[DTrace-devel] [PATCH v2 5/7] string: ensure string size is handled correctly
Eugene Loh
eugene.loh at oracle.com
Thu Aug 14 21:49:19 UTC 2025
Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
On 8/14/25 16:37, Kris Van Hees wrote:
> Apologies - this is v3
>
> On Thu, Aug 14, 2025 at 04:33:37PM -0400, Kris Van Hees via DTrace-devel wrote:
>> A string is defined as a character array of size strsize. Strings
>> that are less that strsize in length are terminated by a NUL byte.
>> This implies that the NUL byte is part of the array and therefore,
>> strsize is indeed the size of the array and not the maximum number
>> of characters in the string.
>>
>> Tests are adjusted to reflect this behaviour.
>>
>> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
>> ---
>> libdtrace/dt_bpf.c | 4 ++--
>> libdtrace/dt_cg.c | 11 +++++------
>> test/unittest/codegen/tst.str_const_length.d | 2 +-
>> test/unittest/codegen/tst.str_data_size.d | 2 +-
>> test/unittest/codegen/tst.str_store_var.d | 2 +-
>> .../funcs/inet_ntoa6/tst.inet_ntoa6.strsize_10.r | 6 +++---
>> test/unittest/funcs/strjoin/tst.strjoin-bordercases.d | 2 +-
>> .../funcs/strjoin/tst.strjoin-capped-size-2.d | 2 +-
>> .../funcs/strjoin/tst.strjoin-capped-size-3.d | 2 +-
>> test/unittest/funcs/strjoin/tst.strjoin-capped-size.d | 2 +-
>> test/unittest/funcs/strjoin/tst.strjoin_nonDPTR.d | 2 +-
>> .../strlen/{tst.capped-sizw.d => tst.capped-size.d} | 2 +-
>> test/unittest/funcs/strtok/tst.strtok_long.d | 4 ++--
>> test/unittest/funcs/strtok/tst.strtok_long.r | 4 ++--
>> test/unittest/funcs/substr/tst.substr-stored-len.d | 2 +-
>> test/unittest/funcs/substr/tst.substr-strsize.d | 2 +-
>> test/unittest/funcs/substr/tst.substr_nonDPTR.d | 2 +-
>> test/unittest/funcs/tst.basename_nonDPTR.d | 2 +-
>> test/unittest/funcs/tst.inet_ntoa_nonDPTR.d | 2 +-
>> test/unittest/funcs/tst.lltostr-short.d | 2 +-
>> test/unittest/variables/tvar/tst.str-size.d | 2 +-
>> 21 files changed, 30 insertions(+), 31 deletions(-)
>> rename test/unittest/funcs/strlen/{tst.capped-sizw.d => tst.capped-size.d} (94%)
>>
>> diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
>> index ddf703ddd..31781ac9f 100644
>> --- a/libdtrace/dt_bpf.c
>> +++ b/libdtrace/dt_bpf.c
>> @@ -910,8 +910,8 @@ gmap_create_strtab(dtrace_hdl_t *dtp)
>> while (buf < end) {
>> uint_t len = strlen((char *)buf);
>>
>> - if (len > strsize)
>> - buf[strsize] = '\0';
>> + if (len >= strsize)
>> + buf[strsize - 1] = '\0';
>>
>> buf += len + 1;
>> }
>> diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
>> index 88dddb087..cd9e7f4e9 100644
>> --- a/libdtrace/dt_cg.c
>> +++ b/libdtrace/dt_cg.c
>> @@ -1741,11 +1741,10 @@ dt_cg_store_val(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind,
>> dt_cg_check_ptr_arg(dlp, drp, dnp, NULL);
>>
>> TRACE_REGSET("store_val(): Begin ");
>> - off = dt_rec_add(dtp, dt_cg_fill_gap, kind, size + 1, 1, pfp,
>> - arg);
>> + off = dt_rec_add(dtp, dt_cg_fill_gap, kind, size, 1, pfp, arg);
>>
>> /*
>> - * Copy the string data (no more than STRSIZE + 1 bytes) to the
>> + * Copy the string data (no more than STRSIZE bytes) to the
>> * buffer at (%r9 + off). We depend on the fact that
>> * probe_read_str() stops at the terminating NUL byte.
