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* [musl] [PATCH] dirent: implement getdents64
@ 2022-05-24  8:07 Jiaqing Zhao
  2022-05-24 12:27 ` Rich Felker
  0 siblings, 1 reply; 3+ messages in thread
From: Jiaqing Zhao @ 2022-05-24  8:07 UTC (permalink / raw)
  To: musl; +Cc: Jiaqing Zhao

In musl, getdents64 is an alias of getdents, but the type annotation
of these two functions are different according to man page[1], causing
compile errors. This patch implements the standard getdents64.
    ssize_t getdents64(int fd, void *dirp, size_t count);

[1] https://man7.org/linux/man-pages/man2/getdents.2.html

Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
---
 include/dirent.h     | 3 ++-
 src/linux/getdents.c | 6 +++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/dirent.h b/include/dirent.h
index 650ecf64..4c5367c2 100644
--- a/include/dirent.h
+++ b/include/dirent.h
@@ -11,6 +11,7 @@ extern "C" {
 #define __NEED_off_t
 #if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
 #define __NEED_size_t
+#define __NEED_ssize_t
 #endif
 
 #include <bits/alltypes.h>
@@ -50,6 +51,7 @@ long           telldir(DIR *);
 #define IFTODT(x) ((x)>>12 & 017)
 #define DTTOIF(x) ((x)<<12)
 int getdents(int, struct dirent *, size_t);
+ssize_t getdents64(int, void *, size_t);
 #endif
 
 #ifdef _GNU_SOURCE
@@ -65,7 +67,6 @@ int versionsort(const struct dirent **, const struct dirent **);
 #define versionsort64 versionsort
 #define off64_t off_t
 #define ino64_t ino_t
-#define getdents64 getdents
 #endif
 
 #ifdef __cplusplus
diff --git a/src/linux/getdents.c b/src/linux/getdents.c
index 796c1e5c..923a8076 100644
--- a/src/linux/getdents.c
+++ b/src/linux/getdents.c
@@ -9,4 +9,8 @@ int getdents(int fd, struct dirent *buf, size_t len)
 	return syscall(SYS_getdents, fd, buf, len);
 }
 
-weak_alias(getdents, getdents64);
+ssize_t getdents64(int fd, void *buf, size_t len)
+{
+	if (len>INT_MAX) len = INT_MAX;
+	return syscall(SYS_getdents64, fd, buf, len);
+}
-- 
2.34.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [musl] [PATCH] dirent: implement getdents64
  2022-05-24  8:07 [musl] [PATCH] dirent: implement getdents64 Jiaqing Zhao
@ 2022-05-24 12:27 ` Rich Felker
  2022-05-24 13:31   ` Jiaqing Zhao
  0 siblings, 1 reply; 3+ messages in thread
From: Rich Felker @ 2022-05-24 12:27 UTC (permalink / raw)
  To: Jiaqing Zhao; +Cc: musl

On Tue, May 24, 2022 at 04:07:04PM +0800, Jiaqing Zhao wrote:
> In musl, getdents64 is an alias of getdents, but the type annotation
> of these two functions are different according to man page[1], causing
> compile errors. This patch implements the standard getdents64.
>     ssize_t getdents64(int fd, void *dirp, size_t count);
> 
> [1] https://man7.org/linux/man-pages/man2/getdents.2.html
> 
> Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
> ---
>  include/dirent.h     | 3 ++-
>  src/linux/getdents.c | 6 +++++-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/include/dirent.h b/include/dirent.h
> index 650ecf64..4c5367c2 100644
> --- a/include/dirent.h
> +++ b/include/dirent.h
> @@ -11,6 +11,7 @@ extern "C" {
>  #define __NEED_off_t
>  #if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
>  #define __NEED_size_t
> +#define __NEED_ssize_t
>  #endif
>  
>  #include <bits/alltypes.h>
> @@ -50,6 +51,7 @@ long           telldir(DIR *);
>  #define IFTODT(x) ((x)>>12 & 017)
>  #define DTTOIF(x) ((x)<<12)
>  int getdents(int, struct dirent *, size_t);
> +ssize_t getdents64(int, void *, size_t);
>  #endif
>  
>  #ifdef _GNU_SOURCE
> @@ -65,7 +67,6 @@ int versionsort(const struct dirent **, const struct dirent **);
>  #define versionsort64 versionsort
>  #define off64_t off_t
>  #define ino64_t ino_t
> -#define getdents64 getdents
>  #endif
>  
>  #ifdef __cplusplus
> diff --git a/src/linux/getdents.c b/src/linux/getdents.c
> index 796c1e5c..923a8076 100644
> --- a/src/linux/getdents.c
> +++ b/src/linux/getdents.c
> @@ -9,4 +9,8 @@ int getdents(int fd, struct dirent *buf, size_t len)
>  	return syscall(SYS_getdents, fd, buf, len);
>  }
>  
> -weak_alias(getdents, getdents64);
> +ssize_t getdents64(int fd, void *buf, size_t len)
> +{
> +	if (len>INT_MAX) len = INT_MAX;
> +	return syscall(SYS_getdents64, fd, buf, len);
> +}
> -- 
> 2.34.1

