->oem_ table_id) ); h->oem_ table_id) , h->oem_ table_id, ACPI_BUILD_ APPNAME4, 4); h->oem_ table_id + 4, sig, 4); .6e8f4e5713 100644 visit-misc. h" report. h" install( const char unsigned *blob, size_t bloblen, le16(acpi_ payload_ size); ext_hdr- >sig, hdrs->sig, sizeof ext_hdr->sig); ext_hdr- >sig, sizeof ext_hdr->sig, hdrs->sig, '\0'); install( const char unsigned *blob, size_t bloblen, ext_hdr- >oem_id, hdrs->oem_id, sizeof ext_hdr->oem_id); ext_hdr- >oem_id, sizeof ext_hdr->oem_id, hdrs->oem_id, '\0'); has_oem_ table_id) { ext_hdr- >oem_table_ id, hdrs->oem_table_id, >oem_table_ id); ext_hdr- >oem_table_ id, sizeof ext_hdr- >oem_table_ id, install( const char unsigned *blob, size_t bloblen, has_asl_ compiler_ id) { ext_hdr- >asl_compiler_ id, hdrs->asl_ compiler_ id, >asl_compiler_ id); ext_hdr- >asl_compiler_ id, sizeof ext_hdr- >asl_compiler_ id, compiler_ id, '\0'); has_asl_ compiler_ rev) {
> hw/acpi/aml-build.c | 6 ++++--
> hw/acpi/core.c | 13 +++++++------
> 2 files changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/hw/acpi/
> index 1e43cd736d.
> --- a/hw/acpi/
> +++ b/hw/acpi/
> @@ -24,6 +24,7 @@
> #include "hw/acpi/
> #include "qemu/bswap.h"
> #include "qemu/bitops.h"
> +#include "qemu/cutils.h"
> #include "sysemu/numa.h"
>
> static GArray *build_
> @@ -1532,13 +1533,14 @@ build_header(
> h->revision = rev;
>
> if (oem_id) {
> - strncpy((char *)h->oem_id, oem_id, sizeof h->oem_id);
> + strpadcpy((char *)h->oem_id, sizeof h->oem_id, oem_id, '\0');
> } else {
> memcpy(h->oem_id, ACPI_BUILD_
> }
>
> if (oem_table_id) {
> - strncpy((char *)h->oem_table_id, oem_table_id, sizeof(
> + strpadcpy((char *)h->oem_table_id, sizeof(
> + oem_table_id, '\0');
> } else {
> memcpy(
> memcpy(
> diff --git a/hw/acpi/core.c b/hw/acpi/core.c
> index aafdc61648.
> --- a/hw/acpi/core.c
> +++ b/hw/acpi/core.c
> @@ -31,6 +31,7 @@
> #include "qapi/qapi-
> #include "qemu/error-
> #include "qemu/option.h"
> +#include "qemu/cutils.h"
>
> struct acpi_table_header {
> uint16_t _length; /* our length, not actual part of the hdr */
> @@ -181,7 +182,7 @@ static void acpi_table_
> ext_hdr->_length = cpu_to_
>
> if (hdrs->has_sig) {
> - strncpy(
> + strpadcpy(
> ++changed_fields;
> }
>
> @@ -200,12 +201,12 @@ static void acpi_table_
> ext_hdr->checksum = 0;
>
> if (hdrs->has_oem_id) {
> - strncpy(
> + strpadcpy(
> ++changed_fields;
> }
> if (hdrs->
> - strncpy(
> - sizeof ext_hdr-
> + strpadcpy(
> + hdrs->oem_table_id, '\0');
> ++changed_fields;
> }
> if (hdrs->has_oem_rev) {
> @@ -213,8 +214,8 @@ static void acpi_table_
> ++changed_fields;
> }
> if (hdrs->
> - strncpy(
> - sizeof ext_hdr-
> + strpadcpy(
> + hdrs->asl_
> ++changed_fields;
> }
> if (hdrs->