>> */
>> @@ -1754,7 +1753,7 @@ dt_cg_store_val(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind,
>>
>> emit(dlp, BPF_MOV_REG(BPF_REG_1, BPF_REG_9));
>> emit(dlp, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, off));
>> - emit(dlp, BPF_MOV_IMM(BPF_REG_2, strsize + 1));
>> + emit(dlp, BPF_MOV_IMM(BPF_REG_2, strsize));
>> emit(dlp, BPF_MOV_REG(BPF_REG_3, dnp->dn_reg));
>> dt_regset_free(drp, dnp->dn_reg);
>> dt_cg_tstring_free(pcb, dnp);
>> @@ -1765,13 +1764,13 @@ dt_cg_store_val(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind,
>> /*
>> * Pad the rest with zeroes, if necessary.
>> */
>> - emit(dlp, BPF_BRANCH_IMM(BPF_JGE, BPF_REG_0, strsize + 1, lbl_ok));
>> + emit(dlp, BPF_BRANCH_IMM(BPF_JGE, BPF_REG_0, strsize, lbl_ok));
>> if (dt_regset_xalloc_args(drp) == -1)
>> longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
>> emit(dlp, BPF_MOV_REG(BPF_REG_1, BPF_REG_9));
>> emit(dlp, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, off));
>> emit(dlp, BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_0));
>> - emit(dlp, BPF_MOV_IMM(BPF_REG_2, strsize + 1));
>> + emit(dlp, BPF_MOV_IMM(BPF_REG_2, strsize));
>> emit(dlp, BPF_ALU64_REG(BPF_SUB, BPF_REG_2, BPF_REG_0));
>> dt_cg_zerosptr(BPF_REG_3, dlp, drp);
>> emit(dlp, BPF_CALL_HELPER(dtp->dt_bpfhelper[BPF_FUNC_probe_read_kernel]));
>> diff --git a/test/unittest/codegen/tst.str_const_length.d b/test/unittest/codegen/tst.str_const_length.d
>> index 1c58ba13d..bfdd00a2e 100644
>> --- a/test/unittest/codegen/tst.str_const_length.d
>> +++ b/test/unittest/codegen/tst.str_const_length.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=5
>> +#pragma D option strsize=6
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/codegen/tst.str_data_size.d b/test/unittest/codegen/tst.str_data_size.d
>> index a928e8299..c93174a4f 100644
>> --- a/test/unittest/codegen/tst.str_data_size.d
>> +++ b/test/unittest/codegen/tst.str_data_size.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=5
>> +#pragma D option strsize=6
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/codegen/tst.str_store_var.d b/test/unittest/codegen/tst.str_store_var.d
>> index c14714c01..cfd37404f 100644
>> --- a/test/unittest/codegen/tst.str_store_var.d
>> +++ b/test/unittest/codegen/tst.str_store_var.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=6
>> +#pragma D option strsize=7
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/funcs/inet_ntoa6/tst.inet_ntoa6.strsize_10.r b/test/unittest/funcs/inet_ntoa6/tst.inet_ntoa6.strsize_10.r
>> index 5e7d49b03..8090daad6 100644
>> --- a/test/unittest/funcs/inet_ntoa6/tst.inet_ntoa6.strsize_10.r
>> +++ b/test/unittest/funcs/inet_ntoa6/tst.inet_ntoa6.strsize_10.r
>> @@ -1,8 +1,8 @@
>> -fe80:7060:
>> -1080::808:
>> +fe80:7060
>> +1080::808
>> ::1
>> ::
>> 127.0.0.1
>> 127.0.0.1
>> -::fffe:7f0
>> +::fffe:7f
>>
>> diff --git a/test/unittest/funcs/strjoin/tst.strjoin-bordercases.d b/test/unittest/funcs/strjoin/tst.strjoin-bordercases.d
>> index 253b2d6ef..1ac5ffd12 100644
>> --- a/test/unittest/funcs/strjoin/tst.strjoin-bordercases.d
>> +++ b/test/unittest/funcs/strjoin/tst.strjoin-bordercases.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=5
>> +#pragma D option strsize=6
