* [FFmpeg-devel] [PATCH] gdigrab: Fix hwnd parameter issues
@ 2023-12-18 8:54 Martin Storsjö
2023-12-18 22:05 ` James Almer
0 siblings, 1 reply; 4+ messages in thread
From: Martin Storsjö @ 2023-12-18 8:54 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Lena
Converting from an integer to HWND (which is a pointer) requires
an explicit cast, otherwise Clang errors out like this:
src/libavdevice/gdigrab.c:280:14: error: incompatible integer to pointer conversion assigning to 'HWND' (aka 'struct HWND__ *') from 'long' [-Wint-conversion]
280 | hwnd = strtol(name, &p, 0);
| ^ ~~~~~~~~~~~~~~~~~~~
(With GCC and MSVC, this was a mere warning, but with recent Clang,
this is an error.)
After adding a cast, all compilers also warn something like this:
src/libavdevice/gdigrab.c:280:16: warning: cast to 'HWND' (aka 'struct HWND__ *') from smaller integer type 'long' [-Wint-to-pointer-cast]
280 | hwnd = (HWND) strtol(name, &p, 0);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
On Windows, long types are 32 bit, so to get a usable pointer, we
need to use long long. And interpret it as unsigned long long
while at it - i.e. using strtoull.
Finally, right above it, the code triggered the following warning:
src/libavdevice/gdigrab.c:278:15: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
278 | char *p;
| ^
---
libavdevice/gdigrab.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
index 41ef370f2b..b2858ecd89 100644
--- a/libavdevice/gdigrab.c
+++ b/libavdevice/gdigrab.c
@@ -274,10 +274,10 @@ gdigrab_read_header(AVFormatContext *s1)
} else if (!strcmp(filename, "desktop")) {
hwnd = NULL;
} else if (!strncmp(filename, "hwnd=", 5)) {
- name = filename + 5;
char *p;
+ name = filename + 5;
- hwnd = strtol(name, &p, 0);
+ hwnd = (HWND) strtoull(name, &p, 0);
if (p == NULL || p == name || p[0] == '\0')
{
--
2.34.1
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [FFmpeg-devel] [PATCH] gdigrab: Fix hwnd parameter issues
2023-12-18 8:54 [FFmpeg-devel] [PATCH] gdigrab: Fix hwnd parameter issues Martin Storsjö
@ 2023-12-18 22:05 ` James Almer
2023-12-18 22:08 ` Stefano Sabatini
0 siblings, 1 reply; 4+ messages in thread
From: James Almer @ 2023-12-18 22:05 UTC (permalink / raw)
To: ffmpeg-devel
On 12/18/2023 5:54 AM, Martin Storsjö wrote:
> Converting from an integer to HWND (which is a pointer) requires
> an explicit cast, otherwise Clang errors out like this:
>
> src/libavdevice/gdigrab.c:280:14: error: incompatible integer to pointer conversion assigning to 'HWND' (aka 'struct HWND__ *') from 'long' [-Wint-conversion]
> 280 | hwnd = strtol(name, &p, 0);
> | ^ ~~~~~~~~~~~~~~~~~~~
>
> (With GCC and MSVC, this was a mere warning, but with recent Clang,
> this is an error.)
>
> After adding a cast, all compilers also warn something like this:
>
> src/libavdevice/gdigrab.c:280:16: warning: cast to 'HWND' (aka 'struct HWND__ *') from smaller integer type 'long' [-Wint-to-pointer-cast]
> 280 | hwnd = (HWND) strtol(name, &p, 0);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~
>
> On Windows, long types are 32 bit, so to get a usable pointer, we
> need to use long long. And interpret it as unsigned long long
> while at it - i.e. using strtoull.
>
> Finally, right above it, the code triggered the following warning:
>
> src/libavdevice/gdigrab.c:278:15: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
> 278 | char *p;
> | ^
> ---
> libavdevice/gdigrab.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
> index 41ef370f2b..b2858ecd89 100644
> --- a/libavdevice/gdigrab.c
> +++ b/libavdevice/gdigrab.c
> @@ -274,10 +274,10 @@ gdigrab_read_header(AVFormatContext *s1)
> } else if (!strcmp(filename, "desktop")) {
> hwnd = NULL;
> } else if (!strncmp(filename, "hwnd=", 5)) {
> - name = filename + 5;
> char *p;
> + name = filename + 5;
>
> - hwnd = strtol(name, &p, 0);
> + hwnd = (HWND) strtoull(name, &p, 0);
>
> if (p == NULL || p == name || p[0] == '\0')
> {
Should be ok.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [FFmpeg-devel] [PATCH] gdigrab: Fix hwnd parameter issues
2023-12-18 22:05 ` James Almer
@ 2023-12-18 22:08 ` Stefano Sabatini
2023-12-18 22:18 ` Martin Storsjö
0 siblings, 1 reply; 4+ messages in thread
From: Stefano Sabatini @ 2023-12-18 22:08 UTC (permalink / raw)
To: FFmpeg development discussions and patches
On date Monday 2023-12-18 19:05:17 -0300, James Almer wrote:
> On 12/18/2023 5:54 AM, Martin Storsjö wrote:
> > Converting from an integer to HWND (which is a pointer) requires
> > an explicit cast, otherwise Clang errors out like this:
> >
> > src/libavdevice/gdigrab.c:280:14: error: incompatible integer to pointer conversion assigning to 'HWND' (aka 'struct HWND__ *') from 'long' [-Wint-conversion]
> > 280 | hwnd = strtol(name, &p, 0);
> > | ^ ~~~~~~~~~~~~~~~~~~~
> >
> > (With GCC and MSVC, this was a mere warning, but with recent Clang,
> > this is an error.)
