* [PATCH] [gdb/testsuite] Fix spurious FAILs with examine-backward.exp, again
@ 2023-11-14 10:58 Tom de Vries
2023-11-21 12:18 ` Tom de Vries
0 siblings, 1 reply; 2+ messages in thread
From: Tom de Vries @ 2023-11-14 10:58 UTC (permalink / raw)
To: gdb-patches
Commit 59a561480d5 ("Fix spurious FAILs with examine-backward.exp") describes
the problem that:
...
The test case examine-backward.exp issues the command "x/-s" after the end
of the first string in TestStrings, but without making sure that this
string is preceded by a string terminator. Thus GDB may spuriously print
some random characters from before that string, and then the test fails.
...
The commit fixes the problem by adding a Barrier variable before the
TestStrings variable:
...
+const char Barrier[] = { 0x0 };
const char TestStrings[] = {
...
There is however no guarantee that Barrier is placed immediately before
TestStrings.
Before recent commit 169fe7ab54b ("Change gdb.base/examine-backwards.exp for
AIX.") on x86_64-linux, I see:
...
0000000000400660 R Barrier
0000000000400680 R TestStrings
...
So while the Barrier variable is the first before the TestStrings variable,
it's not immediately preceding TestStrings.
After commit 169fe7ab54b:
...
0000000000402259 B Barrier
0000000000402020 D TestStrings
...
they're not even in the same section anymore.
Fix this reliably by adding the zero in the array itself:
...
char TestStringsBase[] = {
0x0,
...
};
char *TestStrings = &TestStringsBase[1];
...
and do likewise for TestStringsH and TestStringsW.
Tested on x86_64-linux, and on a pinebook (aarch64 64-bit kernel, 32-bit
userland), where I ran into the issue.
PR testsuite/31064
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31064
---
gdb/testsuite/gdb.base/examine-backward.c | 35 ++++++++++++++-------
gdb/testsuite/gdb.base/examine-backward.exp | 18 +++++------
2 files changed, 33 insertions(+), 20 deletions(-)
diff --git a/gdb/testsuite/gdb.base/examine-backward.c b/gdb/testsuite/gdb.base/examine-backward.c
index 354c2e2f323..5549cc20a4a 100644
--- a/gdb/testsuite/gdb.base/examine-backward.c
+++ b/gdb/testsuite/gdb.base/examine-backward.c
@@ -32,15 +32,12 @@ literals. The content of each array is the same as followings:
};
*/
-/* This is here just to ensure we have a null character before
- TestStrings, to avoid showing garbage when we look for strings
- backwards from TestStrings. */
+unsigned char TestStringsBase[] = {
+ /* This is here just to ensure we have a null character before
+ TestStrings, to avoid showing garbage when we look for strings
+ backwards from TestStrings. */
+ 0x0,
-unsigned char Barrier[] = {
- 0x00,
-};
-
-unsigned char TestStrings[] = {
0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50,
0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
@@ -54,7 +51,14 @@ unsigned char TestStrings[] = {
0x00
};
-short TestStringsH[] = {
+unsigned char *TestStrings = &TestStringsBase[1];
+
+short TestStringsHBase[] = {
+ /* This is here just to ensure we have a null character before
+ TestStringsH, to avoid showing garbage when we look for strings
+ backwards from TestStringsH. */
+ 0x0,
+
0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047, 0x0048,
0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f, 0x0050,
0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057, 0x0058,
@@ -67,7 +71,14 @@ short TestStringsH[] = {
0x0000
};
-int TestStringsW[] = {
+short *TestStringsH = &TestStringsHBase[1];
+
+int TestStringsWBase[] = {
+ /* This is here just to ensure we have a null character before
+ TestStringsW, to avoid showing garbage when we look for strings
+ backwards from TestStringsW. */
+ 0x0,
+
0x00000041, 0x00000042, 0x00000043, 0x00000044,
0x00000045, 0x00000046, 0x00000047, 0x00000048,
0x00000049, 0x0000004a, 0x0000004b, 0x0000004c,
@@ -89,11 +100,13 @@ int TestStringsW[] = {
0x00000000
};
+int *TestStringsW = &TestStringsWBase[1];
+
int
main (void)
{
/* Clang++ eliminates the variables if nothing references them. */
- int dummy = Barrier[0] + TestStrings[0] + TestStringsH[0] + TestStringsW[0];
+ int dummy = TestStrings[0] + TestStringsH[0] + TestStringsW[0];
/* Backward disassemble test requires at least 20 instructions in
this function. Adding a simple bubble sort. */
diff --git a/gdb/testsuite/gdb.base/examine-backward.exp b/gdb/testsuite/gdb.base/examine-backward.exp
index 7c8a08c0726..4e197d7d725 100644
--- a/gdb/testsuite/gdb.base/examine-backward.exp
+++ b/gdb/testsuite/gdb.base/examine-backward.exp
@@ -145,7 +145,7 @@ gdb_test_no_output "set charset ASCII"
with_test_prefix "char-width=1, print-max=20" {
gdb_test_no_output "set print elements 20"
- gdb_test_sequence "x/6s &TestStrings" "take 6 strings forward" {
+ gdb_test_sequence "x/6s TestStrings" "take 6 strings forward" {
"\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
"\"UVWXYZ\""
"\"\""
@@ -162,7 +162,7 @@ with_test_prefix "char-width=1, print-max=20" {
"\"[^\"]+\""
"\"01234567890123456789\"\.\.\."