The inclusion of LFS64 API stuff in musl was a historical mistake that
resulted from attempting glibc ABI-compat, not a set of interfaces we
want. What happened was that the weak aliases for glibc ABI compat
were included, then broken configure scripts that checked only for
symbol linkage but not for a working declaration "detected" these
functions as usable, producing miscompiled code from lack of
declartion. Since it was intended that musl-built programs never
reference these ABI-compat-only symbols, it was "fixed" by adding the
macros to redirect them to the correct functions, but this caused lots
of problems and we're still trying to extricate the mess. If at some
point the glibc ABI-compat stuff can be moved entirely to the external
gcompat project, the macros will be removed entirely.

As such, I think this patch is not appropriate for inclusion.

Rich

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [musl] [PATCH] dirent: implement getdents64
  2022-05-24 12:27 ` Rich Felker
@ 2022-05-24 13:31   ` Jiaqing Zhao
  0 siblings, 0 replies; 3+ messages in thread
From: Jiaqing Zhao @ 2022-05-24 13:31 UTC (permalink / raw)
  To: Rich Felker; +Cc: musl

On 2022-05-24 20:27, Rich Felker wrote:
> On Tue, May 24, 2022 at 04:07:04PM +0800, Jiaqing Zhao wrote:
>> In musl, getdents64 is an alias of getdents, but the type annotation
>> of these two functions are different according to man page[1], causing
>> compile errors. This patch implements the standard getdents64.
>>     ssize_t getdents64(int fd, void *dirp, size_t count);
>>
>> [1] https://man7.org/linux/man-pages/man2/getdents.2.html
>>
>> Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
>> ---
>>  include/dirent.h     | 3 ++-
>>  src/linux/getdents.c | 6 +++++-
>>  2 files changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/dirent.h b/include/dirent.h
>> index 650ecf64..4c5367c2 100644
>> --- a/include/dirent.h
>> +++ b/include/dirent.h
>> @@ -11,6 +11,7 @@ extern "C" {
>>  #define __NEED_off_t
>>  #if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
>>  #define __NEED_size_t
>> +#define __NEED_ssize_t
>>  #endif
>>  
>>  #include <bits/alltypes.h>
>> @@ -50,6 +51,7 @@ long           telldir(DIR *);
>>  #define IFTODT(x) ((x)>>12 & 017)
>>  #define DTTOIF(x) ((x)<<12)
>>  int getdents(int, struct dirent *, size_t);
>> +ssize_t getdents64(int, void *, size_t);
>>  #endif
>>  
>>  #ifdef _GNU_SOURCE
>> @@ -65,7 +67,6 @@ int versionsort(const struct dirent **, const struct dirent **);
>>  #define versionsort64 versionsort
>>  #define off64_t off_t
>>  #define ino64_t ino_t
>> -#define getdents64 getdents
>>  #endif
>>  
>>  #ifdef __cplusplus
>> diff --git a/src/linux/getdents.c b/src/linux/getdents.c
>> index 796c1e5c..923a8076 100644
>> --- a/src/linux/getdents.c
>> +++ b/src/linux/getdents.c
>> @@ -9,4 +9,8 @@ int getdents(int fd, struct dirent *buf, size_t len)
>>  	return syscall(SYS_getdents, fd, buf, len);
>>  }
>>  
>> -weak_alias(getdents, getdents64);
>> +ssize_t getdents64(int fd, void *buf, size_t len)
>> +{
>> +	if (len>INT_MAX) len = INT_MAX;
>> +	return syscall(SYS_getdents64, fd, buf, len);
>> +}
>> -- 
>> 2.34.1
> 
> The inclusion of LFS64 API stuff in musl was a historical mistake that
> resulted from attempting glibc ABI-compat, not a set of interfaces we
> want. What happened was that the weak aliases for glibc ABI compat
> were included, then broken configure scripts that checked only for
> symbol linkage but not for a working declaration "detected" these
> functions as usable, producing miscompiled code from lack of
> declartion. Since it was intended that musl-built programs never
> reference these ABI-compat-only symbols, it was "fixed" by adding the
> macros to redirect them to the correct functions, but this caused lots
> of problems and we're still trying to extricate the mess. If at some
> point the glibc ABI-compat stuff can be moved entirely to the external
> gcompat project, the macros will be removed entirely.
> 
> As such, I think this patch is not appropriate for inclusion.
> 
> Rich

Got your point. In other ABI-compat-symbols, the redirection works as the
function signature are the same, but getdents64 and getdents are not.
A type cast is needed to make them compatible. Modifying the macro can
help solve this difference, will this be an appropriate solution?

#define getdents64(fd, buf, len) getdents((fd), (struct dirent *)(buf), (len))

Jiaqing

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-05-24 13:33 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-05-24  8:07 [musl] [PATCH] dirent: implement getdents64 Jiaqing Zhao
2022-05-24 12:27 ` Rich Felker
2022-05-24 13:31   ` Jiaqing Zhao

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