[opkg] libopkg: pkg_hash: prefer original packages to satisfy dependencies

When one package "provides" another non-virtual package, prefer to use
the original package instead of the providing package.

Example:

Consider packages "foo" and "bar", where "foo" provides "bar".
The current code will sort all candidates by name and use the last entry
by default, so "foo" would be used to satisfy a dependency on "bar".
Change the logic to prefer the actual package "bar" in this case.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
---
 libopkg/pkg_hash.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

On Sat, Mar 13, 2021 at 02:00:40AM +0100, Matthias Schiffer wrote:
> When one package "provides" another non-virtual package, prefer to use
> the original package instead of the providing package.
> 
> Example:
> 
> Consider packages "foo" and "bar", where "foo" provides "bar".
> The current code will sort all candidates by name and use the last entry
> by default, so "foo" would be used to satisfy a dependency on "bar".
> Change the logic to prefer the actual package "bar" in this case.
> 

Reviewed-by: Daniel Golle <daniel@makrotopia.org>

> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
> ---
>  libopkg/pkg_hash.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/libopkg/pkg_hash.c b/libopkg/pkg_hash.c
> index dbed3febfbbe..a07a25ec1e0b 100644
> --- a/libopkg/pkg_hash.c
> +++ b/libopkg/pkg_hash.c
> @@ -284,6 +284,7 @@ pkg_t *pkg_hash_fetch_best_installation_candidate(abstract_pkg_t * apkg,
>  	int nmatching = 0;
>  	int wrong_arch_found = 0;
>  	int arch_priority;
> +	int good_pkg_score = 0;
>  	pkg_vec_t *matching_pkgs;
>  	abstract_pkg_vec_t *matching_apkgs;
>  	abstract_pkg_vec_t *provided_apkg_vec;
> @@ -409,9 +410,18 @@ pkg_t *pkg_hash_fetch_best_installation_candidate(abstract_pkg_t * apkg,
>  	for (i = 0; i < matching_pkgs->len; i++) {
>  		pkg_t *matching = matching_pkgs->pkgs[i];
>  		if (constraint_fcn(matching, cdata)) {
> -			opkg_msg(DEBUG, "Candidate: %s %s.\n",
> -				 matching->name, pkg_get_string(matching, PKG_VERSION));
> +			int score = 1;
> +			if (strcmp(matching->name, apkg->name) == 0)
> +				score++;

++score;

As you are not using the return value, no need for post-increment.
The compiler should be able to recognize and optmize that away by now
though, so probably it doesn't matter.

> +
> +			opkg_msg(DEBUG, "Candidate: %s %s (score %d).\n",
> +				 matching->name, pkg_get_string(matching, PKG_VERSION),
> +				 score);
> +			if (score < good_pkg_score)
> +				continue;
> +
>  			good_pkg_by_name = matching;
> +			good_pkg_score = score;
>  			/* It has been provided by hand, so it is what user want */
>  			if (matching->provided_by_hand == 1)
>  				break;
> -- 
> 2.30.2
> 
> 
> _______________________________________________
> openwrt-devel mailing list
> openwrt-devel@lists.openwrt.org
> https://lists.openwrt.org/mailman/listinfo/openwrt-devel

On 3/13/21 3:52 AM, Daniel Golle wrote:
> On Sat, Mar 13, 2021 at 02:00:40AM +0100, Matthias Schiffer wrote:
>> When one package "provides" another non-virtual package, prefer to use
>> the original package instead of the providing package.
>>
>> Example:
>>
>> Consider packages "foo" and "bar", where "foo" provides "bar".
>> The current code will sort all candidates by name and use the last entry
>> by default, so "foo" would be used to satisfy a dependency on "bar".
>> Change the logic to prefer the actual package "bar" in this case.
>>
> 
> Reviewed-by: Daniel Golle <daniel@makrotopia.org>
> 
>> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
>> ---
>>   libopkg/pkg_hash.c | 14 ++++++++++++--
>>   1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/libopkg/pkg_hash.c b/libopkg/pkg_hash.c
>> index dbed3febfbbe..a07a25ec1e0b 100644
>> --- a/libopkg/pkg_hash.c
>> +++ b/libopkg/pkg_hash.c
>> @@ -284,6 +284,7 @@ pkg_t *pkg_hash_fetch_best_installation_candidate(abstract_pkg_t * apkg,
>>   	int nmatching = 0;
>>   	int wrong_arch_found = 0;
>>   	int arch_priority;
>> +	int good_pkg_score = 0;
>>   	pkg_vec_t *matching_pkgs;
>>   	abstract_pkg_vec_t *matching_apkgs;
>>   	abstract_pkg_vec_t *provided_apkg_vec;
>> @@ -409,9 +410,18 @@ pkg_t *pkg_hash_fetch_best_installation_candidate(abstract_pkg_t * apkg,
>>   	for (i = 0; i < matching_pkgs->len; i++) {
>>   		pkg_t *matching = matching_pkgs->pkgs[i];
>>   		if (constraint_fcn(matching, cdata)) {
>> -			opkg_msg(DEBUG, "Candidate: %s %s.\n",
>> -				 matching->name, pkg_get_string(matching, PKG_VERSION));
>> +			int score = 1;
>> +			if (strcmp(matching->name, apkg->name) == 0)
>> +				score++;
> 
> ++score;
> 
> As you are not using the return value, no need for post-increment.
> The compiler should be able to recognize and optmize that away by now
> though, so probably it doesn't matter.

The difference is only meaningful in C++, where preincrement and 
postincrement may use different operator overloads. In C, I prefer the 
postincrement when I don't need the result, simply for aesthetic reasons ;)

> 
>> +
>> +			opkg_msg(DEBUG, "Candidate: %s %s (score %d).\n",
>> +				 matching->name, pkg_get_string(matching, PKG_VERSION),
>> +				 score);
>> +			if (score < good_pkg_score)
>> +				continue;
>> +
>>   			good_pkg_by_name = matching;
>> +			good_pkg_score = score;
>>   			/* It has been provided by hand, so it is what user want */
>>   			if (matching->provided_by_hand == 1)
>>   				break;
>> -- 
>> 2.30.2
>>
>>
>> _______________________________________________
>> openwrt-devel mailing list
>> openwrt-devel@lists.openwrt.org
>> https://lists.openwrt.org/mailman/listinfo/openwrt-devel