> >
> > After adding a cast, all compilers also warn something like this:
> >
> > src/libavdevice/gdigrab.c:280:16: warning: cast to 'HWND' (aka 'struct HWND__ *') from smaller integer type 'long' [-Wint-to-pointer-cast]
> > 280 | hwnd = (HWND) strtol(name, &p, 0);
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > On Windows, long types are 32 bit, so to get a usable pointer, we
> > need to use long long. And interpret it as unsigned long long
> > while at it - i.e. using strtoull.
> >
> > Finally, right above it, the code triggered the following warning:
> >
> > src/libavdevice/gdigrab.c:278:15: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
> > 278 | char *p;
> > | ^
> > ---
> > libavdevice/gdigrab.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
> > index 41ef370f2b..b2858ecd89 100644
> > --- a/libavdevice/gdigrab.c
> > +++ b/libavdevice/gdigrab.c
> > @@ -274,10 +274,10 @@ gdigrab_read_header(AVFormatContext *s1)
> > } else if (!strcmp(filename, "desktop")) {
> > hwnd = NULL;
> > } else if (!strncmp(filename, "hwnd=", 5)) {
> > - name = filename + 5;
> > char *p;
> > + name = filename + 5;
> > - hwnd = strtol(name, &p, 0);
> > + hwnd = (HWND) strtoull(name, &p, 0);
> > if (p == NULL || p == name || p[0] == '\0')
> > {
>
> Should be ok.
Also LGTM, thanks.
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [FFmpeg-devel] [PATCH] gdigrab: Fix hwnd parameter issues
2023-12-18 22:08 ` Stefano Sabatini
@ 2023-12-18 22:18 ` Martin Storsjö
0 siblings, 0 replies; 4+ messages in thread
From: Martin Storsjö @ 2023-12-18 22:18 UTC (permalink / raw)
To: FFmpeg development discussions and patches,
FFmpeg development discussions and patches
On Mon, 18 Dec 2023, Stefano Sabatini wrote:
> On date Monday 2023-12-18 19:05:17 -0300, James Almer wrote:
>> On 12/18/2023 5:54 AM, Martin Storsjö wrote:
>>> Converting from an integer to HWND (which is a pointer) requires
>>> an explicit cast, otherwise Clang errors out like this:
>>>
>>> src/libavdevice/gdigrab.c:280:14: error: incompatible integer to pointer conversion assigning to 'HWND' (aka 'struct HWND__ *') from 'long' [-Wint-conversion]
>>> 280 | hwnd = strtol(name, &p, 0);
>>> | ^ ~~~~~~~~~~~~~~~~~~~
>>>
>>> (With GCC and MSVC, this was a mere warning, but with recent Clang,
>>> this is an error.)
>>>
>>> After adding a cast, all compilers also warn something like this:
>>>
>>> src/libavdevice/gdigrab.c:280:16: warning: cast to 'HWND' (aka 'struct HWND__ *') from smaller integer type 'long' [-Wint-to-pointer-cast]
>>> 280 | hwnd = (HWND) strtol(name, &p, 0);
>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> On Windows, long types are 32 bit, so to get a usable pointer, we
>>> need to use long long. And interpret it as unsigned long long
>>> while at it - i.e. using strtoull.
>>>
>>> Finally, right above it, the code triggered the following warning:
>>>
>>> src/libavdevice/gdigrab.c:278:15: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
>>> 278 | char *p;
>>> | ^
>>> ---
>>> libavdevice/gdigrab.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavdevice/gdigrab.c b/libavdevice/gdigrab.c
>>> index 41ef370f2b..b2858ecd89 100644
>>> --- a/libavdevice/gdigrab.c
>>> +++ b/libavdevice/gdigrab.c
>>> @@ -274,10 +274,10 @@ gdigrab_read_header(AVFormatContext *s1)
>>> } else if (!strcmp(filename, "desktop")) {
>>> hwnd = NULL;
>>> } else if (!strncmp(filename, "hwnd=", 5)) {
>>> - name = filename + 5;
>>> char *p;
>>> + name = filename + 5;
>>> - hwnd = strtol(name, &p, 0);
>>> + hwnd = (HWND) strtoull(name, &p, 0);
>>> if (p == NULL || p == name || p[0] == '\0')
>>> {
>>
>> Should be ok.
>
> Also LGTM, thanks.
Pushed now, thanks!
// Martin
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2023-12-18 8:54 [FFmpeg-devel] [PATCH] gdigrab: Fix hwnd parameter issues Martin Storsjö
2023-12-18 22:05 ` James Almer
2023-12-18 22:08 ` Stefano Sabatini
2023-12-18 22:18 ` Martin Storsjö
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