}
- gdb_test_sequence "x/6s &TestStrings" "take 6 strings forward again" {
+ gdb_test_sequence "x/6s TestStrings" "take 6 strings forward again" {
"\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
"\"UVWXYZ\""
"\"\""
@@ -187,7 +187,7 @@ with_test_prefix "char-width=1, print-max=20" {
with_test_prefix "char-width=2, print-max=20" {
gdb_test_no_output "set print elements 20"
- gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward" {
+ gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward" {
"u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
"u\"UVWXYZ\""
"u\"\""
@@ -204,7 +204,7 @@ with_test_prefix "char-width=2, print-max=20" {
"u\"[^\"]+\""
"u\"01234567890123456789\"\.\.\."
}
- gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward again" {
+ gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward again" {
"u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
"u\"UVWXYZ\""
"u\"\""
@@ -229,7 +229,7 @@ with_test_prefix "char-width=2, print-max=20" {
with_test_prefix "char-width=4, print-max=20" {
gdb_test_no_output "set print elements 20"
- gdb_test_sequence "x/6sw &TestStringsW" "take 6 strings forward" {
+ gdb_test_sequence "x/6sw TestStringsW" "take 6 strings forward" {
"U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
"U\"UVWXYZ\""
"U\"\""
@@ -246,7 +246,7 @@ with_test_prefix "char-width=4, print-max=20" {
"U\"[^\"]+\""
"U\"01234567890123456789\"\.\.\."
}
- gdb_test_sequence "x/6sw &TestStringsW" "take 6 strings forward again" {
+ gdb_test_sequence "x/6sw TestStringsW" "take 6 strings forward again" {
"U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
"U\"UVWXYZ\""
"U\"\""
@@ -271,7 +271,7 @@ with_test_prefix "char-width=4, print-max=20" {
with_test_prefix "char-width=2, print-max=0" {
gdb_test_no_output "set print elements 0"
- gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward" {
+ gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward" {
"u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
"u\"\""
"u\"\""
@@ -289,7 +289,7 @@ with_test_prefix "char-width=2, print-max=0" {
"u\"012345678901234567890123456789\""
"u\"!!!!!!\""
}
- gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward again" {
+ gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward again" {
"u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
"u\"\""
"u\"\""
@@ -314,7 +314,7 @@ with_test_prefix "char-width=2, print-max=0" {
with_test_prefix "char-width=1, print-max=4" {
gdb_test_no_output "set print elements 4"
- gdb_test_sequence "x/9s &TestStrings" "take 9 strings forward" {
+ gdb_test_sequence "x/9s TestStrings" "take 9 strings forward" {
"\"ABCD\"\.\.\."
"\"EFGH\"\.\.\."
"\"IJKL\"\.\.\."
base-commit: bdc819cd5ca6f3a3915810366155fd4c2ca61fab
--
2.35.3
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] [gdb/testsuite] Fix spurious FAILs with examine-backward.exp, again
2023-11-14 10:58 [PATCH] [gdb/testsuite] Fix spurious FAILs with examine-backward.exp, again Tom de Vries
@ 2023-11-21 12:18 ` Tom de Vries
0 siblings, 0 replies; 2+ messages in thread
From: Tom de Vries @ 2023-11-21 12:18 UTC (permalink / raw)
To: gdb-patches
On 11/14/23 11:58, Tom de Vries wrote:
> Commit 59a561480d5 ("Fix spurious FAILs with examine-backward.exp") describes
> the problem that:
> ...
