Make "info proc cmdline" show args on GNU/Linux

  Currently "info proc cmdline" on GNU/Linux does not show the full command
line, but only argument 0.  And even a warning is shown if there are more.
This was discussed in 2014 already:

  https://sourceware.org/ml/gdb-patches/2014-04/msg00212.html

Follow the advice there and avoid target_fileio_read_stralloc.  Instead,
use target_fileio_read_alloc to read the whole command line and then
replace NUL characters by spaces.  Also add an appropriate test case.
Note that gdbserver already handles this correctly.

gdb/ChangeLog:

	* linux-tdep.c (linux_info_proc): For "info proc cmdline", print
	command line args instead of emitting a warning.

gdb/testsuite/ChangeLog:

	* gdb.base/info-proc.exp: Add test for "info proc cmdline".
---
 gdb/linux-tdep.c                     | 20 ++++++++++++++++----
 gdb/testsuite/gdb.base/info-proc.exp | 13 +++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)
  

On 2018-03-21 09:15 AM, Andreas Arnez wrote:
> Currently "info proc cmdline" on GNU/Linux does not show the full command
> line, but only argument 0.  And even a warning is shown if there are more.
> This was discussed in 2014 already:
> 
>   https://sourceware.org/ml/gdb-patches/2014-04/msg00212.html
> 
> Follow the advice there and avoid target_fileio_read_stralloc.  Instead,
> use target_fileio_read_alloc to read the whole command line and then
> replace NUL characters by spaces.  Also add an appropriate test case.
> Note that gdbserver already handles this correctly.

Hi Andreas,

This LGTM with two minor nits:

> gdb/ChangeLog:
> 
> 	* linux-tdep.c (linux_info_proc): For "info proc cmdline", print
> 	command line args instead of emitting a warning.
> 
> gdb/testsuite/ChangeLog:
> 
> 	* gdb.base/info-proc.exp: Add test for "info proc cmdline".
> ---
>  gdb/linux-tdep.c                     | 20 ++++++++++++++++----
>  gdb/testsuite/gdb.base/info-proc.exp | 13 +++++++++++++
>  2 files changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
> index b4b87dd..0ac78c2 100644
> --- a/gdb/linux-tdep.c
> +++ b/gdb/linux-tdep.c
> @@ -754,10 +754,22 @@ linux_info_proc (struct gdbarch *gdbarch, const char *args,
>    if (cmdline_f)
>      {
>        xsnprintf (filename, sizeof filename, "/proc/%ld/cmdline", pid);
> -      gdb::unique_xmalloc_ptr<char> cmdline
> -	= target_fileio_read_stralloc (NULL, filename);
> -      if (cmdline)
> -	printf_filtered ("cmdline = '%s'\n", cmdline.get ());
> +      gdb_byte *buffer;
> +      ssize_t len = target_fileio_read_alloc (NULL, filename, &buffer);
> +
> +      if (len > 0)
> +	{
> +	  gdb::unique_xmalloc_ptr<char> cmdline ((char *) buffer);
> +	  ssize_t pos;
> +
> +	  for (pos = 0; pos < len - 1; pos++)
> +	    {
> +	      if (buffer[pos] == '\0')
> +		buffer[pos] = ' ';
> +	    }
> +	  buffer[len - 1] = '\0';
> +	  printf_filtered ("cmdline = '%s'\n", buffer);
> +	}
>        else
>  	warning (_("unable to open /proc file '%s'"), filename);
>      }
> diff --git a/gdb/testsuite/gdb.base/info-proc.exp b/gdb/testsuite/gdb.base/info-proc.exp
> index 72355bf..eadcb15 100644
> --- a/gdb/testsuite/gdb.base/info-proc.exp
> +++ b/gdb/testsuite/gdb.base/info-proc.exp
> @@ -38,6 +38,16 @@ gdb_test_multiple "info proc" "info proc without a process" {
>      }
>  }
>  
> +# Set command line arguments to be verified later with "info proc
> +# cmdline".  However, if we're using a stub, then "set args" would not
> +# have any effect, so then just skip this.
> +
> +set cmdline ""
> +if { ! [target_info exists use_gdb_stub] } {

The use_gdb_stub proc from lib/gdb.exp should be used instead (its comment
explains why).