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/funcs/strjoin/tst.strjoin-capped-size-2.d b/test/unittest/funcs/strjoin/tst.strjoin-capped-size-2.d
>> index 625c786b6..44a6acd88 100644
>> --- a/test/unittest/funcs/strjoin/tst.strjoin-capped-size-2.d
>> +++ b/test/unittest/funcs/strjoin/tst.strjoin-capped-size-2.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=6
>> +#pragma D option strsize=7
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/funcs/strjoin/tst.strjoin-capped-size-3.d b/test/unittest/funcs/strjoin/tst.strjoin-capped-size-3.d
>> index 52718325a..d2982a70b 100644
>> --- a/test/unittest/funcs/strjoin/tst.strjoin-capped-size-3.d
>> +++ b/test/unittest/funcs/strjoin/tst.strjoin-capped-size-3.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=6
>> +#pragma D option strsize=7
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/funcs/strjoin/tst.strjoin-capped-size.d b/test/unittest/funcs/strjoin/tst.strjoin-capped-size.d
>> index fe5b323f7..b54fd2f29 100644
>> --- a/test/unittest/funcs/strjoin/tst.strjoin-capped-size.d
>> +++ b/test/unittest/funcs/strjoin/tst.strjoin-capped-size.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option rawbytes
>> -#pragma D option strsize=10
>> +#pragma D option strsize=11
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/funcs/strjoin/tst.strjoin_nonDPTR.d b/test/unittest/funcs/strjoin/tst.strjoin_nonDPTR.d
>> index a1816f975..2b700a5a8 100644
>> --- a/test/unittest/funcs/strjoin/tst.strjoin_nonDPTR.d
>> +++ b/test/unittest/funcs/strjoin/tst.strjoin_nonDPTR.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option quiet
>> -#pragma D option strsize=14
>> +#pragma D option strsize=15
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/funcs/strlen/tst.capped-sizw.d b/test/unittest/funcs/strlen/tst.capped-size.d
>> similarity index 94%
>> rename from test/unittest/funcs/strlen/tst.capped-sizw.d
>> rename to test/unittest/funcs/strlen/tst.capped-size.d
>> index 4e473236c..676ed185e 100644
>> --- a/test/unittest/funcs/strlen/tst.capped-sizw.d
>> +++ b/test/unittest/funcs/strlen/tst.capped-size.d
>> @@ -11,7 +11,7 @@
>> * SECTION: Actions and Subroutines/strlen()
>> */
>>
>> -#pragma D option strsize=5
>> +#pragma D option strsize=6
>> #pragma D option quiet
>>
>> BEGIN
>> diff --git a/test/unittest/funcs/strtok/tst.strtok_long.d b/test/unittest/funcs/strtok/tst.strtok_long.d
>> index 1fbe415dc..254a65485 100644
>> --- a/test/unittest/funcs/strtok/tst.strtok_long.d
>> +++ b/test/unittest/funcs/strtok/tst.strtok_long.d
>> @@ -9,8 +9,8 @@
>>
>> BEGIN
>> {
>> - /* 256-char string ending in "XYZ" */
>> - x = "_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________XYZ";
>> + /* 256-char string ending in "XYZ" (255 chars + NUL byte)*/
>> + x = "____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________XYZ";
>>
>> /* check whether the last char of a long string is seen */
>> y = "a";
>> diff --git a/test/unittest/funcs/strtok/tst.strtok_long.r b/test/unittest/funcs/strtok/tst.strtok_long.r
>> index a752554e8..4b172ca1b 100644
>> --- a/test/unittest/funcs/strtok/tst.strtok_long.r
>> +++ b/test/unittest/funcs/strtok/tst.strtok_long.r
>> @@ -1,5 +1,5 @@