> The test case examine-backward.exp issues the command "x/-s" after the end
> of the first string in TestStrings, but without making sure that this
> string is preceded by a string terminator. Thus GDB may spuriously print
> some random characters from before that string, and then the test fails.
> ...
>
> The commit fixes the problem by adding a Barrier variable before the
> TestStrings variable:
> ...
> +const char Barrier[] = { 0x0 };
> const char TestStrings[] = {
> ...
>
> There is however no guarantee that Barrier is placed immediately before
> TestStrings.
>
> Before recent commit 169fe7ab54b ("Change gdb.base/examine-backwards.exp for
> AIX.") on x86_64-linux, I see:
> ...
> 0000000000400660 R Barrier
> 0000000000400680 R TestStrings
> ...
>
> So while the Barrier variable is the first before the TestStrings variable,
> it's not immediately preceding TestStrings.
>
> After commit 169fe7ab54b:
> ...
> 0000000000402259 B Barrier
> 0000000000402020 D TestStrings
> ...
> they're not even in the same section anymore.
>
> Fix this reliably by adding the zero in the array itself:
> ...
> char TestStringsBase[] = {
> 0x0,
> ...
> };
> char *TestStrings = &TestStringsBase[1];
> ...
> and do likewise for TestStringsH and TestStringsW.
>
Pushed.
Thanks,
- Tom
> Tested on x86_64-linux, and on a pinebook (aarch64 64-bit kernel, 32-bit
> userland), where I ran into the issue.
>
> PR testsuite/31064
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31064
> ---
> gdb/testsuite/gdb.base/examine-backward.c | 35 ++++++++++++++-------
> gdb/testsuite/gdb.base/examine-backward.exp | 18 +++++------
> 2 files changed, 33 insertions(+), 20 deletions(-)
>
> diff --git a/gdb/testsuite/gdb.base/examine-backward.c b/gdb/testsuite/gdb.base/examine-backward.c
> index 354c2e2f323..5549cc20a4a 100644
> --- a/gdb/testsuite/gdb.base/examine-backward.c
> +++ b/gdb/testsuite/gdb.base/examine-backward.c
> @@ -32,15 +32,12 @@ literals. The content of each array is the same as followings:
> };
> */
>
> -/* This is here just to ensure we have a null character before
> - TestStrings, to avoid showing garbage when we look for strings
> - backwards from TestStrings. */
> +unsigned char TestStringsBase[] = {
> + /* This is here just to ensure we have a null character before
> + TestStrings, to avoid showing garbage when we look for strings
> + backwards from TestStrings. */
> + 0x0,
>
> -unsigned char Barrier[] = {
> - 0x00,
> -};
> -
> -unsigned char TestStrings[] = {
> 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
> 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50,
> 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
> @@ -54,7 +51,14 @@ unsigned char TestStrings[] = {
> 0x00
> };
>
> -short TestStringsH[] = {
> +unsigned char *TestStrings = &TestStringsBase[1];
> +
> +short TestStringsHBase[] = {
> + /* This is here just to ensure we have a null character before
> + TestStringsH, to avoid showing garbage when we look for strings
> + backwards from TestStringsH. */
> + 0x0,
> +
> 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047, 0x0048,
> 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f, 0x0050,
> 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057, 0x0058,
> @@ -67,7 +71,14 @@ short TestStringsH[] = {
> 0x0000
> };
>
> -int TestStringsW[] = {
> +short *TestStringsH = &TestStringsHBase[1];
> +
> +int TestStringsWBase[] = {
> + /* This is here just to ensure we have a null character before
> + TestStringsW, to avoid showing garbage when we look for strings
> + backwards from TestStringsW. */
> + 0x0,
> +
> 0x00000041, 0x00000042, 0x00000043, 0x00000044,
> 0x00000045, 0x00000046, 0x00000047, 0x00000048,
> 0x00000049, 0x0000004a, 0x0000004b, 0x0000004c,
> @@ -89,11 +100,13 @@ int TestStringsW[] = {
> 0x00000000
> };
>
> +int *TestStringsW = &TestStringsWBase[1];
> +
> int
> main (void)
> {
> /* Clang++ eliminates the variables if nothing references them. */
> - int dummy = Barrier[0] + TestStrings[0] + TestStringsH[0] + TestStringsW[0];
> + int dummy = TestStrings[0] + TestStringsH[0] + TestStringsW[0];
>
> /* Backward disassemble test requires at least 20 instructions in
> this function. Adding a simple bubble sort. */
> diff --git a/gdb/testsuite/gdb.base/examine-backward.exp b/gdb/testsuite/gdb.base/examine-backward.exp
> index 7c8a08c0726..4e197d7d725 100644
> --- a/gdb/testsuite/gdb.base/examine-backward.exp
> +++ b/gdb/testsuite/gdb.base/examine-backward.exp
> @@ -145,7 +145,7 @@ gdb_test_no_output "set charset ASCII"
>
> with_test_prefix "char-width=1, print-max=20" {
> gdb_test_no_output "set print elements 20"
> - gdb_test_sequence "x/6s &TestStrings" "take 6 strings forward" {
> + gdb_test_sequence "x/6s TestStrings" "take 6 strings forward" {
> "\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
> "\"UVWXYZ\""
> "\"\""
> @@ -162,7 +162,7 @@ with_test_prefix "char-width=1, print-max=20" {
> "\"[^\"]+\""
> "\"01234567890123456789\"\.\.\."