> +    set cmdline "-i foo bar -o baz 1234"
> +    gdb_test_no_output "set args $cmdline" "set args"
> +}
> +
>  if { ! [ runto_main ] } then {
>      untested "could not run to main"
>      return -1
> @@ -50,6 +60,9 @@ gdb_test "info proc mapping" \
>  	"info proc mapping"
>  
>  if {[istarget "*-*-linux*"]} {
> +    if { $cmdline != "" } {
> +	gdb_test "info proc cmdline" "cmdline = \'.* $cmdline\'"

The backslashes are unnecessary.

Simon
  

On Wed, Mar 21 2018, Simon Marchi wrote:

> On 2018-03-21 09:15 AM, Andreas Arnez wrote:
>> Currently "info proc cmdline" on GNU/Linux does not show the full command
>> line, but only argument 0.  And even a warning is shown if there are more.
>> This was discussed in 2014 already:
>> 
>>   https://sourceware.org/ml/gdb-patches/2014-04/msg00212.html
>> 
>> Follow the advice there and avoid target_fileio_read_stralloc.  Instead,
>> use target_fileio_read_alloc to read the whole command line and then
>> replace NUL characters by spaces.  Also add an appropriate test case.
>> Note that gdbserver already handles this correctly.
>
> Hi Andreas,
>
> This LGTM with two minor nits:
>

[...]

>>  
>> +# Set command line arguments to be verified later with "info proc
>> +# cmdline".  However, if we're using a stub, then "set args" would not
>> +# have any effect, so then just skip this.
>> +
>> +set cmdline ""
>> +if { ! [target_info exists use_gdb_stub] } {
>
> The use_gdb_stub proc from lib/gdb.exp should be used instead (its comment
> explains why).

Ah, OK.  There are still some occurrences of "target_info exists
use_gdb_stub" in the test suite.  Should these be replaced as well?

>
>> +    set cmdline "-i foo bar -o baz 1234"
>> +    gdb_test_no_output "set args $cmdline" "set args"
>> +}
>> +
>>  if { ! [ runto_main ] } then {
>>      untested "could not run to main"
>>      return -1
>> @@ -50,6 +60,9 @@ gdb_test "info proc mapping" \
>>  	"info proc mapping"
>>  
>>  if {[istarget "*-*-linux*"]} {
>> +    if { $cmdline != "" } {
>> +	gdb_test "info proc cmdline" "cmdline = \'.* $cmdline\'"
>
> The backslashes are unnecessary.

Right.

Thanks for your review.  Pushed with these fixes.

--
Andreas
  

On 2018-03-22 05:04, Andreas Arnez wrote:
>>> 
>>> +# Set command line arguments to be verified later with "info proc
>>> +# cmdline".  However, if we're using a stub, then "set args" would 
>>> not
>>> +# have any effect, so then just skip this.
>>> +
>>> +set cmdline ""
>>> +if { ! [target_info exists use_gdb_stub] } {
>> 
>> The use_gdb_stub proc from lib/gdb.exp should be used instead (its 
>> comment
>> explains why).
> 
> Ah, OK.  There are still some occurrences of "target_info exists
> use_gdb_stub" in the test suite.  Should these be replaced as well?

Yes, they probably should.

>> 
>>> +    set cmdline "-i foo bar -o baz 1234"
>>> +    gdb_test_no_output "set args $cmdline" "set args"
>>> +}
>>> +
>>>  if { ! [ runto_main ] } then {
>>>      untested "could not run to main"
>>>      return -1
>>> @@ -50,6 +60,9 @@ gdb_test "info proc mapping" \
>>>  	"info proc mapping"
>>> 
>>>  if {[istarget "*-*-linux*"]} {
>>> +    if { $cmdline != "" } {
>>> +	gdb_test "info proc cmdline" "cmdline = \'.* $cmdline\'"
>> 
>> The backslashes are unnecessary.
> 
> Right.
> 
> Thanks for your review.  Pushed with these fixes.

Thanks!

Simon