>> -_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________XYZ
>> +____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________XYZ
>> zyxwvutsrqponmlkjihgfedcba
>> -_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________XY
>> +____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________XY
>> Z
>>
>> diff --git a/test/unittest/funcs/substr/tst.substr-stored-len.d b/test/unittest/funcs/substr/tst.substr-stored-len.d
>> index 97d2b0f61..fa3e5337c 100644
>> --- a/test/unittest/funcs/substr/tst.substr-stored-len.d
>> +++ b/test/unittest/funcs/substr/tst.substr-stored-len.d
>> @@ -13,7 +13,7 @@
>>
>> #pragma D option quiet
>> #pragma D option rawbytes
>> -#pragma D option strsize=13
>> +#pragma D option strsize=14
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/funcs/substr/tst.substr-strsize.d b/test/unittest/funcs/substr/tst.substr-strsize.d
>> index b4d0cc63e..04eab4297 100644
>> --- a/test/unittest/funcs/substr/tst.substr-strsize.d
>> +++ b/test/unittest/funcs/substr/tst.substr-strsize.d
>> @@ -15,7 +15,7 @@
>>
>> #pragma D option quiet
>> #pragma D option rawbytes
>> -#pragma D option strsize=13
>> +#pragma D option strsize=14
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/funcs/substr/tst.substr_nonDPTR.d b/test/unittest/funcs/substr/tst.substr_nonDPTR.d
>> index 9d847ab6f..3e10af08e 100644
>> --- a/test/unittest/funcs/substr/tst.substr_nonDPTR.d
>> +++ b/test/unittest/funcs/substr/tst.substr_nonDPTR.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option quiet
>> -#pragma D option strsize=13
>> +#pragma D option strsize=14
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/funcs/tst.basename_nonDPTR.d b/test/unittest/funcs/tst.basename_nonDPTR.d
>> index 4f93685f7..cecef827b 100644
>> --- a/test/unittest/funcs/tst.basename_nonDPTR.d
>> +++ b/test/unittest/funcs/tst.basename_nonDPTR.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option quiet
>> -#pragma D option strsize=14
>> +#pragma D option strsize=15
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/funcs/tst.inet_ntoa_nonDPTR.d b/test/unittest/funcs/tst.inet_ntoa_nonDPTR.d
>> index 500c53e86..f079c7ef4 100644
>> --- a/test/unittest/funcs/tst.inet_ntoa_nonDPTR.d
>> +++ b/test/unittest/funcs/tst.inet_ntoa_nonDPTR.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option quiet
>> -#pragma D option strsize=14
>> +#pragma D option strsize=15
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/funcs/tst.lltostr-short.d b/test/unittest/funcs/tst.lltostr-short.d
>> index 969045667..65a5714c2 100644
>> --- a/test/unittest/funcs/tst.lltostr-short.d
>> +++ b/test/unittest/funcs/tst.lltostr-short.d
>> @@ -6,7 +6,7 @@
>> */
>>
>> #pragma D option quiet
>> -#pragma D option strsize=7
>> +#pragma D option strsize=8
>>
>> BEGIN
>> {
>> diff --git a/test/unittest/variables/tvar/tst.str-size.d b/test/unittest/variables/tvar/tst.str-size.d
>> index b4ab6ea2b..bd8aac132 100644
>> --- a/test/unittest/variables/tvar/tst.str-size.d
>> +++ b/test/unittest/variables/tvar/tst.str-size.d
>> @@ -12,7 +12,7 @@
>> */
>>
>> #pragma D option quiet
>> -#pragma D option strsize=4
>> +#pragma D option strsize=5
>>
>> BEGIN
>> {
>> --
>> 2.45.2
>>
>>
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