> }
> - gdb_test_sequence "x/6s &TestStrings" "take 6 strings forward again" {
> + gdb_test_sequence "x/6s TestStrings" "take 6 strings forward again" {
> "\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
> "\"UVWXYZ\""
> "\"\""
> @@ -187,7 +187,7 @@ with_test_prefix "char-width=1, print-max=20" {
>
> with_test_prefix "char-width=2, print-max=20" {
> gdb_test_no_output "set print elements 20"
> - gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward" {
> + gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward" {
> "u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
> "u\"UVWXYZ\""
> "u\"\""
> @@ -204,7 +204,7 @@ with_test_prefix "char-width=2, print-max=20" {
> "u\"[^\"]+\""
> "u\"01234567890123456789\"\.\.\."
> }
> - gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward again" {
> + gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward again" {
> "u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
> "u\"UVWXYZ\""
> "u\"\""
> @@ -229,7 +229,7 @@ with_test_prefix "char-width=2, print-max=20" {
>
> with_test_prefix "char-width=4, print-max=20" {
> gdb_test_no_output "set print elements 20"
> - gdb_test_sequence "x/6sw &TestStringsW" "take 6 strings forward" {
> + gdb_test_sequence "x/6sw TestStringsW" "take 6 strings forward" {
> "U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
> "U\"UVWXYZ\""
> "U\"\""
> @@ -246,7 +246,7 @@ with_test_prefix "char-width=4, print-max=20" {
> "U\"[^\"]+\""
> "U\"01234567890123456789\"\.\.\."
> }
> - gdb_test_sequence "x/6sw &TestStringsW" "take 6 strings forward again" {
> + gdb_test_sequence "x/6sw TestStringsW" "take 6 strings forward again" {
> "U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
> "U\"UVWXYZ\""
> "U\"\""
> @@ -271,7 +271,7 @@ with_test_prefix "char-width=4, print-max=20" {
>
> with_test_prefix "char-width=2, print-max=0" {
> gdb_test_no_output "set print elements 0"
> - gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward" {
> + gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward" {
> "u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
> "u\"\""
> "u\"\""
> @@ -289,7 +289,7 @@ with_test_prefix "char-width=2, print-max=0" {
> "u\"012345678901234567890123456789\""
> "u\"!!!!!!\""
> }
> - gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward again" {
> + gdb_test_sequence "x/6sh TestStringsH" "take 6 strings forward again" {
> "u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
> "u\"\""
> "u\"\""
> @@ -314,7 +314,7 @@ with_test_prefix "char-width=2, print-max=0" {
>
> with_test_prefix "char-width=1, print-max=4" {
> gdb_test_no_output "set print elements 4"
> - gdb_test_sequence "x/9s &TestStrings" "take 9 strings forward" {
> + gdb_test_sequence "x/9s TestStrings" "take 9 strings forward" {
> "\"ABCD\"\.\.\."
> "\"EFGH\"\.\.\."
> "\"IJKL\"\.\.\."
>
> base-commit: bdc819cd5ca6f3a3915810366155fd4c2ca61fab
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2023-11-14 10:58 [PATCH] [gdb/testsuite] Fix spurious FAILs with examine-backward.exp, again Tom de Vries
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